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Barometric altimeter

  • US 3,958,459 A
  • Filed: 10/26/1973
  • Issued: 05/25/1976
  • Est. Priority Date: 10/28/1972
  • Status: Expired due to Term
First Claim
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1. A barometric altimeter comprising:

  • means for generating an electrical signal Vr representing the atmospheric pressure at a reference altitude,means including a pressure sensor for generating an electrical signal Vm responsive to the atmospheric pressure at the altitude to be measured,means for generating an electrical signal v varying exponentially with time,means comparing said electrical signal v for coincidence with said electrical signals Vr and Vm for generating electrical pulses at the respective times of coincidence, tr and tm,a function generator containing a shift register loaded with a predetermined initial value, a memory storing a constant value and being non-destructively readable, a delay circuit, a complementer, first and second adders and a command pulse generator producing command pulses of a frequency determined in relation to the known characteristics of the pressure sensor, the output of said shift register being connected to one of the inputs of said first adder and also to the input of said complementer, and the output of said memory being connected to the other input of said first adder, and the output of said first adder being connected to the input of said delay circuit, and the output of said complementer being connected to one of the inputs of said second adder, and the output of said delay circuit being connected to the other input of said second adder, and the output of said second adder being connected to the input of said shift register, said function generator including means for reading out said shift register and said memory simultaneously in response to each of said command pulses in operation of said function generator,means to control the operation of said function generator to initiate operation thereof in response to the earlier generated one of said electrical pulses generated at the times tr and tm and to terminate the operation thereof in response to the later generated one of said electrical pulses generated at the times tr and tm, andsaid register, at termination of operation of said function generator, storing therein a value representative of the altitude to be measured.

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