Abstract: A variable frequency VHF or UHF band oscillator is disclosed. Principal control over the precise location and stability of the frequency of oscillation is provided by a surface wave delay line in the regenerative feedback path of a broadband amplifier. The surface wave delay line is capable of passing substantial energy within each of a plurality of very narrow passbands. Controls are provided for ensuring that at any given time the circuit can oscillate only at the resonant frequency of one of these passbands. Selection of the frequency of oscillation is in accordance with an externally applied digital frequency select signal.

Abstract: An automatic oscillator frequency control is provided for operations such as employed in channel selection in radio and television receiver systems. A code is stored representative of a selected frequency band within which a selected channel is located. The frequency of an oscillator is varied monotonically from a reference frequency at one extremity of a selected frequency range successively to traverse a plurality of such frequency bands. A frequency marker is generated at the margin of each band and the markers are counted. The number of counted markers is compared with the stored code to generate a control state. In response to the control state, a pattern control causes it to dither between limits of the selected band until a signal is encountered at the selected frequency within the selected band. At that point, the oscillator is locked to the frequency of the received signal.