Sweeping receiver

• US 5,146,227 A
• Filed: 05/03/1991
• Issued: 09/08/1992
• Est. Priority Date: 05/03/1991
• Status: Expired due to Term

• Current Assignee: The Whistler Group Incorporated
• Original Assignee: Whistler Corporation of Massachusetts
• Inventors: Papadopoulos, Costas
• Primary Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US07/695,590
• Time in Patent Office: 494 Days
• Field of Search: 342/20, 342/192, 342/98, 342/100, 324/77 C, 324/77 CS, 324/77 B, 455/145-148
• US Class Current: 342/20
• CPC Class Codes: G01S 7/022 Road traffic radar detectors

Abstract

A radar detector including a local oscillator capable of sweeping over a frequency range of sufficient bandwidth to provide a fundamental frequency and, when injected into a multiplier/mixer, harmonics of that fundamental frequency suitable for heterodyning with rf-signals received by an antenna. The heterodyning of the received rf-signals and the local oscillator signal produce an intermediate frequency signal of constant frequency. A sweep controller causes the local oscillator to sweep only through those local oscillator frequencies suitable for heterodyning with those received rf-signals having radio-frequencies which are of interest. The sweep controller causes the sweeping local oscillator not to sweep through those local oscillator frequencies which would heterodyne with received rf-signals that are not of interest.

Claims

1. A radar detector comprising:

a tunable local oscillator for sweeping a first frequency band of interest between a first frequency and a second frequency and for sweeping second frequency band of intersect between a fourth frequency and a fifth frequency; and

a sweep controller for setting said tunable local oscillator to a third frequency, subsequent to said sweeping of said fist frequency band of interest and prior to said sweeping of said second frequency band of interest,

wherein said first frequency band and said second frequency band are non-overlapping, and

wherein said third frequency is a frequency outside the range of frequencies between said list frequency and said fifth frequency.

7. The radar receiver of claim 1 wherein said tunable local oscillator is a voltage controlled oscillator.

13. The radar receiver of claim 1 further comprising a calibration oscillator for producing at least one ef-frequency signal marker suitable for heterodyning with the signal from the local oscillator to produce a detected signal a a predetermined frequency.

14. The radar receiver of claim 13 wherein said calibration oscillator comprises a SAW-device oscillator.

15. The radar receiver of claim 13 wherein said calibration oscillator produces at least on harmonic frequency suitable for use as said rf-frequency signal marker.

16. The radar receiver of claim 13 further comprising a microprocessor, said microprocessor controlling the calibration oscillator.

17. The radar receiver of claim 16 wherein said microprocessor detects said rf-frequency signal marker to modify the rate at which the local oscillator frequency is changing.

18. The radar receiver of claim 13 wherein said sweep controller uses said rf-frequency signal marker to control said tunable local oscillator so as to maintain said rf-frequency signal marker at a predetermined location within said frequency bands of interest.

19. The radar receiver of claim 1 wherein said tunable local oscillator is a voltage controlled oscillator.

20. The radar receiver of claim 19 wherein said sweep controller causes said voltage controlled oscillator not to sweep by maintaining a constant voltage on said voltage controlled oscillator.

21. The radar receiver of claim 20 wherein said sweep controller comprises:

a capacitor for providing said voltage to said voltage controlled oscillator; and

a plurality of switch controlled resistors connected in parallel with said capacitor.

22. The radar receiver of claim 21 wherein said plurality of switch controlled resistors determine the rate of discharge of said capacitor.

23. The radar receiver of claim 22 wherein said switches are controlled by a microprocessor so as to control the frequency generated by said local oscillator.

27. The radar detector of claim 1 further comprising a multiplier/mixer for multiplying said tunable local oscillator frequency by a received rf-signal.

31. The radar detector of claim 27 wherein said tunable local oscillator is adapted for sweeping at lest one additional frequency band of interest between a beginning frequency and an ending frequency, each said additional band being swept at a selected rate,

wherein said sweep controller is adapted for setting said tunable local oscillator to said third frequency, subsequent to said sweeping of said second frequency band of interest and prior to said sweeping of said each additional frequency band of interest,

wherein all said frequency bands of interest are non-overlapping, and

wherein said third frequency is a frequency outside the range of frequencies of all said frequency bands of interest.

2. A radar detector comprising:

a tunable local oscillator capable of sweeping between an initial frequency and a final frequency to produce a local oscillator frequency sweep;

a multiplier/mixer for multiplying said local oscillator frequency sweep by a received rf-signal;

a sweep controller for interrupting the local oscillator frequency sweep at at least one frequency and restarting said frequency sweep at another predefined frequency to reduce the time to sweep desired frequencies between said initial frequency and final frequency; and

a calibration stage for producing at least one rf-frequency signal marker suitable for heterodyning wit the signal from the local oscillator to produce a detected signal at a predetermined frequency.

3. The radar receiver of claim 2 wherein said calibration stage comprises a SAW-device oscillator.

4. The radar receiver of claim 3 wherein said SAW-device oscillator produces at least one harmonic frequency suitable for use as said rf-frequency signal a marker.

5. The radar receiver of claim 2 further comprising a microprocessor, said microprocessor controlling the calibration stage.

6. The radar receiver of claim 5 wherein said microprocessor detects said rf-frequency signal marker to determine the frequency produced by the local oscillator and the rate at which the local oscillator frequency is changing.

8. The radar receiver of c 7 wherein said sweep controller causes said voltage controlled oscillator not to sweep by maintaining a constant voltage on said voltage controlled oscillator.

9. A radar detector comprising:

a tunable local oscillator capable of sweeping between an initial frequency and a final frequency to produce a local oscillator frequency sweep;

a multiplier/mixer for multiplying said local oscillator frequency sweep by a received rf-signal; and

a sweep controller for interrupting the local oscillator frequency sweep at least one frequency and restarting said frequency sweep at another predefined frequency to reduce the time to sweep desired frequencies between said initial frequency and final frequency,

wherein said tunable local oscillator is a voltage controlled oscillator,

wherein said sweep controller causes said voltage controlled oscillator not to sweep by maintaining a constant voltage on said voltage controlled oscillator, and

wherein said sweep controller comprises;

a capacitor for providing said voltage to said voltage controlled oscillator; and

a plurality of switch controlled resistors connected in parallel with said capacitor.

10. The radar receiver of claim 9 wherein said plurality of switch controlled resistors determine the rate of discharge of said capacitor.

11. The radar receiver o claim 10 wherein said switches are controlled by a microprocessor so as to control the frequency generated by said local oscillator.

12. A method for detecting radar rf-signals with a receiver having a tunable local oscillator, said method comprising the steps of:

a. sweeping a first band of interest with said tunable local oscillator between a fist frequency and a second frequency;

setting said tunable local oscillator to a third frequency; and

sweeping a second frequency band of interest with said tunable local oscillator between a fourth frequency and a fifth frequency,

wherein said first frequency band and said second frequency band are non-overlapping,

and wherein said third frequency is outside the range of frequencies between said fist frequency and said fifth frequency.

24. A radar detector comprising:

a controllable oscillator having a control input and a frequency output responsive to said control input,

said controllable oscillator for sweeping a first frequency band of interest between a fist frequency and a second frequency in response to varying the value of said control input between a first value and a second value, and for sweeping a second frequency band of interest between a fourth frequency and a fifth frequency in response to varying said value of said control input between a fourth value and a fifth value; and

a control circuit for setting said value of said control input to a third value, subsequent to said varying said value of said control input between said first value and said second value and prior to said varying said value of said control input between said fourth value and said fifth value,

wherein the values of said control input between said first value and said second value and between said fourth value and fifth value to not overlap,

wherein said third value of said control input is outside the range of values between said list value and said fifth value.

25. A radar detector comprising:

a controllable oscillation circuit for sweeping a first frequency band of interest between sag first frequency and as second frequency and for sweeping a second frequency band of interest between a fourth frequency and a fifth frequency; and

a sweep controller for setting said controllable oscillation circuit to a third frequency, subsequent to said sweeping of said first frequency band of interest and prior to said sweeping of said second frequency band of interest,

wherein said first frequency band and said second frequency band are non-overlapping, and

wherein said third frequency is a frequency outside the range of frequencies between said first frequency and said fifth frequency.

26. The radar detector of claim 25 wherein said controllable oscillation circuit comprises a tunable local oscillator.

28. A radar detector comprising:

a tunable local oscillator for sweeping a first frequency band of interest between a first frequency and a second frequency at a first rate, and for sweeping a second frequency band of interest between a fourth frequency and a fifth frequency at a second rate; and

a sweep controller for setting said tunable local oscillator to a third frequency, subsequent to said sweeping of said first frequency band of interest and prior to said sweeping of said second frequency band of interest,

wherein said first frequency band as said second frequency band are non-overlapping, and

wherein said third frequency is a frequency outside the range of frequencies between said first frequency and said fifth frequency.

29. The radar detector of claim 28 wherein said first rate and said second rate are substantially equal.

30. The radar detector of claim 28 wherein said fist rate and said second rate are not substantially equal.