a clock recovery circuit for producing a clock signal from a baseband information signal that has a data rate r . the information signal is frequency converted to a predetermined intermediate frequency by mixing the information signal with a tunable local oscillator signal having a frequency f . the resulting converted signal is bandpass filtered to extract the clock spectral line at f + r / 2 . the resulting signal is then frequency doubled , producing a signal of 2f + r . after passing through another narrowband filter the doubled signal is reconverted to produce the spectral line at r , filtered to remove the unwanted products produced in the reconversion process , and passed through a comparator to sharpen the signal edges . using this technique , the clock signal can be recovered from information signals of different data rates without having to switch from one bandpass filter to another when the frequency of the information signal changes .