Systems and methods for de-noising gnss signals

A GNSS receiver comprising:

• an antenna;
• a front end;
• an RF to baseband converter;
• one or more analog to digital (A/D) converters;
• a digital signal processing (DSP) processor;
• and
• memory in communication with the DSP processor;
• wherein the GNSS receiver is configured to:
• receive, at the antenna, a first signal and a second signal, wherein at least the second signal includes noise, and wherein the first signal is characterized by a first carrier frequency, and wherein the second signal is characterized by a second carrier frequency;
• filter, by the front end, at least a portion of the received first and second signals;
• down convert, with the RF to baseband converter, the filtered first and second signals to respective first baseband and second baseband signals;
• sample, with the one or more A/D converters, the first baseband and second baseband signals to produce complex first samples and complex second samples;
• accumulate the complex first samples and the complex second samples;
• determine, with the DSP processor, non-ambiguous instantaneous first phase samples of the complex first samples;
• produce normalized non-ambiguous instantaneous first phase samples by multiplying the non-ambiguous instantaneous first phase samples of the complex first samples by the second carrier frequency divided the first carrier frequency;
• construct a normalized first counter rotation phasor by taking a complex exponential of a negated version of the normalized non-ambiguous instantaneous first phase samples;
• generate a counter-rotated second observable by multiplying the complex second samples by the normalized first counter-rotation phasor;
• apply a low pass filter to the counter-rotated second observable to remove noise;
• and
• output the filtered second observable.

A non-transitory computer readable storage medium storing instructions for use with one or more processors in communication with a memory, and wherein the instructions are configured to cause the one or more processors to perform a method comprising:

• receiving, at a GNSS receiver, a first signal and a second signal, wherein at least the second signal includes noise, and wherein the first signal is characterized by a first carrier frequency, and wherein the second signal is characterized by a second carrier frequency;
• down converting the first and second signals to respective first baseband and second baseband signals;
• sampling the first baseband and second baseband signals to produce complex first samples and complex second samples;
• cross-correlating and accumulating the complex first samples and the complex second samples;
• determining ambiguous instantaneous first phase of the complex first samples;
• determining non-ambiguous instantaneous first phase samples of the complex first samples;
• producing normalized non-ambiguous instantaneous first phase samples by multiplying the non-ambiguous instantaneous first phase samples by the second carrier frequency divided the first carrier frequency;
• constructing a normalized first counter rotation phasor by taking a complex exponential of a negated version of the normalized non-ambiguous instantaneous first phase samples;
• generating a counter-rotated second observable by multiplying the complex second samples by the normalized first counter-rotation phasor;
• applying a low pass filter to the counter-rotated second observable to remove noise;
• and
• outputting the filtered second observable.