Night guidance of self-propelled missiles

Claim 1

WHAT WE CLAIM IS:- 1 A method for masking on the display device associated with a thermal telescope for the night guidance of self-propelled missiles carrying an infrared source, the image of a source of relatively intense stray radiations, wherein, on the one hand, the radiations transmitted in the field of vision of the thermal telescope and simultaneously detected in two different spectral bands, of which the one, called the useful band, corresponds to the maximum radiations from the target and the surrounding landscape, and the other one, called the stray band, corresponds to the maximum radiations from the intense infrared sources carried or not by the missile, and on the other hand the signal detected in the first band is corrected by the signal detected in the second band in a manner to leave out the stray portions of the useful signal. 2 A device for performing the method according to claim 1, comprising a ther 50 mal telescope associated with bi-spectral detection means and a display device, further comprising means for processing the signals detected by said bi-spectral detection means, said means correcting the signal detected 55 in the useful spectral band by the signal detected in the stray spectral band in order to decrease the voltage of the stray portion of the first signal down to a value at most equal to that of the useful portion of said 60 signal. 3 A device according to claim 2 wherein the processing means are arranged in such manner as to reduce to zero the voltage of the stray portion 65 4 A device according to claim 2 wherein the processing means are arranged in such manner as to cause the voltage of the stray portion to be brought back to the level of that of the useful portion of the signal 70 A device according to claim 3 wherein the processing means comprise a gate whose control input is fed by the signal detected in the second spectral band after being amplified and thereafter shaped by a thres 75 hold device followed by a peak-shift limiter. 6 A device according to claim 1 wherein the processing means comprise a subtracting device receiving the signals detected in the two spectral bands after adjustable am 80 plification and suitable delay. 7 A device for the night guidance of self propelled missiles substantially as hereinbefore described with reference to and as illustrated in Fig 1 or Fig 3 of the 85 accompanying drawings. 8 A method for the night guidance of self propelled missiles substantially as hereinbefore described with reference to and as illustrated in Figs 1 and 2 or Figs 3 and 90 4 of the accompanying drawings. Agents for the Applicants: WILSON, GUNN & ELLIS Chartered Patent Agents 41 Royal Exchange Manchester M 2 7 DB Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1980. Published at the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.