Universal systems and methods for determining an incoming carrier frequency and decoding an incoming signal
View Patent ↗Consumer infrared (CIR) systems typically are used in remote control systems. Most CIR systems expect a known carrier frequency and encoding scheme. However, there are many applications of a universal CIR receiver which can receive and decode CIR signals regardless of the carrier frequency or encoding scheme. A CIR receiver circuit is disclosed which can both decompose a received CIR signal into run length representation and detect the carrier frequency. The result can then be supplied to a host device for further processing, interpretation and/or actions.
1. A receiver comprising:
a memory coupled to an edge detector and a counter, the edge detector configured to transfer a value from the counter to the memory whenever the edge detector detects an edge in an incoming signal;
a controller configured to cause a switching element to select a modulated signal when the receiver is in a carrier frequency detection mode, the controller further configured to set an adjustable clock to a sampling rate for sampling a carrier signal, the controller further configured to determine a carrier frequency of the modulated signal after a predetermined condition is met while in the carrier frequency detection mode, the controller further configured to cause the switching element to select a demodulated signal and set the adjustable clock to a sampling rate for sampling the demodulated signal when the receiver is in a decoding mode and the controller further configured to add a total elapsed time to a first entry in the memory during a transition between carrier frequency detection mode and decoding mode.
2. The receiver of claim 1 wherein the controller is further configured to set the counter to the total elapsed time when transitioning from carrier frequency detection mode and decoding mode.
3. The receiver of claim 1 wherein the controller is further configured to determine the total elapsed time by adding a time elapsed during edge detections in the carrier frequency detection mode, a time spent determining the carrier frequency, and a time spent transitioning from carrier detection mode and decoding mode.
4. The receiver of claim 1 wherein the controller is further configured to determine a duty cycle of the carrier frequency.
5. The receiver of claim 1 wherein the memory is a first-in first-out (FIFO) memory.
6. The receiver of claim 1 further comprising a band-pass filter and a demodulator for demodulating the modulated signal into the demodulated signal.
7. The receiver of claim 6 wherein the controller is further configured to deactivate the demodulator and/or the band-pass filter when in the carrier frequency detection mode and to activate the demodulator and/or the band-pass filter when in the decoding mode.
8. The receiver of claim 6 wherein the controller is further configured to tune the band-pass filter and/or the demodulator after determining the carrier frequency.
9. The receiver of claim 1 wherein the controller is further configured to determine a carrier frequency by retrieving values in the memory, to calculate a frequency based on the values in memory, and to compare the frequency to a list of known frequencies.
10. The receiver of claim 1 wherein the predetermined condition is a predetermined number of detected edges.
11. The receiver of claim 1 wherein the predetermined condition is a predetermined accuracy of the carrier frequency.
12. The receiver of claim 1 wherein the switching element comprises means for switching between a modulated signal comprising a carrier and a demodulated signal to produce an incoming signal.
13. The receiver of claim 1 further comprising means for converting the modulated signal into the demodulated signal.
14. The receiver of claim 1 further comprising means for converting a CIR signal into the modulated signal.
15. The receiver of claim 1 further comprising means for determining a duty cycle of the carrier by using the cycle between edge detections.
16. A method of determining a carrier frequency of a signal and decoding the signal comprising:
detecting a first plurality of edges in an incoming signal;
counting a first number of clock cycles between edge detections;
storing the first number in a memory;
determining a carrier frequency based on the first number;
switching to a demodulated signal;
detecting a second plurality of edges in the incoming signal;
counting a second number of clock cycles between edge detections;
storing the second number in memory;
detecting a third plurality of edges in the incoming signal;
counting a third number of clock cycles between edge detections;
adding a total elapsed time spent in a carrier frequency detection mode to the third number; and
storing the third number in memory.
17. The method of claim 16 wherein detecting the first plurality of edges in the incoming signal, counting the first number of clock cycles between edge detections and storing the first number in the memory is repeated until a predetermined criterion is met.
18. The method of claim 16 further comprising determining a duty cycle of a carrier using the first number of clock cycles.
19. A receiver comprising:
a memory coupled to an edge detector and a counter, the edge detector configured to transfer a value from the counter to the memory whenever the edge detector detects an edge in an incoming signal;
a controller configured to cause a switching element to select a modulated signal when the receiver is in a carrier frequency detection mode, the controller further configured to cause the switching element to select a demodulated signal and set a clock to a sampling rate for sampling the demodulated signal when the receiver is in a decoding mode, the controller further configured to add a total elapsed time to a data entry in the memory during a transition between carrier frequency detection mode and decoding mode.
20. The receiver of claim 19 wherein the controller is further configured to set a counter to the total elapsed time when transitioning from carrier frequency detection mode to decoding mode.