Wireless data transceiver

• US 5,444,737 A
• Filed: 11/10/1993
• Issued: 08/22/1995
• Est. Priority Date: 05/05/1993
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Szilagyi, Tomany, Cripps, Peter K.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Bocure, Tesfaldet
• Application Number:
  US08/150,401
• Time in Patent Office: 650 Days
• Field of Search: 375/59, 375/60, 375/37, 375/58, 375/75, 375/99, 375/7, 455/126, 455/73, 455/84, 455/85, 455/86, 455/317, 370/32, 370/32.1
• US Class Current: 375/219
• CPC Class Codes: H03C 3/0975 applying frequency modulation in the phase locked loop at components other than the divider, the voltage controlled oscillator or the reference clock
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04L 25/4925 using balanced bipolar ternary codes
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/148 using filters, including PLL-type filters

Abstract

A full duplex data transceiver for transmitting and receiving trinary frequency-modulated ("FM") signals representing binary data includes at least one antenna and a single oscillator which serves as both the radio frequency ("RF") signal source for the transmitter and the local oscillator ("LO") signal source for the receiver. During signal transmission, the oscillator output is frequency-modulated to provide a FM transmit signal to the antenna. The oscillator output is frequency-modulated with binary transmit data by modulating an error feedback signal which serves as the control voltage for a voltage-controlled oscillator in a phase-lock-loop, thereby producing the FM transmit signal. During signal reception, the oscillator output, in the form of the transmitted FM signal, is attenuated and coupled into the receiver along with a FM receive signal from the antenna, or alternatively is received via a separate receive antenna along with the FM receive signal, for mixing therewith to down-convert the FM receive signal. As part of the demodulation of the down-converted FM receive signal, the binary transmit data is subtracted out. The FM transmit and receive signals are trinary (f_-P, f_C, f_+P) and represent encoded binary data. The center frequency f_C corresponds to an absence of a binary data signal transition, the lower peak frequency f_-P corresponds to a negative binary data signal transition and the upper peak frequency f_+P corresponds to a positive binary data signal transition.

Claims

1. A data transceiver for transmitting and receiving modulated radio frequency (RF) signals, comprising:

an antenna for transmitting a first modulated RF signal and receiving a second modulated RF signal;

signal coupler means coupled to said antenna for receiving and coupling thereto a first portion of said first modulated RF signal and for receiving and coupling therefrom said second modulated RF signal;

transmitter means coupled to said signal coupler means for receiving a first modulation signal M1 and generating therefrom a second modulation signal M2, generating a RF signal having a first carrier frequency F1, modulating said RF signal in accordance with said first modulation signal M1, and providing said modulated RF signal to said signal coupler means as said first modulated RF signal; and

receiver means coupled to said signal coupler means and said transmitter means for receiving via said signal coupler means said second modulated RF signal which includes a second carrier frequency F2 modulated by a third modulation signal M3, receiving further via said signal coupler means a second portion of said first modulated RF signal, and mixing said received second portion of said first modulated RF signal and said received second modulated RF signal to produce a modulated intermediate frequency (IF) signal having a modulated center frequency F3 equal to a difference |F1-F2| between said first carrier frequency F1 and said second carrier frequency F2, and further for receiving from said transmitter means said second modulation signal M2 and in accordance therewith demodulating said modulated IF signal.

2. A data transceiver as recited in claim 1, wherein said signal coupler means comprises an attenuator.

3. A data transceiver as recited in claim 1, wherein said signal coupler means comprises a directional coupler for receiving said first modulated RF signal, outputting said first portion of said first modulated RF signal to said antenna and coupling said second portion of said first modulated RF signal to said receiver means.

4. A data transceiver as recited in claim 1, wherein said transmitter means comprises a phase-lock-loop which includes a frequency-controllable oscillator, wherein a frequency error signal is generated and combined with said received first modulation signal M1 to produce a frequency control signal for said frequency-controllable oscillator.

5. A data transceiver as recited in claim 4, wherein said first modulated RF signal comprises a frequency-modulated signal.

6. A data transceiver as recited in claim 4, wherein said frequency control signal comprises said second modulation signal M2.

7. A data transceiver as recited in claim 1, wherein said receiver means comprises:

an IF circuit for receiving and mixing said second portion of said first modulated RF signal and said second modulated RF signal to produce said modulated IF signal; and

a demodulator connected to said IF circuit for receiving said second modulation signal M2 and in accordance therewith receiving and demodulating said modulated IF signal.

8. A data transceiver as recited in claim 7, wherein said IF circuit comprises a single-input mixer which receives said first and second modulated RF signals on a single signal line from said receiver antenna.

9. A data transceiver as recited in claim 7, wherein said demodulator comprises a frequency discriminator.

10. A data transceiver as recited in claim 1, wherein said receiver means comprises:

an IF circuit for receiving and mixing said second portion of said first modulated RF signal and said second modulated RF signal to produce said modulated IF signal; and

a demodulator connected to said IF circuit for receiving and demodulating said modulated IF signal to produce a baseband signal, and for receiving and subtracting said second modulation signal M2 from said baseband signal.

11. A data transceiver as recited in claim 10, wherein said IF circuit comprises a single-input mixer which receives said first and second modulated RF signals on a single signal line from said receiver antenna.

12. A data transceiver as recited in claim 10, wherein said demodulator comprises a frequency discriminator.

13. A data transceiver for transmitting and receiving modulated radio frequency (RF) signals, comprising:

an antenna which transmits a first modulated RF signal and receives a second modulated RF signal;

a signal coupler, connected to said antenna, which receives and couples thereto a first portion of said first modulated RF signal and receives and couples therefrom said second modulated RF signal;

a modulator-transmitter, connected to said signal coupler, which receives a first modulation signal M1 and generates therefrom a second modulation signal M2, generates a RF signal having a first carrier frequency F1, modulates said RF signal in accordance with said first modulation signal M1, and provides said modulated RF signal to said signal coupler as said first modulated RF signal; and

a demodulator-receiver, connected to said signal coupler and said modulator-transmitter, which receives via said signal coupler said second modulated RF signal including a second carrier frequency F2 modulated by a third modulation signal M3, receives further via said signal coupler a second portion of said first modulated RF signal, and mixes said received second portion of said first modulated RF signal and said received second modulated RF signal to produce a modulated intermediate frequency (IF) signal having a modulated center frequency F3 equal to a difference |F1-F2| between said first carrier frequency F1 and said second carrier frequency F2, and further which receives from said modulator-transmitter said second modulation signal M2 and in accordance therewith demodulates said modulated IF signal.

14. A data transceiver as recited in claim 13, wherein said signal coupler comprises an attenuator.

15. A data transceiver as recited in claim 13, wherein said signal coupler comprises a directional coupler which receives said first modulated RF signal, outputs said first portion of said first modulated RF signal to said antenna and couples said second portion of said first modulated RF signal to said demodulator-receiver.

16. A data transceiver as recited in claim 13, wherein said modulator-transmitter comprises a phase-lock-loop which includes a frequency-controllable oscillator, wherein a frequency error signal is generated and combined with said received first modulation signal M1 to produce a frequency control signal for said frequency-controllable oscillator.

17. A data transceiver as recited in claim 16, wherein said first modulated RF signal comprises a frequency-modulated signal.

18. A data transceiver as recited in claim 16, wherein said frequency control signal comprises said second modulation signal M2.

19. A data transceiver as recited in claim 13, wherein said demodulator-receiver comprises:

an IF circuit which receives and mixes said second portion of said first modulated RF signal and said second modulated RF signal to produce said modulated IF signal; and

a frequency demodulator, connected to said IF circuit, which receives and frequency-demodulates said modulated IF signal to produce a baseband signal, and which receives and subtracts said second modulation signal M2 from said baseband signal.

20. A data transceiver as recited in claim 19, wherein said IF circuit comprises a single-input mixer which receives said first and second modulated RF signals on a single signal line from said signal coupler.

21. A data transceiving method for transmitting and receiving modulated radio frequency (RF) signals, comprising the steps of:

receiving a first modulation signal M1 and generating a second modulation signal M2 therefrom;

generating a RF signal having a first carrier frequency F1;

modulating said RF signal in accordance with said first modulation signal M1;

transmitting said modulated RF signal as a first modulated RF signal via an antenna;

receiving via said antenna a second modulated RF signal having a second carrier frequency F2 modulated by a third modulation signal M3;

receiving via a signal coupler a portion of said first modulated RF signal;

mixing said received portion of said first modulated RF signal and said received second modulated RF signal to produce a modulated intermediate frequency (IF) signal having a modulated center frequency F3 equal to a difference |F1-F2| between said first carrier frequency F1 and said second carrier frequency F2; and

receiving said second modulation signal M2 and in accordance therewith demodulating said modulated IF signal.

22. A data transceiving method as recited in claim 21, wherein said step of generating a RF signal having a first carrier frequency F1 comprises generating a frequency error signal in a phase-lock-loop which includes a frequency-controllable oscillator and combining said frequency error signal with said first modulation signal M1 to produce a frequency control signal for said frequency-controllable oscillator.

23. A data transceiving method as recited in claim 22, wherein said step of modulating said RF signal in accordance with said first modulation signal M1 comprises frequency-modulating said RF signal in accordance with said first modulation signal M1.

24. A data transceiving method as recited in claim 22, wherein said step of modulating said RF signal in accordance with said first modulation signal M1 comprises modulating said RF signal with said second modulation signal M2 as said frequency control signal.

25. A data transceiving method as recited in claim 21, wherein said step of receiving via a signal coupler a portion of said first modulated RF signal comprises receiving said first modulated RF signal portion via an attenuator.

26. A data transceiving method as recited in claim 21, wherein said step of mixing said received portion of said first modulated RF signal and said received second modulated RF signal to produce a modulated IF signal comprises inputting said first and second modulated RF signals to a single-input mixer on a single signal line from said signal coupler.

27. A data transceiving method as recited in claim 21, wherein said step of receiving said second modulation signal M2 and in accordance therewith demodulating said modulated IF signal comprises demodulating said modulated IF signal to produce a baseband signal and subtracting said second modulation signal M2 from said baseband signal.

28. A data transceiving method as recited in claim 27, wherein said step of demodulating said modulated IF signal to produce a baseband signal comprises frequency discriminating said modulated IF signal.