Abstract: Digital ratiometer and amplitude analyzer using such a ratiometer.It is possible to solve the problems of the calculation and display of the ratio of two or more quantities, provided that the latter are converted into frequencies. Counting registers are used for evaluating these quantities. The filling of these counting registers (6,13) is prevented by bringing about a shift to the right (10,19) of all the registers as soon as (15) one of them is filled.

Abstract: The present invention relates to a process for the detection of superimposed sheets, the apparatus making it possible to perform this process and the application thereof to bank notes. The process for detecting superimposed sheets by evaluating their surface mass is characterized in that it comprises the stages of passing the sheets oriented in the direction of their width between a beta particle source and a Geiger-Muller counter, counting the number of particles received by the counter by measuring the frequency F.sub.g of the pulses from the Geiger counter to determine the surface mass and eliminating the notes having a high superimposition level by comparison with a limit value.

Abstract: The invention relates to a process for using a binary register with n bistable cells making it possible to determine the ratio of two frequencies and an apparatus for performing the process. This use process consists of supplying to a counting input of the binary register with n bistable cells a first pulse signal S.sub.1 of frequency F.sub.1 and to a shift input of said register a second pulse signal S.sub.2 of frequency F.sub.2 with F.sub.1 >>F.sub.2, the register content being incremented at each pulse of the first signal S.sub.1 and divided by two at each pulse of the second signal S.sub.2, whereby the register content can also be loaded into a buffer register at each pulse of the second signal S.sub.2. The invention more particularly applies frequency discrimination, the determination of an unknown frequency on the basis of a known frequency and to the control of analog display means of the logarithm to base two of the ratio of two frequencies.