Audience survey system

Claim 2

An incasting communication system comprising: a plurality of distributed sources; a central sink; a plurality of communication paths for connecting said sources to said sink; means located at each of said sources for generating and transmitting on a respective one of the paths a signal having predetermined characteristics; and means located at the sink for detecting the presence of said signal on any one of a plurality of said communication paths, said detector means being concurrently connected to said pluRality of communication paths.

Claim 3

An incasting communication system using the telephone network for the transmission of signals from distributed sources to a central sink, comprising: means located at each of said distributed sources for generating and transmitting on respective subscriber telephone lines a signal having predetermined characteristics; and means located at the central sink for detecting the presence of said signals, said detector means being connected to a plurality of said telephone lines.

Claim 4

An incasting communication system using the telephone network for the transmission of signals from distributed sources to a central sink, comprising: means located at each of said distributed sources for generating and transmitting on respective subscriber telephone lines a signal having predetermined characteristics; and means located at the central sink for detecting the presence of said signals, said detector means being connected to a plurality of said telephone lines.

Claim 5

An incasting system using the telephone network for the transmission of signals from subscriber terminals to a central office, comprising: signal generator means located at each of said subscriber terminals for generating and transmitting on a respective telephone line an incast signal having predetermined characteristics, said signal generator means being connected across said respective telephone line in parallel with its associated conventional telephone subset; detector means located at the central office for inductively detecting the presence of said signal, said detector means being connected to a plurality of said telephone lines and being responsive to the signal appearing on any one of said plurality of telephone lines for providing a corresponding output signal.

Claim 6

An incasting system using the telephone network for the transmission of signals from subscriber terminals to a central office, comprising: signal generator means located at each of said subscriber terminals for generating and transmitting on a respective telephone line an incast signal having predetermined characteristics, said signal generator means being connected across said respective telephone line in parallel with its associated conventional telephone subset; detector means located at the central office for inductively detecting the presence of said signal, said detector means being connected to a plurality of said telephone lines and being responsive to the signal appearing on any one of said plurality of telephone lines for providing a corresponding output signal.

Claim 7

An incasting system as defined in claim 3 wherein said incast signal comprises at least one current pulse having a predetermined shape whereby a minimum of impulse noise is caused to be generated and wherein said pulse is transmitted between one side of the telephone line and ground.

Claim 8

An incasting system as defined in claim 4 wherein said signal generator means comprises a capacitance element, a current pulse generator and shaper, and switch means for connecting said capacitance element through a high impedance to the tip and ring leads of the subscriber loop in a first position, and for connecting said capacitance element to ground and to one side of the telephone line through said current pulse generator and shaper in a second position, whereby said capacitance element charges up in said first position and discharges through said current generator and shaper in said second position to cause said current pulse to be generated and transmitted on the line.

Claim 9

An incasting system as defined in claim 5 further comprising a visual indicator serially connected between said signal generator means and said one side of the telephone line for indicating that said current pulse has been transmitted.

Claim 10

An incasting system as defined in claim 4 wherein said detector means is a current sensing transformer comprising, a core of magnetic material adapted to have a plurality of conductors passing therethrough, each of said conductors forming a primary winding, and a secondary winding comprising a plurality of turns of wire wound about said core, said transformer being adapted to provide an output signal on the output leads of said secondary winding in response to said current pulse passing through at least one of said conductors.

Claim 11

An incasting system as defined in claim 7 wherein the secondary winding of the transformer is divided in two halves, each half comprising a plurality of turns of wire wound about a respective portion of the core and the two halves being connected in series aiding for the desired signal.

Claim 12

An incasting system as defined in claim 8 wherein said detector means further includes a damping circuit comprising a parallel circuit of a resistance element and a capacitance element connected across the output leads of the secondary winding of the transformer.

Claim 13

An incasting system using the telephone network for the transmission of signals from distributed sources to a central source, comprising: signal generator means located at each of said distributed sources for generating and transmitting on a respective telephone line a signal having predetermined characteristics; detector means located at the central sink for inductively dEtecting the presence of said signal, said detector means being responsive to the signal appearing on any one of a plurality of said telephone lines for providing a corresponding output signal; and circuit means responsive to said output signal for validating it as to amplitude and identifying it as to polarity and for providing corresponding signals to a totalizing circuit.

Claim 14

An incasting system using the telephone network for the transmission of signals from distributed sources to a central source, comprising: signal generator means located at each of said distributed sources for generating and transmitting on a respective telephone line a signal having predetermined characteristics; detector means located at the central sink for inductively dEtecting the presence of said signal, said detector means being responsive to the signal appearing on any one of a plurality of said telephone lines for providing a corresponding output signal; and circuit means responsive to said output signal for validating it as to amplitude and identifying it as to polarity and for providing corresponding signals to a totalizing circuit.

Claim 15

An incasting system as defined in claim 10 wherein said circuit means comprises: a differential amplifier having its input terminal connected to receive said output signal from said detector means and a pair of output terminals; a pair of threshold circuits each having its input terminal connected to a respective one of the output terminals of the amplifier and a pair of output terminals for providing said corresponding signals.