Recording of physiological signals with domestic videotape storage

A system is presented for the recording of physiological signals on an unmodified domestic videocassette recorder (VCR). A modification in the vertical synchronism pulses permits the recording of continuous analogue signals without significant loss of samples. The system allows up to 16 input channels, with a maximum bandwidth of 20 kHz for one channel (10 kHz for two channels, 5 kHz for four, or 2.5 kHz for eight) and a minimum of 1.25 kHz for 16 channels, 12-bit resolution, a signal-to-noise ratio of nearly 70 dB and an additional channel for the recording of control and alphanumeric information. The resulting system is reliable, inexpensive, compact and of large capacity, allowing up to 8 h of uninterrupted recording.