Stv Subscriber address system

A method for selectively addressing a plurality of television receivers, each of said television receivers being identified by a unique address code, comprising the steps of:

• identifying a group of said address codes having a common prefix comprising a predetermined number of most significant bits whereby each of said identified address codes is characterized by a different suffix comprising a predetermined number of least significant bits;
• transmitting said common prefix during a first predetermined horizontal scanning line of the vertical interval of a broadcast television signal;
• and
• transmitting a plurality of said different suffixes during a second predetermined horizontal scanning line of the vertical interval of a broadcast television signal.

A system for selectively addressing a plurality of television receivers, each of said television receivers being identified by a unique n-bit address code, comprising:

• means for transmitting during a first predetermined horizontal scanning line of a broadcast television signal a prefix code which is characterized by a sequence of bits which are identical to a predetermined number p of the most significant bits of each of a group of said n-bit address codes;
• means for transmitting during a second predetermined horizontal scanning line a plurality of suffix codes each comprising the n-p least significant bits of a different one of said n-bit address codes of said group;
• and
• decoding means associated with each of said television receivers for identifying the television receivers associated with an address code corresponding to said transmitted prefix code and to one of said transmitted suffix codes.

A decoding circuit operable in association with a television receiver for determining coincidence between an n-bit receiver address code identifying said television receiver and an n-bit transmitted address code comprising a p-bit prefix code and an (n-p) bit suffix code, said prefix and suffix codes being transmitted respectively during different ones of the horizontal scanning lines of a broadcast television signal, said decoding circuit comprising:

• first means for storing said n-bit receiver address code;
• second means responsive to said transmitted television signal for storing the p-bit prefix code and the (n-p) bit suffix code transmitted during said different ones of said horizontal scanning lines;
• means responsive to said first and second means for comparing said stored p-bit prefix code with the p most significant bits of said stored receiver address code and for comparing said stored (n-p) bit suffix code with the (n-p) least significant bits of said stored receiver address code;
• and
• logic means for developing a signal indicating coincidence between said receiver address code and said transmitted address code in response to both of said comparisons indicating conditions of equality.

A decoding circuit operable in association with a television receiver for determining coincidence between an n-bit receiver address code identifying said television receiver and an n-bit transmitted address code comprising a p-bit prefix code and an (n-p) bit suffix code, said prefix code being transmitted during one of the horizontal scanning lines of a broadcast television signal and a plurality of different ones of said suffix codes being transmitted during a different one of the horizontal scanning lines of said broadcast television signal, said decoding circuit comprising:

• first means for storing said n-bit receiver address code;
• second means responsive to said transmitted television signal for storing said p-bit prefix code and said plurality of (n-p) bit suffix codes transmitted during said different ones of said horizontal scanning lines;
• means responsive to said first and second means for comparing said stored p-bit prefix code with the p most significant bits of said stored receiver address code and for comparing each of said plurality of stored (n-p) bit suffix codes with the (n-p) least significant bits of said stored receiver address code;
• and
• logic means for developing a signal indicating coincidence between said receiver address code and a transmitted address code in response to said prefix comparison and any one of said suffix comparisons indicating conditions of equality.

A decoding circuit operable in association with a television receiver for determining coincidence between an n-bit receiver address code identifying said television receiver and an n-bit transmitted address code comprising a p-bit prefix code and an (n-p) bit suffix code, said prefix code being transmitted during one of the horizontal scanning lines of a broadcast television signal and a plurality of different ones of said suffix codes being transmitted during a different one of the horizontal scanning lines of said broadcast television signal, said decoding circuit comprising:

• first means for storing said n-bit receiver address code;
• second means responsive to said transmitted television signal for temporarily storing in time succession the p-bit prefix code transmitted during said one horizontal scanning line and the plurality of (n-p) bit suffix codes transmitted during said different horizontal scanning line;
• prefix comparator means for comparing said temporarily stored p-bit prefix code with the p most significant bits of said stored receiver address code and including first latch means for developing an output signal in response to an equality condition therebetween;
• suffix comparator means for comparing each of said plurality of temporarily stored (n-p) bit suffix codes with the (n-p) least significant bits of said stored receiver address code and including second latch means for developing an output signal in response to an equality condition between any one of said plurality of comparisons;
• and
• logic means coupled to said first and second latch means for developing a signal indicating coincidence between said receiver address code and a transmitted address code in response to coincidence between said latch means output signals.