Radio frequency modem and method
First Claim
1. A radio frequency modulator/demodulator comprising:
- receiving section means for producing a demodulated data output signal from a modulated R.F. signal received on an R.F. data link, said receiving means includinglocal oscillator means for generating a local oscillator signal;
mixer means for combining said local oscillator signal and said received R.F. signal and producing an intermediate frequency signal;
variable gain amplifier means for amplifying said intermediate frequency signal with a gain which is a function of an automatic gain control signal;
detector means for demodulating said amplified intermediate frequency signal;
digitizing means for receiving a demodulated output signal from said detector means and for producing a digital data output signal, said digitizing means including(a) first peak signal means for producing a first peak signal representative of a maximum excursion of said demodulated output signal in a first direction, said first peak signal means comprising a first comparator circuit;
(b) second peak signal means for producing a second peak signal representative of a maximum excursion of said demodulated output signal in a second direction opposite said first direction, said second peak signal means comprising a second comparator circuit;
automatic gain control signal generating means for producing said automatic gain control signal indicative of the amplitude of said demodulated output signal in response to said first peak signal, said automatic gain control signal generating means comprising a third comparator circuit; and
transmitting section means for producing a modulated R.F. signal output signal on the data link utilizing an input data signal.
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Accused Products
Abstract
A radio frequency modulator/demodulator (modem) and method for receiving and transmitting data over a radio frequency data link. The modem has a transmitting section which includes a modulator which modulates a radio frequency signal in response to data provided by, for example, an associated processor. The transmitting section further includes a watchdog or enable circuit which monitors a request-to-send signal produced by the associated processor, with the request-to-send signal being present when the processor is generating data to be transmitted over the data link. The enable circuit will disable the modulator should a transmission exceed a maximum predetermined time period, thereby preventing the associated processor from monopolizing the data link in the event of a processor failure.
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Citations
7 Claims
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1. A radio frequency modulator/demodulator comprising:
receiving section means for producing a demodulated data output signal from a modulated R.F. signal received on an R.F. data link, said receiving means including local oscillator means for generating a local oscillator signal; mixer means for combining said local oscillator signal and said received R.F. signal and producing an intermediate frequency signal; variable gain amplifier means for amplifying said intermediate frequency signal with a gain which is a function of an automatic gain control signal; detector means for demodulating said amplified intermediate frequency signal; digitizing means for receiving a demodulated output signal from said detector means and for producing a digital data output signal, said digitizing means including (a) first peak signal means for producing a first peak signal representative of a maximum excursion of said demodulated output signal in a first direction, said first peak signal means comprising a first comparator circuit; (b) second peak signal means for producing a second peak signal representative of a maximum excursion of said demodulated output signal in a second direction opposite said first direction, said second peak signal means comprising a second comparator circuit; automatic gain control signal generating means for producing said automatic gain control signal indicative of the amplitude of said demodulated output signal in response to said first peak signal, said automatic gain control signal generating means comprising a third comparator circuit; and transmitting section means for producing a modulated R.F. signal output signal on the data link utilizing an input data signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
Specification