System and method for communicating with plural remote transmitter
First Claim
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1. A system for communicating digital information from a mobile transmitter to a receiver in a fixed location wherein:
- (a) the mobile transmitter comprises;
(i) a source of digital data to be transmitted;
(ii) a chirp generator;
(iii) a control circuit for causing said chirp generator to generate plural chirp signals, the timing between some of said chirp signals being related to said digital data;
(iv) a source of a carrier signal;
(v) a modulator for modulating said carrier signal with said chirp signals to produce a modulated signal;
(vi) a radio frequency transmitter for transmitting said modulated signal; and
(b) the receiver in a fixed location comprises;
(i) a radio frequency receiver for receiving said transmitted modulated signal;
(ii) a chirp signal generator for generating plural chirp signals;
(iii) a demodulator which periodically demodulates said received signal with said plural chirp signals to produce a periodic wave signals, each wave signal having a frequency related to the time relationship between the start of one of the chirp signals and the start of the digital data within said received signal;
(iv) a frequency detector for determining the frequency of said wave signals; and
,(v) a detector for decoding the digital data from the time relationship between wave signals.
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Abstract
A system for communicating with plural remote transmitters in which the transmitters send messages without a common synchronization source or polling by a controlling receiver. In one embodiment, the system uses the time position of frequency chirp signals to encode the identity and/or other information sent from the receiver. The system may use relatively low cost transmitters because the transmitters do not need to have a message or clocking signal receiving capability and the internal clocking signal source within the transmitter may be a relatively inexpensive device or circuit.
81 Citations
14 Claims
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1. A system for communicating digital information from a mobile transmitter to a receiver in a fixed location wherein:
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(a) the mobile transmitter comprises; (i) a source of digital data to be transmitted; (ii) a chirp generator; (iii) a control circuit for causing said chirp generator to generate plural chirp signals, the timing between some of said chirp signals being related to said digital data; (iv) a source of a carrier signal; (v) a modulator for modulating said carrier signal with said chirp signals to produce a modulated signal; (vi) a radio frequency transmitter for transmitting said modulated signal; and (b) the receiver in a fixed location comprises; (i) a radio frequency receiver for receiving said transmitted modulated signal; (ii) a chirp signal generator for generating plural chirp signals; (iii) a demodulator which periodically demodulates said received signal with said plural chirp signals to produce a periodic wave signals, each wave signal having a frequency related to the time relationship between the start of one of the chirp signals and the start of the digital data within said received signal; (iv) a frequency detector for determining the frequency of said wave signals; and
,(v) a detector for decoding the digital data from the time relationship between wave signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for communicating digital data comprising:
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(a) a transmitter for transmitting a data signal, said data signal comprising a carrier signal modulated by two or more chirp signals, the length of time between chirp signals representing digital data to be communicated; (b) a receiver for receiving said transmitted data signal, said receiver demodulating said data signal and determining the digital data to be communicated from the length of time between chirp signals.
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9. A transmitter for transmitting digital data comprising:
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(a) an input terminal for receiving digital data to be transmitted; (b) a chirp generator; (c) a control circuit for causing said chirp generator to generator a string of chirp signals, the timing between some of said chirp signals being related to the received digital data to be transmitted; (d) a carrier signal source providing a carrier signal; (e) a modulator for modulating said carrier signal with said string of chirp signals to produce a modulated signal; (f) an amplifier for amplifying said modulated signal; and
,(g) an antenna for radiating said amplified modulated signal.
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10. A receiver for receiving digital data comprising:
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(a) an antenna for receiving a radiated signal containing digital data modulated thereon; (b) a down converter for down converting said received radiated signal to a lower frequency signal; (c) a chirp signal generator; (d) a demodulator which periodically demodulates said lower frequency signal with a chirp signal received from said chirp signal generator to produce a wave signal having a frequency related to the time relationship between the start of the chirp signal and the start of the digital data; (e) a filter circuit for filtering said wave signal to remove wave signals outside a predetermined range of frequencies; (f) a frequency detector for determining the frequency of the filtered wave signal; and
,(g) a detector for decoding the digital data within the filtered wave signal from the time relationship between successively demodulated filtered wave signals.
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11. In a system for locating a mobile transmitter, a transmitter comprising:
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(a) means for uniquely identifying said transmitter from other similar types of transmitters said means being located at said transmitter; (b) means for transmitting a modulated signal having encoded therein said unique identification, said encoding comprising a period of time between successive pulses related to the content of the unique identification wherein said means for transmitting further comprises; (c) a chirp signal generator; (d) a source of a carrier signal; (e) a modulator having as one of its inputs said carrier signal; and
,(f) a timing control circuit to apply chirp signals to said modulator in a timed relationship between chirp signals to encode the unique identification as a modulation of said carrier signal. - View Dependent Claims (12, 13, 14)
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Specification