WO1990010340A1

WO1990010340A1 - Booster system for hand-held radiotelephone

Info

Publication number: WO1990010340A1
Application number: PCT/CA1990/000059
Authority: WO
Inventors: Paul L. Camwell; Arunas G. Slekys
Original assignee: Novatel Communications Ltd.
Priority date: 1989-02-22
Filing date: 1990-02-21
Publication date: 1990-09-07
Also published as: CA2010536A1; AU5176390A

Abstract

In an improved system for boosting the performance of a hand-held radiotelephone using a separate booster unit, direct connection between the transmitter and receiver sections of the hand-held unit and the transmitter and receiver amplifiers of the booster unit respectively.

Description

03 " "

BOOSTER SYSTEM FOR HAND-HELD RADIOTELEPHONE

FIELD OF THE INVENTION

This invention is generally related to the field of radiotelephones. The invention provides an improved means of using a relatively low-power hand-held radiotelephone in a higher-power mobile context by connecting the transmitter and receiver sections of the hand-held radio¬ telephone directly to amplifiers within a "booster" unit, using a new cable structure for connection.

BACKGROUND OF THE INVENTION Radiotelephones, that is, radios operating in a duplex, "listen while you speak," mode, have become popular in recent years. This is particularly true in the context of cellular telephone systems. In a cellular telephone system, a "mobile" radiotelephone unit having no fixed location communicates with a fixed, "base" radiotelephone station that is located in and acts as a communications "hub" for a particular and exclusive geographic region known as a "cell." Once communication is established between a given mobile unit and base station and the mobile unit is moved into another cell, communications with the unit is "passed off" from the first base station to the base station for the second cell. Typically the base station is linked to a conven¬ tional local telephone trunk so that the mobile user can communicate with a conventional "wire line" telephone user from his mobile site.

While the cellular telephone concept has been implemented for air and sea use also, its most popular use has been in the automotive context. Hand-held cellular telephones, providing telephone service without the geographic restriction of an ordinary telephone line and jack, have also become popular. Because of their size, however, hand-held cellular telephones have been limited in power, so that their performance may be degraded when they are used in locations which are relatively remote or which include obstacles to radio transmission or reception. Mobile units installed in vehicles (or in fixed locations where wire line service is uneconomical) typically operate at considerably higher power levels than hand-held units.

Because much of the value of a cellular telephone unit is in its microprocessor and signal processing components, it is economical for users of hand-held units to adapt those units for vehicular or fixed location use by using a power "booster" unit and an external antenna, both installed in an automobile, for example. It is now common to disengage the antenna of a hand-held unit and attach its duplexed input/output terminal to a booster unit using a cable, such as a coaxial cable, suitable for radio fre¬ quency transmission. (The cable is typically housed within a single tube with other wires, which may supply power or control signals, all wound in a spiral fashion for a portion of their length to facilitate extension and retraction and commonly known as a "coil cord.¹¹) Duplexing is typically accomplished using an antenna coupler known as a "duplexer," which connects the antenna to the transmitter and receiver sections of the radiotelephone (collectively known as a "transceiver") , but isolates the transmitter section from the receiver section and vice versa through selective filtering.

At the conventional booster unit, the cable (or its extension after a connector) connects to another duplexer which in turn directs transmitted signals to an amplifer to boost their power. The duplexer also directs received signals, which may also be pre-filtered and/or boosted, through the same cable to the hand-held unit. The conventional booster unit has a third duplexer for directing the boosted transmit signal to an external antenna and for directing the signals received on that antenna to a filter/booster for received signals.

Summary of the Invention

In summary, the invention provides a more economical means for connecting a hand-held radiotelephone unit to a booster unit by eliminating the need for one of the three duplexers used in the conventional booster system. This is accomplished by connecting the output of the transmitter section of the hand-held unit directly to the booster unit transmitter amplifier and by separately connecting the output of the booster unit received signal filter/booster directly to receiver section of the hand¬ held unit, bypassing the duplexer in the hand-held unit and eliminating the need for a duplexer at the booster unit terminus of the connecting cable.

The invention thus has the advantage of saving the cost of a relatively expensive duplexer at the relatively smaller cost of an additional coaxial cable. This second coaxial cable may be combined conveniently with the first cable and other wires in a coil cord arrangement.

Brief Description of the Drawings In order that the invention may be more clearly understood, reference is made to the accompanying drawings which show the preferred embodiment and details of its operation:

Fig. 1 depicts a hand-held radiotelephone in its hand-held mode;

Fig. 2 depicts a conventional booster system for the use of a hand-held radiotelephone;

Fig. 3 depicts the improved booster system for the use of a hand-held radiotelephone;

Fig. 4 depicts the improved booster system where the hand-held unit uses a two antenna system; and

Fig. 5 depicts a coil cord usable in the improved booster system. Detailed Description of an Illustrative Embodiment Fig. 1 shows the portions of a hand-held radio¬ telephone 101 relevant to the invention. A duplexer 104 connects the transmitter section 102 (shown fragmentarily, as the final amplifier) and receiver section 103 (also shown fragmentarily, as a preamplifier) 101 to an antenna 105.

Fig. 2 shows the "prior art," a conventional booster system with the hand-held unit 201, the connecting cable 207 (shown in a coil cord configuration) and the booster unit 208. The antenna 205 is disengaged in this embodiment by a switch 206, which may be activated physic¬ ally by a connecting jack for the connecting cable 207. In the booster mode, switch 206 closes a circuit which connects the antenna input/output terminal of duplexer 204 in the hand-held unit 201 with the input/output terminal of duplexer 209 of booster unit 208 via a connecting cable 207. Cable 207 thereby connects to duplexer 209 which in turn directs transmitter signals to a transmitter amplifer

210. Duplexer 209 also directs filtered or boosted received signals from a receiver filter/booster 211 to cable 207. A duplexer 212 directs the boosted transmit signal to an external antenna 213 and directs the signals received on the antenna 213 to the receiver filter/booster

211. Thus, there are three duplexers 204, 209, and 212. Duplexers, which generally consist of band pass filters allowing selective passage of frequency bands on the appropriate legs, are among the more expensive components of a typical radiotelephone.

Fig. 3 shows the improved booster system, in which the hand-held unit 301 is connected to the booster unit 308 by means of two cables 307' and 307", which may be included within a coil cord structure 307 along with other wires carrying power and control information. Duplexer 304 and antenna 305 are disconnected by switch 306, which may be activated physically or electronically (using, for example, information on other wires included in the coil cord structure). Cable 307' connects the output of transmitter section 302 (again shown fragmentarily) directly and in simplex fashion (unidirectional flow) to transmitter amplifier 310 in booster unit 308, with the possible intervention of cable connectors (not shown) and possibly tapping into the transmitter section 302 at an earlier stage than the final drivers (not shown separately) .

Similarly, cable 307" connects the output of receiver filter/booster 311 in booster unit 308 directly and in simplex fashion to receiver section 303 (again shown fragmentarily) of the hand-held unit 301, again with the possible intervention of cable connectors (again not shown) . Although it is not shown in the figures, the . receiver filter/booster 311 may be omitted, in which case the cable 305 will connect receiver section 303 in the hand-held unit 301 directly to duplexer 312 in booster unit 308. As in the prior art booster 208 in Fig. 2, duplexer 312 directs the boosted signal for transmission to external antenna 313 and directs the signals received on the antenna 313 to the receiver filter/booster 311 or directly to receiver section 303 in the hand-held unit 301.

Thus, only one duplexer 312 is used in the embodiment of the invention shown in Fig. 3. The transmitter signal path is isolated from the receiver signal path, both paths being simplex, except at antenna 313 and the antenna output of duplexer 312. The hand-held unit duplexer 304 corresponding to duplexer 204 in Fig. 2 is bypassed, and there is no need for a duplexer corresponding to duplexer 209 in the prior art booster unit 208 in Fig. 2.

Fig. 4 shows an alternative embodiment of the improved booster system, where hand-held unit 401 has an antenna system with separate antennas 405 and 405', with filters 404 and 404', respectively for the transmit and receive functions. Switch 406, activated physically or electronically (possibly using information on the other wires in the coil cord structure) disengages the antenna system 404, 404', 405, 405', and engages booster unit 408. In all other respects, the description in the preceding three paragraphs of the operation of the embodiment shown in Fig. 3 applies mutatis mutandis to Fig. 4.

Fig. 5 shows a coil cord 507 that may be used in the improved booster system. Coaxial cables 507' and 507" are used to directly connect the transmitter section 302 or 402 with the booster transmitter amplifier 310 or 410 and the receiver section 303 or 403 with the booster receiver filter/booster 311 or 411 respectively in Figs. 3 and 4. Additional wires 514 may be used for power supply or control purposes, which may include the disengagement of the hand-held unit antenna 305 or 405 and 405" and the engagement of the booster unit 308 or 408.

The above are illustrative embodiments of the invention. As already recited- there may be variations in the means of physical connection, engaging and disengaging the hand-held unit antenna, and engaging and disengaging the booster unit. In fact, the invention, although embodied here in a hand-held unit, may be useful for boosting the performance of other relatively low-powered transceivers.

Having described this invention, what is claimed as new and secured by Letters Patent are:

Claims

1. A booster system for a relatively low-powered radiotelephone unit comprising:

A. radiotelephone transceiver unit including a transmitter section and a receiver section;

B. a booster unit in a housing separate from the transceiver unit and including a transmitter amplifier connected to provide an output to an antenna system and means for receiving signals from the antenna system;

C. a cable, suitable for transmitting radio frequency signals, directly connecting the transmitter section of the transceiver unit to the transmitter amplifier of the booster unit and electrically isolated from the receiver section of the transceiver unit; and

D. a second cable, suitable for transmitting radio frequency signals,^" directly connecting the receiver section of the transceiver unit to the signal receiving means of the booster unit and electrically isolated from the transmitter section of the transceiver unit.

2. The booster system of Claim 1 wherein the antenna system is duplexed.

3. The booster system of Claim 1 wherein the receiving means of the booster unit includes a filter/booster. -

4. The booster system of Claim 3 wherein the antenna system is duplexed.

5. The booster system of Claim 1 wherein the cables are housed in a tube formed in a spiral along at least part of their length.

6. The booster system of Claim 3 wherein the cables are housed in a tube formed in a spiral along at least part of their length.

7. The booster system of Claim 4 wherein the cables are housed in a tube formed in a spiral along at least part of their length.