Design and Field Test of a 256-QAM DIV Modem

Author

Chamberlin, James W. ; Hester, Cary E. ; Meyers, Jeffrey J. ; Mock, Thomas C. ; Moody, Frank A. ; Simons, Richard S., III ; Bahm, Ernest B D ; Ritchie, John A., Jr.

Author_Institution

Digital Transmission Systems Inc., Norcross, GA

Volume

5

Issue

3

fYear

1987

fDate

4/1/1987 12:00:00 AM

Firstpage

349

Lastpage

356

Abstract

The increasing demand for digital transmission facilities has led to the development of modems which allow the transmission of T1 (1.544 Mbit/s) data streams over the existing analog FM and AM/SSB links. The DTS model 2001 data in voice (DIV) modem uses 256-QAM modulation to transmit a T1 data stream in a single supergroup. This paper describes the technical requirements and design of the modem. A number of particularly interesting aspects of the design are discussed in more detail. These items are 1) the extensive use of digital signal processing in the implementation; 2) the techniques used in the demodulator control loops; 3) the use of a low-rate error correction codec and interleaver for random and burst error correction; and 4) the use of signaling constellation customization as a design tool.

Keywords

Digital modulation/demodulation; Integrated voice/data communication; Quadrature amplitude modulation; Amplitude modulation; Codecs; Constellation diagram; Demodulation; Digital signal processing; Error correction codes; Modems; Signal design; Signal processing; Testing;

fLanguage

English

Journal_Title

Selected Areas in Communications, IEEE Journal on

Publisher

ieee

ISSN

0733-8716

Type

jour

DOI

10.1109/JSAC.1987.1146558

Filename

1146558