Frequency synchronisers

Claim 2

In a frequency synchroniser, the combination of: means for receiving a frequency to be synchronised; reference frequency generator means; resettable divider means for dividing the frequency to be synchronised by a selected factor, said divider means having a reset input connected with its divided frequency output; comparator means for comparing the output of the resettable divider means with a signal derived from the reference frequency generator means; indicator means for indicating when the frequency compared in the comparator means differ from one another; and a timing circuit connected to said reset input for resetting the resettable divider means when a predetermined time lapses without there being produced a signal at the output of said resettable divider means.

Claim 3

A frequency synchroniser as claimed in claim 1 including a further comparison means to which both the standard frequency and the derived frequency are applied, said further comparison means including means, for resetting the said resettable divider when an incorrect ratio is detected.

Claim 4

A frequency synchroniser as claimed in claim 1 wherein said comparator comprises a phase sensitive detector of kind which provides a predetermined d.c. output voltage when the frequencies applied to it are in the predetermined ratio.

Claim 5

A frequency synchronizer system comprising, in combination: adjustable frequency generating means having a manual coarse frequency selection input and an electrical fine tuning input for producing an output signal which is intended to be of a selected frequency; divider means connected to the output of said adjustable frequency generating means for dividing down the output signal thereof by a selected factor n, said divider means including counter means having a resettable input for initiating successive frequency dividing counts; reference frequency generating means for generating a reference frequency signal harmonically related to said selected frequency; phase detector means connected to the outputs of said divider means and of said reference frequency generating means for producing a control signal proportional to the difference between such outputs, said control signal being connected to said fine tuning input of said adjustable frequency generating means for fine tuning the latter within the limits of fine tuning thereof; indicator means connected to the control signal output of the phase detector means for providing an operator with an indication of variation which may occur in said control signal; multiple-input gate means having one input thereof constituted by the output of said divider means for resetting said counter means in synchronism with the output of said divider means; and means providing a further input to said gate means which is out of synchronism with the input from said divider means when the output of said divider means differs from said reference frequency signal ay an amount exceeding said limits of the fine tuning, whereby to cause fluctuations of the indicated control signal.

Claim 6

A frequency synchronizer system comprising, in combination: adjustable frequency generating means having a manual coarse frequency selection input and an electrical fine tuning input for producing an output signal which is intended to be of a selected frequency; divider means connected to the output of said adjustable frequency generating means for dividing down the output signal thereof by a selected factor n, said divider means including counter means having a resettable input for initiating successive frequency dividing counts; reference frequency generating means for generating a reference frequency signal harmonically related to said selected frequency; phase detector means connected to the outputs of said divider means and of said reference frequency generating means for producing a control signal proportional to the difference between such outputs, said control signal being connected to said fine tuning input of said adjustable frequency generating means for fine tuning the latter within the limits of fine tuning thereof; indicator means connected to the control signal output of the phase detector means for providing an operator with an indication of variation which may occur in said control signal; multiple-input gate means having one input thereof constituted by the output of said divider means for resetting said counter means in synchronism with the output of said divider means; and means providing a further input to said gate means which is out of synchronism with the input from said divider means when the output of said divider means differs from said reference frequency signal ay an amount exceeding said limits of the fine tuning, whereby to cause fluctuations of the indicated control signal.

Claim 7

A frequency synchronizer system as defined in claim 4 wherein the means last mentioned includes a pulse generating means connected to the output of said divider means for producing a pulse output delayed in time from said output of the divider means by an amount slightly longer than the period of said selected frequency.

Claim 8

A frequency synchronizer system comprising, in combination: an oscillator having a coarse manual adjustment for manually setting the oscillator approximately to produce an output of a selected frequency and having an electrical fine tuning input whereby the manually adjusted output of the oscillator may be tuned toward said selected frequency within narrow limits; resettable counter means for dividing down the output of said oscillator by a predetermined factor to produce a first signal harmonically related to said output of the oscillator, means for comparing said first signal with a reference signal related to said selected frequency for providing said electrical fine tuning input; a visual indicator connected to said fine tuning input to display fluctuations of such input which would be indication of a coarse setting of the oscillator which is outside said limits of fine tuning thereof; said first signal being connected to the resettable counter means for resetting same upon occurrence of said first signal; and means for resetting said counter means out of synchronism with said first signal output of the resettable divider means when said coarse setting of the oscillator is outside said limits of fine tuning whereby to cause fluctuations in said fine tuning input for display by said indicator correspondingly to apprise an operator that further manual setting is required in order to produce said selected frequency output from the oscillator.

Claim 9

A frequency synchronizer system comprising, in combination: an oscillator having a coarse manual adjustment for manually setting the oscillator approximately to produce an output of a selected frequency and having an electrical fine tuning input whereby the manually adjusted output of the oscillator may be tuned toward said selected frequency within narrow limits; resettable counter means for dividing down the output of said oscillator by a predetermined factor to produce a first signal harmonically related to said output of the oscillator, means for comparing said first signal with a reference signal related to said selected frequency for providing said electrical fine tuning input; a visual indicator connected to said fine tuning input to display fluctuations of such input which would be indication of a coarse setting of the oscillator which is outside said limits of fine tuning thereof; said first signal being connected to the resettable counter means for resetting same upon occurrence of said first signal; and means for resetting said counter means out of synchronism with said first signal output of the resettable divider means when said coarse setting of the oscillator is outside said limits of fine tuning whereby to cause fluctuations in said fine tuning input for display by said indicator correspondingly to apprise an operator that further manual setting is required in order to produce said selected frequency output from the oscillator.