Modem in-band secondary channel via radial modulation

• US 4,525,846 A
• Filed: 12/27/1982
• Issued: 06/25/1985
• Est. Priority Date: 12/27/1982
• Status: Expired due to Term

• Current Assignee: Paradyne Corporation (Dasan Networks Incorporated)
• Original Assignee: Paradyne Corporation (Dasan Networks Incorporated)
• Inventors: Bremer, Gordon, Betts, William L., Greene, Robert T.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Chin, Stephen
• Application Number:
  US06/453,165
• Time in Patent Office: 911 Days
• Field of Search: 375/38, 375/39, 375/40, 375/96, 370/20, 455/52, 455/132
• US Class Current: 375/261
• CPC Class Codes: H04L 27/2071 in which the data are represented by the carrier phase, e.g. systems with differential coding
• CPC Class Codes: H04L 27/3472 by switching between alternative constellations

Abstract

A transmission system for transmitting a first data series, and a second data series from a first modem to a second modem using QAM or PSK type modulation techniques. The first data series is sent using standard QAM techniques such as an 8-point scheme, wherein each point has a radial component. The second data series is sent by modulating slightly the radial components of the transmitted symbols between two values in accordance with the second data series.

Claims

1. A method of transmitting a first and second input series of input bits simultaneously, over a single data channel comprising:

generating a series of symbols having a radial amplitude and corresponding to said first series of input bits;

maintaining the radial amplitude of said symbols at a first level if said second input bits have a first value and alternating said radial amplitude between said first value and a second value for consecutive symbols when said second input bits have a second value;

sending said symbols over said communication channel, to a receiver;

detecting the radial amplitudes of the signals received by said receiver;

correlating the radial amplitudes of a last preselected number of received signals to obtain a correlated value;

comparing said correlated value to a threshold value; and

generating a series of output bits having a first value if said correlated value is above said threshold value; and

a second value if said correlated value is below said threshold value.

2. The method of claim 1 wherein said first and second series of input bits have corresponding first and second data rates, said first data rate exceeding said second data rate.