Digital RF receiver

A method for digitally processing a signal in a noisy environment, comprising the steps of:

• inputting the signal into a receiver;
• attenuating the signal prior to said inputting with a digital attenuator driven by a digital processor to prevent saturation of the receiver and the loss of useful information from the signal;
• processing the attenuated signal with the receiver;
• sampling and digitizing the processed signal from the receiver with a sampling A/D converter at a predetermined rate;
• routing the digitized signal from the sampling A/D converter through a multi-pass loop a predetermined number of times, said loop comprising an array of digital processors configured as a multi-bandpass filter section operably configured to receive and filter the digitized signal from the sampling A/D converter, a narrow band finite impulse response bandpass filter section operably configured to receive and filter the digitized signal from the multi-bandpass finite impulse response filter section, and a matched filter section operably configured to receive the digitized signal from the narrow band finite impulse response bandpass filter section to flush valid binary data from the digitized signal;
• and
• outputting the valid binary data as serial data for further processing.

A digitally enhanced receiving system for processing radio frequency signals, comprising:

• an antenna for receiving an incoming RF signal;
• a superheterodyne receiver for filtering and mixing the received signal, said receiver comprising
• a first mixer and intermediate frequency section;
• a first filter device connected in series with said first mixer and intermediate frequency section;
• a second mixer and intermediate frequency section connected in series with said first filter device;
• a second filter device connected in series with said second mixer and intermediate frequency section;
• and
• a third mixer and intermediate frequency section connected in series with said second filter device;
• automatic gain control means for attenuating the incoming signal before said signal is processed by said receiver, said automatic gain control means comprising
• a flash A/D converter;
• a digital signal processor;
• and
• a digital attenuator, said flash A/D converter sampling the received signal at the output of said second mixer and intermediate frequency section at a rate substantially equal to the speed of said digital processor, said digital signal processor responding to the sampled signal from said flash A/D converter to drive said digital attenuator so as to attenuate said incoming radio frequency signal prior to said signal being processed by said receiver;
• a variable gain amplifier for increasing the level of the signal emerging from said receiver, said variable gain amplifier being driven by said digital processor;
• a sampling A/D converter for sampling and digitizing the signal emerging from said receiver at a rate of at least one and a half times the Nyquist rate;
• a microprocessor array for processing useful information from the digitized signal emerging from said sampling A/D converter, said microprocessor array further comprising
• a multiband finite impulse response bandpass filter operably configured to receive and filter the digitized signal from said sampling A/D converter;
• at least two narrow band finite impulse response bandpass filters configured in parallel to receive and filter the digitized signal from said multiband finite impulse response bandpass filter;
• a matched filter operably configured to receive and filter the digitized signal from said parallel narrow band finite impulse response bandpass filters;
• and
• an auto-recursive loop for passing the digitized signal through said microprocessor array filters a predetermined number of passes to flush valid data therefrom, said microprocessor shifting the bandpass of said filters to change the characteristics thereof prior to each said pass of the digitized signal;
• a buffer for storing valid binary data flushed from the digitized signal through said filters;
• and
• means for outputting the valid binary data as serial data.

A digitally enhanced radio frequency receiving system for receiving and demodulating signals in a noisy environment, said system comprising:

• receiver circuitry means for filtering and mixing an incoming analog signal;
• automatic gain control means for digitally attenuating said incoming signal before said incoming signal is processed by said receiver circuitry means so that any useful information contained in said incoming signal will not be lost due to saturation of said receiver circuitry means, said automatic gain control means comprising a digital attenuator upstream from said receiver circuitry means, a flash A/D converter sampling the output from said digital attenuator before complete processing thereof by said receiver circuitry means, and a gain control digital processor in operative communication with said flash A/D converter and said digital attenuator, said flash A/D converter sampling at a rate compatible with said gain control digital processor, said gain control digital processor receiving the sampled and digitized signal from said flash A/D converter and driving said digital attenuator in response to said sampled and digitized signal;
• converter means for sampling and digitizing the output signal from said receiver circuitry means at a predetermined rate;
• and
• digital circuitry means for processing the digitized signal from said converter means into useful digital information, said digital circuitry means further controlling said automatic gain control means.

A digitally enhanced radio frequency receiving system for receiving and demodulating signals in a noisy environment, said system comprising:

• receiver circuitry means for filtering and mixing an incoming analog signal;
• automatic gain control means for digitally attenuating said incoming signal before said incoming signal is processed by said receiver circuitry means so that any useful information contained in said incoming signal will not be lost due to saturation of said receiver circuitry means;
• converter means for sampling and digitizing the output signal from said receiver circuitry means at a predetermined rate;
• and
• digital circuitry means for processing the digitized signal from said converter means into useful digital information, said digital circuitry means further controlling said automatic gain control means, said digital circuitry means comprising narrow band and wide band digital filtering means for filtering the digitized signal from said converter means, and multi-loop auto-recursive means for flushing valid binary data by passing the digitized signal through said filtering means a predetermined number of passes.

A long range radio frequency transmitting and acknowledgement receiving system, comprising:

• a transmitting station;
• a remote portable receiver for receiving a radio frequency signal from said transmitting station;
• a remote portable transmitter for transmitting an acknowledgement return signal to said transmitting station;
• digital means at a receiving station for receiving and processing said return signal in the presence of narrow band and wide band interference, said digital receiving and processing means comprising:
• receiver circuitry for filtering and mixing said return signal to a desired carrier frequency;
• automatic gain control means operatively configured to attenuate said return signal to a level so as not to drive said receiver circuitry into saturation thereby preventing clipping of said return signal and the loss of useful information contained in said return signal, said automatic gain control means comprising a digital attenuator upstream from said receiver circuitry means, a flash A/D converter sampling the output from said digital attenuator before complete processing thereof by said receiver circuitry means, and a gain control digital processor in operative communication with said flash A/D converter and said digital attenuator, said flash A/D converter sampling at a rate compatible with said gain control digital processor, said gain control digital processor receiving the sampled and digitized signal from said flash A/D converter and driving said digital attenuator in response to said sampled and digitized signal;
• converter means for sampling and digitizing the output signal from said receiver circuitry means at a predetermined rate;
• and
• digital circuitry means for processing the digitized signal from said converter means into useful digital information, said digital circuitry means further controlling said automatic gain control means.