System and method for inserting and recovering an on data signal for transmission with a video signal
US5739866A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1996 |
| Grant date | Apr 14, 1998 |
| Priority date | — |
| Expiry date | Nov 25, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/0803
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system and method for modulating a data signal uses a phase shifting transformer function to phase shift the lower and upper sidebands of the data signal so that the sidebands of the data signal have a 180.degree. phase shift with respect to each other (i.e., are complementary). The phase shifted sidebands are added to a standard video signal and then transmitted. A television or other video receiver demodulates the video signal with a simple demodulator circuit, which causes the upper and lower sidebands to be summed together. The data signal, with complementary sidebands, cancels out so that the data signal does not interfere with normal video operation. The upper and lower sidebands of the data signal are processed separately from the video processing circuitry of the television receiver. An inverse phase shifting circuit performs a second phase shift operation on the upper and lower sidebands of the data signal so that the data signal can be demodulated and the data signal recovered.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.