CA1159903A - Radio transmitter/receiver for digital and analog communications system - Google Patents
Radio transmitter/receiver for digital and analog communications systemInfo
- Publication number
- CA1159903A CA1159903A CA000361201A CA361201A CA1159903A CA 1159903 A CA1159903 A CA 1159903A CA 000361201 A CA000361201 A CA 000361201A CA 361201 A CA361201 A CA 361201A CA 1159903 A CA1159903 A CA 1159903A
- Authority
- CA
- Canada
- Prior art keywords
- analog
- signal
- digital
- control signal
- signals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/22—Demodulator circuits; Receiver circuits
- H04L27/227—Demodulator circuits; Receiver circuits using coherent demodulation
- H04L27/2275—Demodulator circuits; Receiver circuits using coherent demodulation wherein the carrier recovery circuit uses the received modulated signals
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0008—Modulated-carrier systems arrangements for allowing a transmitter or receiver to use more than one type of modulation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
- H04L27/14—Demodulator circuits; Receiver circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
- H04L27/2032—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner
- H04L27/2035—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using a single or unspecified number of carriers
Abstract
ABSTRACT
A radio apparatus comprises a receiver section for receiving both analog and digital angle-modulated carrier waves. Circuitry including a clock recovery circuit and a level decision circuit is capable of deciding which of the two types of carrier waves is being received so as to automatically switch in the appropriate demodulating circuit.
A radio apparatus comprises a receiver section for receiving both analog and digital angle-modulated carrier waves. Circuitry including a clock recovery circuit and a level decision circuit is capable of deciding which of the two types of carrier waves is being received so as to automatically switch in the appropriate demodulating circuit.
Description
~ l~9gO3 RADIO TRANSMITTER/RECEIVER
FOR DIGITAL AND ANA~LOG COMMUNIGATIONS SYSTEM
The present invention relates to a radio transmitter/receiver and, more particularly to a radio transmitter/receiver for both analog and digital angle-modulated carrier waves.
In a portable radio transmitter/receiver for business or 5 commercial use, the 60-called analog frequency modulation (FM) or analog phase modulation (PM) system, in which an audio or tone signal is caused to angle-modulate a carrier wave, have so far been used. The analog angle modulation system iB highly suitable for use in a compact form and under stringent electric field conaitions, for 10 instance in mobile radio communication. However, the analog angle modulation system has a disadvantage of being highly susceptible to tapping. Some secret communication systems have been proposed, but not yet ha~ been proposed any analog system which is compact and light, provides high speech quality and yet 15 does not allow ready tapping.
On the other hand, digital angle modulation communication system, in which analog signal is once converted into digital code and the converted digital code angle-modulates a carrier wave to be transmitted, can keep the secret communication from parties having 20 different code or conventional analog angle modulation receivers by ~ 159903 changing the sequence of digital code in accordance with a specified code, and further provides high speech quality. Well known among these digital angle modulation systems are phase shift keying (PSK) and frequency shift keying (FSK) systems. The PSK
5 modulation system is an excellent system for the transmission of a large quantity of information per unit frequency band and requiring no large signal-to-noise power ratio to reduce the error rate to a given level. The FSK modulation system, which can cause class C
amplifiers or the like to act nonlinearly because its amplitude 10 component is constant, is superior in power efficiency and can be effectively used for apparatuse6 with small battery capacities, such as mobile communication units.
The current standard of channel allocation for mobile communication on land i6 such that a party using the F3 type, for 15 example, is allocated 25 KHz per channel, and analog angle modulation transmitter-receivers are designed and operate in conformity with this standard. To promote extensive use of digital modulation system, which has the aforementioned secret communication function and excellent interference characteristi~:s 20 among other advantages, it is more desirable for effective frequency utilization to allocate a channel within a 25-KHz band. In other words, it is more advantageous to use both analog and digital modulation systems within a common ~and in such a combination as to effectively utilize the advantageous points of each.
An objective of the present invention therefore is to provide a receiver capable of receiving both analog and digital angle-modulated signals, automatically distinguishing them from each other and accordingly selecting the appropriate demodulating circuit, or an apparatus comprising this receiver and a transmitter capable of automatically selecting a modulator operating in either of the two modulation systems in accordance with the receive modulation system distinguished by the receiver.
According to one aspect of the present invention, there is provided a method of securely encoding communication, the method comprising the steps of:
(a) converting an analog signal into a digitally encoded signal, ~b~ selecting between said analog signal and digitally encoded signal for transmission in response to a control signal, (c) angle modulating a carrier wave with one of the selected analog signal and digitally encoded signal, (d) transmitting the angle-modulated carrier wave, ~e) receiving and demodulating said angle-modulated carrier wave to produce one of analog and encoded signals, (f) re-generating a clock signal responsive to the received signal of step (e), (g) generating said control signal responsive to said clock signal of step (f), (h) decoding said encoded signal of step (e) to produce an analog signal, (i) selecting either said analog signals of steps (e) and (h) in response to said control signal.
According to another aspect of the present invention, there is provided a radio apparatus comprising: receiver means for receiving both analog and digital angle-modulated carrier waves transmitted over a radio frequency;
means connected to the output of said receiver means for respectively demodu-lating said analog and digital angle-modulated carrier waves to provide first and second demodulated signals; means for regenerating a clock signal from the output of said receiver means; first switching means responsive to a control signal for selectively passing either of said first and second demodulated signals; analog-digital decision means responsive to said clock signal for generating said control signal; means for analog and digital modulating a signal to be transmitted to produce first and second modulated signals, respectively; second switching means responsive to said control signal for selectively passing either of said first and second modulated signals; and means for transmitting the output of said second switching means over a radio frequency .
According to a further aspect of the present invention, there is pro-vided a radio device having secure transmission capabilities, said device comprising means transmitting carrier waves which are angle-modulated by either of analog and digital signàls; first selecting means for selecting either of the analog and digital angle modulated carrier waves in response to a control signal; means for receiving both analog and digital angle-modulated carrier waves and demodulating them to provide a demodulated analog and digital signals, respectively; means for regenerating a clock signal from the output of said receiving means; analog-digital decision means responsive to said clock signal for generating said control signal; and second selecting means responsive to said control;signal for selecting either of said demodula-ted analog and digital signals.
Other features and advantages of the invention will be more apparent from the detailed description hereunder taken in conjunction with the accom-panying drawingsJ wherein:
FIGURE 1 is a block diagram illustrating a conventional analog FM
transmitter/receiver;
-3a-, . ~
~ 1$9903 FIG. 2 is a block diagram illustrating a transmitter/receiver which is one embodiment of the present invention; and FIG. 3 is a block diagram illustrating another embodiment of the present invention.
In FIG. 1, reference numeral 1 represents a receiver section;
FOR DIGITAL AND ANA~LOG COMMUNIGATIONS SYSTEM
The present invention relates to a radio transmitter/receiver and, more particularly to a radio transmitter/receiver for both analog and digital angle-modulated carrier waves.
In a portable radio transmitter/receiver for business or 5 commercial use, the 60-called analog frequency modulation (FM) or analog phase modulation (PM) system, in which an audio or tone signal is caused to angle-modulate a carrier wave, have so far been used. The analog angle modulation system iB highly suitable for use in a compact form and under stringent electric field conaitions, for 10 instance in mobile radio communication. However, the analog angle modulation system has a disadvantage of being highly susceptible to tapping. Some secret communication systems have been proposed, but not yet ha~ been proposed any analog system which is compact and light, provides high speech quality and yet 15 does not allow ready tapping.
On the other hand, digital angle modulation communication system, in which analog signal is once converted into digital code and the converted digital code angle-modulates a carrier wave to be transmitted, can keep the secret communication from parties having 20 different code or conventional analog angle modulation receivers by ~ 159903 changing the sequence of digital code in accordance with a specified code, and further provides high speech quality. Well known among these digital angle modulation systems are phase shift keying (PSK) and frequency shift keying (FSK) systems. The PSK
5 modulation system is an excellent system for the transmission of a large quantity of information per unit frequency band and requiring no large signal-to-noise power ratio to reduce the error rate to a given level. The FSK modulation system, which can cause class C
amplifiers or the like to act nonlinearly because its amplitude 10 component is constant, is superior in power efficiency and can be effectively used for apparatuse6 with small battery capacities, such as mobile communication units.
The current standard of channel allocation for mobile communication on land i6 such that a party using the F3 type, for 15 example, is allocated 25 KHz per channel, and analog angle modulation transmitter-receivers are designed and operate in conformity with this standard. To promote extensive use of digital modulation system, which has the aforementioned secret communication function and excellent interference characteristi~:s 20 among other advantages, it is more desirable for effective frequency utilization to allocate a channel within a 25-KHz band. In other words, it is more advantageous to use both analog and digital modulation systems within a common ~and in such a combination as to effectively utilize the advantageous points of each.
An objective of the present invention therefore is to provide a receiver capable of receiving both analog and digital angle-modulated signals, automatically distinguishing them from each other and accordingly selecting the appropriate demodulating circuit, or an apparatus comprising this receiver and a transmitter capable of automatically selecting a modulator operating in either of the two modulation systems in accordance with the receive modulation system distinguished by the receiver.
According to one aspect of the present invention, there is provided a method of securely encoding communication, the method comprising the steps of:
(a) converting an analog signal into a digitally encoded signal, ~b~ selecting between said analog signal and digitally encoded signal for transmission in response to a control signal, (c) angle modulating a carrier wave with one of the selected analog signal and digitally encoded signal, (d) transmitting the angle-modulated carrier wave, ~e) receiving and demodulating said angle-modulated carrier wave to produce one of analog and encoded signals, (f) re-generating a clock signal responsive to the received signal of step (e), (g) generating said control signal responsive to said clock signal of step (f), (h) decoding said encoded signal of step (e) to produce an analog signal, (i) selecting either said analog signals of steps (e) and (h) in response to said control signal.
According to another aspect of the present invention, there is provided a radio apparatus comprising: receiver means for receiving both analog and digital angle-modulated carrier waves transmitted over a radio frequency;
means connected to the output of said receiver means for respectively demodu-lating said analog and digital angle-modulated carrier waves to provide first and second demodulated signals; means for regenerating a clock signal from the output of said receiver means; first switching means responsive to a control signal for selectively passing either of said first and second demodulated signals; analog-digital decision means responsive to said clock signal for generating said control signal; means for analog and digital modulating a signal to be transmitted to produce first and second modulated signals, respectively; second switching means responsive to said control signal for selectively passing either of said first and second modulated signals; and means for transmitting the output of said second switching means over a radio frequency .
According to a further aspect of the present invention, there is pro-vided a radio device having secure transmission capabilities, said device comprising means transmitting carrier waves which are angle-modulated by either of analog and digital signàls; first selecting means for selecting either of the analog and digital angle modulated carrier waves in response to a control signal; means for receiving both analog and digital angle-modulated carrier waves and demodulating them to provide a demodulated analog and digital signals, respectively; means for regenerating a clock signal from the output of said receiving means; analog-digital decision means responsive to said clock signal for generating said control signal; and second selecting means responsive to said control;signal for selecting either of said demodula-ted analog and digital signals.
Other features and advantages of the invention will be more apparent from the detailed description hereunder taken in conjunction with the accom-panying drawingsJ wherein:
FIGURE 1 is a block diagram illustrating a conventional analog FM
transmitter/receiver;
-3a-, . ~
~ 1$9903 FIG. 2 is a block diagram illustrating a transmitter/receiver which is one embodiment of the present invention; and FIG. 3 is a block diagram illustrating another embodiment of the present invention.
In FIG. 1, reference numeral 1 represents a receiver section;
2, a transmitter section; and 100, a frequency converting section.
The transmitter and receiver sections are connected by way of an antenna switch 3 to an antenna 4. An FM signal received at the antenna 4, amplified by a high frequency amplifier 11, is frequency-converted by a first mixer 12; after only the wave of the desired frequency is selected by a band-pass filter 14, the selected signal is further frequency-converted by a ~econd mixer 15, band-re jtricted by a band-pass filter 17 and sufficiently amplified by an intermediate-frequency (IT) amplifier 18. Reference numerals 13 and 16 represent first and second local oscillators, respectively, whose outputs are fed to the mixers 12 and 15. An input FM signal amplified and amplitude-restricted by the IF amplifier 18 is demodulated by a frequency discriminator 19, to provide a demodulated audio ~ignal to be delivered from a speaker 23 as audible sounds through a low-pass filter 20, integrator 21 and amplifier 22.
In the transmitter section 2, audio or tone signal is provided to an F~ modulator 35 through a microphone 31, amplifier 32, differentiation circuit 33 and limiter 34, and is FM-modulated there.
The modulated signal wh~ch has passed through a frequency multiplier 36 and band-pass filter 37 is amplified by a high frequency amplifier 38 to a required transmission power level.
The integrator 21 of the receiver section 1 and the differentiation circuit 33 of the transmitter section Z constitute an emphasis circuit 5 each.
This analog FM transmitter/receiver illustrated in FIG. 1 is unable to demodulate digital FM (or angle-modulated) wave, which has various advantages, or to effectively prevent tapping.
FIG. 2 is a block diagram illustrating a preferred composition 10 of radio transmitter/receiver in accordance with the present invention, wherein reference numerals 101 and 201 respectively represent receiver and transmitter sections corresponding to the receiver section 1 and transmitter section 2 of FIG. 1. Components referred to in FIG. 2 by the same numerals as in FIG. 1 have the 15 same functions as the respectively corre6ponding ones in FIG. 1.
In the receiver section 101, input signal, after being frequency-converted and amplified in the same manner as in the frequency converting section 100 of FIG. 1, is demodulated into a baseband signal by a frequency discriminator 19. The demodulated baseband 20 signal is led into two low-pass filters 20 and 41.
Suppose now that input signal is a digital FM wave. The base-band signal, band-restricted by the low-pass filter 41, is converted into digital signal having logic level "1" or "0" by a level decision circuit 42, whose output is fed to a clock recovering circult 45.
1 1599~3 At the same tirne, the output of the level decision circuit 42 is also supplied to a wave shaping circuit 43, where it undergoes wave shaping at the timing of the regenerated clock signal from the clock recovering circuit 45. The wave-shaped signal is converted into 5 analog signal by a digital/analog (D/A) converter 44 with reference to the timing of the regenerated clock signal. The clock recovering circuit 45 can consist, for instance, of a timing recovering circuit like the one described in the paper entiled Floyd M. Gardner, "Phaselock Techniques", John Wiley & Sons, Inc., 1966, pp. 117--119.
An analog/digital (A/D) decision circuit 46, in response to the output of the clock recovering circuit 45, decides whether received signal i8 an analog or a digital FM wave. The output ~ignal of the clock recovering circuit is regular signal having logic level "1" and 15 "0" alternating in a fixed cycle when input signal is digital FM wave, while it i8 irregular signal having "1" and "0" when it is analog FM
wave. Therefore, if the output of the clock recovering circuit 45 i8 rectified by a rectifying circuit 462 after being amplified by an amplifier 461, there will arise a difference in D.C. component of 20 rectified signal depending on whether the input signal is an analog modulated wave or a digital modulated wave. This D. C. component is subjected to discrimination by a voltage comparator 463 to determine the modulation system of the input ~ignal. This structure enables the deciding circuit 46, when the input signal is a digital FM
wave, to tu~n on switches 47 and 52 and to turn off switches 48 and 53, whereas when an analog FM wave, to turn on switches 48 and 53 and to turn off switches 47 and 52.
When the input signal is a digital FM wave, since the switch 47 5 is turned on and the switch 48 is turned off then, the output of the D/A converter 44 is supplied to an amplifier 22 to be delivered from a speaker 23 as reproduced signal. On the other hand, when the input signal is an analog FM wave, demodulated analog signal obtained from the output of the frequency discriminator 19 through 10 the low-pass filter 20 and an integrator 21 is delivered from the speaker 23, after going through the switch 48 and amplified by the amplifier 22.
Reference numeral 201 in FIG. 2 represent~ a radio transmitter section, wherein components bearing the same reference 15 numerals as in the transmitter section 2 of FIG. 1 respectively have . the same functions as the corresponding ones therein. An audio or tone signal entered into a microphone 31, after passing through an amplifier 32, is supplied to an analog/digital (A/D) converter 51 to be converted into digital code. The output of the amplifier 32 is 20 also subjected to amplitude restriction by a limiter 34 after being differentiated by a differentiation circuit 33. Hereupon, the switch 52 or 53, selected by the output o. the A/D decision circuit 46 of the receiver section 101 a~ described above, is .urned on. If the switch 52 is tumed cm, the output of the A/D converter 51 is transmitted as a digital FM wave, or if the switch 53 is turned on the output of the limiter 34 is transmitted as an analog FM wave, through frequency divider 36, band-pass filter 37, amplifier 38, and an antenna 4.
- 5 As hitherto described, the present invention enables a conventional analog FM transmitter/receiver to transmit and receive digital FM wave as well by merely adding to it a digital signal decoding circuit, analog 6ignal coding circuit and A/D deci6ion circuit. In addition, the transmitter/receiver according to the 10 pre~ent invention can automatically select either of its analog and digital receiving section~, to which the tran~mitting ~ection corresponding to the receiving section can be al60 automatically selected.
Although the foregoing description merely referred to digital 15 FM wave, the pre6ent invention permits transmission/reception of PSK modulated wave too, if the equipment used has a comparatively large battery capacity. Thus, as illu6trated in FIG. 3, a PSK
modulated wave i6 demodulated by 6upplying the output of the frequency converting circuit 100 to a PSK demodulator 54. As PSK
20 demodulator 54, the pertinent con6tituent element of the invention disclo6ed in U. S. Patent No. 3, 878, 475 can be used. Clock 6ignal i6 regenerated from the output of the frequency converting circuit 100 by mean6 of a clock recovering circuit, like the one illustrated in FIG. 1 of Charles R. Hogge, Jr., "Carrier and Clock Recovery for 8PSK Synchronous Demodulation, " IEE, National C;ommunications Conference, 1977, and supplied to the PSK demodulator 54 and A/D
decision circuit 46. An analog FM wave is demodulated in the same manner as illustrated in FIG. 2. In the transmitter section 202, 5 an audio or tone signal to be tran~mitted, deriving from the output of the amplifier 32, is either turned into a PSK modulated wave by a PSK modulator 56 (see, for instance, U.S. Patent No. 4, 168, 3~7) or entered into the differentiation circuit 33 side to become an analog FM wave. This PSK modulated or analog FM wave 10 selectively passes the switch 52 or 53 and is transmitted from the antenna 4.
The switches 52 and 53 of the transmitter sections 201 and 202 of FIGS. 2 and 3 can as well be inserted into the input side of the A/D converter 51 or PSK demodulator 56 and that of the differentia-15 tion circuit 33, respectively. It can also be readily inferred that,although the receiver section 101 or 102 and transmitter section 201 or 202 are integrated in these embodiments, the receiver section 101 or 102 can be isolated from the transmitter section 201 or 202 and used exclusively for the reception purpose as required.
The transmitter and receiver sections are connected by way of an antenna switch 3 to an antenna 4. An FM signal received at the antenna 4, amplified by a high frequency amplifier 11, is frequency-converted by a first mixer 12; after only the wave of the desired frequency is selected by a band-pass filter 14, the selected signal is further frequency-converted by a ~econd mixer 15, band-re jtricted by a band-pass filter 17 and sufficiently amplified by an intermediate-frequency (IT) amplifier 18. Reference numerals 13 and 16 represent first and second local oscillators, respectively, whose outputs are fed to the mixers 12 and 15. An input FM signal amplified and amplitude-restricted by the IF amplifier 18 is demodulated by a frequency discriminator 19, to provide a demodulated audio ~ignal to be delivered from a speaker 23 as audible sounds through a low-pass filter 20, integrator 21 and amplifier 22.
In the transmitter section 2, audio or tone signal is provided to an F~ modulator 35 through a microphone 31, amplifier 32, differentiation circuit 33 and limiter 34, and is FM-modulated there.
The modulated signal wh~ch has passed through a frequency multiplier 36 and band-pass filter 37 is amplified by a high frequency amplifier 38 to a required transmission power level.
The integrator 21 of the receiver section 1 and the differentiation circuit 33 of the transmitter section Z constitute an emphasis circuit 5 each.
This analog FM transmitter/receiver illustrated in FIG. 1 is unable to demodulate digital FM (or angle-modulated) wave, which has various advantages, or to effectively prevent tapping.
FIG. 2 is a block diagram illustrating a preferred composition 10 of radio transmitter/receiver in accordance with the present invention, wherein reference numerals 101 and 201 respectively represent receiver and transmitter sections corresponding to the receiver section 1 and transmitter section 2 of FIG. 1. Components referred to in FIG. 2 by the same numerals as in FIG. 1 have the 15 same functions as the respectively corre6ponding ones in FIG. 1.
In the receiver section 101, input signal, after being frequency-converted and amplified in the same manner as in the frequency converting section 100 of FIG. 1, is demodulated into a baseband signal by a frequency discriminator 19. The demodulated baseband 20 signal is led into two low-pass filters 20 and 41.
Suppose now that input signal is a digital FM wave. The base-band signal, band-restricted by the low-pass filter 41, is converted into digital signal having logic level "1" or "0" by a level decision circuit 42, whose output is fed to a clock recovering circult 45.
1 1599~3 At the same tirne, the output of the level decision circuit 42 is also supplied to a wave shaping circuit 43, where it undergoes wave shaping at the timing of the regenerated clock signal from the clock recovering circuit 45. The wave-shaped signal is converted into 5 analog signal by a digital/analog (D/A) converter 44 with reference to the timing of the regenerated clock signal. The clock recovering circuit 45 can consist, for instance, of a timing recovering circuit like the one described in the paper entiled Floyd M. Gardner, "Phaselock Techniques", John Wiley & Sons, Inc., 1966, pp. 117--119.
An analog/digital (A/D) decision circuit 46, in response to the output of the clock recovering circuit 45, decides whether received signal i8 an analog or a digital FM wave. The output ~ignal of the clock recovering circuit is regular signal having logic level "1" and 15 "0" alternating in a fixed cycle when input signal is digital FM wave, while it i8 irregular signal having "1" and "0" when it is analog FM
wave. Therefore, if the output of the clock recovering circuit 45 i8 rectified by a rectifying circuit 462 after being amplified by an amplifier 461, there will arise a difference in D.C. component of 20 rectified signal depending on whether the input signal is an analog modulated wave or a digital modulated wave. This D. C. component is subjected to discrimination by a voltage comparator 463 to determine the modulation system of the input ~ignal. This structure enables the deciding circuit 46, when the input signal is a digital FM
wave, to tu~n on switches 47 and 52 and to turn off switches 48 and 53, whereas when an analog FM wave, to turn on switches 48 and 53 and to turn off switches 47 and 52.
When the input signal is a digital FM wave, since the switch 47 5 is turned on and the switch 48 is turned off then, the output of the D/A converter 44 is supplied to an amplifier 22 to be delivered from a speaker 23 as reproduced signal. On the other hand, when the input signal is an analog FM wave, demodulated analog signal obtained from the output of the frequency discriminator 19 through 10 the low-pass filter 20 and an integrator 21 is delivered from the speaker 23, after going through the switch 48 and amplified by the amplifier 22.
Reference numeral 201 in FIG. 2 represent~ a radio transmitter section, wherein components bearing the same reference 15 numerals as in the transmitter section 2 of FIG. 1 respectively have . the same functions as the corresponding ones therein. An audio or tone signal entered into a microphone 31, after passing through an amplifier 32, is supplied to an analog/digital (A/D) converter 51 to be converted into digital code. The output of the amplifier 32 is 20 also subjected to amplitude restriction by a limiter 34 after being differentiated by a differentiation circuit 33. Hereupon, the switch 52 or 53, selected by the output o. the A/D decision circuit 46 of the receiver section 101 a~ described above, is .urned on. If the switch 52 is tumed cm, the output of the A/D converter 51 is transmitted as a digital FM wave, or if the switch 53 is turned on the output of the limiter 34 is transmitted as an analog FM wave, through frequency divider 36, band-pass filter 37, amplifier 38, and an antenna 4.
- 5 As hitherto described, the present invention enables a conventional analog FM transmitter/receiver to transmit and receive digital FM wave as well by merely adding to it a digital signal decoding circuit, analog 6ignal coding circuit and A/D deci6ion circuit. In addition, the transmitter/receiver according to the 10 pre~ent invention can automatically select either of its analog and digital receiving section~, to which the tran~mitting ~ection corresponding to the receiving section can be al60 automatically selected.
Although the foregoing description merely referred to digital 15 FM wave, the pre6ent invention permits transmission/reception of PSK modulated wave too, if the equipment used has a comparatively large battery capacity. Thus, as illu6trated in FIG. 3, a PSK
modulated wave i6 demodulated by 6upplying the output of the frequency converting circuit 100 to a PSK demodulator 54. As PSK
20 demodulator 54, the pertinent con6tituent element of the invention disclo6ed in U. S. Patent No. 3, 878, 475 can be used. Clock 6ignal i6 regenerated from the output of the frequency converting circuit 100 by mean6 of a clock recovering circuit, like the one illustrated in FIG. 1 of Charles R. Hogge, Jr., "Carrier and Clock Recovery for 8PSK Synchronous Demodulation, " IEE, National C;ommunications Conference, 1977, and supplied to the PSK demodulator 54 and A/D
decision circuit 46. An analog FM wave is demodulated in the same manner as illustrated in FIG. 2. In the transmitter section 202, 5 an audio or tone signal to be tran~mitted, deriving from the output of the amplifier 32, is either turned into a PSK modulated wave by a PSK modulator 56 (see, for instance, U.S. Patent No. 4, 168, 3~7) or entered into the differentiation circuit 33 side to become an analog FM wave. This PSK modulated or analog FM wave 10 selectively passes the switch 52 or 53 and is transmitted from the antenna 4.
The switches 52 and 53 of the transmitter sections 201 and 202 of FIGS. 2 and 3 can as well be inserted into the input side of the A/D converter 51 or PSK demodulator 56 and that of the differentia-15 tion circuit 33, respectively. It can also be readily inferred that,although the receiver section 101 or 102 and transmitter section 201 or 202 are integrated in these embodiments, the receiver section 101 or 102 can be isolated from the transmitter section 201 or 202 and used exclusively for the reception purpose as required.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A radio apparatus comprising: receiver means for receiving both analog and digital angle-modulated carrier waves transmitted over a radio frequency;
means connected to the output of said receiver means for respectively demodu-lating said analog and digital angle-modulated carrier waves to provide first and second demodulated signals; means for regenerating a clock signal from the output of said receiver means; first switching means responsive to a control signal for selectively passing either of said first and second demodu-lated signals; analog-digital decision means responsive to said clock signal for generating said control signal; means for analog and digital modulating a signal to be transmitted to produce first and second modulated signals, respectively; second switching means responsive to said control signal for selectively passing either of said first and second modulated signals; and means for transmitting the output of said second switching means over a radio frequency.
means connected to the output of said receiver means for respectively demodu-lating said analog and digital angle-modulated carrier waves to provide first and second demodulated signals; means for regenerating a clock signal from the output of said receiver means; first switching means responsive to a control signal for selectively passing either of said first and second demodu-lated signals; analog-digital decision means responsive to said clock signal for generating said control signal; means for analog and digital modulating a signal to be transmitted to produce first and second modulated signals, respectively; second switching means responsive to said control signal for selectively passing either of said first and second modulated signals; and means for transmitting the output of said second switching means over a radio frequency.
2. A radio device having secure transmission capabilities, said device comprising means transmitting carrier waves which are angle-modulated by either of analog and digital signals; first selecting means for selecting either of the analog and digital angle modulated carrier waves in response to a control signal; means for receiving both analog and digital angle-modulated carrier waves and demodulating them to provide a demodulated analog and digi-tal signals, respectively; means for regenerating a clock signal from the out-put of said receiving means; analog-digital decision means responsive to said clock signal for generating said control signal; and second selecting means responsive to said control signal for selecting either of said demodu-lated analog and digital signals.
3. A radio apparatus, as claimed in claim 1 or 2, wherein said analog-digital decision means comprises an amplifier for amplifying said clock signal, a rectifying circuit for rectifying the output of said amplifier, and a voltage comparator for comparing the output voltage of said rectifying circuit with a reference voltage to provide said control signal.
4. A method of securely encoding communication, the method comprising the steps of: (a) converting an analog signal into a digitally encoded signal, (b) selecting between said analog signal and digitally encoded signal for transmission in response to a control signal, (c) angle modulating a carrier wave with one of the selected analog signal and digitally encoded signal, (d) transmitting the angle-modulated carrier wave, (e) receiving and demodula-ting said angle-modulated carrier wave to produce one of analog and encoded signals, (f) regenerating a clock signal responsive to the received signal of step (e), (g) generating said control signal responsive to said clock signal of step (f), (h) decoding said encoded signal of step (e) to produce an analog signal, (i) selecting either said analog signals of steps (e) and (h) in response to said control signal.
5. A method, as claimed in claim 4, wherein said transmission of step (d) is in the 25 kHz band.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP124951/1979 | 1979-09-28 | ||
| JP12495179A JPS5648732A (en) | 1979-09-28 | 1979-09-28 | Radio equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1159903A true CA1159903A (en) | 1984-01-03 |
Family
ID=14898241
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000361201A Expired CA1159903A (en) | 1979-09-28 | 1980-09-29 | Radio transmitter/receiver for digital and analog communications system |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4355401A (en) |
| JP (1) | JPS5648732A (en) |
| AU (1) | AU531747B2 (en) |
| CA (1) | CA1159903A (en) |
| GB (1) | GB2062993B (en) |
Families Citing this family (68)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5222076A (en) * | 1981-04-15 | 1993-06-22 | Ng William K Y | Data communication apparatus and method with low power standby mode |
| US4796026A (en) * | 1982-02-16 | 1989-01-03 | Western Atlas International, Inc. | Noise tool and method |
| US4608699A (en) * | 1982-12-27 | 1986-08-26 | Motorola, Inc. | Simulcast transmission system |
| JPS60501086A (en) * | 1983-04-11 | 1985-07-11 | アメリカン テレフオン アンド テレグラフ カムパニ− | Simultaneous transmission of voice and data over analog channels |
| US4512013A (en) * | 1983-04-11 | 1985-04-16 | At&T Bell Laboratories | Simultaneous transmission of speech and data over an analog channel |
| US4523311A (en) * | 1983-04-11 | 1985-06-11 | At&T Bell Laboratories | Simultaneous transmission of speech and data over an analog channel |
| DE3481887D1 (en) * | 1983-09-29 | 1990-05-10 | Nippon Telegraph & Telephone | RADIO RECEIVING SYSTEM FOR A PHASE-MODULATED SIGNAL. |
| DE3482363D1 (en) * | 1983-09-30 | 1990-06-28 | Nippon Telegraph & Telephone | RADIO TRANSMITTER SYSTEM FOR A PHASE-MODULATED SIGNAL. |
| JPS627226A (en) * | 1985-07-04 | 1987-01-14 | Nec Corp | System for switching common standby line |
| US5345473A (en) * | 1987-01-22 | 1994-09-06 | Outokumpu Oy | Apparatus for providing two-way communication in underground facilities |
| US4928100A (en) * | 1987-10-20 | 1990-05-22 | Telefind Corporation | Paging receiver for receiving pages from analog or digital paging transmitters |
| US5257401A (en) * | 1989-04-17 | 1993-10-26 | Telefonaktiebolaget L M Ericsson | Method of maintaining an established connection in a mobile radio system comprising both analog and digital radio channels |
| US5163159A (en) * | 1990-07-30 | 1992-11-10 | Motorola, Inc. | Dual mode automatic frequency control |
| WO1992003892A1 (en) * | 1990-08-24 | 1992-03-05 | Motorola, Inc. | Dual mode automatic gain control |
| US5187809A (en) * | 1990-08-24 | 1993-02-16 | Motorola, Inc. | Dual mode automatic gain control |
| US5450442A (en) * | 1990-11-02 | 1995-09-12 | Kabushiki Kaisha Toshiba | Digital radio telephone apparatus having an equalizer selectively employed in the apparatus |
| FI89848C (en) * | 1991-09-25 | 1993-11-25 | Nokia Mobile Phones Ltd | Generation of the transmission signal in a mobile phone |
| JP2970226B2 (en) * | 1992-05-20 | 1999-11-02 | 日本電気株式会社 | Digital receiver circuit |
| US5867537A (en) * | 1992-10-27 | 1999-02-02 | Ericsson Inc. | Balanced tranversal I,Q filters for quadrature modulators |
| US5745523A (en) * | 1992-10-27 | 1998-04-28 | Ericsson Inc. | Multi-mode signal processing |
| US5727023A (en) * | 1992-10-27 | 1998-03-10 | Ericsson Inc. | Apparatus for and method of speech digitizing |
| US5530722A (en) * | 1992-10-27 | 1996-06-25 | Ericsson Ge Mobile Communications Inc. | Quadrature modulator with integrated distributed RC filters |
| US5479480A (en) * | 1993-12-30 | 1995-12-26 | At&T Corp. | Dual mode cellular modem |
| US6381250B1 (en) | 1998-01-23 | 2002-04-30 | Innovative Communications Technologies, Inc. | Capacity allocation system using semi-autonomous network elements to implement and control a transmission schedule |
| US6426959B1 (en) | 1998-01-20 | 2002-07-30 | Innovative Communications Technologies, Inc. | System and method for facilitating component management in a multiple vendor satellite communications network |
| AU749128B2 (en) * | 1998-04-14 | 2002-06-20 | Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. | Dual-mode receiver for receiving satellite and terrestrial signals in a digital broadcast system |
| US6694128B1 (en) | 1998-08-18 | 2004-02-17 | Parkervision, Inc. | Frequency synthesizer using universal frequency translation technology |
| US7515896B1 (en) | 1998-10-21 | 2009-04-07 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
| US6061551A (en) | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals |
| US6091940A (en) | 1998-10-21 | 2000-07-18 | Parkervision, Inc. | Method and system for frequency up-conversion |
| JP2972740B1 (en) * | 1998-09-01 | 1999-11-08 | 静岡日本電気株式会社 | Four-level FSK receiver and signal determination method thereof |
| US7295826B1 (en) | 1998-10-21 | 2007-11-13 | Parkervision, Inc. | Integrated frequency translation and selectivity with gain control functionality, and applications thereof |
| US7027786B1 (en) | 1998-10-21 | 2006-04-11 | Parkervision, Inc. | Carrier and clock recovery using universal frequency translation |
| US7039372B1 (en) | 1998-10-21 | 2006-05-02 | Parkervision, Inc. | Method and system for frequency up-conversion with modulation embodiments |
| US6061555A (en) | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
| US6542722B1 (en) | 1998-10-21 | 2003-04-01 | Parkervision, Inc. | Method and system for frequency up-conversion with variety of transmitter configurations |
| US6370371B1 (en) | 1998-10-21 | 2002-04-09 | Parkervision, Inc. | Applications of universal frequency translation |
| US6560301B1 (en) | 1998-10-21 | 2003-05-06 | Parkervision, Inc. | Integrated frequency translation and selectivity with a variety of filter embodiments |
| US6813485B2 (en) | 1998-10-21 | 2004-11-02 | Parkervision, Inc. | Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same |
| US7236754B2 (en) | 1999-08-23 | 2007-06-26 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US6049706A (en) * | 1998-10-21 | 2000-04-11 | Parkervision, Inc. | Integrated frequency translation and selectivity |
| US7006805B1 (en) | 1999-01-22 | 2006-02-28 | Parker Vision, Inc. | Aliasing communication system with multi-mode and multi-band functionality and embodiments thereof, such as the family radio service |
| US6704549B1 (en) | 1999-03-03 | 2004-03-09 | Parkvision, Inc. | Multi-mode, multi-band communication system |
| US6704558B1 (en) | 1999-01-22 | 2004-03-09 | Parkervision, Inc. | Image-reject down-converter and embodiments thereof, such as the family radio service |
| US6853690B1 (en) | 1999-04-16 | 2005-02-08 | Parkervision, Inc. | Method, system and apparatus for balanced frequency up-conversion of a baseband signal and 4-phase receiver and transceiver embodiments |
| US6879817B1 (en) | 1999-04-16 | 2005-04-12 | Parkervision, Inc. | DC offset, re-radiation, and I/Q solutions using universal frequency translation technology |
| US6873836B1 (en) | 1999-03-03 | 2005-03-29 | Parkervision, Inc. | Universal platform module and methods and apparatuses relating thereto enabled by universal frequency translation technology |
| US7110435B1 (en) | 1999-03-15 | 2006-09-19 | Parkervision, Inc. | Spread spectrum applications of universal frequency translation |
| US7065162B1 (en) | 1999-04-16 | 2006-06-20 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same |
| US7693230B2 (en) | 1999-04-16 | 2010-04-06 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
| US7110444B1 (en) | 1999-08-04 | 2006-09-19 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments and circuit implementations |
| US8295406B1 (en) | 1999-08-04 | 2012-10-23 | Parkervision, Inc. | Universal platform module for a plurality of communication protocols |
| US7072390B1 (en) | 1999-08-04 | 2006-07-04 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments |
| US7054296B1 (en) | 1999-08-04 | 2006-05-30 | Parkervision, Inc. | Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation |
| US7082171B1 (en) | 1999-11-24 | 2006-07-25 | Parkervision, Inc. | Phase shifting applications of universal frequency translation |
| US6963734B2 (en) | 1999-12-22 | 2005-11-08 | Parkervision, Inc. | Differential frequency down-conversion using techniques of universal frequency translation technology |
| US7292835B2 (en) | 2000-01-28 | 2007-11-06 | Parkervision, Inc. | Wireless and wired cable modem applications of universal frequency translation technology |
| US7010286B2 (en) | 2000-04-14 | 2006-03-07 | Parkervision, Inc. | Apparatus, system, and method for down-converting and up-converting electromagnetic signals |
| US7010559B2 (en) | 2000-11-14 | 2006-03-07 | Parkervision, Inc. | Method and apparatus for a parallel correlator and applications thereof |
| US7454453B2 (en) | 2000-11-14 | 2008-11-18 | Parkervision, Inc. | Methods, systems, and computer program products for parallel correlation and applications thereof |
| US7072427B2 (en) | 2001-11-09 | 2006-07-04 | Parkervision, Inc. | Method and apparatus for reducing DC offsets in a communication system |
| US7085335B2 (en) | 2001-11-09 | 2006-08-01 | Parkervision, Inc. | Method and apparatus for reducing DC offsets in a communication system |
| US6975848B2 (en) | 2002-06-04 | 2005-12-13 | Parkervision, Inc. | Method and apparatus for DC offset removal in a radio frequency communication channel |
| US7321640B2 (en) | 2002-06-07 | 2008-01-22 | Parkervision, Inc. | Active polyphase inverter filter for quadrature signal generation |
| US7379883B2 (en) | 2002-07-18 | 2008-05-27 | Parkervision, Inc. | Networking methods and systems |
| US7460584B2 (en) | 2002-07-18 | 2008-12-02 | Parkervision, Inc. | Networking methods and systems |
| KR20060056095A (en) * | 2004-11-19 | 2006-05-24 | 지씨티 세미컨덕터 인코포레이티드 | An integrated wireless receiver and a wireless receiving method thereof |
| US11381430B2 (en) * | 2020-03-19 | 2022-07-05 | Cypress Semiconductor Corporation | Phase/frequency tracking transceiver |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3939431A (en) * | 1974-11-25 | 1976-02-17 | Motorola, Inc. | Muting circuit for a radio receiver |
| US4167700A (en) * | 1977-05-02 | 1979-09-11 | Motorola, Inc. | Digital voice protection system and method |
-
1979
- 1979-09-28 JP JP12495179A patent/JPS5648732A/en active Granted
-
1980
- 1980-09-26 US US06/191,154 patent/US4355401A/en not_active Expired - Lifetime
- 1980-09-29 AU AU62799/80A patent/AU531747B2/en not_active Expired
- 1980-09-29 CA CA000361201A patent/CA1159903A/en not_active Expired
- 1980-09-29 GB GB8031371A patent/GB2062993B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU531747B2 (en) | 1983-09-01 |
| JPS5648732A (en) | 1981-05-02 |
| AU6279980A (en) | 1981-10-01 |
| JPS6211826B2 (en) | 1987-03-14 |
| US4355401A (en) | 1982-10-19 |
| GB2062993A (en) | 1981-05-28 |
| GB2062993B (en) | 1983-10-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1159903A (en) | Radio transmitter/receiver for digital and analog communications system | |
| EP0574273B1 (en) | A receiver compriser a combined AM-FM demodulator | |
| US4955083A (en) | Dual mode radio transceiver for an SSB communication system | |
| US4541118A (en) | SSB System with pilot coded squelch | |
| US4817192A (en) | Dual-mode AFC circuit for an SSB radio transceiver | |
| US4852086A (en) | SSB communication system with FM data capability | |
| CA2303553A1 (en) | A system and method for mitigating intermittent interruptions in an audio radio broadcast system | |
| EP0046682B1 (en) | Single channel duplex communication system | |
| CA1204188A (en) | Privacy signal transmission system | |
| JP2501713B2 (en) | Receiver for signal distribution system | |
| AU632707B2 (en) | Dual mode automatic gain control | |
| WO1988003342A1 (en) | Ssb communiction system with fm data capability | |
| JPH06276158A (en) | Optical space transmitting device | |
| US5878084A (en) | Method and apparatus for recovering the independent bit streams from each of two co-channel frequency modulated carriers | |
| JP3306177B2 (en) | Digital frequency modulation cordless telephone | |
| JP3009025U (en) | Transmitter | |
| KR100285756B1 (en) | Apparatus for tracking carrier in wireless transfer system | |
| JP2702912B2 (en) | Transmission signal transmission method and apparatus | |
| JP2723510B2 (en) | Wireless telephone equipment | |
| JPS59186452A (en) | Demodulator for continuous phase fsk signal | |
| JPS59167166A (en) | Service channel modulating system | |
| WO2000057553A1 (en) | System and method for communicating band limited complex waveform having information encoded thereon through angle modulation | |
| JPH07105940B2 (en) | Transmission signal reproducing method and transmission signal reproducing apparatus | |
| JPWO2003067840A1 (en) | Wireless information communication apparatus and method | |
| JPH02123857A (en) | Fm multiplex broadcast reception circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |