Oscillators having arbitrary frequencies and related systems and methods
Systems and methods for operating with oscillators configured to produce an oscillating signal having an arbitrary frequency are described. The frequency of the oscillating signal may be shifted to remove its arbitrary nature by application of multiple tuning signals or values to the oscillator. Alternatively, the arbitrary frequency may be accommodated by adjusting operation one or more components of a circuit receiving the oscillating signal.
1. A method comprising:
downconverting a cellular telephone signal, the cellular telephone signal modulated with data, using an oscillating reference signal having an arbitrary frequency to generate a downconverted signal including the data;
sampling the downconverted signal with an analog-to-digital converter (ADC) using a sampling rate selected to induce a shift of the data of the downconverted signal in a frequency domain; and
receiving an indication of a value of the arbitrary frequency and selecting the sampling rate of the ADC in response to receiving the indication,
wherein receiving the indication comprises receiving the indication from memory of an oscillator.
2. The method of claim 1 , further comprising receiving the cellular telephone signal modulated with data.
3. The method of claim 1 , further comprising receiving, from the oscillator, the oscillating reference signal having an arbitrary frequency, the oscillator having a mechanical resonator.
4. The method of claim 1 , further comprising generating the oscillating reference signal from an oscillator output signal of the oscillator.
5. The method of claim 4 , wherein generating the oscillating reference signal comprises receiving, from the oscillator, the oscillator output signal at a frequency synthesizer and synthesizing the oscillating reference signal, wherein the oscillating reference signal differs in frequency from a frequency of the oscillator output signal, and wherein the oscillator has a mechanical resonator.
6. The method of claim 5 , wherein the frequency synthesizer is a phase-locked loop (PLL).
7. A method comprising:
downconverting a first signal, the first signal modulated with data, using an oscillating reference signal having an arbitrary frequency to generate a downconverted signal including the data;
sampling the downconverted signal with an analog-to-digital converter (ADC) to produce a digital signal including digital data corresponding to the data;
shifting, using a digital signal processor (DSP), the digital data in a frequency domain; and
receiving an indication of a value of the arbitrary frequency and, in response to receiving the indication, selecting an amount by which to shift the digital data in the frequency domain using the DSP,
wherein receiving the indication comprises receiving the indication from memory of an oscillator.
8. The method of claim 7 , further comprising receiving the first signal modulated with data.
9. The method of claim 7 , further comprising receiving, from the oscillator, the oscillating reference signal having an arbitrary frequency, the oscillator having a mechanical resonator.
10. The method of claim 7 , further comprising generating the oscillating reference signal from an oscillator output signal of the oscillator.
11. The method of claim 10 , wherein generating the oscillating reference signal comprises receiving, from the oscillator, the oscillator output signal at a frequency synthesizer and synthesizing the oscillating reference signal, wherein the oscillating reference signal differs in frequency from a frequency of the oscillator output signal, and wherein the oscillator has a mechanical resonator.
12. The method of claim 11 , wherein the frequency synthesizer is a phase-locked loop (PLL).
13. The method of claim 7 , wherein the first signal is a cellular telephone signal.
14. The method of claim 7 , wherein the arbitrary frequency differs from a standard oscillator frequency and wherein sampling the downconverted signal with an ADC comprises using a sampling rate corresponding to the standard oscillator frequency.
15. The method of claim 14 , wherein the first signal is modulated with analog data, and further comprising:
applying the digital signal to a carrier tracking loop.
16. The method of claim 15 , wherein the carrier tracking loop comprises a numerically controlled oscillator (NCO) configured to digitally shift the digital data in a frequency domain.
17. The method of claim 15 , wherein the first signal is a cellular telephone signal modulated with cellular telephone data.
18. The method of claim 15 , wherein the first signal is a global positioning system (GPS) signal.