Transmission system for sending two signals simultaneously on the same communications channel
First Claim
1. A method of transmitting first and second signals by the same transmitter on a single channel, comprising:
- multiplying signals from a first signal source with a pseudo-random code to produce a spread spectrum signal,producing a modulated second signal which is not a spread spectrum signal and which includes a synchronization signal for the pseudo-random code and other information,combining the spread spectrum signal and the modulated signal so that the modulated second signal lies within the bandwidth occupied by the spread spectrum signal, andtransmitting the combined signals on a single communications channel.
1 Assignment
0 Petitions
Accused Products
Abstract
A transmission system in which a suitably modulated speech or data signal is combined with a low bit rate (100b/s) spread spectrum signal and transmitted simultaneously on the same channel with the modulated speech lying within the bandwidth of the spread spectrum signal.
At a receiver the modulated speech or data signal is demodulated and the modulated speech or data signal together with the spread spectrum signal are applied to a multiplier in which the spread spectrum signal is despread.
A code synchronizing signal may be included in the modulated signal prior to transmission and when recovered in the receiver, the synchronizing signal is applied to a pseudo-random code generating means. The transmission system may include a text transmission system in which case the low bit rate signal comprises pages of data. A number of pages may be transmitted simultaneously by spreading the data associated with each page by orthogonal psuedo-random codes.
286 Citations
17 Claims
-
1. A method of transmitting first and second signals by the same transmitter on a single channel, comprising:
-
multiplying signals from a first signal source with a pseudo-random code to produce a spread spectrum signal, producing a modulated second signal which is not a spread spectrum signal and which includes a synchronization signal for the pseudo-random code and other information, combining the spread spectrum signal and the modulated signal so that the modulated second signal lies within the bandwidth occupied by the spread spectrum signal, and transmitting the combined signals on a single communications channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A transmitting apparatus comprising a multiplier having a first input connected to a source of first signals;
- a second input connected to a source of a pseudo-random code and an output for a spread spectrum first signal;
means for producing a modulated second signal which is not a spread spectrum signal, and which includes a synchronization signal for said pseudo-random code and other information; and
means for combining the spread spectrum first signal and the modulated second signal so that the modulated second signal lies within the bandwidth occupied by the spread spectrum signal and for transmitting the combined signals on a single communications channel. - View Dependent Claims (16, 17)
- a second input connected to a source of a pseudo-random code and an output for a spread spectrum first signal;
Specification