Solid state barometric altimeter-encoder

• US 4,106,343 A
• Filed: 05/31/1977
• Issued: 08/15/1978
• Est. Priority Date: 05/31/1977
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Cook, Harry
• Primary Examiner(s): Ciarlante, Anthony V.
• Application Number:
  US05/801,937
• Time in Patent Office: 441 Days
• Field of Search: 73/384, 73/387, 73/386, 235/151.32, 235/150.2, 340/27 NA, 340/347 NT
• US Class Current: 73/387
• CPC Class Codes: G01C 5/06 by using barometric means
• CPC Class Codes: G01L 9/06 of piezo-resistive devices

Abstract

A solid-state barometric altimeter-encoder. The atmospheric pressure is cared to a reference vacuum on a hybrid IC pressure transducer which generates a proportional signal. This analog signal is then converted into digital data, corrected for atmospheric to altitude non-linearity by use of a ROM look-up table, displayed as a digital readout and also converted to Grey code format for transponder MC (altitude) transmission.

Claims

1. A barometric altimeter-encoder which comprises:

pressure sensing means to electronically sense pressure and to generate an analog voltage signal which is proportional to the applied atmospheric pressure;

analog-to-digital converter means to convert said analog voltage signal into a corresponding digital pressure signal;

memory means including look-up table means, having address inputs, a first set of data outputs, and a second set of data outputs, with connections from the analog-to-digital converter means to said address inputs, so that for each possible value of the digital pressure signal there are output signals at the first set of data outputs in a first digital code indicating altitude, and output signals at the second set of data outputs in a second digital code also indicating altitude;

baroset digital switch means for setting a value representing the current site atmospheric pressure, baroset converter means to convert the last said value to the first digital code, arithmetic combining means with input connections from the first set of data outputs and from the baroset converter means to correct the signals from the first set of data outputs to give the true altitude above sea level;

display means to visually display the output from said combining means;

and a transponder having inputs from said second set of data outputs for transmitting signals representing the altitude in said second digital code to a remote receiver.

2. The altimeter-encoder according to claim 1, wherein said digital pressure signals are in straight binary code, said first digital code is binary-coded-decimal, and said second digital code is a gray code;

wherein said pressure sensing means includes temperature compensation means, and there further being a temperature compensating circuit coupled between the output of said pressure sensing means and said analog-to-digital converter means.

3. The altimeter-encoder according to claim 1, wherein said memory means comprises a first set of read-only-memory modules connected between said address inputs and said first data outputs, and a second set of read-only-memory modules connected between said first data outputs and said second data outputs.

4. The altimeter-encoder according to claim 1, wherein said display means comprises a numeric display to display the current altitude, and a plurality of circumferentially disposed light-emitting diodes to generate an analog display.