CA1324209C - Distributed monitoring system - Google Patents

Abstract

ABSTRACT

A distributed monitoring system is disclosed which may be used for collecting television channel tuning data, household purchase data, VCR channel usage data and the like;
on site at a plurality of preselected households, wherein the system concentrates and transmits the collected data to a central site in a fault tolerant manner, transparent to the occupants of the household. The novel system features a hub and spoke architecture for effecting communications between the central site and each household (remote site). The hub and spoke architecture at each remote site comprises a hub unit, and a set of spoke meters. The hub unit is adapted to be coupled, in a variety of ways, to a set of metering devices, one or more of which is coupled to one or more television receivers and/or cable television converters. Not all of the metering devices need be coupled to the television receiver or cable converter, e.g., stand alone purchase meters and wands may be coupled to the hub. The meters may be polled systemati-cally, e.g. on a virtually continuous or periodic basis, by the hub, which then collects and concentrates the data acquired by each meter. As a result of this arrangement standard communications and data transmission "smarts" can be used at the meter level, meter storage requirements are kept to a minimum and no meter communications programming is required. Additionally, the hub can be easily reprogrammed by downloading control software from the central site without having to modify the meters.

Description

13242~9 DISTRI~UTED MONITORING SYSTEM

BACKGROUND O~ THE INVENTION

1. Field of the Invention The invention generally relates to a system for monitoring, collecting and concentratin~ data on site at a plurality of remote sites, for transmitting the data concen-trated at each site to a cent~llocation and for performing said monitoring, collecting, concentrating and transmitting functions in a manner that is transparent to persons located at a aiven re~ote site. More particularly, the invention comprises a distributed monitoring system for collecting television channel tuning data, household purchase data, VCR
channel usage data and the like on site at a plurality of preselected households, wherein the system concentrates and transmits the collected data to a central site in a fault tolerant manner, transparent to the occupants of the household.

2. Description of the Related Art The prior art is replete with various systems and arrangements for monitoring viewing habits and product purchase preferences of television viewers, sometimes referred to hereinafter as panelists. The earliest such systems merely , .. . . .

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collected data on site for eventual manual collection as to the television channels viewed and the times of viewing for various panels of viewers in order to determine market share and ratings of various television proqrams. Later, systems came into being for use with cable television systems with two way communications over the cable system between the head end thereof and various cable subscribers. In such a system the television sets are typically interrogated periodically from this central location over the cable, with the channel selection and time information being sent back to the central location and logged for statistical compilation. Such systems have also been used in the past in so-called pay television systems in which billing information is sent over the cable system to a central location from the various subscribers to the pay television system. The prior art also includes such systems in which a memory means is provided at the remote location, e.g. at the television receiver, for accumulating data as to the channel being viewed and time. The accumulated data is then periodically transmitted over conventional tele-phone lines from the remote locations to the central location, by telephone calls initiated by either the remote stations or the central location.

Systems for remotely accumulating data regarding the habits of television viewers and their qualitative reaction to material have today become important from the standpoint of market research. For example, the effectiveness of television .

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commercials can be monitored by correlating viewing of those commercials with subsequent purchase decisions made by panelists whose viewing habits are being monitored. One manner of achieving this which has been utilized in the past is to have the cooperating panelists keep a diary as to purchase of products. The purchase information recorded in these diaries is then correlated with the commercials viewed by those cooperating panelists. In an alternative arrangement disclosed in the prior art, in areas where universal product ~ code automated check-outs are available, such as grocery stores and at the check-out counter, a cooperating panelist presents a card coded with a unique scanner panelist identification similar to the universal product code symbol on the products purchased. The store's computer can automatically retain such purchase data for subsequent transfer to a market research company computer data base for correlation with the data regarding the various panelists viewing of commercials. Such arrangements of course require cooperation of stores within the area of the panelist locations, and are therefore more suited i for limited qeographic groupings of panelists in a single locale i or city, and are not readily applicable to a national assemblage of panelists extending across an entire country.

In market research relating to commercials and their effectiveness, it also is sometimes important to evaluate the effectiveness of alternative forms of a commercial. One way of achieving this in the context of a cable television system , .

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13212i3~3 is to split the subscribers or panelists into two or more groups, and then show the alternative forms of commercials to the respective groups of panelists. Correlation of product purchase information regarding those panelists with the forms of the co~mercials they viewed can then be used to a8sess the effectiveness of the various alternative forms of the commer-cial. The prior art also includes examples of systems wherein certain portions of viewing audience can be selected on a dynamic basis and furnished with substitute programming. Such a system is disclosed, for example, in U.S. Patent No. 3,639,686 to Wal~er et al. In accordance with that system, an auxillary television signal is broadcast which contains not only substi-tute programming, i.e. video signal information, but also control information such as pulse code information for remotely selecting panelists which are to receive the substitute programming. Digital address information is provided for each of the panelists, and the portion of the panelists which are to receive the substitute programming are selected by the pulse code information. The Walker et al patent notes that in selecting the panelists which are to receive the substitute programming, the number of categories available is dependent on the number of digital information bits that are incorporated in the system. A later U.S. Patent No. 4,331,974 to Cogswell et al also discloses an arrangement for selecting portions of a viewing audience on a dynamic basis and furnishing those portions with substitute proqramming.

i32~2~9 A more recent invention for data gathering with particular utility in market research type applications is described in U.S. Patent No. 4,658,290 to McKenna et al. This patent teaches a system that includes a plurality of remote units which are controlled from a central location. Each of the remote units is attached to a television receiver which is generally but not necessarily attached to a cable system. Each of the remote units can function to determine which of several TV modes is in use as well as to store TV channel selector data, data from an optical input device, and/or data input by viewers representative of the composition of the viewing audience. The data is stored for either later collection by a portable data collector, or for direct transmission to the central location by each of the remote units. A video message for a TV viewer, such as a survey, may be transmitted from the central location and stored at the remote units, for later display on the TV receiver associated with the remote units.
Substitution of alternate programming information may also be achieved by the central contlol p~int on -elected of the remote units.

The remote units described in the 4,658,290 patent are well known in the prior art and are typified by a channel meter, as described in U.S. Patent No. 4,605,958 to Machnik et al and a VCR meter asdescribed in U.S. Patent No. 4,633,302 to Damoci.

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l32'~2as In sum, a variety of television related meterin~
devices and data collection systems are well known which are placed in a household, monitor TV channel changes, accumulate time on a given channel and other information, and communicate the data gathered to a central computer using dedicated telephone lines.

As TV technology rapidly advances and data gatherin~
needs chanc~ (e.g., re cable, VCRs, active and passive people meters, single source purchase meters, etc.), meters change accordingly. Each new meter type must be separately accommo-dated at the central site, necessitating reprogramming of central site software. Additionally, each meter currently requires the built-in "smarts" needed for collection of data and transmission either to a central household collector or via the telephone lines to the central site.

It would be desirable to have a communications system that is flexible enough to support new meter types and new metering applications as they are identified.

It would also be desirable to have a communications system that is situated in such a manner as to eliminate the need for reprogramming central site software as new meter types and new metering applications come on line.

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- It would be further desirable to be able to direct a set of relatively "dumb" meters, each having limited data collection capabilities, using a single smart "hub" unit located at each remote si~e wherein the hub unit handles communication between the central site and the household via a household telephone and wherein communications between the hub and the meters may be accomplished over a variety of communication links such as hardwired, RF or carrier current links.

In effect, it would be desirable to structure a distributed system into a "hub and spoke" arrangement where the hub unit includes a sophisticated microprocessor and memory and the "spokes" are the communication links to the metersO The spoke meters could then be systematically polled and two way communication could be employed to not only permit the spoke meter to upload data,but allow the spoke meter to be remotely reprogrammed from the central site via the hub unit.

It would be further desirable if the monitoring - system, structured in the indicated desirable way, collected data in a fault tolerant manner, e.g., could recover from remote location power failures, etc., and be operated trans-parently with respect to the panelists occupying a remote site household. For example, if the system hub was utilizing the 132~12~9 telephone and a household occupant picks up the telephone to make a call, the system should be able to get off the telephone and keep track of the task it was last performing in order to pick up where it left off once the household telephone user, unaware that the system was even utilizing the phone, hangs up.

SUM~lARY OP THE INVENTION
According to the invention, a distributed monitoring system is disclosed which, in at least one of a plurality of panelist households ~remote sites), has the aforesaid desirable hub and spoke organization for communications between a central site computer, a hub unit located at the remote site, and a set of spoke meters also located at the remote site. In one embodiment of the invention, a hub unit is provided at each of a plurality of panelist locations. Ea~h hub unit is adapted to be coupled to a set of metering devices, one or more of which is coupled to one or more television receivers at each panelist location, or to one or more cable television converters in the context of a cable television system. Not all of the metering devices need be coupled to the television receiver or cable converter. For example, stand alone, special meters such as purchase meters and wands, may be coupled to the hub independent of any TV receiver or cable converter connec-tion.

In onc embodiment of the invention the coupling between the hub and spoke meters may take the form of an r~

link, a hardwired connection, a carrier current link, or . . :
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some combination of these links as desired by the system architecture. For example, a tuning meter may be coupled to the hub via an RP link while a purchase meter i8 hardwired to the hub unit.

In one embodiment of the invention the hub unit includes memory means, a clock, a backup power supply, means for interfacing with the household telephone in a manner transparent to the occupants of the household, and means for interfacing with the set of metering devices located at the remot site via any one of the previously mentioned communi-cation links.

In one embodiment of the invention the spoke meters (set of meters) may include meters for monitoring and temporarily storing information regarding which of a plurality of television modes are in use, for obtaining viewer identification data, for injecting signals into the TV receiver's video stream, etc.
hlith respect to the purchase type meters, data collection can be accomplished via means for optically scanning bar codes and the like and storing information regarding same. Such bar codes and the like can be representative of-product purchase informa-tion or panelist responses to market research surve;~s and the like.

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~ y utilizing the aforesaid hub and spoke system architecture, the spoke meters may, for example, be polled periodically or on a virtually continuous basis by the hub, which then collects and concentrates the data acquired by each meter. As a result of this arrangement standard communi-cations and data transmission "smarts" can be used at the meter level, meter storage reguirements are kept to a minimum and no meter communications programming is required. ~he hub is responsible for uploading data collected by a meter in a systematic fashion, for example, by using a preselected polling frequency. The hub also monitors meter failures and serves as the interface with the distant central site computer. The remote system can be easily reprogrammed by only downloading control software from the central site, without having to modify the meters themselves.

It is an object of the invention to provide a distributed monitoring system for monitoring, collecting and concentrating data at a plurality of remote sites, for trans-mission over telephone lines, in a manner which is flexible enough to support new meter types and new metering application without having to reprogram existing central site software.

-It is further an object of the invention to be ableto direct a set of relatively "dumb" meters, each having limited data collection capabilities, using a single smart "hub" unit located at each remote site wherein the hub unit handles communication between the central site and the house-132~2~

hold via a household telephone and wherein communicationsbetween the hub and the meters may be accomplished over a variety of communication links such as hardwired, RF or carrier current links.

It is still a further object of the invention to structure said distributed monitoring system into a "hub" and "spoke" arrangement where spoke meters are systematically polled by the hub unit, to collect and concentrate data and to employ two way communications between both the hub unit and spoke meters and hub unit and central site computer to permit the spoke meter to upload data to the hub for trans-mission to the central site and to permit the spoke meters to be remotely reprogrammed from the central site via the hub unit or to download data for display on a television set associted with a spoke meter.

It is yet another object of the invention to collect data in a fault tolerant manner and in a manner that is transparent to the occupants of a remote site household.

Other objects, advantages, and features of the present invention will become apparent to those skilled in the art from the detailed description of the invention to be set forth hereinafter, taken in conjunction with the accompanyin9 Drawing.

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Accordiny to a broad aspect of the invention there is provided a distributed monitoring system for monltoring data associated with a ~irst ~et of devices, including at least one self contained receiver, for collecting monitored data on ~ at a plurality of remote sites, and for transmitting such data from said remote sites to a central site, comprising host computer means, including means for receiving transmitted data, located at said central site, and first means, coupled to said first set of devices for monitorlng, collecting and concentrating said data on site at each of sald plurality of remote sites and for systematically transmitting said concentrated data to said host computer means, said first means including a hub means and a plurality of monitoring devices, said hub means being operative to perform said data collection, concentration and transmission functions and sald plurality of monitoring devices being operative to perform said monitoring function; said hub means being operative to carry out said collection function by systematically polling each of said plurality of monitoring devices at a respective scanning frequency selected in accordance therewith.
According to another broad aspect of the invention there is provided a method of monitoring data generated at a plurality of remote sites utilizing a distributed monitoring system that includes a host computer located at a central site, comprising the steps of utilising first means, located at said remote site, to monitor, collect, concentrate and transmit data to said host computer, and organising said first means in a hub and spoke arrangement wherein a plurality of monitoring devices of said lla ~' i'.
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first means monitors the data generated at each remote site and a second portion of said first means, also located at each remote site, serves as both an interface between sald monitoring devlces and said host computer and as a programmable means for collectlng, concentrating and transmitting the data being monltored, sald second portion of said first means systematically polling each of the plurality of monitoring devices at a respective scanning frequency selected in accordance therewith for collecting the data being monitored thereby.
Accordlng to another broad aspect of the invention there is provided a data collectlon and transmisslon unlt for collecting data from a plurality of monitoring devices monitoring television channel tuning data, household purcha~e data, VCR usage data or the like at a remote site and transmitting the collected data to a host data processing means at a central site, comprising: data collection means coupled with each of the plurality of monitoring devices for collecting data monitored thereby by systematically polling each of the plurality of monitoring devices at a respective scanning frequency selected in accordance therewith;
storage means for storing the data collected by the data collection means; and transmission means for systematically transmitting the stored data to the host data processing means.

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`` ~ 3 2 ~ 3 ~ RIEF DESCRIPTION OF THE DRAWING
FIG. 1 depicts the novel distributed monitoring system architecture, shown to include a remotely located hub unit and a representative set of spoke meters, which may be coupled to the hub unit via a variety of depicted communi-cation modules, wherein the system includes a bidirectional communications path between the depicted hub and a centralized host computer system which utilizes the public (dial up) switched telephone network over non-dedicated telephone lines.

DETAILED DESCRIPTION
FIG. 1 depicts the novel distributed monitoring system to be described in detail hereinafter.

The preferred embodiment of the invention is a modular system to facilitate easy expansion.

Conceptually, the system is one in which there are a number of different devices installed in any household. Each device has a unique set of functions to perform. The core device in the household is the "hub unit", shown in FIG. 1 as unit 101, which acts as the interface between the household and the central data collection computer system, shown in FIG. ~ as host computer Cystem 102.

Various peripheral units, examples of which are depicted in FIG. 1, are used to meter televisions, cable 132~2~

converters, product purchase data, viewer IDs, VCRs, etc. as required. Cable meter 110, TV meter 111, VCR meter 112, purchase meter 113, test set 114 and new device meter 115, are all depicted in FIG. 1 to illustrate a set of meters that could be coupled to hub 101 and to sets and VCRs located at the remote site. These peripheral units communicate with hub 101, which concentrates the generated data and forwards it to host computer 102. The flexibility and expandability of the system design is a result of the very non-specific nature of the interface between the hub and the peripheral units.
New peripheral units can be introduced at any time and old peripheral units may be remotely reprogrammed and~or retired without decommissioning the entire system. For example, add-on memory can be introduced by coupling module 116 to hub 101 as shown in FIG. 1.

Host-hub communication takes place using the house-hold telephone line. This is depicted in FIG. 1 as taking place via the hub telecommunication interface (150), a data communication link 151, the public ~dial-up) switched tele-phone network (175) and a set of telecommunications interfaces ~TCIl-TCIn) with host computer 175. This system supports two means of establishing the connection between host computer 175 and household hub 101. The primary means is dial-out in which the household hub phones the central computer. Once the connection is established, the central computer takes control of the communication session. For installation and maintenance ' 132~2~

purposes, the hub can detect ring and answer an incoming phone call ~dial-in) from the central computer. According to one embodiment of the invention this installation capabil~ty may be enabled by depressing a protected pushbutton in the hub.
Another embodiment could have these features reversed, i.e., pushbutton for dial-out or have both on programmable schedules conditional upon host down loaded data.

Communication between the hub 101 and the spoke meters is achieved, according to the preferred embodiment of the invention, via plug-in communication modules. Examples of communication links which could be supported from a set of available communication links include hardwire, AC carrier current and RF communication links.

Each peripheral is uniquely addressable by the hub.
The preferred embodiment of the invention supports a maximum ; of 126 peripherals with each hub, however a greater or lesser number of peripherals may be easily accommodated as the appli-cation dictates.

According to the preferred embodiment of the invention, the hub unit and each peripheral has a self test capability for all crucial system components. If the system is implemented in this manner, service calls at the remote site can be kept to a minimum. During any of the aforesaid communication sessions with host 175 the host computer can ~i' .
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~ recover error logs maintained for each unit in the system.
This feature will be described in greater detail hereinafter.

Also, further details regarding system fault toler-ance generally will be set forth hereinafter. For now, suffice it to say that, according to the preferred embodiment of the invention, the peripheral units should be provided with sufficient power reserve capabilities to report to the hub if AC power is lost. The hub can thus discriminate between peripherals that do not respond due to loss of power and those that do not respond due to hardware failure. This capability would permit peripherals on switched outlets to effectively report loss of AC power.

Furthermore, according to the preferred embodiment of the invention, the hub contains an accurate time-of-day clock with a resolution of .01 second and an acoumulated error of less than 1 second per day. The peripherals used in this embodiment can track elapsed time with 0.1 second accuracy. Obviously, greater or lesser resolution capabi-lities can be used as the application dictates without departing from the scope of the invention.

When peripheral units that generate time specific events (such as tuning meters and injection meters) include the 0.1 second resolution timers, polling these units causes the tenth count at the time of the event to be transmitted to -' - 132'~2~

the hub along with the current count of tenths of a second that the peripheral maintains. The hub can use the difference between successive counts of tenths of seconds, for example, as an offset from the correct local time to determine the exact time at which the event occurred and store the data accordin~ly.

~ y sending a command from the host to the hub which causes an immediate response, one can measure the time elapsed between the sending and receipt of the response. Dividing this value in half enables extremely accurate time setting of the hub.
This feature can ~e used to create a commercial monitoring peripheral device for precise measurement of commercial broadcast times.

The purchase data meter included in some configura-tions of the system should collect UPC codes, EAN codes and JAN symbols. The preferred embodiment of the invention is a system that includes a handheld symbol reader that is capable of automatically decoding UPC symbols both with and without supplemental codes. However, the invention does not require the use of such a reader, requiring only the use of well known symbol reading devices (such as a h'AND), as contemplated by the patents referred to hereinbefore, should a recording of purchases at the remote site be desired.

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- Looking st the system from a data collection point of view, data is collected from each peripheral unit and stored as separate information in the hub 101. Host computer 175 recovers each data set from hub 101 separately.

According to the preferred embodiment of the invention, television set tuning data is reported to the central site with 1 second resolution. This data includes date, time, channel tuned, CATV or off-air or auxiliary input selection. Viewer ID data is reported for each television set. This data includes household members and number of guests defined in the categories of sex and age. Purchase data is reported by ~PC code; EAN code;
JAN codeor other commonly used code types.

VCR usage data typically collected includes data, time, duration and channel of record. VCR playback includes time and duration of playback.

~ he preferred embodiment of the invention provides for a limited degree of operation in some of the peripherals after power failure. This is to enable peripheral units powered from switched outlets to report to the hub that power has been lost.

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The tuning meter/people meter used with the prefer-red embodiment includes an alphanumeric display capability of 9 lines by 20 characters which can overlap or substitute for a television picture. The tuning meter also includes volume control. System characteristics such as meter line display capability, inclusion of a volume control option, etc., are variables those skilled in the art will appreciate as possibly enhancing a particular version of the disclosed system, but are not options which expand or limit the scope of the invention.

Since hub 101 is the heart of the novel system, a detailed description of its structure and function will now be set forth. Hub 101 is the interface between the set of meters coupled to the hub and central computer system 175 of FIG. 1. As indicated hereinbefore, hub 101 continually polls all the peripheral units to monitor peripheral status and collect generated data. The peripherals are generally polled on a once per second basis, but some peripherals may be polled on a longer cycle. The cycle time can be varied dynamically to accommodate peaks in the communications traffic. Data is collected in real time and stored (concentrated) in the hub.
At a predetermined time, typically every night, the hub uses the household phone line to call the host computer 175 and off-load the collected data.

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A suitable hub unit can be based on an INTEL 80C186 microprocessor. This CMOS microprocessor is capable of addressing up to 1 MEG of memory through an on-chip memory management unit, contains three 16 bit timer counters, two independent high speed channel8, a programmable interrupt controller and a programmable wait state generator. In addition to this microprocessor, the illustrative hub unit includes:
1. EPROM memory expandable to a maximum of 128K;
2. CMOS ram expandable to a maximum of 512K;

3. a time of day clock chip, shown in FIG. 1 as clock 199, accurate to within +/- 1 second per day and a resolution of 1/100 of a second;

4. battery backup capable of maintaining the clock chip and CMOS RAM for a period of at least 1 month;

5. a lK bit EEP~OM;

6. an HDLC synchronous communications controller chip;

7. power up/down seguencing hardware for CMOS RAM
protection;

8. a stall alarm which can be jumpered out of the circuit;

9. a total of 2 connectors for the modular insertion of various communication interface modules with some units containing a built in module;

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10. a single connector for standard asynchronous communication with a diagnostic tester and development hardware (at TTL levels);

11. a Bell 212A modem board operating on switchable S and 12 volt supplies and capable of ring detection, dialing ~both pulse and DTMF), off-hook detection and call progress tone detection; and 12. a separate power supply board with +5, ~8 and ~12 volt outputs. The illustrative power supply has the aforementioned battery backup with suffi-cient capacity to insure that the hub unit has the ability to communicate with the host once per day, 2 minutes per day, for power outages of up to one month duration. The mechanism by which this power supply is actually utilized is described hereinafter in the context of abnormal system conditions.

To appreciate system operation the hub memory system, shown in FIG. 1 as memory 198, will be described, followed by a detailed description of hub/peripheral communications, hub/host communications, a detailed description of the hub power supply, suitable hub unit packaging, temperature operating range and hub responses to abnormal conditions which help achieve the system fault tolerance objective.

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The memory of the hub can be viewed as being composed of three distinct components. They are EPROM, battery backed up CMOS RAM and EEPROM. The EPROM and CMOS RAM reside within the normal address space of the microprocessor, while the EEPROM
can be accessed by the microprocessor in a bit serial fashion.
Jumpers are provided to allow the use of various capacity EPRO~I and RAM devices.

The preferred embodiment of the hub unit includes two sockets, along with appropriate jumper options, to accept most 27XX, 27XXX EPROMS. The actual EPROM used can be dictated by storage requirements. EPROM is used to dead start a program and should be located at the high end of memory as a reset goes to address FFFFD S~EX.

As is well known and appreciated by those skilled in the art, firmware can be provided within the EPRnS~ to allow the hub to power up from a "cold start" and perform internal self diagnostics as well as initial communications with central site computer 175. During such a communication session the central site can download an operating system, system configura-tion parameters and the peripheral communication drivers to the CMOS RAM of hub 101.

132~2~3 Upon a system reset or power-up, firmware resident within the EPROM can also be used to perform a sequence of diagnostic tests to not only verify the operational status of various hub components, but also the validity of programs and data resident within its CMOS RAM and EEPROM. If these tests pass, the hub simply commences normal operation. A
failure of any of the diagnostic tests, in accordance with the preferred embodiment of the invention, will result in the hub performing an out-dial, if possible, to inform the host of its failure.

The illustrative hub unit also includes a total of four sockets, along with two jumpers, to accept either 32 or 128K by 8 static RAM devices. Each of these sockets is decoded to be contiguous. In addition, each RAM is provided with battery backup power and should be controlled by power up/down sequencing hardware to insure reliable data integrity.

The CMOS RAM memory serves several distinct functions within the hub. First, it is used to store the operating system which is transmitted to RAM by the central site com-puter 175.

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Second, RAM contains the system configuration parameters and communication drivers (including survey and people meter screens) reguired by the hub for communication and control of the peripherals connected to the hub. Finally, RA~ is used to log hub and peripheral events for trans-mission to the host computer.

The lK bit EEPROM is used to store various critical system parameters. Normally this memory may only be read by the microprocessor. Writing to it is only allowed under certain specifically defined conditions to be described hereinafter.
Both reading from and writing to the EEPROM is accomplished, according to the preferred embodiment of the invention, using a bit serial format.

The critical parameters stored in EEPROM include, for example, the serial number of the hub itself, a market qroup code, the main and backup phone numbers of the host computer and the timing and pulse/DTMF information required for the dialing process for each. Separate check bytes are also desirably maintained within the EEPROM for each of these items.

- According to the preferred embodiment of the invention, data (other than the serial number of the hub) which is stored within the EEPROM may be altered by the host or tester. The serial number stored in the EEPROM may be altered only by the test set when locally connected to the hub.

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- Turning to hub/peripheral communications, it should be remembered that a main purpose of the hub is to concentrate data generated by itself and received from its peripherals and transmit this data to the host computer on a periodic basis.
To communicate with peripherals, the hub is equipped with a high level data link control ~HDLC) chip. Communications are configured in a synchronous half duplex format. In addition the hub includes two slots to accept any combination of a set of communication modules. The preferred embodiment of the invention supports RF, carrier current, and hardwire modules.

The hub is capable of determining which type of interface module ~if any) is installed in each of its communi-cation module slots. To facilitate this three connector pins have been defined which either will or will not be pulled to ground within the communication modules. This will allow expansion to up to 7 different types of modules in the illus-trative hub being described herein.

The illustrative hub is also capable of automatically selecting baud rate for communications with its peripherals as a function of module type.

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The hub unit used in the novel system functionally has the capability of individually activating the communication modules installed in it and the ability to place them in either transmit or receive mode. Various communications protocols 132 ~2i3~

can be supported with different downloadable software and communications modules. Furthermore, the hub scans each defined peripheral in the system on an adjustable time and priority basis. For example, some peripherals may be scanned at a rate of once every two seconds, others either more or less frequently with some peripherals having priority over others. The hub supports requests from peripheral drivers to alter the scan rate and priority level of the peripheral they support. With this ability, the scan rate of a peripheral may be optimi2ed for current conditions.

~ he illustrative hub supports proper error detection and communication protocols to insure error free communications between itself and its peripherals, and supports communication with up to 252 addressable peripherals. In the preferred embodiment of the invention, address 00 is reserved for use by the hub, OFFH is not allowed, OFEH is reserved for the tester and OFDH is reserved as the install address.

The communication modules of the preferred hub are modular, i.e., have the same physical dimensions and are equipped with a standard connector adhering to a defined electrical interface. Such modules are completely inter-changeable throughout the novel system. When deactivated by the hub, the modules consume a minimum amount of power and do not-in any way impair communications among any remaining modules , . . . .
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in the system. Similarly a loss of power to a module does not impede communications among any remaining modules in the system. For example, an unpowered hardwire module would not load a hardwire communication path to the extent that communication among other peripherals using hardwire modules is impaired. A suitable physical size for the modules contemplated is approximately 3.0 x 5.0 x 1.0 inches.

The hardwire module simply provides an interface to a twisted pair communication media. Data is transmitted and received at 5 volt levels. Two pairs of connect terminals are provided on the back plate of the module to allow for ease of hooking peripherals together.

The RF module simply provides an RF communication medium. A switch ~or switches) are provided on these modules so that their communication frequency is selectable. This is to insure that two adjacent installations do not have cross-talk problems. If switch selection of frequency is not desirable, then modules of different frequencies can be assigned different module type codes.

The carrier current module simply allows communica-tions over the household electrical wiring. In using these modules, consideration must be given to adjacent installation or other interference, and operation of a peripheral powered by a switched AC outlet. Four different carrier current module , .

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frequencies are supported in the preferred embodiment of the invention. Obviously, a fewer or greater number of frequencies could be supported.

Hub/host computer communications are accomplished over the public switched telephone network, using a sell 212A
compatible modem. The modem is contained within the hub (although it could be located externally) on a separate circuit board that also provides the capability ofrout-dialing in either pulse of DTMF formats, call progress tone detection and ring detection to support instances requiring in-dial.
The Bell 212A protocol supports full duplex communications.
The hub/host communications can be configured as half duplex as well. For example, one system configuration envisaged has a communication rate of 1200 baud, 1 start, a stop and 8 data bits.

Ideally, the modem is integrated on a single chip and is linked to associated controller chips. Regardless of the modem chip set used, the modem should meet the following minimum criteria:
1. a bus interface controller;
2. full sell 212A implementation;
3. call progress tone detection in hardware;
4. pulse and DTMF dialing;
5. answer and originate mode capability;
6. carrier detect capability at -43/-48 dBm, with 25 m on/off delay;

`` 132~2 ~3 7. remote digital loopback ability; and 3 8. local analog loopback ability.

Since the hub will utilize the householders phone line for communication with the host, should the householder attempt to use the line while it is being used by the hub, the hub must be able to detect the attempted usage and abort its communication with the host. It therefore must relinquish the line to the householder. To allow this detection of an extension off-hook, a circuit is provided which causes the hub modem to go off-hook and leave an unusually high voltage on the tele-phone line. ~his varies from approximately 12 to 17 volts.
When an extension goes into the off-hook state,it will drop the line to the usual 6 volts (approximately) causing a circuit to be actuated which disconnects the hub modem from the line.

~ In the event that an off-hook condition is sensed 3`~ after the hub has established communications with the host, the hub will immediately return to an on-hook condition and 1~ log the aborted communication. After its out-dial retry time 3 has passed the hub will attempt to re-establish communication with the host.

Whenever a special answer pushbutton on the hub is depressed to set an "answer arming" circuit, the hub will answer the first call received at the household within the next five minute period. During this time, the signal from ~: .

~,,.~.-. .....
., 132 ~2~

the ring detection circuit wil] be monitored and if it goes active, the hub will immediately go off-hook and attempt to establish communications with the host. It is only during periods when the "arming" circuit is set that the hub will go off-hook in response to a ring signal. It will be ignored at all other times.

On phone answer or pulse dial circuits are provided to assure that electronic phones with unusually sensitive ring detection circuitry do not chirp momently. On pulse dial, this is done by slowing the rate at which current is introduced to the line. On phone answer an extremely fast ring detect/off-hook latch is used.

The hub operating modes are described next. There are two modes of operation for communication with the central site, in-dial and out-dial. Regardless of where the call is initiated, the communications protocols between the two devices should be identical. The host computer acts as the controller, i.e., during normal communication the hub only transmits in response to a packet from the host. This rule may be broken by the hub if it determines that it must transmit an end of transmission ~EOT) packet and terminate transmission.

A point to note is that the modem operates in originate mode if it initiated the call, otherwise it operates in answer mode.

132'~2~

The out-dial sequence will be described first followed by a description of the in-dial sequence.

An out-dial sequence is initiated by the hub whenever the out-dial window opens or at the retry time following an aborted communication session. The out-dial sequence is composed of the following steps:
1. Check if the householder is currently using the phone. Abort and reschedule out-dial if in use. Log reason for abort in the hub's log;

.

2. Go off-hook and check for a dial tone.
Abort if not present, reschedule out-dial and log the abort;

3. Determine which phone number to use ~either primary or alternate) and perform the out-dial while monitoring off-hook. Abort if off-hook sensed, reschedule out-dial and log the abort;

4. Monitor call progress tones. Abort on timeout, off-hook, or busy. Reschedule out-dial and log abort;

,- ~
~' ' 132~2~) 5. Await carrier and an enquire (ENQ) packet from the host. Abort on timeout or off-hook, reschedule out-dial and log abort; and 6. Process and respond to packets received from the host while monitoring off-hook and carrier. Abort on off-hook or loss of carrier,reschedule out-dial and log the abort.

Note that any abort results in an event being loaged in the event log of the hub. A variety of different event codes can be employed so that it can be determined what caused a call to be aborted and during which portion of the out-dial or communication session it occurred. This provides valuable analysis information.

~ he time and number used by the hub when performin~
an out-dial to the host is controlled by the real-time cloc~
in conjunction with a group of variables specified by the hub which may, for example, include:
~ 1. an initial out-dial time, specified as year, month, day, hour, minute, second;
2. a primary retry interval specified in minutes and seconds. I(p);

~' ' 132~9 - 3. a secondary retry interval specified in minutes and seconds. I(s);
4. a value indicating the number of retries to be performed using the primary and secondary phone number. N~p);
5. a value indicating the number of retries to perform using the primary and backup phone number alternately. N(a).

Upon the occurrence of the out-dial time, the hub will commence out-dialing to the host either until a successful communication session has been completed or until the complete retry sequence, such as the one set forth detailed below, has been exhausted.
1. N(p) attempts at the interval specified by I(p), using the primary phone number;
2. N(p) attempts at the interval specified by I(p), using the backup phone number;
3. N(a) attempts at the interval specified by I(s), usinq the primary and backup phone numbers alternately.

Note that it is the responsibility of the host to insure that the total span of retries does not exceed 21 hours.
That is 2*(I(p)*N~p~)~(N~a)*I(s)) is less than 21 hours.

`` 132~2~3 ~`
~ pon exhaustion of the above sequence, the hub will reschedule its next out-dial time for 24 hours after the initial out-dial time.

.

- The in-dial sequence will be described next. For in-dial (a ring) the hub should only respond if its "answer arming" circuit is set. If this is the case, the hub will answer immediately upon sensing the ring. It will then simply:
1. monitor for carrier and the ENQ packet from the host. Abort on timeout or off-hook and log the abort; and 2. process and respond to packets received from the host while monitoring off-hook and carrier.
Abort if required and log the abort.

The aborting of a communication session preferably causes the "answer arming" circuit to be cleared immediately.

Communications between the hub and host are accom-plished by utilizing various defined packets of data as alluded to hereinbefore. The definitions of the packet formats and their contents can be varied to suit the application without affectin~ the scope of the invention.

.

,j. .
r : ' ' '~;'-~ , ' ' 132~2 u~3 .
Communications failures between the hub and host and the system response thereto, will now be described. The failures fall into two broad categories. Those that occur prior to the log-on of a hub to the host, and those that occur after.

Those that occur prior to a log on are: failure of the host to answer (line busy, etc.) and householder off-hook detected. In either case, the hub simply aborts its attempt, logs the failure, returns to an on-hook condition and reschedules another attempt at the retry time into the future.

Those that occur after the initial log-on, include a simple failure of communication ~i.e., noisy phone line that eventually results in a communication timeout), abrupt broken communication (sensed by loss of carrier from host), or a householder off-hook detected. In all cases, the hub will return to an on-hook condition, log the failure and reschedule another attempt at the retry time into the future.

The hub power supply will now be described. The power supply for the illustrative hub is designed to provide +5, and +12 volts and hav~ battery backup capacity to main-tain these volta~es as well as provide an AC loss signal ' 132~21~

to the microprocessor board so that it may detect both loss and restoration to the AC line and incorporate the necessary components to provide carrier current coupling to the AC line.

Al 1 power supply components, with the possible exception of the batteries required for backup power, are preferably mounted on a single circuit board. For safety and RFI reasons, the components on this board should be physically placed as to segregate those connected on the AC line from the remaining components. These components include the power supply transformer, line circuit brea~er and carrier current coupling components.

Battery backup of the two volta~es can be provided by a lead acid battery. ~he required charging circuits should also be included.

To attain voltage regulation at a desired level of accuracy and to minimize battery cost, three-terminal IC
regulators should be utilized.

A suitable power supply specification is as follows:
1. Nominal Load: 12 volts at 200 ma., and 5 volts at 450 ma., ~all of which are switchable from the time of day clock when AC power is off), and a separate unswitched +5 volt sup~ly at 10 ma. for memory and time of day clock retention ( 1 ma. typical).

-132~239 2. AC line input: 90-135 volts, 60 H~, 15 watts nominal at 115 volts, 25 watts maximum.

3. Load regulation: switched 12 volt output, +/- 1 volt, 50 ma to 200 load including ` backup;
switched 5 volt output, ~/- 200 mv. 20 ma to 500 ma load including backup;
unswitched +5 volt output, +200/-500 mv., 0.1 to 10 ma, including backup.

4. ~attery charging: automatic and regulated over a 100 to 135 volt AC input range.

i 5. Backup capability (all outputs): 6 hours minimum (for ~5 volts) at 100 ma load 1 month minimum for unswiched +5 volts at 200 microamp load.

6. ESD: sparkgap from AC line to chassis at 5000 volts nominal.

7. Carrier current: line coupling components on board.

l32~2a3 9. AC line protection: AC circuit breaker, PC
mounted, accessible reset.

As far as packaging is concerned, the illustrative hub may be packaged in a metal enclosure 14 inches wide, 6 inches deep and 3 inches high. It has rubber feet on two sides so that it can be set on either of two faces. Means are pro-vided such that it may be hung on a vertical surface.

The illustrative hub is provided with a 6 foot AC
line cord with a 3-prong electrical plug. The hub power supply is protected by a circuit breaker. The actuator of the breaker is red, located near the line cord and projects through the case.

A standard 6 conductor phone jack is provided for connection to the household phone line. The button that is actuated to arm the hub to intercept an incoming telephone call is white and located near the telephone jack.

Two LEDs are viewable on the exterior of the hub.
One LED indicates the presence of AC power and the other LED
is illuniated when the hub is armed to intercept an incoming phone call.

Obviously the use of the LEDs, colored actuator buttons, etc. are illustrative only and can be modified, eliminated or supplemented to suit the application of the hub unit.

.

`- 132~2~9 According to the illustrative embodiment of the invention, a 8tandard 4 conductor phone ~ack i9 provided for connection of the hub to test set 114 shown in FIG. 1.

The preferred embodiment of the invention includes a hub unit that will operate over the temperature range -30 degrees C to ~50 degrees C when AC power is present. Since some of the electronics within the hub may not be rated for operation below O degrees C, an internal heater has been provided to ensure that these components are not subjected to temperatures below their operations range.

The heater is not operational when AC power has failed ~in the illustrative hub). Therefore, if AC power fails and the ambient temperatures of the hub falls below O degrees C, a thermal sensor is provided to prevent the microprocessor within the hub from powering up. However, all memory and the time-of-day clock continue to be maintained under these condi-tions. When AC power is restored, the normal operation will resume after the heater has warmed the hub-electronics to O
degrees C.

To conclude the detailed description of the invention, a description of how the novel system responds to abnormal conditions, will now be set forth.

3a ~ - , 13212~

One of the tasks performed upon system reset, as well as on a routine basis by the operating system, i9 the monitoring and verification of various critical portions of the software within the hub. Verification checks are performed on the contents of the EPROM, the EEPROM contents, clock chip time, the event memory sector allocation map and portions of the operating system. In addition, the hub must handle communication failures, either with its peripheral or the host, in a logical and well defined fashion.

System memories failures will be addressed first.

As indicated previously, the systems CMOS memory is utilized for a variety of functions, the more critical of which will be monitored for validity of content on a periodic basis.
~hese areas are the sector allocation map, event logs and critical portions of the operating system itself. In addition, other memory components are part of the system memory and the critical functions present in them are monitored as well.

In particular, with respect to EPROM failure, two check codes are maintained within the systems EPROM so that its integrity can be verified. One check code is used to verify those sections of code required to support a communica-tion session with the host and the second is used to verify various utility routines resident in the EPROM. A check of the EPROM is, according to the preferred embodiment of the invention, only performed following a hardware reset.
~9 1 32 ~ 2 IJl~

If it is determined that the utility routine portion of the EPROM is no longer valid, an appropriate error flag will be set and the unit will attempt to perform an immediate out-dial to the host computer and inform the host of its conditions.
If however, it is determined that the communication support code in the EPROM is invalid, it will simply place itself in a"sleep"
mode awaiting a resurrection by human hands.

If it is determined that the operating system is no lonqer valid, the hub will simply perform a software reset. The reset will verify invalid operating system status and the hub will set the appropriate status flags and attempt to communicate with the host ~assuming the EEPROM data is still valid).

- Another key memory to monitor is a hub/peripheral configuration table. The hub/peripheral configuration table is an area of memory which contains the map to correlate the physi-cal address of devices to be polled, with their logical device types and the medium over which they are to be polled. This area of memory should be checked for validity both periodically and upon system reset. Should it be found to be invalid, the hub sets a status flag and performs a software reset. It will then initiate a out-dial to the host. Once communication is established, the host may request this table and correlate it with that stored in its data base. It will then be the responsibility of the host to download a new table. Note that polling of the peripherals should be suspended until a new table has been received from the host.

132~23 ,:~
; Eventlog failure should also be monitored. The event log of each peripheral in the preferred embodiment of the invention, has an associated block check code. This code should be routinely verified and updated during the logging process. Should it be determined that the block check code is invalid, an appropriate status flag can be set, an event logged in the log in question and a new block check code generated.
Q
3 If, after the above actions, the block check code remains valid, the hub continues routine normal operation.
it If the refreshed block check code cannot be verified, a permanent memory failure will be recorded for the hub.
log for the peripheral in question will be moved to alternate memory, a new bloc~ check generated and the condition reported.

Clock chip time failure should also be monitored.
~he time in the clock chip should be verified upon a system reset and on a second by second basis by the operating system.
If the time is found to be invalid ~out of range) the hub, in the preferred system will:
1. reset the time to a default value (JAN 1, 1987, j 00:00:00 for example);
2. log a time failure event ~utilizing the last valid time read) in event lo~s of the hub ard all peripherals that require time stamping o~
their events;

.

. ~....
;
y~

132~2~9 , .

3. set a status flag indicating the failure;
4. perform a verification of the contents of the EEPROM and if valid, begin attempts to communi-cate with the host; and 5. continue normal operation and event logging using the new time base ~at least until a new time is loaded by the host).

Upon established communications with the host, the host would determine the failure and reset the time in the cloc~ chip. After resetting the time in the clock chip, the hub would ascertain if resetting of the time was required as a result of a time failure. If this was the case, the hub would log a special event indicating this fact in all event logs of peripherals requirin~ time stamping. In this way any event logged between the time of the clock time failure and its reset will be bounded by two uniqued event codes. These codes would be detected in the event logs obtained by the host and with proper correlation the host would be able to determine the tru times of the events and thus no data loss would occur.

Finally, with respect to memory failure checks, the EEPROM should be monitored. If upon system reset or during periodic checks by the operating system it is determined that the contents of the EEPROM are invalid, the preferred hub will set a status flag indicating EEPROM failure and then simply resume normal operation with the exception. At the next occurrence of out-dial time, the action taken by the hub will 4?

,., , :

132 12 ~

be determined by what data within the EEPROM has failed. If the serial number and at least one of the phone numbers is intact, a out-dial will be performed using a valid phone number. Upon establishing communications with the host, the host would ascertain and re-load the correct data. If at out-dial it was determined that either the serial number of both phone numbers within the EEPROM were invalid, the hub would not perform a out-dial. At this point, it would be up to the central site operators to identify that the hub is failing to call in. It will then be necessary to arm the EEPROM circuit as described previously and have the host call the unit. Upon requesting status from the hub, the host will determine that the EEPROM data is invalid and will then attempt to re-establish it.
Regardless of whether or not this task was completed success-fully the host can obtain event log data if it so desires. In essence, failure of the EEPROM will not affect the operational ability of the hub with the exception of its out-dial capability.

It will be understood by those skilled in the art that the described monitoring and recovery sequences were set forth for the sake of illustration only and could be modified to suit a particular application and/or desired level of fault tolerance without departing from the scope or spirit of the invention.

In illustration of hub fault detection and recovery techniques for loss of AC power and of how the system may be globally reset will now be set forth.

` 132~2~J

- The power supply within the preferred hub contains an AC detection circuit which signals the microprocessor of 120 VAC
being lost. Upon sensing the loss, the illustrative hub scans all peripherals as rapidly as possible (i.e., normal scan rates will be ignored) to determine if the power outage is local to itself or is "global" in nature. The results of this scan are log~ed, status flags set appropriately, a "wakeup" time equal to the next out-dial time is loaded into the real time clock chip and upon completion of this, the system performs a power supply shutdown.

~ he hub can remain shutdown ~note that the CMOS RAM
and the real time clock are maintained on battery backup) until the system cupply voltage is restored either as a result of restoration of 1~0 VAC or the "wakeup" time occurring. Restora-tion of the 120 VAC shall cause an event to be logged indicating time of return.

If the system supply is restored as a result of wakeup time, the hub can make a single attempt at communicating ¦ with the host. If successful, the hub will simply inform the host of its condition and upon completion of cummunications return itself to a shutdown condition. If unsuccessful, the hub can also return itself to a shutdown state. No further wakeup time will be scheduled according to the illustrative embodiment of the invention.

132~2~

If the system supply returns as a result of restoration of 120 VAC, the hub can schedule a out-dial at the next possible out-dial time (if it has not already pagsed) and resume normal operation. If the out-dial time has passed, the hub will commence attempts to communicate with the host.
Note that appropriate logging of the above will be performed for analysis by the host.

Finally, with respect to reset, a hardware reset only occurs, according to the preferred embodiment of the invention, upon restoration of 120 VAC, manual operation of the reset pushbutton, a system stall or the occurence of the wakeup time that had been previously stored in the clock chip.
Any of these events causes the memory to be configured with the EPROM enabled. Execution begins at address zero where calls are made to the various verification routines resident in the EPROM. One of the main areas that is verified is the operating system which is reside in RAM. If it is determined that the operating system is not longer valid, the operating system will be overwritten with the contents of the EPROM, the EPROM will then be disabled and out-dial attempts will be commenced. If it is found that the operating system is intact and other verification check pass, the EPROM will be disabled, a reset event will be logged in the log of the hub and normal operation will resume. Upon resuming normal operation, a comparison will be performed between the current time and the out-dial window open and close times. If the current time precedes the out-dial window open time, no special action will be taken. If 13 2 !~ 2 tJi .J

this is not the case, the hub will begin repeated out-dials in an attempt to establish communications with the central site.

Failure of any of the verification will result in the actions being taken that are detailed hereinbefore.

With respect to software reset, it should be noted that initiation of a software reset does not result in the automatic enabling of the EPROM. As with the hardware reset, various verification checks are performed with one of the main check being the operating system itself. Should the operating system be found to be invalid, the software will enable the EPROM and jump to address 0 (in essence it performs a hardware reset). Aside from enabling the EP~OM if required, the soft-ware reset is virtually identical to the hardware reset.

Finally, with respect to system stall, the occurrence of a stall will, according to the preferred embodiment of the invention, cause a hardware reset, followed by the logging of an appropriate event in the event log. The action taken by the reset routine is as set forth hereinbefore .

.. ..

- `-- .

i32~20~

The for~going description of a preferred embodiment of the novel diQtributed monitoring system, including its novel hub and spoke architecture, has been presented for the purposes of illustration and description only. The description is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. For example, since the disclosed system supports the systematic transmission of concentrated data, whether periodic or aperiodic, between the hub to the host computer, unusual events in addition to emergency calls can be supported in alternate embodiments of the invention. Also, diverse types of self-contained receivers, including but not limited to TV broadcast receivers, may be monitored via systems that are configured in accordance with the teachings set forth herein. Still further, an alternate embodiment of the invention can support data transfer between two meters (or indeed any set of meters) via the hub.

The embodiment and examples set forth herein were presented in order to best explain the principles of the instant invention and its practical application to thereby enable other skilled in the art to best utilize the instant invention in various embodiments and applications, with various modifications as are suited to the particular use contemplated. Those skilled in the art will readily appreciate that the stated objectives of the invention have been met.

It is intended that the scope of the instant invention be defined by the claims appended hereto.

', ` , ' .
.

Claims (45)

1. A distributed monitoring system for monitoring data associated with a first set of devices, including at least one self contained receiver, for collecting monitored data on site at a plurality of remote sites, and for transmitting such data from said remote sites to a central site, comprising host computer means, including means for receiving transmitted data, located at said central site, and first means, coupled to said first set of devices for monitoring, collecting and concentrating said data on site at each of said plurality of remote sites and for systematically transmitting said concentrated data to said host computer means, said first means including a hub means and a plurality of monitoring devices, said hub means being operative to perform said data collection, concentration and transmission functions and said plurality of monitoring devices being operative to perform said monitoring function; said hub means being operative to carry out said collection function by systematically polling each of said plurality of monitoring devices at a respective scanning frequency selected in accordance therewith.

2. A system according to claim 1, including second means arranged to provide a bi-directional communications interface between said first means and said host computer means.

3. A system according to claim 2, in which said second means comprise tele-communications interface means, including a modem and a non-dedicated telephone line, at each of said remote sites for coupling said first means to said host computer means utilising the public switched telephone network.

4. A system according to claim 3, including means for utilising the non-dedicated telephone line at each of said remote sites in a manner that is transparent to any other user of the telephone line at a given remote site.

5. A system according to claim 3 or 4, in which said first means is operative to systematically perform an out dial sequence in order to establish communication over said non-dedicated telephone line with said host computer means and is further operative to be responsive to an in dial sequence initiated by said host computer means and received over said telephone line to facilitate receiving enquiries and data from said host computer means.

6. A system according to claim 1, in which said hub means includes interface module means operative to permit said hub means to be coupled to said monitoring devices via at least one type of communication link selected from a set of communication links including RF, hardwire and carrier current links.

7. A system according to claim 6, in which said hub means further comprises memory means and a micro-processor coupled to said memory means, said interface modules and said second means, for controlling the collection and concentration of data from said monitoring devices and for controlling communications with said host computer means via said second means, and a time of day clock, coupled to said micro-processor, for synchronising the operation of said micro-processor and said memory means and for time stamping events to be logged in said memory means by said micro-processor.

8. A system according to claim 7, in which at least a part of a processing control function for at least one of said monitoring devices is performed by said hub means.

9. A system according to claim 7, in which said hub means is programmable and may be reprogrammed by down loading control software from said host computer means without having to modify said monitoring devices.

10. A system according to claim 9, in which at least one of said monitoring devices is remotely programmable.

11. A system according to claim 7, including means for measuring the elapsed time between the sending to said hub means of a host computer means command and the receipt by said host computer means of a response to said command, and means for setting said time of day clock as a function of said elapsed time.

12. A system according to claim 7, in which the cycle time of said microprocessor can be varied dynamically.

13. A system according to claim 7 or claim 9, in which said memory means comprises a CMOS static RAM for storing an operating system capable of being furnished to said hub means by said host computer means via said second means.

14. A system according to claim 13, in which said CMOS
static RAM is further operative to store system configuration parameters and drivers to facilitate communications between said hub means and said monitoring devices, and is also operative to store event logs generated by said hub means and said monitoring devices for subsequent transmission to said host computer means by said hub means.

15. A system according to claim 14, including means for segmenting and allocating said CMOS static RAM.

16. A system according to claim 15, in which said memory means further comprises an EPROM for storing data which permits said hub means to perform initialisation, self diagnostics and hub/host computer means communication tasks.

17. A system according to claim 16, including means for performing memory mapping of said EPROM and said CMOS static RAM.

18. A system according to claim 7, in which said memory means further comprises an EEPROM for storing critical system parameters.

19. A system according to claim 7, including means for operating said hub means in a fault tolerant manner.

20. A system according to claim 19, in which said means for operating said hub means in a fault tolerant manner comprises an AC power loss detection circuit for signalling said micro-processor of AC power loss, and battery back-up power supply means arranged to be activated upon detection of AC power loss by said micro-processor.

21. A system according to claim 19 or 20, in which said means for operating said hub means in a fault tolerant manner comprises a heater element for maintaining circuit components of said hub means above a pre-selected temperature level.

22. A system according to claim 21, including re-set means for performing system re-initialisation.

23. A method of monitoring data generated at a plurality of remote sites utilizing a distributed monitoring system that includes a host computer located at a central site, comprising the steps of utilising first means, located at said remote site, to monitor, collect, concentrate and transmit data to said host computer, and organising said first means in a hub and spoke arrangement wherein a plurality of monitoring devices of said first means monitors the data generated at each remote site and a second portion of said first means, also located at each remote site, serves as both an interface between said monitoring devices and said host computer and as a programmable means for collecting, concentrating and transmitting the data being monitored, said second portion of said first means systematically polling each of the plurality of monitoring devices at a respective scanning frequency selected in accordance therewith for collecting the data being monitored thereby.

24. A method according to claim 23, including the step of utilising a programmable hub unit, to which said monitoring devices are coupled, to perform said interface, data collection, concentration and transmission functions of said second portion of said first means.

25. A method according to claim 24, including the step of utilising said hub unit to perform processing control functions for at least one of said monitoring devices.

26. A method according to claim 24, including the step of utilising a non-dedicated telephone line at each remote site, coupled to the public switched telephone network, to serve as a means for coupling said hub unit to said host computer.

27. A method according to claim 26, including the steps of utilising said hub unit to perform a dial out operation, whenever concentrated data is to be transmitted to said host computer, and arming said hub unit, selectively, to receive a dial in code and inputs from said host computer over said non-dedicated telephone line.

28. A method according to claim 27, in which the step of utilising a non-dedicated telephone line at a given remote location is performed in a manner that is transparent to any other user of the same non-dedicated telephone line.

29. A method according to claim 23, including the step of coupling said hub unit to said plurality of monitoring devices via a set of plug-in communications modules, which interface with a set of communications links including RF, hardwire and carrier current links.

30. A method according to any one of claims 24 to 29, including the steps of creating and maintaining an error log at said remote site, via said hub unit, capable of being recovered and analysed by said host computer.

31. A method according to any one of claims 24 to 29, including the steps of sending a command from said host computer to said hub unit, measuring the elapsed time between the sending of said command and the receipt of a response by said host computer, and setting a hub unit clock as a function of said elapsed time measurement.

32. A method according to any one of claims 24 to 29, in which the cycle time of said hub unit may be varied dynamically.

33. A method according to any one of claims 24 to 29, including the step of down loading control software from said host computer to said programmable hub unit in a manner that does not require the replacement, reconfiguration or programming of said monitoring devices coupled to said hub unit.

34. A method according to claim 33, including the step of programming a given monitoring device by down loading software from said host computer to said given monitoring device via said hub unit.

35. A method according to claim 33, including the step of storing said control software in a CMOS static RAM included in said hub unit.

36. A method according to claim 35, including the steps of storing system configuration parameters, drivers and time stamped event log data in said CMOS static RAM.

37. A method according to claim 35, including the steps of segmenting and allocating said CMOS static RAM to facilitate the storing of data sets therein that are each uniquely associated with one of said monitoring devices.

38. A method according to claim 35, including the step of storing data in an EPROM which facilitates the initialisation of said hub unit and which permits said hub unit to perform self diagnostics and initiate communication with said host computer.

39. A method according to claim 38, including the step of performing memory mapping of said EPROM and said CMOS static RAM.

40. A method according to claim 33, including the step of storing critical system parameters in an EEPROM.

41. A method according to claim 23, including the steps of providing fault tolerant means for operating the system during AC
power failures and at low temperatures, and providing means for re-setting the system at user pre-selected intervals and on the occurrence of user specified events.

42. A method according to claim 24, including the steps of heating hub unit components to permit system operation at remote site temperature levels which would otherwise be below component ratings, and providing back-up battery power for said hub unit in the event of an AC power loss.

43. A data collection and transmission unit for collecting data from a plurality of monitoring devices monitoring television channel tuning data, household purchase data, VCR usage data or the like at a remote site and transmitting the collected data to a host data processing means at a central site, comprising: data collection means coupled with each of the plurality of monitoring devices for collecting data monitored thereby by systematically polling each of the plurality of monitoring devices at a respective scanning frequency selected in accordance therewith;
storage means for storing the data collected by the data collection means; and transmission means for systematically transmitting the stored data to the host data processing means.

44. The data collection and transmission unit of claim 43, wherein the data collection means is operative to adjust the respective scanning frequency at which it polls a corresponding one of said devices in response to a request thereby.

45. The data collection and transmission unit of claim 43, wherein the data collection means includes at least one data communications module for coupling with at least one of the plurality of monitoring devices and interfacing means for releasably coupling the at least one data communications module with the data collection and transmission unit.