Estimation of the cut-off frequency of an electronic filter

A radio transceiver comprising a local oscillator, a transmitter circuit portion, a mixer and an electronic filter having a nominal cut-off frequency and a nominal transfer function, the radio transceiver being configured to:

• generate first and second modulated synthesised signals by modulating a signal output by the local oscillator using the transmitter circuit portion with respective first and second modulations;
• mix a radio-frequency continuous-wave signal with the first modulated synthesised signal using the mixer in order to generate a first signal at a first frequency, the first frequency being less than the nominal cut-off frequency;
• mix the radio-frequency continuous-wave signal with the second modulated synthesised signal using the mixer in order to generate a second signal at a second frequency, the second frequency being greater than the nominal cut-off frequency;
• apply the first signal to an input of the filter while sampling an output of the filter in order to obtain a first magnitude measurement;
• apply the second signal to the input of the filter while sampling the output of the filter in order to obtain a second magnitude measurement;
• and
• estimate a cut-off frequency of the filter based on the nominal transfer function, the first magnitude measurement and the second magnitude measurement.