Digital radiofrequency transceiver

• US 6,434,187 B1
• Filed: 10/26/1998
• Issued: 08/13/2002
• Est. Priority Date: 10/14/1997
• Status: Expired due to Term

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Harrington, Drew M., Beard, Paul F., Moore, Mark D.
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US09/179,212
• Time in Patent Office: 1,387 Days
• Field of Search: 375/219, 375/295, 375/296, 375/297, 375/306, 375/307, 375/316, 375/318, 375/327, 375/328, 375/239, 375/326, 455/73, 455/76, 455/86, 370/213, 332/112, 332/127, 332/128, 329/307, 329/313, 331/1.R, 331/10, 331/14, 331/25
• US Class Current: 375/219
• CPC Class Codes: H03C 3/0908 using a phase locked loop
• CPC Class Codes: H03D 3/00 Demodulation of angle-, frequency- or phase- modulated oscillations H03D5/00, H03D9/00, H03D11/00 take precedence
• CPC Class Codes: H03D 7/00 Transference of modulation from one carrier to another, e.g. frequency-changing H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F
• CPC Class Codes: H04B 1/403 using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency

Abstract

A method for radiofrequency (RF) transmission of digital information includes generating an RF signal using a voltage-controlled oscillator (VCO), stabilizing the RF signal from the VCO by providing an error signal from a phase-locked loop (PLL) to an input of the VCO, and combining the digital information with the error signal of the PLL input to the VCO, thereby causing variations in frequency of the RF signal from the VCO that represent the digital information. Apparatus for RF transmission of digital information includes a VCO, the VCO arranged to generate an RF signal, a PLL, the frequency input of the PLL coupled to the RF signal output of the VCO, an encoder, the encoder arranged to convert the digital information into a form where it has a data rate faster than a response time of the PLL, and a coupler, the coupler coupling both the error signal output of the PLL and the encoded digital information to an input of the VCO.

Claims

1. A method for radio frequency (RF) transmission of digital information comprising the steps of:

(A) generating an RF signal using a voltage-controlled oscillator (VCO);

(B) providing an error signal from a phase-locked loop (PLL) responsive to the RF signal to an input of the VCO;

(C) filtering the error signal with a loop filter;

(D) combining the digital information with the error signal in the loop filter; and

(E) receiving the digital information combined with the error signal at the VCO, thereby causing variations in frequency of the RF signal from the VCO that represent the digital information.

2. The method of claim 1, further comprising the step of broadcasting the RF signal.

3. The method of claim 1, wherein the rate of change of the digital information is faster than a response time of the PLL.

4. The method of claim 3, wherein the digital information is encoded to have a duty cycle which is substantially constant.

5. The method of claim 4, wherein the digital information is encoded according to a pulse position modulation (PPM) scheme defined by an Infrared Data Association (IrDA) 4PPM data encoding standard.

6. The method of claim 1, further comprising the step of changing a channel frequency of the RF signal according to a series of channel frequencies, wherein the series of channel frequencies is determined by the steps of:

generating a series of at least a first and a second channel-select signals, each channel-select signal comprising an enable bit and at least one frequency coefficient;

sending each channel-select signal in turn to the PLL; and

changing a tuning frequency of the PLL according to the frequency coefficient of the first channel-select signal upon receiving the enable bit of the second channel-select signal.

7. The method of claim 6, wherein a number of distinct channel frequencies in the series of channel frequencies is a prime number.

8. The method of claim 7, further comprising the step of repeating the series of channel frequencies such that each channel frequency within the series of channel frequencies is used no more than once in each repetition of the series of channel frequencies.

9. The method of claim 1, further comprising the steps of:

receiving a second RF signal;

demodulating the second RF signal to produce a demodulated second RF signal;

determining a signal level threshold from the demodulated second RF signal; and

comparing the demodulated second RF signal to the signal level threshold to regenerate a second digital information from the demodulated second RF signal.

10. The method of claim 9, further comprising the step of using the RF signal from the VCO as a local oscillator signal to demodulate the second RF signal.

11. A method for radio frequency (RF) transmission of digital information comprising the steps of:

(A) generating an RF signal using a voltage-controlled oscillator (VCO);

(B) providing an error signal from a phase-locked loop (PLL) to the VCO;

(C) encoding the digital information to have a duty cycle which is substantially constant;

(D) forming a data packet containing the digital information in response to encoding; and

(E) combining the data packet with the error signal of the PLL before providing to the VCO, thereby causing whereby variations in frequency in the RF signal from the VCO that represent the data packet.

12. The method of claim 11, wherein the data packet has a duty cycle which is substantially constant.

13. The method of claim 11, wherein both the digital information is encoded and the data packet is formed according to a pulse position modulation (PPM) scheme defined by an Infrared Data Association (IrDA) 4PPM data encoding standard.

14. A method for receiving digital information sent by a radio frequency (RF) transmitter using an Infrared Data Association (IrDA) 4 pulse position modulation (PPM) data encoding standard comprising the steps of:

(A) receiving an RF signal;

(B) demodulating the RF signal to present a demodulated RF signal;

(C) determining a signal level threshold from the demodulated RF signal;

(D) comparing the demodulated RF signal to the determined signal level threshold to thereby regenerate IrDA-formatted data from the demodulated RF signal; and

(E) decoding the IrDA-formatted data to reproduce the digital information.

15. A method of implementing communication between a plurality of host computers comprising the steps of:

(A) exchanging digital information between a first host computer and a first radio frequency (RF) transceiver;

(B) encoding the digital information using pulse position modulation (PPM) according to an Infrared Data Association (IrDA) 4PPM data encoding standard;

(C) forming a data packet from the encoded digital information according to the IrDA 4PPM data encoding standard;

(D) generating an RF signal using a first voltage-controlled oscillator (VCO);

(E) providing an error signal from a first phase-locked loop (PLL) to the VCO;

(F) combining the data packet with the error signal of the first PLL before providing to the VCO, thereby causing variations in frequency in the RF signal from the first VCO that represent the data packet;

(G) transmitting the RF signal to a second RF transceiver;

(H) receiving the RF signal at the second RF transceiver;

(I) demodulating the RF signal at the second RF transceiver to produce a demodulated RF signal;

(J) determining a signal level threshold from the demodulated RF signal;

(K) comparing the demodulated RF signal to the determined signal level threshold to thereby regenerate the data packet from the demodulated RF signal;

(L) reproducing the digital information by decoding the data packet; and

(M) exchanging the digital information with a second host computer.

16. The method of claim 15, wherein media access control (MAC) functions are located in host computer software at both the first and the second host computers.

17. The method of claim 15, further comprising the step of changing a channel frequency of the RF signal according to a series of channel frequencies determined by the steps of:

generating a series of at least a first and a second channel-select signals, each channel-select signal comprising an enable bit and at least one frequency coefficient;

sending each channel-select signal in turn to the first PLL; and

changing the tuning frequency of the first PLL according to the frequency coefficient of the first channel-select signal upon receiving the enable bit of the second channel-select signal.

18. The method of claim 17, wherein a number of distinct channel frequencies in the series of channel frequencies is a prime number.

19. The method of claim 18, further comprising the step of repeating the series of channel frequencies such that each channel frequency within the series of channel frequencies is used no more than once in each repetition of the series of channel frequencies.

20. The method of claim 15, further comprising the step of waiting a pseudorandom time from an end of a last transmission or reception before transmitting.

21. The method of claim 20, wherein the pseudorandom time is determined by a pseudorandom number generator.

22. The method of claim 20, wherein the pseudorandom time is determined by clock drift of one of the host computers relative to another of the host computers.

23. The method of claim 20, wherein the pseudorandom time is determined by interrupts generated by other operations of the host computers.

24. An apparatus for radio frequency (RF) transmission of digital information comprising:

a voltage-controlled oscillator (VCO) arranged to generate an RF signal;

a phase-locked loop (PLL) arranged to (i) receive the RF signal and (ii) present an error signal;

an encoder arranged to convert the digital information into a form having a data rate faster than a response time of the PLL; and

a coupler arranged to couple both the error signal and the digital information as encoded to the VCO.

25. The apparatus of claim 24, further comprising an antenna coupled to the VCO to receive the RF signal.

26. The apparatus of claim 24, wherein the coupler is a loop filter.

27. The apparatus of claim 24, wherein the encoder is further arranged to convert the digital information into a form having a duty cycle which is substantially constant.

28. The apparatus of claim 27, wherein the encoder is further arranged to convert the digital information according to a pulse position modulation (PPM) scheme defined by an Infrared Data Association (IrDA) 4PPM data encoding standard.

29. The apparatus of claim 24, further comprising a selector arranged to change a channel frequency of the RF signal according to a series of channel frequencies determined by (i) generating a series of at least a first and a second channel-select signals, each channel-select signal comprising an enable bit and at least one frequency coefficient and (ii) sending each channel-select signal in turn to the PLL, wherein the PLL changes a tuning frequency according to the frequency coefficient of the first channel-select signal upon receiving the enable bit of the second channel-select signal.

30. The apparatus of claim 29, wherein a number of distinct channel frequencies used by the selector in the series of channel frequencies is a prime number.

31. The apparatus of claim 30, wherein the selector repeats the series of channel frequencies such that each channel frequency within the series of channel frequencies is used no more than once in each repetition of the series of channel frequencies.

32. An apparatus for radio frequency (RF) reception of digital information comprising:

an antenna configured to receive an RF signal containing the digital information;

a low-noise amplifier configured to amplify the RF signal received by the antenna;

a local RF oscillator configured to produce a signal having a frequency in proximity to a channel frequency of the RF signal;

a mixer configured to present an intermediate signal in response to the signal provided by the local RF oscillator and the RF signal presented by the low-noise amplifier;

an FM demodulator configured to demodulate the intermediate signal to produce a baseband signal; and

a decoder configured to extract the digital information from the baseband signal according to a pulse position modulation (PPM) scheme defined by an Infrared Data Association (IrDA) 4PPM data encoding standard.

33. An apparatus for radio frequency (RF) transmission and reception of digital information comprising:

a voltage-controlled oscillator (VCO) arranged to generate an RF signal;

a phase-locked loop (PLL) arranged to receive the RF signal from the VCO;

an encoder arranged to convert the digital information into a form having a data rate faster than a response time of the PLL;

a coupler coupling both an error signal presented by the PLL and the digital information as encoded to the VCO;

a switch configured to couple the RF signal to at least one of a plurality of outputs;

a first antenna coupled to a first output of the switch and arranged to transmit the RF signal;

an antenna arranged to receive a second RF signal;

a low-noise amplifier coupled to the antenna, the low-noise amplifier amplifying and filtering the second RF signal;

a mixer configured to present an intermediate signal in response to the second RF signal provided by the low-noise amplifier and the RF signal presented by the switch;

an FM demodulator configured to demodulate the intermediate signal to produce a baseband signal; and

a decoder reproducing the digital information from the baseband signal.

34. The apparatus of claim 33, wherein the antenna arranged to receive the second RF signal is the same antenna as the first antenna, and further comprising:

a power amplifier coupled to the first output of the first switch; and

a second switch configured to couple the first antenna either to the low-noise amplifier for reception of the second RF signal, or to the power amplifier for transmission of the RF signal.

35. The apparatus of claim 33, wherein the coupler is a loop filter.

36. The apparatus of claim 33, wherein the encoder is arranged to convert the digital information into a form having a duty cycle which is substantially constant.

37. The apparatus of claim 36, wherein the encoder converts the digital information according to a pulse position modulation (PPM) scheme defined by an Infrared Data Association (IrDA) 4PPM data encoding standard.

38. The apparatus of claim 33, a further comprising a selector arranged to change a channel frequency of the RF signal according to a series of channel frequencies determined by (i) generating a series of at least a first and a second channel-select signals, each channel-select signal comprising an enable bit and at least one frequency coefficient and (ii) sending each channel-select signal in turn to the PLL, wherein the PLL changes a tuning frequency according to the frequency coefficient of the first channel-select signal upon receiving the enable bit of the second channel-select signal.

39. The apparatus of claim 38, wherein a number of distinct channel frequencies used by the selector in the series of channel frequencies is a prime number.

40. The apparatus of claim 39, wherein the selector repeats the series of channel frequencies such that each channel frequency within the series of channel frequencies is used no more than once in each repetition of the series of channel frequencies.

41. The apparatus of claim 33, wherein the decoder reproduces the digital information from the baseband signal according to a pulse position modulation (PPM) scheme defined by an Infrared Data Association (IrDA) 4PPM data encoding standard.