Video transmission and control system utilizing internal telephone lines
View Patent ↗A video transmission system for facilitating transmission of video and control signals, particularly infrared remote control signals, between different locations in a residence using existing telephone wiring. Simultaneous transmission of signals of both types over active telephone lines is possible without interference with telephone communications. Transmission succeeds without requiring special treatment of the video signals beyond RF conversion, despite signal attenuation inherent in transmission over the telephone line media. Two or more video sources may be tied into the system, and selected as desired. Remote control signals generated in one room may be utilized without requiring a clear line of sight between the remote control device and the receiver.
1. A method for communicating information over a conductive path, comprising:
encoding a first information set in a first signal and encoding a second information set in a second signal, wherein the first signal and the second signal are electrical signals and the power spectrum of the first signal overlaps the power spectrum of the second signal;
transmitting the first signal onto the conductive path at a first point, and transmitting the second signal onto the conductive path at a second point, wherein the first signal is transmitted during a first set of time intervals, the second signal is transmitted during a second set of time intervals, and the first set and the second set of time intervals are substantially non-overlapping;
receiving the first signal at a third point on the path and recovering substantially all of the first information set from the first signal received at the third point; and
receiving the second signal at the third point and recovering substantially all of the second information set from the second signal received at the third point,
wherein the first, second, and third points are at different locations on the conductive path.
2. The method according to claim 1 , further including transmitting a third signal onto the conductive path during at least part of the first set of time intervals, wherein (a) the power spectrum of the third signal is substantially confined to frequencies below 3 KHz, (b) the power spectrum of the first signal is substantially confined to frequencies above 3 KHz, and (c) the transmitting the first signal comprises presenting a high impedance to said third signal.
3. The method according to claim 1 , further comprising transmitting ordinary telephone signals onto the conductive path at voiceband frequencies while simultaneously transmitting at least part of said first signal onto the conductive path.
4. The method according to claim 3 , wherein transmitting ordinary telephone signals further comprises presenting a high impedance to said first signal.
5. The method according to claim 4 , wherein presenting a high impedance to the first signal substantially prevents attenuation of the first signal.
6. The method according to claim 1 , wherein:
the power spectrum of the first signal is substantially confined within a plurality of bands;
the bands of said plurality of bands are non-overlapping frequency bands and include a first band and a second band;
substantially all of the power spectrum of the first signal is confined to frequencies outside a band of frequencies separating the first band and the second band; and
the first information set is recoverable from any signal that is created by excluding a portion of the first signal, wherein said portion is substantially confined within a band in the plurality of bands.
7. The method according to claim 6 , wherein the band separating the first band and the second band substantially overlaps a radio band allocated to amateur radio transmission.
8. The method of claim 7 , wherein the radio band is located below 30 MHz.
9. The method according to claim 8 , wherein (a) a telephone signal is transmitted onto said path during at least part of said first set of time intervals (b) the transmitting of said telephone signal comprises presenting a high impedance to said first signal, and (c) said telephone signal is confined to frequencies below 3 KHz.
10. The method according to claim 8 , further including transmitting a third signal onto the conductive path during at least part of the first set of time intervals, wherein (a) the power spectrum of the third signal is substantially confined to frequencies below 3 KHz, (b) the power spectrum of the first signal is substantially confined to frequencies above 3 KHz and (c) the transmitting the first signal comprises presenting a high impedance to said third signal.
11. The method according to claim 6 , wherein the band separating the first band and the second band spans amateur radio located at one of 7 MHz, 14 MHz, and 21 MHz.
12. The method according to claim 1 , further comprising allowing signals above voiceband on the conductive path to pass and blocking signals within voiceband, wherein the signals within voiceband are telephone signals.
13. The method according to claim 12 , wherein the blocking of voiceband signals includes presenting a high impedance to voiceband signals to substantially prevent attenuation of voiceband signals.
14. The method according to claim 1 , further comprising allowing signals within voiceband on the conductive path to pass and blocking signals above voiceband, wherein the signals within voiceband are telephone signals.
15. The method according to claim 14 , wherein the blocking of signals above voiceband includes presenting a high impedance to signals above voiceband to substantially prevent attenuation of signals above voiceband.
16. The method according to claim 1 , wherein on the conductive path there are reflections of the first signal that are created by impedance discontinuities, and wherein substantially all of the first information set is recoverable despite the reflections.
17. The method according to claim 1 , wherein the first information set includes video information.
18. The method according to claim 17 , further comprising converting the video information in the first information set to moving images.
19. The method according to claim 1 , wherein the first information set includes audio information.
20. The method according to claim 19 , further comprising converting the audio information to sound.