An automatic tune-measurement system for the CELSIUS ring

In CELSIUS, the tunes are up till now measured by FFT-analysing the response, at a beam position monitor, of a transverse kick of the beam. This FFT has to be performed over a wide frequency range and requires a high sampling frequency, and thus a large number of samples. By mixing-down the frequency range of interest, with a signal equal to the RF-frequency multiplied by the expected tune, and measuring the deviation from the expected tune-value, the FFT can be made with a smaller number of samples and in the same frequency range independently of the RF-frequency. This way the FFT will be calculated faster by the computer, making it possible to measure the Q-values with a higher repetition rate. The set-up of this system and the results will be reported