CA1198778A - Radio transmitter/receivers - Google Patents
Radio transmitter/receiversInfo
- Publication number
- CA1198778A CA1198778A CA000423659A CA423659A CA1198778A CA 1198778 A CA1198778 A CA 1198778A CA 000423659 A CA000423659 A CA 000423659A CA 423659 A CA423659 A CA 423659A CA 1198778 A CA1198778 A CA 1198778A
- Authority
- CA
- Canada
- Prior art keywords
- frequency
- receiver
- transmitter
- radio
- local oscillator
- 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
- 230000005540 biological transmission Effects 0.000 claims description 17
- 230000010355 oscillation Effects 0.000 abstract description 10
- 230000005855 radiation Effects 0.000 description 6
- 230000001702 transmitter Effects 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B15/00—Suppression or limitation of noise or interference
- H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
- H04B15/04—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
- H04B15/06—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder by local oscillators of receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/26—Circuits for superheterodyne receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/50—Circuits using different frequencies for the two directions of communication
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/403—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency
- H04B1/408—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency the transmitter oscillator frequency being identical to the receiver local oscillator frequency
Abstract
Abstract of the Disclosure In a radio transmitter/receiver comprising a transmitter, a superheterodyne receiver, and a local oscillator for supplying a local oscillation signal to the superheterodyne receiver, the intermediate frequency fif of the superheterodyne receiver is set to have a value expressed by fif = (2K - 1) x fch/2 where fch represents a frequency spacing between radio frequencies assigned to a communication and K represents a natural number.
Description
/, '/ ~ ,4 '7'~ t'~
Specification Title of the Invention Radio Transmitter/Receivers Background of the Invention This invention relates tv a radio transmitter/
receiver in which unwanted radiation from a local oscillator does not act as an interferring wave.
In recent years, as th~ number of mobile radio transmitter/receivers increases, interference is increasingly caused by unwanted radiations from the radio transmitter/receiver~ Particularly, the interference due to unwanted radiations from the loc~l oscillator of a transmitter/receiver raises a serious problem because once h~e ~c power is supplied to the radio transmitter~receiver, interferr~ng wave is constantly ra~iated~ For exam~le~.in a multi-channel type radio transmitter/receiver in which one channel is used as a control channel and the other channels are used as talking channels, when the control channel is interferred with unwanted radiation of the radio transmitter/receiver of its own system or other system, the performance of the system will be adversely affectedO Especially, when the inter~erence is caused by a moving radio transmitter/receiver, it is difficult to find out a source of interference.
Heretofore, in the receivers operating at VHF and UHF bands, intermediate frequencies which are integer '7~7~
multiples of a frequency spacincJ of 20 l~llz or 25 K~lz of radio channels of 10.7 Mllz, 2:L.~ M~ 5 M~lz and 70 M~lz have been used. The frequencies of the radio channels have also been integer mult:iples of the frequency spacing.
Accordingly, the frequencies of the local oscillators have been integer multiples of the frequency spacings so tha-t when local oscilla-tion waves are radiated from a local oscillator, another radio device would be interferred.
Summary of the Invention ~ccordingly, it is an object of this invention to provide an improved radio transmitter/receiver capable of preventing interference to other radio devices caused by unwanted radiation from a local oscillator of the radio transmitter~receiver.
~ nother object of this invention is to provide a novel radio transmitter/receiver capable of readily determining a transmission frequency.
Still another object of this invention is to provide a radio transmitter/receiver of the mul-ti-channel type in which it is not necessary to provide any transmission oscillator.
The basic principle of this invention lies in that the intermediate frequency is made to be an odd multiple of one half a channel frequency spacing. Then, the local oscillation frequency also becomes an odd multiple of half the frequency spacing which does not coincide with the radio . .
kh/~,c c., ~, '7~
channel frequency, thereby minimizing the interference.
According to this invention, there is provided a radio transmi-tter/receiver comprising a transmitter, a superheterodyne receiver, and a local oscillator ~or supplying the transmi-tter and receiver with local signals at a pluralit~ of frequencies; the transmitter and receiver operating on a plurality of radio channels with differen-t transmission and reception frequencies for each ch~nnel, the transmission and reception frequencies being a natural number multiple of the fre~uency spacing between the radio channels and the output Erequencies of the local oscillator being between the transmission frequencies of two adjacent channels; mixing means in the receiver for mixing an output from the local oscillator with a reception frequency to provide an intermediate frequency fi~ wherein the inte-mediate frequency fif of the superheterodyne receiver is set to have a Y if (2K - 1) x ~ch/2 where f h represents a frequency spacing between radio frequencies assigned to adjacent channels, and K represents a natural number.
~0 According to one embodiment, in a raclio transmitter/
receiver in which the transmission frequency o-i the transmitter and the receiving frequency of the superheteroclyne receiver differ from each other, the local oscillator is constituted by a diyital frequency synthesizer and the output of the local oscillator is supplied to the transmitter.
Brief Description of the Drawing Fig. 1 is a block diagram showing a preferred embodiment of this invention;
kh/)~
3'7'~
Fig. 2 is a graph showing an at-tenuation/frequency characteristic of -the embodiment shown in Fig. 1; and Fig. 3 is a yraph showing a frequenc~ spec-trum oE the embodiment shown in Fig. 1.
.~
3a -i'''?
kh/)~-'7~
Description of -the Pre~erred Embodiment ~ pre~erred ~mbodirnent of this invention shown in Fig. 1 comprises a receiver 1, a local oscillator 2 utilizing a digital frequency synthesizer, and a transmitter 3.
~ xadio wave rece:ived by an antenna 10 is sent to a mixer 12 through an antenna duplexer 11. The lnixer 12 mixes together the local oscillation wave of the local oscillator 2 and the received wave to form an intermediate frequency signal. Unwanted signals in the intermediate .'0 frequency signal are removed by an intermediate frequency filter 13 and then the intermediate si~nal is amplified by an intermediate frequency amplifier 14 and demodulated by a demodulator 15. The demodulated signal is amplified by a lo-~ frequency amplifier 16 and then supplied to a loudspeaker 17 to produce a voice output. Thus, the receiver
Specification Title of the Invention Radio Transmitter/Receivers Background of the Invention This invention relates tv a radio transmitter/
receiver in which unwanted radiation from a local oscillator does not act as an interferring wave.
In recent years, as th~ number of mobile radio transmitter/receivers increases, interference is increasingly caused by unwanted radiations from the radio transmitter/receiver~ Particularly, the interference due to unwanted radiations from the loc~l oscillator of a transmitter/receiver raises a serious problem because once h~e ~c power is supplied to the radio transmitter~receiver, interferr~ng wave is constantly ra~iated~ For exam~le~.in a multi-channel type radio transmitter/receiver in which one channel is used as a control channel and the other channels are used as talking channels, when the control channel is interferred with unwanted radiation of the radio transmitter/receiver of its own system or other system, the performance of the system will be adversely affectedO Especially, when the inter~erence is caused by a moving radio transmitter/receiver, it is difficult to find out a source of interference.
Heretofore, in the receivers operating at VHF and UHF bands, intermediate frequencies which are integer '7~7~
multiples of a frequency spacincJ of 20 l~llz or 25 K~lz of radio channels of 10.7 Mllz, 2:L.~ M~ 5 M~lz and 70 M~lz have been used. The frequencies of the radio channels have also been integer mult:iples of the frequency spacing.
Accordingly, the frequencies of the local oscillators have been integer multiples of the frequency spacings so tha-t when local oscilla-tion waves are radiated from a local oscillator, another radio device would be interferred.
Summary of the Invention ~ccordingly, it is an object of this invention to provide an improved radio transmitter/receiver capable of preventing interference to other radio devices caused by unwanted radiation from a local oscillator of the radio transmitter~receiver.
~ nother object of this invention is to provide a novel radio transmitter/receiver capable of readily determining a transmission frequency.
Still another object of this invention is to provide a radio transmitter/receiver of the mul-ti-channel type in which it is not necessary to provide any transmission oscillator.
The basic principle of this invention lies in that the intermediate frequency is made to be an odd multiple of one half a channel frequency spacing. Then, the local oscillation frequency also becomes an odd multiple of half the frequency spacing which does not coincide with the radio . .
kh/~,c c., ~, '7~
channel frequency, thereby minimizing the interference.
According to this invention, there is provided a radio transmi-tter/receiver comprising a transmitter, a superheterodyne receiver, and a local oscillator ~or supplying the transmi-tter and receiver with local signals at a pluralit~ of frequencies; the transmitter and receiver operating on a plurality of radio channels with differen-t transmission and reception frequencies for each ch~nnel, the transmission and reception frequencies being a natural number multiple of the fre~uency spacing between the radio channels and the output Erequencies of the local oscillator being between the transmission frequencies of two adjacent channels; mixing means in the receiver for mixing an output from the local oscillator with a reception frequency to provide an intermediate frequency fi~ wherein the inte-mediate frequency fif of the superheterodyne receiver is set to have a Y if (2K - 1) x ~ch/2 where f h represents a frequency spacing between radio frequencies assigned to adjacent channels, and K represents a natural number.
~0 According to one embodiment, in a raclio transmitter/
receiver in which the transmission frequency o-i the transmitter and the receiving frequency of the superheteroclyne receiver differ from each other, the local oscillator is constituted by a diyital frequency synthesizer and the output of the local oscillator is supplied to the transmitter.
Brief Description of the Drawing Fig. 1 is a block diagram showing a preferred embodiment of this invention;
kh/)~
3'7'~
Fig. 2 is a graph showing an at-tenuation/frequency characteristic of -the embodiment shown in Fig. 1; and Fig. 3 is a yraph showing a frequenc~ spec-trum oE the embodiment shown in Fig. 1.
.~
3a -i'''?
kh/)~-'7~
Description of -the Pre~erred Embodiment ~ pre~erred ~mbodirnent of this invention shown in Fig. 1 comprises a receiver 1, a local oscillator 2 utilizing a digital frequency synthesizer, and a transmitter 3.
~ xadio wave rece:ived by an antenna 10 is sent to a mixer 12 through an antenna duplexer 11. The lnixer 12 mixes together the local oscillation wave of the local oscillator 2 and the received wave to form an intermediate frequency signal. Unwanted signals in the intermediate .'0 frequency signal are removed by an intermediate frequency filter 13 and then the intermediate si~nal is amplified by an intermediate frequency amplifier 14 and demodulated by a demodulator 15. The demodulated signal is amplified by a lo-~ frequency amplifier 16 and then supplied to a loudspeaker 17 to produce a voice output. Thus, the receiver
2 is of a well known superheterodyne type.
The local oscillator 2 is constituted by a digital frequency synthesi~er as shown in Fig. 1. In the local oscillator, the output of a voltage controlled oscillator (VCo) 21 is frequency divided by a variable frequency divider 22 whose outpu-t is supplied to a phase comparator 23 to be compared wi-th the output frequency of a reference oscillator 24, and the phase error is applied -to the voltage controlled oscillator 21 through a loop filter 25.
In the transmit-ter 3, a voice signal produced by -- 4 ~
,--kh/~
a microphone 33 is amplified by a ]ow frequenc~ amplifier 32 and then supplied -to the volt:acJe controlled oscilla-tor 21 to effect frequency modula-tion. The output of the voltage controlled oscilla-tor 21, that is, the ou-tput of the local oscilla-tor 2 is amplified to a predetermined power level by a power amplifier 31 whose output is radiated through antenna 10 via the antenna duplexer 11.
With the above construction, according to the present invention, the intermediate frequency fif of the superheterodyne receiver is se-t to be an odd multiple of half the frequency spacing fch between channel frequencies, and it is expressed by~
if (2K - 1) x fCh/2 where K represents a natural number.
The local oscillator 2 in the form of the digital freqency synthesizer is advantageous because the digital frequency synthesizer is easy to change frequency division so tha-t the in-termediate frequency which is an odd multiple of half the frequency spacing in the receiving mode can , 10 readily be switched to the transmitting frequency which is an even multiple of half the frequency spacing in the transmission mode, or vice versa.
For example, let us assume that the transmission frequency is 450 MHz, the receiving frequency is 460 MHz and the frequency spacing between adjacent channels is 25 KHz.
Thus the next lower channel frequency is 450 MHz - 24KHz =
~49,975 MHz. Assume also that the intermediate frequency is selected to be 10.0125 MHz, an odd multiple of a frequency of 25/2 X~lz.
kh/)~
~9~'7'~
Where the lower ].ocal oscillation frequency i.s assumed with respect to the received frequenc~y, the local osci.llation frequency fL becornes: fL = fR ~ Fif or fL = 460 - 10.0125 = 449.9875 MHz Whe.re the output frequency of the reference oscillator 24 is equal to 12.5 ICHz, the frequency divi.sion ratio N of the variable frequency divider 22 that is needed for this value of fL is N = 449.9875/0.9125 = 35999 at the time of receiving, while at the time of transmission (fT = 450 MHz) it becomes N = 450/0.0125 = 3~000 In other words, when the frequency division ratio N is 36000, the output of the local oscillator 2 becomes 450 MHz, which is a transmission frequency that is amplified by power amplifier 31.
Thus, according to this invention, the local oscillation frequency fL becomes fL = 449.9875 MHz which is different by 12.5 KHz from (i.e. half way between) the closest radio channel frequencies. 449.975 MHz and 450 MHz of the assumed example.
Fig. 2 shows an attenuation/frequency characteristic of the receiver 1 in which fR designates a receiving frequency, and f'R and f"R show radio channel frequencies. The ordinate shows atenuation in decibel (dB). At frequencies f'R and f"R, attenuations are sufficiently large, whereas when the receiving frequency shif-ts by one half the Erequency spacingr ,~
.~
kh/J~-attenuation of abo~ 70 ds can oxdinarily ~e obtained.
This amount of attenuation is common in communication receivers opera-ting in VIIF band and UIIF
band. Eor this reason, even when an interfering wave having a frequency different from the receiviny frequency by one half of -the frequency spacing is present, it causes no trouble. More particularly, the unwanted local oscillation frequency radiated from a radio transmitter/receiver of this invention does not coincide with the radio channel frequencies, and when it is radiated, it can be sufficiently attenuated by an intermediate frequency filter or the like of the receiver.
Fig. 3 shows the relation among radio channel frequencies fl to f4 and the local oscillation frequency fL
of this invention. As shown, the local oscillation frequency fL is positioned hàlf way between radio channel frequencies f2 and f3.
As described above, according to this invention, since the local oscillation frequency is positioned between two adjacent radio channel frequencies, interference which would be caused by unwanted radiation from the local oscillator can be removed at the time of receiving. Furthermore, since a dlgital frequency synthesizer is used for a local oscillator, a transmission frequency can readily be obtained by varying the ratio of frequency division for transmission at the time of frequency division. This makes i-t unnecessary to use an independent oscillator for transmission, thereby simplifying the construction of a multi-channel type radio transmitter/
receiver.
)2, ....
kh/l~,
The local oscillator 2 is constituted by a digital frequency synthesi~er as shown in Fig. 1. In the local oscillator, the output of a voltage controlled oscillator (VCo) 21 is frequency divided by a variable frequency divider 22 whose outpu-t is supplied to a phase comparator 23 to be compared wi-th the output frequency of a reference oscillator 24, and the phase error is applied -to the voltage controlled oscillator 21 through a loop filter 25.
In the transmit-ter 3, a voice signal produced by -- 4 ~
,--kh/~
a microphone 33 is amplified by a ]ow frequenc~ amplifier 32 and then supplied -to the volt:acJe controlled oscilla-tor 21 to effect frequency modula-tion. The output of the voltage controlled oscilla-tor 21, that is, the ou-tput of the local oscilla-tor 2 is amplified to a predetermined power level by a power amplifier 31 whose output is radiated through antenna 10 via the antenna duplexer 11.
With the above construction, according to the present invention, the intermediate frequency fif of the superheterodyne receiver is se-t to be an odd multiple of half the frequency spacing fch between channel frequencies, and it is expressed by~
if (2K - 1) x fCh/2 where K represents a natural number.
The local oscillator 2 in the form of the digital freqency synthesizer is advantageous because the digital frequency synthesizer is easy to change frequency division so tha-t the in-termediate frequency which is an odd multiple of half the frequency spacing in the receiving mode can , 10 readily be switched to the transmitting frequency which is an even multiple of half the frequency spacing in the transmission mode, or vice versa.
For example, let us assume that the transmission frequency is 450 MHz, the receiving frequency is 460 MHz and the frequency spacing between adjacent channels is 25 KHz.
Thus the next lower channel frequency is 450 MHz - 24KHz =
~49,975 MHz. Assume also that the intermediate frequency is selected to be 10.0125 MHz, an odd multiple of a frequency of 25/2 X~lz.
kh/)~
~9~'7'~
Where the lower ].ocal oscillation frequency i.s assumed with respect to the received frequenc~y, the local osci.llation frequency fL becornes: fL = fR ~ Fif or fL = 460 - 10.0125 = 449.9875 MHz Whe.re the output frequency of the reference oscillator 24 is equal to 12.5 ICHz, the frequency divi.sion ratio N of the variable frequency divider 22 that is needed for this value of fL is N = 449.9875/0.9125 = 35999 at the time of receiving, while at the time of transmission (fT = 450 MHz) it becomes N = 450/0.0125 = 3~000 In other words, when the frequency division ratio N is 36000, the output of the local oscillator 2 becomes 450 MHz, which is a transmission frequency that is amplified by power amplifier 31.
Thus, according to this invention, the local oscillation frequency fL becomes fL = 449.9875 MHz which is different by 12.5 KHz from (i.e. half way between) the closest radio channel frequencies. 449.975 MHz and 450 MHz of the assumed example.
Fig. 2 shows an attenuation/frequency characteristic of the receiver 1 in which fR designates a receiving frequency, and f'R and f"R show radio channel frequencies. The ordinate shows atenuation in decibel (dB). At frequencies f'R and f"R, attenuations are sufficiently large, whereas when the receiving frequency shif-ts by one half the Erequency spacingr ,~
.~
kh/J~-attenuation of abo~ 70 ds can oxdinarily ~e obtained.
This amount of attenuation is common in communication receivers opera-ting in VIIF band and UIIF
band. Eor this reason, even when an interfering wave having a frequency different from the receiviny frequency by one half of -the frequency spacing is present, it causes no trouble. More particularly, the unwanted local oscillation frequency radiated from a radio transmitter/receiver of this invention does not coincide with the radio channel frequencies, and when it is radiated, it can be sufficiently attenuated by an intermediate frequency filter or the like of the receiver.
Fig. 3 shows the relation among radio channel frequencies fl to f4 and the local oscillation frequency fL
of this invention. As shown, the local oscillation frequency fL is positioned hàlf way between radio channel frequencies f2 and f3.
As described above, according to this invention, since the local oscillation frequency is positioned between two adjacent radio channel frequencies, interference which would be caused by unwanted radiation from the local oscillator can be removed at the time of receiving. Furthermore, since a dlgital frequency synthesizer is used for a local oscillator, a transmission frequency can readily be obtained by varying the ratio of frequency division for transmission at the time of frequency division. This makes i-t unnecessary to use an independent oscillator for transmission, thereby simplifying the construction of a multi-channel type radio transmitter/
receiver.
)2, ....
kh/l~,
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A radio transmitter/receiver comprising:
a transmitter;
a superheterodyne receiver, and a local oscillator for supplying said transmitter and receiver with local signals at a plurality of frequencies;
said transmitter and receiver operating on a plurality of radio channels with different transmission and reception frequencies for each channel, said transmission and reception frequencies being a natural number multiple of the frequency spacing between said radio channels and the output frequencies of said local oscillator being between the transmission frequencies of two adjacent channels;
mixing means in said receiver for mixing an output from said local oscillator with a reception frequency to provide an intermediate frequency fif wherein said intermediate frequency fif of said superheterodyne receiver is set to have a value expressed by fif = (2K - 1) x fch/2 where fch represents a frequency spacing between radio frequencies assigned to adjacent channels, and K
represents a natural number.
a transmitter;
a superheterodyne receiver, and a local oscillator for supplying said transmitter and receiver with local signals at a plurality of frequencies;
said transmitter and receiver operating on a plurality of radio channels with different transmission and reception frequencies for each channel, said transmission and reception frequencies being a natural number multiple of the frequency spacing between said radio channels and the output frequencies of said local oscillator being between the transmission frequencies of two adjacent channels;
mixing means in said receiver for mixing an output from said local oscillator with a reception frequency to provide an intermediate frequency fif wherein said intermediate frequency fif of said superheterodyne receiver is set to have a value expressed by fif = (2K - 1) x fch/2 where fch represents a frequency spacing between radio frequencies assigned to adjacent channels, and K
represents a natural number.
2. The radio transmitter/receiver according to claim 1 wherein said local oscillator comprises a digital frequency synthesizer and an output of said local oscillator is supplied to said transmitter.
3. The radio transmitter/receiver according to claim 2 wherein the output frequency of said local oscillator is varied by an odd multiple of fch/2 to obtain a transmission frequency.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57043966A JPS58161432A (en) | 1982-03-18 | 1982-03-18 | Radio transmitter and receiver |
| JP43966/'82 | 1982-03-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1198778A true CA1198778A (en) | 1985-12-31 |
Family
ID=12678443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000423659A Expired CA1198778A (en) | 1982-03-18 | 1983-03-15 | Radio transmitter/receivers |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4542531A (en) |
| EP (1) | EP0089649B1 (en) |
| JP (1) | JPS58161432A (en) |
| CA (1) | CA1198778A (en) |
| DE (1) | DE3380338D1 (en) |
Families Citing this family (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60117927A (en) * | 1983-11-30 | 1985-06-25 | Clarion Co Ltd | Synthesizer receiver |
| GB8806194D0 (en) * | 1988-03-16 | 1988-04-13 | Shaye Communications Ltd | Transceivers |
| US5291474A (en) * | 1989-05-18 | 1994-03-01 | Nokia Mobile Phones Ltd. | Procedure for forming frequencies of a digital radio telephone |
| US5152005A (en) * | 1990-01-22 | 1992-09-29 | Motorola, Inc. | High resolution frequency synthesis |
| DE4021294A1 (en) * | 1990-07-04 | 1992-01-09 | Grundig Emv | TRANSMITTER AND N-TRAY SUPERHET RECEIVER FOR A DEVICE OF TELECOMMUNICATIONS |
| DE4036418A1 (en) * | 1990-11-15 | 1992-05-21 | Grundig Emv | RADIO DEVICE FOR AN FDM-TDM RADIO TRANSMISSION SYSTEM |
| JPH04269021A (en) * | 1991-02-25 | 1992-09-25 | Nec Corp | Two-way paging system |
| JP2800858B2 (en) * | 1991-09-18 | 1998-09-21 | 日本電気株式会社 | Wireless telephone equipment |
| DE4201415A1 (en) * | 1992-01-21 | 1993-07-22 | Telefunken Microelectron | COMBINED RADIO TRANSMITTER AND RECEIVER WITH A PLL CIRCUIT |
| WO1994006206A1 (en) * | 1992-08-27 | 1994-03-17 | Motorola Inc. | Push pull buffer with noise cancelling symmetry |
| US5453714A (en) * | 1993-03-10 | 1995-09-26 | National Semiconductor Corporation | Binary FM demodulator with self-adjusting resonant operating frequency according to demodulated binary output signal duty cycle |
| JPH08507667A (en) * | 1993-03-10 | 1996-08-13 | ナショナル・セミコンダクター・コーポレイション | Radio frequency communication transceiver |
| US5465418A (en) * | 1993-04-29 | 1995-11-07 | Drexel University | Self-oscillating mixer circuits and methods therefor |
| GB2279848B (en) * | 1993-06-02 | 1997-04-23 | Vtech Communications Ltd | A transmitting and receiving system and transmitter-receiver utilized therein |
| US5423076A (en) * | 1993-09-24 | 1995-06-06 | Rockwell International Corporation | Superheterodyne tranceiver with bilateral first mixer and dual phase locked loop frequency control |
| US6118984A (en) * | 1997-04-08 | 2000-09-12 | Acer Peripherals, Inc. | Dual conversion radio frequency transceiver |
| EP1042871B1 (en) * | 1997-10-14 | 2009-04-15 | Cypress Semiconductor Corporation | Digital radio-frequency transceiver |
| US6587670B1 (en) * | 1998-12-22 | 2003-07-01 | Harris Corporation | Dual mode class D amplifiers |
| US6757906B1 (en) | 1999-03-30 | 2004-06-29 | Tivo, Inc. | Television viewer interface system |
| US8346172B2 (en) * | 2009-05-27 | 2013-01-01 | Csr Technology Inc. | Systems and methods providing wideband tuners controlling spurious signal placement in the capture bandwidth |
| JP5759422B2 (en) * | 2012-06-25 | 2015-08-05 | 日本電信電話株式会社 | Receiver and receiving method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR932631A (en) * | 1941-08-20 | 1948-03-26 | Pye Ltd | High frequency modulated carrier wave signaling system |
| US3983484A (en) * | 1974-12-06 | 1976-09-28 | Nihon Dengyo Co., Ltd. | Multichannel signal transmitting and receiving apparatus |
| JPS524105A (en) * | 1975-06-27 | 1977-01-13 | Trio Kenwood Corp | Frequency synthesizer-method transmitter-receiver |
| US4002995A (en) * | 1975-07-07 | 1977-01-11 | Motorola, Inc. | Digital frequency synthesizer having selectable frequency offset between transmit and receive frequencies |
| JPS53130911A (en) * | 1977-04-20 | 1978-11-15 | Matsushita Electric Ind Co Ltd | Pll synthesizer |
| JPS54127209A (en) * | 1978-03-27 | 1979-10-03 | Hitachi Denshi Ltd | Structure system of radio equipment |
| JPS5820172B2 (en) * | 1979-02-28 | 1983-04-21 | 日本電信電話株式会社 | How to set the intermediate frequency of mobile radio equipment |
| US4476575A (en) * | 1982-12-13 | 1984-10-09 | General Electric Company | Radio transceiver |
-
1982
- 1982-03-18 JP JP57043966A patent/JPS58161432A/en active Granted
-
1983
- 1983-03-15 US US06/475,539 patent/US4542531A/en not_active Expired - Lifetime
- 1983-03-15 CA CA000423659A patent/CA1198778A/en not_active Expired
- 1983-03-18 DE DE8383102720T patent/DE3380338D1/en not_active Expired
- 1983-03-18 EP EP83102720A patent/EP0089649B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3380338D1 (en) | 1989-09-07 |
| US4542531A (en) | 1985-09-17 |
| EP0089649A2 (en) | 1983-09-28 |
| EP0089649B1 (en) | 1989-08-02 |
| JPS58161432A (en) | 1983-09-26 |
| JPH0123012B2 (en) | 1989-04-28 |
| EP0089649A3 (en) | 1986-04-16 |
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