Multi-channel signal transmission

• US 4,891,840 A
• Filed: 03/10/1986
• Issued: 01/02/1990
• Est. Priority Date: 03/10/1986
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: Reudink, Douglas O.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Merecki, John A.
• Application Number:
  US06/837,798
• Time in Patent Office: 1,394 Days
• Field of Search: 381/29-33, 381/36-40, 375/122, 358/133, 370/118
• US Class Current: 704/203
• CPC Class Codes: H04B 1/667 using a division in frequency subbands for TV signals H04N19/63

Abstract

A system for communicating a wide band signal across a plurlaity of narrow band channels by separating the wide band signal into two or more narrower sub-bands and modulating the developed narrower sub-bands down to baseband. The baseband channels are algebraically combined to form unique combination signals, and the combination signals are transmitted over the narrowband channels. On the receiving end, the combination signals are algebraically combined to recreate the original baseband channels. The channels are modulated up to their original frequency bands, and arithmetically combined to recreate the desired broadband signal.

Claims

1. A signal conditioner responsive to a wide band signal for developing a plurality of narrow band signals representative of said wide band signal, comprising:

first means responsive to said wide band signal for separating said wide band signal into N narrow band signals where N is a positive integer greater than 1;

second means responsive to said first means for developing a baseband signal for each of said N narrow band signals, thus forming N baseband signals; and

third means responsive to said second means for developing N combination signals, where each of said combination signals is a unique algebraic combination of said N baseband signals.

2. The conditioner of claim 1 wherein N is two, said second means develops a baseband signal A and a baseband signal B, and said third means develops a first combination signal corresponding to A+B and a second combination signal corresponding to A-B.

3. The signal conditioner of claim 1 wherein said second means comprises N-1 processing elements, each of which is responsive to one of said narrow band signals and modulates the narrow band signal to which it is responsive by a different preselected carrier frequency to form a modulation result, and passes the modulation result through a low pass filter to develop said baseband signal.

4. A signal conditioner responsive to N baseband signals, N being a positive integer greater than 1 comprising:

N processing units, each responsive to said N baseband signals and each algebraically combining said N baseband signals to develop a combination signal having a frequency band, thereby developing N combination signals;

N-1 modulation means responsive to said processing units, each connected to a preselected one of said combination signals leaving a chosen one of said combination signals unconnected to any of said modulation means, for shifting the frequency band of its applied combination signal to develop narrow band signals; and

means for combining said narrow band signals with said chosen one of said combination signals to develop a wide band signal.

5. The signal conditioner of claim 4 wherein each of said modulation means employs a unique modulation frequency to perform said shifting of the frequency band.

6. A signal conditioner responsive to a signal A that corresponds to an algebraic combination of a baseband signal C and a translated baseband signal D, and to a signal B that corresponds to an algebraic combination of said baseband signal C and the negative of said translated baseband signal D comprising:

first arithmetic means responsive to signals A and B for developing an output signal equal to the sum of signals A and B;

second arithmetic means responsive to signals A and B for developing an output signal equal to the difference of signals A and B;

modulation means responsive to said second arithmetic means for shifting the input signal of said modulation means by a preselected frequency; and

means for combining said output signal of said first arithmetic means with output signal of said modulation means to develop an output signal of said signal conditioner.

7. A communications system, having a transmitter and a receiver, for transmitting a wide band signal over a plurality of narrow band transmission channels, with said transmitter comprising:

first means responsive to said wide band signal for separating said wide band signals into N narrow band signals, where N is a positive integer, second means for developing a baseband signal corresponding to each of said N narrow band signals thereby developing N baseband signals, and third means for developing N combination signals, where each of said combination signals is a unique algebraic combination of said N baseband signals; and

said receiver comprising;

N processing units, each responsive to said N baseband signals and each algebraically combining said N baseband signals to develop a combination signal having a frequency band, thereby forming N combination signals, N-1 modulation means, each connected to a preselected one of said combination signals leaving a chosen one of said combination signals unconnected to any of said modulation means, for shifting the frequency band of its applied combination signal to develop narrow band signals, and means for combining said narrow band signals with said chosen one of said combination signals to develop a wide band signal.