Attenuation equalizer for correcting a temperature and frequency-dependent cable attenuation

Claim 1

An attenuation equalizer for correcting within a frequency range the temperature and frequency-dependent attenuation variation of cables, comprising a fixed attenuation correction circuit an adjustable attenuation correction circuit connected in cascade with the fixed attenuation correction circuit, and a control circuit connected to said adjustable attenuation correction circuit and including a means for receiving a temperature variable electrical signal, said adjustable attenuation circuit comprising a bridged-T network having a series arrangement of two identical series resistors bridged by an adjustable series impedance and a parallel impedance connected between these two series resistors, the fixed attenuation correction circuit having for higher frequencies a lower attenuation than for lower frequencies, the value of the bridging impedance at higher temperatures is smaller and the value of the parallel impedance is greater than at lower temperatures in order to obtain for one and the same frequency variation an attenuation variation of the variable attenuation correction circuit which is greater at lower temperatures than at higher temperatures, the bridging impedance being inductive and the parallel impedance capacitive in said frequency range, and the difference between the attenuation of the fixed attenuation correction circuit at the extremes of its frequency range being at least substantially equal to the sum of the difference of the attenuation of the cable measured at the maximum cable temperature and any given operating temperature and the difference of the attenuation of the variable attenuation correction circuit measured at the minimum cable operating temperature and said given operating temperature.