Frequency ramp modulation
A frequency ramp modulation technique that encodes information using frequency ramps in a transmit signal. Frequency ramp modulation according to the present teachings may be employed in a communication system that includes a narrow band receiver to maintain communication even as the pass band of the narrow band receiver drifts with temperature or other factors.
1 . A communication system, comprising:
transmitter that generates a transmits signal such that an information carried in the transmit signal is indicated by a frequency ramp in the transmit signal;
receiver that obtains the information from the transmit signal by detecting the frequency ramp.
2 . The communication system of claim 1 , wherein the frequency ramp comprises an increase in a frequency of the transmit signal over time.
3 . The communication system of claim 1 , wherein the frequency ramp comprises a decrease in a frequency of the transmit signal over time.
4 . The communication system of claim 1 , wherein the frequency ramp comprises a step-wise increase in a frequency of the transmit signal over time.
5 . The communication system of claim 1 , wherein the frequency ramp comprises a step-wise decrease in a frequency of the transmit signal over-time.
6 . The communication system of claim 1 , wherein the transmitter includes a frequency-ramp modulator comprising:
ramp generator that generates a ramp signal in response to the information;
voltage controlled oscillator that generates the transmit signal in response to the ramp signal.
7 . The communication system of claim 1 , wherein the receiver includes a frequency ramp demodulator that recovers the information from the transmit signal.
8 . The communication system of claim 1 , wherein the receiver comprises:
filter that provides a filter output signal by filtering the transmit signal;
frequency ramp demodulator that recovers the information from the filter output signal.
9 . The communication system of claim 8 , wherein a frequency range of the transmit signal is selected in response to a variability in a pass band of the filter.
10 . A method for communication, comprising:
generating a transmits signal such that an information carried in the transmit signal is indicated by a frequency ramp in the transmit signal;
obtaining the information from the transmit signal by detecting the frequency ramp.
11 . The method of claim 10 , wherein generating a transmits signal includes generating the frequency ramp having an increase in a frequency of the transmit signal over time.
12 . The method of claim 10 , wherein generating a transmits signal includes generating the frequency ramp having a decrease in a frequency of the transmit signal over time.
13 . The method of claim 10 , wherein generating a transmits signal includes generating the frequency ramp having a step-wise increase in a frequency of the transmit signal over time.
14 . The method of claim 10 , wherein generating a transmits signal includes generating the frequency ramp having a step-wise decrease in a frequency of the transmit signal over time.
15 . The method of claim 10 , wherein generating a transmits signal comprises:
generating a ramp signal in response to the information;
generating the transmit signal in response to the ramp signal.
16 . The method of claim 10 , wherein obtaining comprises:
generating a filter output signal by filtering the transmit signal;
recovering the information from the filter output signal.
17 . The method of claim 16 , further comprising selecting a frequency range of the transmit signal in response to a variability in a pass band of the filter output signal.