Electrical multi-channel signal transmission systems

Claim 2

A cable television system for reducing second order intermodulation products caused by interaction between carriers in non-linear electrical devices in the system wherein the carrier frequencies of the channels shown in the first column of the following table are re-assigned as expressed in analytical form in the fourth column of the table, the standard frequencies given in the second column being expressable in analytical form as shown in the third column of the table where x = 6 and y = 0.25, and the values of x and y for the re-assigned frequencies being found by selecting frequencies for two channels, setting them equal to the corresponding expressions in the fourth column to form two simultaneous equations, and solving for x and y: TABLE ______________________________________ Channel Freq. MHz Standard New Assignment ______________________________________ 2 55.25 9x + 5y 9x + 5y 3 61.25 10x + 5y 10x + 5y 4 67.25 11x + 5y 11x + 5y 5 77.25 13x - 3y 13x - 3y 6 83.25 14x - 3y 14x - 3y C 133.25 22x + 5y 22x + 2y D 139.25 23x + 5y 23x + 2y E 145.25 24x + 5y 24x + 2y F 151.25 25x + 5y 25x + 2y G 157.25 26x + 5y 26x + 2y H 163.25 27x + 5y 27x + 2y I 169.25 28x + 5y 28x + 2y 7 175.25 29x + 5y 29x + 7y 8 181.25 30x + 5y 30x + 7y 9 187.25 31x + 5y 31x + 7y 10 193.25 32x + 5y 32x + 7y 11 199.25 33x + 5y 33x + 7y 12 205.25 34x + 5y 34x + 7y 13 211.25 35x + 5y 35x + 7y ______________________________________ said system comprising two oscillator means for generating the frequencies of said two channels, means for combining the two generated frequencies to produce a third frequency, a harmonic generator means for generating a channel spacing frequency and harmonics thereof, and means for combining and filtering frequencies from the two oscillator means, said third frequency and the harmonic generator means to derive other re-assigned channel frequencies.

Claim 3

A system as claimed in claim 1 wherein said oscillator means generate frequencies corresponding to channels 3 and E and said harmonic generator means generates frequencies of 6, 12 and 18 MHz.

Claim 4

A system as claimed in claim 1 wherein the frequencies of said two channels are standard frequencies.

Claim 5

A system as claimed in claim 3 including means for phase-locking the frequencies of said two channels to off-air signals of corresponding frequency.

Claim 6

A cable television system for reducing second order intermodulation products caused by interaction between carriers in non-linear electrical devices in the system wherein the carrier frequencies of the channels shown in the first column of the following table are re-assigned so that they have the frequencies shown in the third column and are expressable in analytical form as shown in the second column and where x, u and v are constants having the values 6, 0.25 and 1.125, respectively: TABLE ______________________________________ Re-assigned Frequency Channel Equation Frequency (MHz) Deviation (KHz) ______________________________________ 2 9x + v 55.125 -125 3 10x + v 61.125 -125 4 11x + v 67.125 -125 5 13x + u - v 77.125 -125 6 14x + u - v 83.125 -125 C 22x + u 132.250 -1000 D 23x + u 138.250 -1000 E 24x + u 144.250 -1000 F 25x + u 150.250 -1000 G 26x + u 156.250 -1000 H 27x + u 162.250 -1000 I 28x + u 168.250 -1000 7 29x + u + v 175.375 +125 8 30x + u + v 181.375 +125 9 31x + u + v 187.375 +125 10 32x + u + v 193.375 +125 11 33x + u + v 199.375 +125 12 34x + u + v 205.375 +125 13 35x + u + v 211.375 +125 ______________________________________ said system comprising first, second and third oscillators for generating first, second and third re-assigned channel frequencies, means for combining said first frequency with said second frequency and said second frequency with said third frequency to produce fourth and fifth frequencies, means for producing harmonics of said fifth frequency, and means for combining and filtering the first, second, third, fourth and fifth frequencies and harmonics to produce the other reassigned channel frequencies.

Claim 7

A cable television system for reducing second order intermodulation products caused by interaction between carriers in non-linear electrical devices in the system wherein the carrier frequencies of the channels shown in the first column of the following table are re-assigned so that they have the frequencies shown in the third column and are expressable in analytical form as shown in the second column and where x, u and v are constants having the values 6, 0.25 and 1.125, respectively: TABLE ______________________________________ Re-assigned Frequency Channel Equation Frequency (MHz) Deviation (KHz) ______________________________________ 2 9x + v 55.125 -125 3 10x + v 61.125 -125 4 11x + v 67.125 -125 5 13x + u - v 77.125 -125 6 14x + u - v 83.125 -125 C 22x + u 132.250 -1000 D 23x + u 138.250 -1000 E 24x + u 144.250 -1000 F 25x + u 150.250 -1000 G 26x + u 156.250 -1000 H 27x + u 162.250 -1000 I 28x + u 168.250 -1000 7 29x + u + v 175.375 +125 8 30x + u + v 181.375 +125 9 31x + u + v 187.375 +125 10 32x + u + v 193.375 +125 11 33x + u + v 199.375 +125 12 34x + u + v 205.375 +125 13 35x + u + v 211.375 +125 ______________________________________ said system comprising first, second and third oscillators for generating first, second and third re-assigned channel frequencies, means for combining said first frequency with said second frequency and said second frequency with said third frequency to produce fourth and fifth frequencies, means for producing harmonics of said fifth frequency, and means for combining and filtering the first, second, third, fourth and fifth frequencies and harmonics to produce the other reassigned channel frequencies.

Claim 8

A cable television system for reducing second order intermodulation products caused by interaction between carriers in non-linear electrical devices in the system wherein the carrier frequencies of the channels shown in the first column of the following table are re-assigned so that they are expressable in analytical form as shown in the fourth column, the standard frequencies given in the second column being expressable in analytical form as shown in the third column of the table where x = 6 and y = 0.25, the values of x, u and v for the re-assigned frequencies being found by selecting frequencies for three channels, setting them equal to the corresponding expressions in the fifth column to form three simultaneous equations, and solving the equations for x, u and v: TABLE ______________________________________ Re-assigned Frequency Channel Freq. MHz Standard (MHz) Equation ______________________________________ 2 55.25 9x + 5y 55.125 9x + v 3 61.25 10x + 5y 61.125 10x + v 4 67.25 11x + 5y 67.125 11x + v 5 77.25 13x - 3y 77.125 13x + u - v 6 83.25 14x - 3y 83.125 14x + u - v C 133.25 22x + 5y 132.250 22x + u D 139.25 23x + 5y 138.250 23x + u E 145.25 24x + 5y 144.250 24x + u F 151.25 25x + 5y 150.250 25x + u G 157.25 26x + 5y 156.250 26x + u H 163.25 27x + 5y 162.250 27x + u I 169.25 28x + 5y 168.250 28x + u 7 175.25 29x + 5y 175.375 29x + u + v 8 181.25 30x + 5y 181.375 30x + u + v 9 187.25 31x + 5y 187.375 31x + u + v 10 193.25 32x + 5y 193.375 32x + u + v 11 199.25 33x + 5y 199.375 33x + u + v 12 205.25 34x + 5y 205.375 34x + u + v 13 211.25 35x + 5y 211.375 35x + u + v ______________________________________ said system comprising first, second and third oscillators for generating first, second and third channel frequencies, means for combining said first frequency with said second frequency and said second frequency with said third frequency to produce fourth and fifth frequencies, means for producing harmonics of said fifth frequency, and means for combining and filtering the first, second, third, fourth and fifth frequencies and harmonics to produce the other re-assigned channel frequencies.

Claim 9

A cable television system for reducing second order intermodulation products caused by interaction between carriers in non-linear electrical devices in the system wherein the carrier frequencies of the channels shown in the first column of the following table are re-assigned so that they are expressable in analytical form as shown in the fourth column, the standard frequencies given in the second column being expressable in analytical form as shown in the third column of the table where x = 6 and y = 0.25, the values of x, u and v for the re-assigned frequencies being found by selecting frequencies for three channels, setting them equal to the corresponding expressions in the fifth column to form three simultaneous equations, and solving the equations for x, u and v: TABLE ______________________________________ Re-assigned Frequency Channel Freq. MHz Standard (MHz) Equation ______________________________________ 2 55.25 9x + 5y 55.125 9x + v 3 61.25 10x + 5y 61.125 10x + v 4 67.25 11x + 5y 67.125 11x + v 5 77.25 13x - 3y 77.125 13x + u - v 6 83.25 14x - 3y 83.125 14x + u - v C 133.25 22x + 5y 132.250 22x + u D 139.25 23x + 5y 138.250 23x + u E 145.25 24x + 5y 144.250 24x + u F 151.25 25x + 5y 150.250 25x + u G 157.25 26x + 5y 156.250 26x + u H 163.25 27x + 5y 162.250 27x + u I 169.25 28x + 5y 168.250 28x + u 7 175.25 29x + 5y 175.375 29x + u + v 8 181.25 30x + 5y 181.375 30x + u + v 9 187.25 31x + 5y 187.375 31x + u + v 10 193.25 32x + 5y 193.375 32x + u + v 11 199.25 33x + 5y 199.375 33x + u + v 12 205.25 34x + 5y 205.375 34x + u + v 13 211.25 35x + 5y 211.375 35x + u + v ______________________________________ said system comprising first, second and third oscillators for generating first, second and third channel frequencies, means for combining said first frequency with said second frequency and said second frequency with said third frequency to produce fourth and fifth frequencies, means for producing harmonics of said fifth frequency, and means for combining and filtering the first, second, third, fourth and fifth frequencies and harmonics to produce the other re-assigned channel frequencies.

Claim 10

A system as claimed in claim 6 wherein said first, second and third frequencies are standard frequencies.

Claim 11

A system as claimed in claim 7 including means for phase-locking said first, second and third frequencies to off-air signals of corresponding frequency.