Circuit arrangement with frequency synthesis for the tuning of receiving sets
AssigneeIndesit Industria Elettrodomestici Italiana S.p.A.
InventorAttilio Farina
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Abstract
A circuit arrangement for the selection and the tuning of a radio-electric signal in a signal receiving set is described. The main feature of this set, which comprises a controllable local oscillator whose frequency is controlled by a control loop which maintains it in a fixed relationship with a number N, is the provision of means for calculating at least a substantial part of said number N, by starting from a plurality of signals representing a number K indicative of the signal to be tuned. In particular the signal receiving set can be a television receiver, and said radio-electric signal to be tuned belongs to a television channel.
Claims18
In an electronic circuit arrangement having a programmable frequency divider arranged to obtain from a voltage controlled tuning oscillator, as a function of a respective dividing number "N" in binary form for the tuning of each of a plurality of tunable channels in a receiver, a respective frequency signal, and means for comparing said respective frequency signal with a frequency reference oscillation and producing a resultant signal supplied to said voltage controlled tuning oscillator for the desired tuning, the improvement comprising:
- (a) a control panel having push buttons;
- (b) first means actuable by at least one of said push buttons to produce signals representing at least one binary coded number K indicative of the number of a channel to which said receiver is to be tuned according to a predetermined assigned channel frequency;
- (c) second means for producing output signals representing in binary coded form the value of the respective frequency of said voltage controlled oscillator, said value corresponding, for the various tunable channels, to the sum of a first constant binary coded number with the product of said binary coded number K and a second constant binary coded number and being obtained indirectly from said first and second constant binary coded numbers through intermediate expressions for each channel in response to the signals produced by said first means;
- and
- (d) third means for obtaining said number N by multiplying said value of the respective frequency of said voltage controlled tuning oscillator obtained from said second means by a coefficient depending on the value of said reference oscillation frequency.
Dependencies are inferred from the claim text.