Signal ratio meter for laser gas analyzer

The device separates the two components of a voltage pulse, namely, the pedestal u{sub p} and the signal u{sub s}, which is measured with respect to the pedestal top, and determines the ratio u{sub s}/u{sub p}. The ratio circuit includes a ten-bit ADC. The ratio is measured in three ranges and can vary between 0.00024 and 0.999. The time of ratio measurement is 120 {mu}sec. The rms noise in terms of the input signal is 25 {mu}V.