Gps receiver with improved immunity to burst transmissions

A radio receiver for receiving radio signals, the radio receiver comprising:

• an automatic gain control (AGC) component adapted to control a gain value of the automatic gain control component based on a signal identifying a received signal overload condition;
• a converter for deriving a bit-stream of digital data from a received radio signal;
• and
• a data modifier for substituting the bit-stream of digital data with a locally generated bit pattern in response to a signal identifying the received signal overload condition, the locally generated bit pattern being selected such that when processed it causes less noise to accumulate in the radio receiver back-end than if the bit-stream of digital data were processed using the gain of the AGC component;
• wherein when a signal overload condition is identified the AGC is configured to:
• capture a given value of the gain value that occurred at a point in time prior to the received signal overload condition being identified;
• wherein during the signal overload condition:
• instead of using the AGC component to control the gain applied to a received radio signal, the data modifier couples the locally generated bit pattern into the radio receiver back-end;
• wherein after the received signal overload condition is identified to have ended the AGC is configured to:
• set the gain value of the AGC component to the given value and process the received radio signal using the gain of the AGC component.

A method of limiting the effect of interfering transmission on a GPS receiver, the method comprising:

• controlling a gain value of an AGC component based on a signal identifying a received signal overload condition provided by a transmitter local to the GPS receiver;
• wherein the step of controlling a gain value comprises:
• when a signal overload condition is identified:
• capturing a given value of the gain value that occurred at a point in time prior to the received signal overload condition being identified;
• during the signal overload condition:
• instead of using the AGC component to control the gain applied to a received radio signal, coupling a locally generated bit pattern into a radio receiver back-end in response to a presence of the signal identifying the received signal overload condition, the locally generated bit pattern selected such that when processed causes less noise to accumulate in the radio receiver back-end than if a bit-stream derived from the received radio signal were processed using the gain of the AGC component;
• after the received signal overload condition is identified to have ended:
• setting the gain value of the AGC component to the given value and processing the received radio signal using the gain of the AGC component.