Digital frequency synthesizer receiver

Abstract

A scanning type frequency synthesized receiver utilizing a voltage controlled oscillator (VCO) for producing a local oscillator signal. The control voltage for the VCO is provided in response to the division rate of a programmable divider. A control circuit programs the divider which control circuit operates to vary the divisor of the divider within a predetermined range as determined by information stored in a memory corresponding to a range of frequencies in a frequency band to be scanned and received by the receiver. Upon a command signal the control circuit operates to vary the divisor of the divider either up or down to cause the frequency of VCO, and thereby the receiver, to scan in a given direction and upon a signal being received the variation of the divider divisor and the receiver scanning is terminated. The VCO can be scanned either up or down in frequency, and the scanning can be either from the upper (or lower) end of a frequency range back to the lower (or upper) end and then reversed or a repetitive scanning from one end of the range to the other in the same direction. In the preferred embodiment disclosed is a multiband scanning receiver in which the stored information for the control circuit corresponds to the extremities of each of a plurality of frequency bands, the information corresponding to a particular band being utilized in response to selection of the band for reception by a band switching means.