Digital receiver techniques in radar detectors
A method and apparatus are provided for detecting a RADAR signal. RADAR channel data in a frequency range is received, where the frequency range is divided into a plurality of equally wide channels. The received RADAR channel data is digitally processed and analyzed to identify a signal in the RADAR channel data in the frequency range. The frequency range is advanced to a next channel of the plurality of channels, where the frequency range of the next channel of the plurality of channels is nonsequential with the frequency range of the first channel. The steps of receiving, processing, and analyzing are repeated for the next channel of the plurality of channels.
1. A method of detecting a RADAR signal, comprising:
a. receiving a RADAR signal in a police RADAR frequency range, into a heterodyne receiver utilizing a local oscillator, the heterodyne receiver frequency shifting the RADAR signal to a baseband;
b. sampling the RADAR signal in the baseband with an analog to digital converter to produce a time domain sampled representation of the baseband RADAR signal;
c. wherein a frequency of the local oscillator is not swept during the steps of receiving and sampling the RADAR signal;
d. analyzing the time domain sampled representation of the baseband RADAR signal to identify an apparent police originated signal in a police RADAR frequency range;
e. alerting to the present of the apparent police originated signal.
2. The method of claim 1 , wherein the police frequency range encompasses the X, K, and Ka RF bands.
3. The method of claim 1 , further comprising converting the time domain sampled representation of the baseband RADAR signal to a frequency domain representation.
4. The method of claim 1 , further comprising forming an average of the frequency domain representation of the baseband RADAR signal with a frequency domain representation of a previously received RADAR signal.
5. The method of claim 4 , further comprising comparing the average of the frequency domain representations to a threshold.
6. The method of claim 5 wherein the threshold is a dynamic self-adapting threshold.
7. The method of claim 1 , further comprising altering the frequency of the local oscillator and then performing the steps of:
a. receiving a further RADAR signal in a police RADAR frequency range into a heterodyne receiver utilizing a local oscillator, the heterodyne receiver frequency shifting the further RADAR signal to a baseband, and
b. sampling the further RADAR signal in the baseband with an analog to digital converter to produce a time domain sampled representation of the baseband further RADAR signal.
8. The method of claim 1 wherein the frequency of the local oscillator is altered repeatedly to receive RADAR signals in a plurality of RADAR frequency ranges.
9. An apparatus for detecting a RADAR signal, comprising:
a. a heterodyne receiver receiving a RADAR signal in a police RADAR frequency range, comprising a local oscillator and a mixer using the local oscillator to frequency shift the RADAR signal to a baseband;
b. an analog to digital converter sampling the RADAR signal in the baseband to produce a time domain sampled representation of the baseband RADAR signal wherein a frequency of the local oscillator is not swept during the steps of receiving and sampling the RADAR signal; and
c. a processor analyzing the time domain sampled representation of the baseband RADAR signal to identify an apparent police originated signal in a police RADAR frequency range.
10. The apparatus of claim 9 , wherein the wherein the police frequency range encompasses the X, K, and Ka RF bands.
11. The apparatus of claim 9 , wherein the processor digitally processes the received RADAR channel data by converting the time domain sampled representation of the baseband RADAR signal to a frequency domain representation.
12. The apparatus of claim 9 , wherein the processor is configured to form an average of the frequency domain representation of the baseband RADAR signal with a frequency domain representation of previously received RADAR signal.
13. The apparatus of claim 12 , wherein the processor is configured to compare the average of the frequency domain representations to a threshold wherein the threshold is a dynamic self-adapting threshold.
14. The apparatus of claim 13 wherein the threshold is a dynamic self-adapting threshold.
15. The apparatus of claim 9 , wherein the processor is configured to alter the frequency of the local oscillator and then cause the heterodyne receiver to receive a further RADAR signal in a police RADAR frequency range and frequency shift the RADAR signal to a baseband, and cause the analog to digital converter to produce a time domain sampled representation of the baseband further RADAR signal.
16. The apparatus of claim 9 , wherein the processor is configured to cause the frequency of the local oscillator to alter repeatedly to receive RADAR signals in a plurality of RADAR frequency ranges.
17. The apparatus of claim 9 , further comprising a user interface.
18. The apparatus of claim 17 , wherein the user interface comprises:
a. a speaker;
b. a display; and
c. a keypad.