The Cancellation of Permanent Echoes by the Use of Coherent Pulses.
Interim technical note,
ROYAL AIRCRAFT ESTABLISHMENT FARNBOROUGH (ENGLAND)
Pagination or Media Count:
The problem of removing the clutter permanent echoes on ground radar stations is one of some importance, and the method of cancellation using the coherent pulse technique theoretically provides one of the most complete answers to this problem. In practice it has been applied to 50 cm. radar equipments A.M.E.S. Type 11 and though not perfect, has shown very satisfactory results, a demonstration on a P.P.I. display having already been given at the R.A.E. The signalnoise gain or loss varies with the radial velocity of the target, but the range of velocity effectively coverd can of course be shifted by adjustment of the recurrence period, and the corresponding delay time. The technique of permanent echo cancellation described consists of two stages. The first stage is the application of the Doppler technique and the second is the elimination of the P.E.s. by means of a delay line. One set of echoes is stored by the latter until the next set arrives and the two sets are then subtracted. Test results have been sufficiently satisfactory to justify further work being put in hand.