Apparatus and method for transmitting audio over a dedicated video line

An apparatus for transmitting an analog audio signal over a dedicated video transmission line in a closed circuit television system comprising:

• a. a modulator having an analog audio input, an analog video input, and a first synchronization device all attached to a first analog switching device capable of toggling between said video input and said audio input, the default position being the video input, said first switching device having an analog output;
• b. a demodulator having an analog audio output, an analog video output, and a second synchronization device all attached to a second analog switching device capable of toggling between said video output and said audio output, the default position being the video output, said second switching device having an analog input;
• and
• c. a single transmission line connecting the output from said first switching device to the input of said second switching device
• wherein said first and second synchronization devices are identically synchronized with each other, audio signal samples are inserted into the endings of the active video scan lines of a video signal at regular intervals according to said first synchronization device through the toggling action of said first switching device in said modulator, and said audio signal samples are removed from the endings of the active video scan lines of the video signal at regular intervals according to said second synchronization device through the toggling action of said second switching device in said demodulator.

An apparatus for transmitting dual analog audio signals over a dedicated video transmission line comprising:

• a. a modulator having first and second analog audio inputs, an analog video input, first and second analog switching devices each having an output, and a first synchronization device wherein said synchronization device and said first and second audio inputs are attached to said first switching device, and wherein the output of said first switching device, said video input and said synchronization device are attached to said second switching device;
• b. a demodulator having first and second analog audio outputs, an analog video output, third and fourth analog switching devices each having an input, and a second synchronization device wherein said video output, the input to said fourth switching device and said synchronization device are attached to said third switching device, and wherein said first and second audio outputs and said synchronization device are attached to said fourth switching device;
• and
• c. a single transmission line connecting the output from said second switching device to the input of said third switching device
• wherein said first and second synchronization devices are identically synchronized with each other, audio signal samples from said first audio input are inserted into the endings of the active video scan lines of a video signal at regular intervals according to said first synchronization device through the toggling action of said first and second switching devices in said modulator, and said audio signal samples are removed from the endings of the active video scan lines of the video signal at regular intervals according to said second synchronization device through the toggling action of said third and fourth switching devices in said demodulator, and wherein audio signal samples from said second audio input are inserted into the beginnings of said active video scan lines at regular intervals according to said first synchronization device through the toggling action of said first and second switching devices in said modulator, and said second audio signal samples are removed from the beginnings of the active video scan lines at regular intervals according to said second synchronization device through the toggling action of said third and fourth switching devices in said demodulator.

An apparatus for transmitting dual analog audio signals over a dedicated video transmission line comprising:

• a. a modulator having first and second analog audio inputs, an analog video input, first and second analog switching devices each having an output, and a first synchronization device wherein said synchronization device and said first and second audio inputs are attached to said first switching device, and wherein the output of said first switching device, said video input and said synchronization device are attached to said second switching device;
• b. a demodulator having, first and second analog audio outputs, an analog video output, third and fourth analog switching devices each having an input, and a second synchronization device wherein said video output, the input to said fourth switching device and said synchronization device are attached to said third switching device, and wherein said first and second audio outputs and said synchronization device are attached to said fourth switching device;
• and
• c. a single transmission line connecting the output from said second switching device to the input of said third switching device wherein said first and second synchronization devices are identically synchronized with each other, audio sisal samples from said first audio input are inserted into the beginnings of the active video scan lines of a video signal at regular intervals according to said first synchronization device through the toggling action of said first and second switching devices in said modulator, and said audio signal samples are removed from the beginnings of the active video scan lines of the video signal at regular intervals according to said second synchronization device through the toggling action of said third and fourth switching devices in said demodulator, and wherein audio signal samples from said second audio input are inserted into the endings of said active video scan lines at regular intervals according to said first synchronization device through the toggling action of said first and second switching devices in said modulator, and said second audio signal samples are removed from the endings of the active video scan lines at regular intervals according to said second synchronization device through the toggling action of said third and fourth switching devices in said demodulator.

A method for transmitting an analog audio signal over a dedicated video transmission line in a closed circuit television system comprising the steps of:

• a. inputting a synchronized analog video signal to a switching device in a modulator;
• b. inputting an analog audio input signal to said switching device;
• c. inserting samples of said audio input signal into the beginnings of the active video scan lines of the video signal at regular synchronized intervals through the toggling action of said switching device creating a combined signal;
• d. transmitting said combined signal from said modulator through a dedicated transmission line to a demodulator;
• e. removing the samples of said audio signal from the beginnings of said active video scan lines at regular identically synchronized intervals through the toggling action of a second switching device in said demodulator;
• f. outputting the video signal from said second switching device to a video monitor;
• and
• g. outputting the removed samples of said audio signal from said second switching device.

An apparatus for transmitting bi-directional audio signals over a dedicated video transmission line comprising:

• a. a modulator having an audio input, a video input, and a first synchronization device all attached to a first switching device capable of toggling between said video input and said audio input, said first switching device having an output;
• b. a demodulator having an audio output, a video output, and a second synchronization device all attached to a second switching device capable of toggling between said video output and said audio output, said second switching device having an input;
• c. a single transmission line connecting the output from said first switching device to the input of said second switching device;
• d. a third switching device in said demodulator attached to said second synchronization device and to a second audio input, said third switching device having an output connected to said transmission line;
• and
• e. a fourth switching device in said modulator attached to said first synchronization device and to a second audio output, said fourth switching device having an input connected to said transmission line;
• wherein said first and second synchronization devices are identically synchronized with each other, first direction audio signal samples are inserted into the beginnings of the active video scan lines of the video signal at regular intervals according to said first synchronization device through the toggling action of said first switching device in said modulator, and said first direction audio signal samples are removed from the beginnings of the active video scan lines of the video signal at regular intervals according to said second synchronization device through the toggling action of said second switching device in said demodulator;
• and wherein opposite direction audio signal samples are inserted into the endings of the active video scan lines of the video signal at regular intervals according to said second synchronization device through the toggling action of said third switching device in said demodulator, and said opposite direction audio signal samples are removed from the endings of the active video scan lines of the video signal at regular intervals according to said first synchronization device through the toggling action of said fourth switching device in said modulator.

An apparatus for transmitting bi-directional audio signals over a dedicated video transmission line comprising:

• a. a modulator having an audio input, a video input, and a first synchronization device all attached to a first switching device capable of toggling between said video input and said audio input, said first switching device having an output;
• b. a demodulator having an audio output, a video output, and a second synchronization device all attached to a second switching device capable of toggling between said video output and said audio output, said second switching device having an input;
• c. a single transmission line connecting the output from said first switching device to the input of said second switching device;
• d. a third switching device in said demodulator attached to said second synchronization device and to a second audio input, said third switching device having an output connected to said transmission line;
• and
• e. a fourth switching device in said modulator attached to said first synchronization device and to a second audio output, said fourth switching device having an input connected to said transmission line;
• wherein said first and second synchronization devices are identically synchronized with each other, first direction audio signal samples are inserted into the endings of the active video scan lines of the video signal at regular intervals according to said first synchronization device through the toggling action of said first switching device in said modulator, and said first direction audio signal samples are removed from the endings of the active video scan lines of the video signal at regular intervals according to said second synchronization device through the toggling action of said second switching device in said demodulator;
• and wherein opposite direction audio signal samples are inserted into the beginnings of the active video scan lines of the video signal at regular intervals according to said second synchronization device through the toggling action of said third switching device in said demodulator, and said opposite direction audio signal samples are removed from the beginnings of the active video scan lines of the video signal at regular intervals according to said first synchronization device through the toggling action of said fourth switching device in said modulator.

A method for transmitting bi-directional audio signals over a dedicated video transmission line comprising the steps of:

• a. inputting a synchronized video signal to a switching device in a modulator;
• b. inputting an audio input signal to said switching device;
• c. inserting samples of said audio input signal into the beginnings of the active video scan lines of the video signal at regular synchronized intervals through the toggling action of said switching device creating a combined signal;
• d. transmitting said combined signal from said modulator through a dedicated transmission line to a demodulator;
• e. removing the samples of said audio signal from the beginnings of said active video scan lines at regular identically synchronized intervals through the toggling action of a second switching device in said demodulator;
• f. outputting the video signal from said second switching device to a video monitor;
• g. outputting the removed samples of said audio signal from said second switching device;
• h. inputting a second audio input signal to a third synchronized switching device in said demodulator;
• i. inserting samples of said second audio input signal into the endings of the active video scan lines of the video signal at regular synchronized intervals through the toggling action of said third switching device to create a second audio signal;
• j. transmitting said second audio signal from said demodulator through a dedicated transmission line to said modulator;
• k. removing the samples of said second audio signal from the endings of said active video scan lines at regular identically synchronized intervals through the toggling action of a third switching device in said modulator;
• and
• l. outputting the removed samples of said second audio signal from said second switching device.