Atmospheric pressure calibration systems and methods

A system for deriving atmospheric deviation data for a location in the atmosphere, in cooperation with an airborne transponder providing response signals which may be subject to signal turnaround delay and which include current barometric altitude data, comprising:

• one or more transmitting means for transmitting first signals to said airborne transponder;
• a plurality of receiving means, positioned at spaced positions, for receiving response signals transmitted by said airborne transponder from an atmospheric location in response to said first signals, said response signals being subject to a signal turnaround delay and said response signals including barometric altitude data based on current barometric pressure in the vicinity of said atmospheric location;
• signal processing means, coupled to said receiving means and responsive to timing differences between said transmitting of said first signals and said receiving of said response signals, said signal processing means utilizing data regarding said spaced positions to adjust said timing differences to compensate for said signal turnaround delay to provide adjusted timing differences, and utilizing said adjusted timing differences to derive data representative of geometric height of said atmospheric location;
• and
• comparison means, coupled to said signal processing means, utilizing said data representative of geometric height and said barometric altitude data from said airborne transponder to derive atmospheric deviation data representative of deviation between said barometric altitude data and atmospheric pressure reference data applicable to said atmospheric location.

A system for deriving atmospheric deviation data for a location in the atmosphere comprising:

• input means for coupling input data including data based upon barometric pressure measured in the vicinity of an atmospheric location and range data representative of approximate distances to said atmospheric location from a plurality of reference points at spaced positions, and which may include azimuth data representative of approximate azimuths of said atmospheric location relative to said reference points;
• signal processing means, coupled to said input means, utilizing said range data, available azimuth data as may be selected, and data regarding said spaced positions of said reference points to derive data representative of the geometric height of said atmospheric location;
• and
• comparison means, coupled to said signal processing means, utilizing said data representative of geometric height and said data based upon barometric pressure to derive atmospheric deviation data representative of deviation between said data based upon barometric pressure and atmospheric reference data applicable to said atmospheric location.

A system, for determining geometric height in cooperation with an airborne transponder providing response signals, comprising:

• one or more transmitting means for transmitting first signals to said airborne transponder;
• a plurality of receiving means positioned at spaced positions, for receiving response signals from said airborne transponder in response to said first signals;
• and
• signal processing means, coupled to said transmitting means and responsive to timing differences between said transmitting of said first signals and said receiving of said response signals, said signal processing means utilizing data regarding said spaced positions to determine geometric height of said airborne transponder. representing successive cycles of transmitting of a said first signal by said transmitting means and receiving of a said response signal by the same one of said receiving means.

A system, for determining geometric height in cooperation with an airborne transponder providing response signals which are subject to signal turnaround delay, comprising:

• one or more transmitting means for transmitting first signals to said airborne transponder;
• a plurality of receiving means positioned at spaced positions, for receiving response signals, which are subject to a signal turnaround delay between reception of a first signal and transmission of a response signal, from said airborne transponder in response to said first signals;
• and
• signal processing means, coupled to said transmitting means and responsive to timing differences between said transmitting of said first signals and said receiving of said response signals, said signal processing means utilizing data regarding said spaced positions to adjust said timing differences to compensate for said signal turnaround delay to provide adjusted timing differences and utilizing said adjusted timing differences to determine geometric height of said airborne transponder.

A system, for deriving an approximate value of signal turnaround delay between reception of an interrogation signal by an airborne transponder and transmission of a response signal by said airborne transponder, comprising:

• one or more transmitting means for transmitting interrogation signals to an airborne transponder;
• a plurality of receiving means, positioned at spaced positions, for receiving response signals, which are subject to said turnaround delay, from said airborne transponder in response to said interrogation signals;
• and
• signal processing means, coupled to said receiving means and responsive to timing differences between said transmitting of said interrogation signals and said receiving of said response signals, said signal processing means utilizing data on said spaced positions to determine an approximate value of said turnaround delay between reception of an interrogation signal by said airborne transponder and transmission of a response signal by said airborne transponder in response to said interrogation signal;
• whereby, said approximate value of said turnaround delay is usable for calibration of transmission and reception timing characteristics of said airborne transponder.

A method, for deriving atmospheric deviation data for a location in the atmosphere, in cooperation with an airborne transponder providing response signals including current data based upon barometric pressure, comprising the steps of:

• (a) transmitting first signals to said airborne transponder;
• (b) receiving, at a plurality of spaced positions, response signals transmitted by said airborne transponder from an atmospheric location in response to said first signals, said response signals including data based upon barometric pressure in the vicinity of said atmospheric location;
• (c) utilizing timing differences between said transmitting of said first signals in step (a) and said receiving of said response signals in step (b), with geometric data regarding said spaced positions, for deriving data representative of geometric height of said geometric location;
• (d) comparing said geometric height data as derived in step (c) with said data based upon barometric pressure as received in step (b) from said airborne transponder;
• and
• (e) utilizing the results of said step (d) comparison to derive atmospheric deviation data representative of deviation between said data based upon barometric pressure and atmospheric reference data applicable to said atmospheric location.

A method, for deriving atmospheric deviation data for a location in the atmosphere, comprising the steps of:

• (a) receiving input data including data based upon barometric pressure measured in the vicinity of an atmospheric location and range data representative of approximate distances to said atmospheric location from a plurality of reference points at spaced positions, and which may include azimuth data representative of approximate azimuths of said atmospheric location relative to said reference points;
• (b) utilizing said range data and/or said azimuth data, together with geometric data regarding said spaced positions of said reference points, for deriving data representative of the geometric height of said atmospheric location above a datum level;
• (c) comparing said geometric height data as derived in step (b) with said data based upon barometric pressure as received in step (a);
• and
• (d) utilizing the results of said step (c) comparison to derive atmospheric deviation data representative of deviation between said data based upon barometric pressure and atmospheric reference data applicable to said atmospheric location.

A method for inflight calibration of a barometric altimeter located in an aircraft, comprising the steps of;

• (a) transmitting first signals to an airborne transponder located in said aircraft;
• (b) receiving, at a plurality of spaced positions, response signals transmitted by said airborne transponder in response to said first signals;
• (c) utilizing timing differences between said transmitting of said first signals and said receiving of said response signals and geometric data regarding said spaced positions for determining geometric height of said airborne transponder;
• (d) transmitting data representative of said geometric height to said aircraft;
• and
• (e) utilizing said data to adjust the calibration of said barometric altimeter as necessary to achieve desired consistency between said geometric height and altitude measurements provided by said barometric altimeter.