GB1311337A - Altimeter range computer - Google Patents

Abstract

1311337 Altimeter MESSERSCHMITT-BOLKOW-BLOHM GmbH 10 Sept 1970 [14 Oct 1969] 43362/70 Heading H4D In an altimeter emitting pulses of radiation, preferably laser light radiation, and having an automatic tracking gate facility, loss of the echo in the tracking circuit causes a change over to a search mode and the movement of the range gate, initially through a range in the vicinity of the range of the echo when lost and then, if acquisition is not obtained, through the whole range of the altimeter. Production of the range gate is by standard comparison in gate generator 3 of a sawtooth voltage from generator 2 starting synchronously with each transmitted pulse, and a voltage from generator 4 representative of the tracked range, the tracking loop being completed by the output of gate error amplifier 6 controlling generator 4. If the echo is lost a search generator 9, Fig. 2, causes the range voltage generator 4 to produce a slow sawtooth varying by a small amount about the voltage representative of the lost range. If the echo is not reacquired the generator 4 is caused to produce a slow sawtooth extending over the full range voltage. In the tracking mode with switches 51 and 52 as shown, the range representative voltage is fed in at 110 and is stored across capacitor 35. Loss of the echo causes switch 52 to move to its centre-" no input "-position and a sawtooth generator 12, 13, 21, 31 to produce a sawtooth at the input of transistor 14. Conduction of transistor 14 at predetermined level of the sawtooth causes a pulse which via inverter NAND element 41, transistor 15, Schmitt trigger 43, 44 and NAND gate 43, causes the enabling of transistor 11 and the cessation of the sawtooth. The sawtooth output 100 thus varies about a voltage proportional to the voltage across capacitor 35. If the echo is not thus reacquired the switches 52 and 51 are set to their lower positions such that the full range voltage on input 54 is applied across the capacitor.