Digital Time-Base Error Compensator for Wideband Telemetry Recorder/Reproducers

Abstract

An advanced development model of a telemetry predetection recording error compensator was designed to reduce flutter and time displacement errors in magnetic tape instrumentation recorder/reproducers so that the final intra-channel timebase error (TBE) does not exceed ±0.1 μsec. The device will operate with recorder/reproducers having bandwidths up to 1.5 MHz and as much as a millisecond of TBE. The incoming waveform is sampled, digitized, and stored in a memory on a recorded pilot tone at a rate determined by the flutter, using phase-lock techniques. Subsequent readout of the memory, composed of MOS shift registers, at a synchronous rate, produces a replica of the playback waveform with wow, flutter, and TBE significantly reduced. This technique offers the following advantages over other approaches: direct delay/BW trade-off (i.e. , 1 msec TBE correction at 120 ips, 2 msec TBE correction at 60 ips, etc.), small size, lightweight, low power requirements, and extensive use of MOS and IC devices, amenable to future LSI construction.