Programmable Matched Filtering with Acousto-electric Convolvers in Spread-Spectrum Systems.

摘要

Acoustoelectric convolvers for a spread-spectrum communication application are described with a 100-MHz-bandwidth capability. The use of convolvers as programmable matched filters provides the ability to change the coding waveform from bit-to-bit, thus offering improved multipath performance, security against decoding, and protection against repeat jamming. In this paper we describe design and performance details of a prototype convolver which processes signals of 10 microseconds duration with a 100-MHz bandwidth. A dynamic range of 50 dB is obtained and error signals are 30 dB below the output signal with input signal levels of +14 dBm. A test circuit is described which creates typical spread-spectrum signals in which each bit is encoded into 512 chips and data is encoded by inverting the phase of an entire bit at a data rate of 100 kbits/s. Examples of typical convolver outputs will be described, including spurious artifacts due to a pseudorandom-shift-register code, with a code-cycle time of 36 minutes. (Author)