Radio frequency (RF) system loss compensation method using power measurement of pulsed RF source

• US 6,690,922 B1
• Filed: 05/11/2000
• Issued: 02/10/2004
• Est. Priority Date: 12/23/1998
• Status: Expired due to Term

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Lindemann, Brian
• Primary Examiner(s): Vo, Nguyen T.
• Assistant Examiner(s): Nguyen, Simon
• Application Number:
  US09/569,235
• Time in Patent Office: 1,370 Days
• Field of Search: 455/67.1, 455/69, 455/75, 455/115, 455/123, 455/126, 455/127, 455/129, 455/134, 455/522, 455/423, 455/425, 455/226.1, 324/76-1-
• US Class Current: 455/69
• CPC Class Codes: H03G 3/3047 for intermittent signals, e.g. burst signals
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A method and circuit for accurately measuring radio frequency power level in a pulsed RF transmission.

Claims

1. A method for measuring radio frequency power level in a pulsed radio frequency (RF) transmission, the method comprising:

determining a time during a RF transmission period to measure RF power, including determining said time to measure RF power level as a function of a priori knowledge of a transmission frame protocol practiced by the RF transmission source and determining the peak periods for each of a plurality of bits contained in the RF transmission;

averaging a value of said RF power level measurement across an appropriate time period; and

reporting said average RF power level measurement value.

2. The method recited in claim 1, wherein said a priori knowledge of a transmission frame protocol further comprises a priori knowledge of a modulation scheme, burst timing practiced by the RF transmission system, and transmission burst frequency.

3. The method recited in claim 1, wherein said averaging a value of said RF power level measurement further comprises measuring the RF energy contained in each said bit and averaging said RF energy.

4. The method recited in claim 3, wherein measuring said RF energy contained in each said bit further comprises computing an instantaneous power level for each said bit using a Square Root (I*I+Q*Q) formula.

5. The method recited in claim 3, wherein said reporting said average RF power level measurement value further comprises reporting said average power measurement value as constant between measurements.

6. The method recited in claim 5, wherein said reporting said average power measurement value further comprises reporting said average power measurement value to the source generating said RF power.

7. The method recited in claim 6, wherein said RF power level measurement further comprises measuring the RF power of a transmission signal at a measurement point in the RF transmission system where any RF power losses between said measurement point and the radio transmission system antenna are essentially predetermined.

8. The method recited in claim 7, wherein said reporting further comprises communicating said RF power level via preexisting receiver cabling within the radio system.

9. The method recited in claim 8, wherein said reporting further comprises:

generating a signal indicative of said RF power level measurement and

combining said signal indicative of RF power level measurement with a RF signal originating externally to the radio transmission system and received thereby.

10. The method recited in claim 9, wherein said signal indicative of RF power level measurement further comprises a frequency signal in a frequency range different from the frequency of the RF transmission originated by the radio transmission system.

11. The method recited in claim 10, wherein said reporting further comprises generating a sinusoidal signal proportional to said RF power level of the RF transmission.

12. The method recited in claim 10, wherein said reporting further comprises generating a frequency modulated digital signal having digital information contained in the modulation, said digital information representative of the RF power level of the RF transmission.

13. The method recited in claim 10, further comprising utilizing said RF power level measurement for controlling RF power gains.

14. A method for using an electronic circuit to measure radio frequency power level in a radio frequency (RF) transmission system using transmission methods having a duty cycle of less than 100%, the method comprising:

a) tuning the electric circuit to the frequency of the transmission;

b) recalling stored information describing a transmission frame protocol utilized by the RF transmission system;

c) with the electronic circuit, determining as a function of said protocol points during a RF transmission period at which to start and stop measuring RF transmission power level;

d) with the electronic circuit, measuring said RF transmission power level by;

i) determining a peak period for each of a plurality of bits contained in the RF transmission between said start and stop points,

ii) determining a value of the RF energy contained in each said bit, and

iii) determining an average of said values of RF energy; and

e) with the electronic circuit, generating a signal representative of said RF transmission power level.

15. The method recited in claim 14, wherein said determining a value of the RF energy contained in each said bit further comprises determining an instantaneous power level per bit.

16. The method recited in claim 14, wherein said determining a value of the RF energy contained in each said bit further comprises determining said instantaneous power level per bit only during RF transmission.

17. The method recited in claim 16, wherein said determining an average of said values of RF energy further comprises assigning a constant value to said values of RF energy during periods between incidents of said determining a value of the RF energy contained in each said bit.

18. An electronic circuit for determining the radio frequency power level in a pulsed radio frequency (RF) transmission, the electronic circuit comprising:

a memory having stored therein information describing the transmission frame protocol operated by a system generating a pulsed RF transmission;

a circuit coupled to said memory and adapted to receive as an input a portion of the RF energy in a pulsed RF transmission and output a signal representative of said RF energy, said circuit operating a function for

i) determining a peak period for each of a plurality of bits contained in the RF transmission as a function of said protocol,

ii) measuring the RF energy contained in each said bit, and

iii) computing an average of said RF energy measurements, and

iv) generating said output signal representative of RF energy as a function of said average of RF energy measurements.

19. The electronic circuit recited in claim 18, wherein said protocol further comprises a definition of a modulation scheme and burst timing operated the pulsed RF transmission generating system.

20. The electronic circuit recited in claim 19, wherein said memory further comprises a non-volatile memory module.

21. The electronic circuit recited in claim 20, wherein said non-volatile memory module further comprises an erasable programmable read-only memory chip.

22. The electronic circuit recited in claim 18, wherein said computing an average of said RF energy measurements further comprises substituting a constant value for said RF energy during periods occurring between measurements of said RF energy contained in said bits.

23. The electronic circuit recited in claim 22, wherein measuring said RF energy contained in said bits further comprises computing an instantaneous power level for each said bit using a Square Root (I*I+Q*Q) formula.

24. The electronic circuit recited in claim 22, further comprising an analog-to-digital converter adapted to receive as an input in analog format said portion of the RF energy in a pulsed RF transmission and coupled to output to said circuit a digital signal representative of said RF energy.

25. The electronic circuit recited in claim 24, further comprising a down-converter adapted to receive as an input said portion of the RF energy in a pulsed RF transmission and coupled to output to said analog-to-digital converter a baseband transmission representative of said RF energy.

26. The electronic circuit recited in claim 25, wherein said baseband transmission further comprises analog In-phase and Quadrature-phase levels corresponding to said transmission frame protocol.

27. The electronic circuit recited in claim 26, wherein said In-phase and Quadrature-phase levels are proportional to respective In-phase and Quadrature-phase levels generated at the pulsed RF transmission source.

28. The electronic circuit recited in claim 24, further comprising a RF coupler adapted both to receive a pulsed RF transmission and to pass a large portion of the energy in a pulsed RF transmission to a transmission line of the system generating the pulsed RF transmission, said RF coupler is further coupled to output a small portion of the energy to said down-converter.

29. The electronic circuit recited in claim 28, wherein said RF coupler further comprises a directional coupler.

30. The electronic circuit recited in claim 28, wherein said RF coupler further comprises a −

20 dB directional coupler.

31. The electronic circuit recited in claim 28, further comprising:

a transmission line coupled to said RF coupler; and

a source of a pulsed RF transmission coupled to transmit said pulsed RF transmission on said transmission line and coupled to transmit to said down-converter a tuning signal representative of a transmission burst frequency corresponding to a next transmission and to receive said output signal representative of RF energy generated by said circuit.

32. The electronic circuit recited in claim 29, further comprising:

a signal amplifier coupled between said transmission source and said coupler; and

a power control circuit coupled between said circuit and said transmission source to receive said output signal of said circuit, said power control circuit generating a power control signal and transmitting said power control signal to said amplifier.

33. The electronic circuit recited in claim 32, further comprising:

a RF receiver;

a RF receiver line coupled receive a RF signal generated external to said transmission source and coupled to said RF receiver;

said circuit coupled to transmit said output signal on said RF receiver line; and

a signal splitter coupled to said RF receiver line to receive each of the externally generated RF signal and said circuit output signal, said signal splitter to output the received RF signal to said receiver and said circuit output signal to said power control circuit.

34. The electronic circuit recited in claim 32, further comprising a RF antenna coupled to said RF coupler to accept said energy passed by said coupler and coupled to said RF receiver line to transmit the externally generated RF signal.

35. An electronic circuit for determining the radio frequency power level in a pulsed radio frequency (RF) transmission, the electronic circuit comprising:

a directional coupler adapted to receive a pulsed RF transmission, said coupler directing a first portion of the RF energy in said pulsed RF transmission to a first output and a second portion of the RF energy to a second output;

a down-converter coupled receive the RF energy in one of said first and second outputs of said directional coupler, said down-converter responsively tuned to a tuning signal preceding said pulsed RF transmission and converting said RF energy into an analog baseband signal representative of said RF energy;

an analog-to-digital converter coupled to receive said baseband signal, said analog-to-digital converter converting said analog baseband signal into a digital signal representative of said RF energy; and

a computing circuit coupled to receive said digital signal, said computing circuit

a) determining a peak period for each of one or more bits contained in the pulsed RF transmission,

b) measuring the RF energy contained in each said bit, and

c) averaging said RF energy measurements, and

d) generating an output signal representative of RF energy.

36. The electronic circuit recited in claim 35, wherein said determining a peak period for each of one or more bits contained in the pulsed RF transmission further comprises determining said peak period as a function of the transmission frame protocol operated by the source of the pulsed RF transmission.

37. The electronic circuit recited in claim 36, wherein said generating an output signal representative of RF energy further comprises generating said output signal as a function of said averaging of said RF energy measurements.

38. The electronic circuit recited in claim 37, further comprising a memory coupled to said computing circuit, said memory having stored therein information describing the transmission frame protocol operated by the source of the pulsed RF transmission.