Double phase lock loop arrangement

A radio receiving apparatus including an RF amplifier, a mixer having inputs coupled to an output of the RF amplifier and a voltage controlled local oscillator and a first phase sensitive detector which are included in a first feedback loop, an IF filter coupled to an output of the mixer, a second feedback loop including an IF voltage controlled oscillator for providing a reference signal, said first phase sensitive detector and second and third phase sensitive detectors, each detector having first and second inputs and an output, each first input being coupled to an output of the IF filter, the IF voltage controlled oscillator being connected to the second inputs of the first and second phase sensitive detectors and via phase shifting means to the second input of the third phase sensitive detector on whose output a lock signal is produced in response to the signals on its first and second inputs being in a desired phase relationship, the output of said second phase sensitive detector being coupled to said IF voltage controlled oscillator, the output of the first phase sensitive detector comprising a correction signal, and switching means coupling, in response to absence of the lock signal, the output of said first phase sensitive detector to the IF voltage controlled oscillator for adjusting the output frequency thereof and for coupling, in response to the presence of the lock signal, the output of said first phase sensitive detector to the voltage controlled local oscillator for adjusting the frequency thereof.