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 consumer infrared (CIR) receiver comprising:
a switching element configured to select between a modulated signal and a demodulated signal to produce an incoming signal;
an edge detector coupled to the switching element;
an adjustable clock;
a counter, having a value, coupled to the edge detector and the adjustable clock, wherein the counter is incremented for each clock cycle of the adjustable clock and wherein the counter is reset whenever the edge detector detects an edge in the incoming signal;
a memory coupled to the edge detector and the counter wherein the value is transferred from the counter to the memory whenever the edge detector detects an edge in the incoming signal; and
a controller;
wherein when the CIR receiver is in a carrier frequency detection mode the controller causes the switching element to select the modulated signal;
sets the adjustable clock to a sampling rate for sampling a carrier signal; and
determines a carrier frequency of the modulated signal after a sufficiency condition is met while in the carrier frequency detection mode;
when the CIR receiver is in a decoding mode, the controller causes the switching element to select the demodulated signal and sets the adjustable clock to a sampling rate for sampling a demodulated signal, and wherein, the controller adds a total elapsed time to a first entry in the memory during a transition from carrier frequency detection mode and decoding mode.
2. The CIR receiver of claim 1 wherein the controller sets the counter to the total elapsed time when transitioning from carrier frequency detection mode and decoding mode.
3. The CIR receiver of claim 1 wherein the total elapsed time comprises 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 CIR receiver of claim 1 wherein the controller determines a duty cycle of the carrier frequency.
5. The CIR receiver of claim 1 wherein the memory is a first-in first-out (FIFO) memory.
6. The CIR receiver of claim 1 further comprising a band-pass filter and a demodulator for demodulating the modulated signal into the demodulated signal.
7. The CIR receiver of claim 6 wherein the controller deactivates the demodulator and/or the band-pass filter when in the carrier frequency detection mode and activates the demodulator and/or the band-pass filter when in the decoding mode.
8. The CIR receiver of claim 6 wherein the controller tunes the band-pass filter and/or the demodulator after determining the carrier frequency.
9. The CIR receiver of claim 1 wherein the controller determines a carrier frequency by retrieving values in the memory, calculating a frequency based on the values in memory, and comparing the frequency to a list of known frequencies.
10. The CIR receiver of claim 1 wherein the sufficiency condition is met after a predetermined number of edges is encountered.
11. The CIR receiver of claim 1 wherein the sufficiency condition is met after estimates of the carrier frequency meet an accuracy condition.
12. The CIR receiver of claim 1 wherein the switching element comprises a means for switching between a modulated signal comprising a carrier and a demodulated signal to produce an incoming signal.
13. The CIR receiver of claim 1 further comprising a means for converting the modulated signal into the demodulated signal.
14. The CIR receiver of claim 1 further comprising a means for converting a CIR signal into the modulated signal.
15. The CIR receiver of claim 1 further comprising a means for determining a duty cycle of the carrier by using the cycle between edge detections.
16. The CIR receiver of claim 1 wherein the edge detector comprises means for detecting an edge in the incoming signal.
17. The CIR receiver of claim 1 wherein the counter comprises cans for counting a number of cycles of the adjustable clock between edge detections.
18. A method of determining a carrier frequency of a consumer infrared (CIR) signal and decoding the CIR signal comprising:
switching to a modulated signal;
setting an adjustable clock to a carrier frequency detection sampling rate;
detecting an edge in the incoming signal;
counting a first number of clock cycles between edge detections;
temporarily storing the first number in a memory;
determining a carrier frequency based on the first number;
switching to a demodulated signal;
setting the adjustable clock to a decoding sampling rate; and
repeating an iteration comprising:
detecting an edge in the incoming signal;
counting a second number of clock cycles between edge detections;
temporarily storing the second number in memory;
detecting an edge in the incoming signal;
counting a third number of clock cycles between edge detections;
adding a total elapsed time spent in carrier frequency detection mode to the third number; and
temporarily storing the third number in memory.
19. The method of claim 18 wherein:
detecting the edge in the incoming signal;
counting the first number of clock cycles between edge detections; and
temporarily storing the first number in the memory;
are repeated until a sufficiency criteria is met.
20. The method of claim 18 further comprising determining a duty cycle of the carrier by using the first number of clock cycles.