Analog Data Recording with a Video Cassette Recorder

A multichannel, analog data storage system is presented which utilizes a compact video cassette recorder. Typical video cassette recorders operate at 3¿ips and consequently allow up to one hour of continuous recording. The rotary two-head, helical-scan system employed yields a relative head-to-tape speed of 404.3 ips and a bandwidth of 3 to 4 MHz. The analog recording system described herein consists of an encoder which multiplexes and digitizes eight analog signals, a video recorder for storage of the digital data, and a decoder which demultiplexes and recovers the analog information. One unique feature of this system is that digital words which are generated consist of the channel number as well as the analog information present on that channel at the time of sampling. All information is combined serially and recorded with each word uniquely separated by a special "sync pulse." Another system feature is the ability to individually select the data bandwidth of each analog channel from values between approximately 25 kHz to 3 Hz. Design, fabrication, and evaluation is given. Interfacing to computing systems and microprocessors is discussed. An eight channel system with eight bit data words is described yielding approximately one-half percent resolution. However, the system is readily expandable to any number of channels and up to 16 bit data words yielding more resolution or higher signal-to-noise ratio.