A MAGNETIC DIGITAL RECORDING SYSTEM FOR FIELD USE

Abstract : A digital recording system for field use is discussed. The system has been in use for over three years and has presented little or no operational difficulties. Five basic sections make up the recording system in the following order: analog, sampling and quantizing, magnetic tape assembly, visual monitor, and system control. The analog section consists of eight bandpass filters which feed the chopper-stabilized dc amplifiers capable of 66-db maximum gain. The sampling-and-quantizing section consists of an 8-channel multiplexer which receives the signals from the eight isolation transformers and samples them either in parallel or sequentially. At the time of sampling, the instantaneous voltage values are held on eight sample-and-hold circuits for sequential processing by an analog-to-digital converter. The converter encodes the value held on each circuit into binary digits consisting of ten bits and a plus or minus sign (11-bit word). This will give the analog sample a quantized value of one part in 1024, plus and minus, representing about 0.1 percent resolution. The magnetic tape assembly section consists of a 16channel dual-head, digital recorder which accepts the binary output from the converter. The visual monitor section of the system makes use of the dual-head recorder to visually check the information written on the tape. (Author)