Frequency synthesizing system

Claim 2

A frequency synthesizing system, comprising frequency synthesizing means operative to produce an adjustable intermediate frequency, frequency dividing means connected to receive the intermediate frequency and to divide it by an adjustable division factor to produce an output frequency, setting means operable to set up a desired value of the output frequency, and control means connected to the setting means to respond to the value of the output frequency set up thereby and also connected to the synthesizing means and the dividing means to control the values of the said intermediate frequency and of the division factor in dependence on the value of the output frequency set up, such that the value of intermediate frequency produces, when divided by the division factor of the dividing means, the desired output frequency.

Claim 3

A system according to claim 1, in which the control means comprises selecting means operative to produce, for each desired vAlue of the output frequency set up by the setting means, a different and predetermined first control output representing a particular value of division factor, multiplying means connected to the setting means and the selecting means and operative to multiply the desired value of the output frequency set up by the setting means and the first control output to produce a second control output, means feeding the first control output to the dividing means to set the division factor thereof, and means feeding the second control output to the frequency synthesizing means to set the value of the said intermediate frequency.

Claim 4

A system according to claim 2, in which the dividing means comprises means operative to divide the intermediate frequency by a division factor of Xx, where X is a fixed integer and x is an integer which is varied in dependence on the value of the first control output whereby to vary the value of the division factor.

Claim 5

A system according to claim 3, in which the dividing means comprises means for dividing the intermediate frequency by an additional factor of Yy, where Y is a fixed integer and y is an integer which is manually variable to alter the range of the output frequency.

Claim 6

A system according to claim 2, in which the dividing means comprises means operative to divide the intermediate frequency by a division factor of Xx . Yy, where X and Y are fixed integers, and x and y are integers which are varied in dependence on the value of the first control output, whereby to vary the value of the division factor.

Claim 7

A system according to claim 5, in which X is 2 and Y is 10.

Claim 8

A system according to claim 1, in which the frequency synthesizing means comprises a plurality of synthesizer arrangements each operative to synthesize a separate frequency, and summing means connected to sum the separate frequencies to produce the said intermediate frequency, each synthesizing arrangement comprising means responsive to the control means to set the value of the said separate frequency which it synthesizes whereby that frequency determines the value of a respective one of the decades of the said intermediate frequency.

Claim 9

A system according to claim 2, in which the frequency synthesizing means comprises a plurality of synthesizer arrangements each operative to synthesize a respective individually variable frequency which is variable stepwise from a predetermined datum frequency, and summing means for summing the individually variable frequencies to produce the said intermediate frequency, each synthesizer arrangement comprising means responsive to the said second control output to vary the value of the respective individually variable frequency stepwise in dependence thereon, the various datum frequencies and the step sizes in the synthesizer arrangements being selected such that the value of each individually variable frequency determines a different one of the decades of the said intermediate frequency.

Claim 10

A system according to claim 2, in which the frequency synthesizing means comprises a plurality of synthesizer arrangements each operative to synthesize a separate frequency, and output means connected to add these separate frequencies to produce the intermediate frequency, each synthesizer arrangement comprising means for adding two frequencies each having a predetermined datum value and at least one of which is variable stepwise in predetermined steps from the datum value, and means responsive to the said second control output to vary the variable frequency, the said datum value and the sizes of the step variations in the variable frequencies being such that the frequency synthesized by each synthesizer arrangement determines the value of a respective one of the decades of the said intermediate frequency.

Claim 11

A system according to claim 9, in which the intermediate frequency comprises the sUm of a fixed frequency and a variable frequency, the variable frequency comprising four decades, and in which: there are three said synthesizing arrangements, the first synthesizer arrangement is connected to add a first fixed frequency fixed at a predetermined value and a first variable frequency variable in predetermined steps from a predetermined datum value, and includes means responsive to the said second control output to vary the value of the first variable frequency stepwise whereby to produce a first synthesized frequency, the second synthesizer arrangement is connected to add the said first synthesized frequency and a second variable frequency which is variable in predetermined steps from a predetermined datum value, and includes means responsive to the said second control output to vary the value of the second variable frequency stepwise whereby to produce a second synthesized frequency, the third synthesizer arrangement is connected to add third and fourth variable frequencies variable in predetermined steps from respective predetermined datum values, and includes means responsive to the said second control output to vary the values of the third and fourth variable frequencies stepwise whereby to produce a third synthesized frequency, the said output summing means is connected to receive and sum the said second and third synthesized frequencies whereby to produce the said intermediate frequency, the datum values of the first fixed frequency and of the first, second, third and fourth variable frequencies and the sizes of the predetermined steps of the latter frequencies are such that the first variable frequency is variable to vary the value of the least significant decade in the said intermediate frequency, the second variable frequency is variable to vary the value of the next more significant decade thereof, and the third and fourth variable frequencies are respectively variable to vary the values of the two most significant decades thereof.