Heterodyning circuit for changing frequencies of received signal

Claim 2

A frequency changing stage for changing the frequency of a high frequency input signal which is within a predetermined range of high frequencies, comprising a frequency source of high stability, frequency dividers coupled to said source and capable of furnishing a plurality of successive multiples of a predetermined frequency f, associated with the frequency changing stage, a mixer circuit capable of mixing the input signal with a heterodyne signal, and switch means for selectively connecting one of the successive multiples of the frequency f as a heterodyne signal to the mixer circuit, the selected heterodyne signal being of such frequency that the output signal of the mixer circuit has a frequency between f/2 and f.

Claim 3

A frequency changing stage according to claim 1 wherein the multiples of the frequency f are between 3f and 6f inclusive, and the frequency of the source is 60f.

Claim 4

A frequency changing stage for changing the frequency of a high frequency input signal which is within a predetermined range of high frequencies, comprising a heterodyne frequency source of high stability, frequency dividers coupled to said source and capable of furnishing a plurality of successive multiples of a predetermined frequency f, associated with the frequency changing stage, a plurality of mixers, each for mixing the input signal with a respective one of said plurality of successive multiples of the predetermined frequency f, and switch means for selecting the output of one of the mixers, the selected mixer having such a heterodyne frequency that the selected output signal has a frequency between f/2 and f.

Claim 5

A frequency changing stage for changing the frequency of a high frequency input signal which is within a predetermined range of high frequencies, comprising a heterodyne frequency source of high stability, frequency dividers coupled to said source and capable of furnishing a plurality of successive multiples of a predetermined frequency f, associated with the frequency changing stage, a plurality of mixers, each for mixing the input signal with a respective one of said plurality of successive multiples of the predetermined frequency f, and switch means for selecting the output of one of the mixers, the selected mixer having such a heterodyne frequency that the selected output signal has a frequency between f/2 and f.

Claim 6

A frequency changing stage according to claim 3 wherein the multiples of the frequency f are between 3f and 6f inclusive, and the frequency of the source is 60f.

Claim 7

A frequency changing device for transforming the frequency of input signals having frequencies which are within a predetermined range to a signal of low frequency included in a fixed passband, using a frequency source of high stability, including connected in series, I. at least one frequency changing stage of a first type comprising a divider circuit for dividing the frequency of the said source and capable of furnishing at least one heterodyne signal the frequency of which is one of a pluralitY of successive multiples of a predetermined frequency f, associated with the frequency changing stage, a circuit for mixing the input signal with said heterodyne signal, said heterodyne signal being of such frequency that the output signal of the mixer circuit has a frequency between f/2 and f, and II. a final frequency changing stage of a second type comprising a bandpass filter adapted to pass the output signal from the preceding frequency changing stage, a synthesizer frequency divider circuit for receiving a signal derived from the frequency source and producing an output signal having a frequency n/K1 X F, where F is the frequency of said source, K1 is a whole number characteristic of the synthesizer-divider circuit, and n is a whole number between zero and K1 - 1, a circuit for mixing the output signal from the bandpass filter and the output signal from the synthesizer-frequency divider circuit, and a low frequency filter of fixed passband, the synthesizer-divider circuit being controlled in such manner that the heterodyne frequency is such that the output signal from the mixer is within the fixed passband of the low frequency filter.

Claim 8

A frequency changing device for transforming the frequency of input signals having frequencies which are within a predetermined range to a signal of low frequency included in a fixed passband, using a frequency source of high stability, including connected in series, I. at least one frequency changing stage of a first type comprising a divider circuit for dividing the frequency of the said source and capable of furnishing at least one heterodyne signal the frequency of which is one of a pluralitY of successive multiples of a predetermined frequency f, associated with the frequency changing stage, a circuit for mixing the input signal with said heterodyne signal, said heterodyne signal being of such frequency that the output signal of the mixer circuit has a frequency between f/2 and f, and II. a final frequency changing stage of a second type comprising a bandpass filter adapted to pass the output signal from the preceding frequency changing stage, a synthesizer frequency divider circuit for receiving a signal derived from the frequency source and producing an output signal having a frequency n/K1 X F, where F is the frequency of said source, K1 is a whole number characteristic of the synthesizer-divider circuit, and n is a whole number between zero and K1 - 1, a circuit for mixing the output signal from the bandpass filter and the output signal from the synthesizer-frequency divider circuit, and a low frequency filter of fixed passband, the synthesizer-divider circuit being controlled in such manner that the heterodyne frequency is such that the output signal from the mixer is within the fixed passband of the low frequency filter.

Claim 9

Frequency changing device according to claim 5, characterized in that the synthesizer-divider circuit includes a controlled synthesizer followed by a frequency divider, and means for controlling the controlled synthesizer so as to control the synthesizer-divider circuit

Claim 10

Frequency changing device according to claim 6, characterised in that the step in frequency of the synthesiser divided by the division factor of the frequency divider that follows it is at most equal to the said fixed passband of the low frequency filter, thereby enabling the use of any high frequency in the said predetermined range.

Claim 11

Frequency changing device according to claim 6, for high frequencies in the said predetermined range separated from one another by intervals which are multiples of a known elementary step, characterised in that the step in frequency of the synthesiser divided by the division factor of the frequency divider that follows it is equal to the said known elementary step.

Claim 12

Frequency changing device according to claim 6, for high frequencies in the predetermined range which are all multiples of a known low frequency, characterised in that it includes means for generating, from the frequency source of high stability, an auxiliary signal of fixed frequency equal to the product of the said known low frequency and the division factor of the frequency divider following the controlled synthesiser, and that it includes an algebraic frequency adder between the said controlled synthesiser and the frequency divider that follows it for algebraically adding the said fixed frequency to the output frequency of the controlled synthesiser for application to the frequency divider that follows it.

Claim 13

Frequency changing device according to claim 9, for also effecting synchronous detection by means of a synchronous detector that receives the output signal from the low frequency filter of fixed passband, characterised in that it includes another frequency divider circuit having the same division factor as that which is connected to the output of the frequency adder, for dividing the frequency of the auxiliary signal and furnishing its output signal as a local signal to othe said synchronous detector.

Claim 14

Frequency changing device according to claim 5, characterised in that the final frequency changing stage of the second type includes means for eliminating the image frequency associated with it.

Claim 15

Frequency changing device according to claim 5, characterised in that the final stage of frequency changing is adapted to receive a frequency different from that of the high stability source and derived from the latter for generating its heterodyne signal.

Claim 16

A frequency changing device for transforming the frequency of input signals haVing frequencies which are within a predetermined range to a signal of low frequency included in a fixed passband, using a frequency source of high stability, including connected in series, I. at least one frequency changing stage of a first type comprising frequency dividers coupled to said source and capable of furnishing a plurality of successive multiples of a predetermined frequency f, associated with the frequency changing stage, a plurality of mixers, each for mixing the input signal with a respective one of said plurality of successive multiples of the predetermined frequency f, and II. a final frequency changing stage of a second type comprising a plurality of bandpass filters each adapted to pass the output signal of a respective one of the mixers in the preceding frequency changing stage, a plurality of synthesizers each coupled to the frequency source and capable of producing an output signal having a frequency n/K1 X F, where F is the frequency of said source, K1 is a whole number characteristic of the synthesizer, and n is a whole number between zero and K1 - 1, a plurality of mixers each for mixing the output signal from a respective one of the bandpass filters and the output signal from a respective one of the synthesizers, and a plurality of low frequency filters of fixed passband respectively coupled to the outputs of the mixers, the synthesizers being controlled in such manner that the heterodyne frequencies are such that the output signal of each of the mixers is within the fixed passband of the respective low frequency filter to which it is coupled.

Claim 17

A frequency changing device for transforming the frequency of input signals haVing frequencies which are within a predetermined range to a signal of low frequency included in a fixed passband, using a frequency source of high stability, including connected in series, I. at least one frequency changing stage of a first type comprising frequency dividers coupled to said source and capable of furnishing a plurality of successive multiples of a predetermined frequency f, associated with the frequency changing stage, a plurality of mixers, each for mixing the input signal with a respective one of said plurality of successive multiples of the predetermined frequency f, and II. a final frequency changing stage of a second type comprising a plurality of bandpass filters each adapted to pass the output signal of a respective one of the mixers in the preceding frequency changing stage, a plurality of synthesizers each coupled to the frequency source and capable of producing an output signal having a frequency n/K1 X F, where F is the frequency of said source, K1 is a whole number characteristic of the synthesizer, and n is a whole number between zero and K1 - 1, a plurality of mixers each for mixing the output signal from a respective one of the bandpass filters and the output signal from a respective one of the synthesizers, and a plurality of low frequency filters of fixed passband respectively coupled to the outputs of the mixers, the synthesizers being controlled in such manner that the heterodyne frequencies are such that the output signal of each of the mixers is within the fixed passband of the respective low frequency filter to which it is coupled.

Claim 18

Frequency changing device according to claim 13, characterised in that it includes switching means for selecting in a controlled manner the output of one of the mixers of the final stage of frequency changing in order to furnish the output signal of the device.

Claim 19

Frequency changing device according to claim 13, for using simultaneously a known plurality of high frequency signals from the predetermined range, characterised in that the final frequency changing stage includes mixers each associated with a synthesiser followed by a divider for supplying it with a heterodyne frequency, of a number at least equal to the said known number of high frequency signals.