An efficient fractional sample delayer for digital beam steering

In this paper we propose to use digital fractional sample delayers to perform high precision beam steering at the baseband sampling frequency. The major advantages of the proposed technique are that the fractional sample delayer (FSD) used has a very flat magnitude response within the baseband width allowing greater than 20-bit resolution for a 35-tap finite impulse response filter. It also has a delay which is continuously variable providing resolutions greater than 220,000ths of the baseband sampling time. Owing to the signal delay being performed at the baseband rate, elements with different delays may be placed in parallel, allowing for the formation of multiple beams (e.g. tracking and surveillance capability simultaneously).