A Generator for Testing Signals of Electroencephalographs and Electrocardiographs

Abstract

Testing of electrocardiographic (ECG) and electroencephalographic (EEG) channels of medical devices includes application of: 1) signals of standard (harmonic and meander) waveform used to measure the amplification parameters; 2) simulated electrophysiological signals used to assess the performance of algorithms for recognition and data processing. Standard signals are usually generated using laboratory function generators. Reference ECG and EEG signals can be obtained using programmable function generators (such as GF05), special generators of ECG and EEG signal [5-7], or computer DAC cards with appropriate software. To facilitate testing of ECG and EEG equipment and improve the noise immunity of the signal source, we combined a generator of standard signals and a simulator of electrophysiological signals in the single inexpensive portable device Neirotest7A with self-contained power supply (Fig. 1). The device has the following performance characteristics: − 9 types of test signals (2 standard and 7 special signals); − output signal amplitude, ±1.25, 0.63, or 0.31 V (selected by user); − signal repetition rate is selected by user within a given range (depending on the signal type); − amplitude error, <1.2%; − accuracy of frequency adjustment, ≥99.8%; − output resistance, ≤110 Ω ± 5%; − clock signal output, TTL-compatible; − power supply, AAA galvanic cell; current consumption, ≤14 mA; uninterrupted operation time, ≥100 h; battery discharge indication; automatic switching off; − dimensions, 74 × 49 × 18 mm; − weight (with power supply), ≤50 g. The Neirotest7A device generates the following standard test signals. 1. Harmonic (sinusoidal) signal with a frequency of 0.5 to 99 Hz. This signal is used to determine the degree of nonuniformity of the amplitude–frequency characteristics [4].