Title :
Data compression of voiceband modem signals
Author :
Lin, D. ; Kurtz, S. ; McCarthy, B.
Author_Institution :
Int. Mobile Machines, Philadelphia, PA, USA
Abstract :
The development of an integrated data-compression system for speech and voiceband modem signals is described. The integrated source coder performs a quadrature decomposition of a bauded signal prior to quantization. A detection algorithm is used to determine the presence and the carrier frequency of the bauded signal. The coder is currently implemented with a TMS 32020 digital signal processor in a basic exchange radio system to provide wireless digital access for rural subscribers. Performance of the integrated source coder was evaluated in the lab and in a field trial. Using a radio link in the lab, the coder support the following data communication standards: 300 b/s Bell 103, CCITT V.21; 1200 b/s Bell 212A, CCITT V.22; 2400 b/s CCITT V.22 bis; and 2400 b/s CCITT V.24 ter. Tests were also conducted for the transmission of facsimiles between a dozen of the popular low-priced telecopiers. The reproduction quality of the system for various types of documents and drawings were near transparent
Keywords :
computerised signal processing; data compression; digital radio systems; digital signal processing chips; encoding; facsimile; 1200 bit/s; 2400 bit/s; 300 bit/s; TMS 32020 digital signal processor; bauded signal; data communication standards; facsimiles; field trial; integrated data-compression system; integrated source coder; quadrature decomposition; telecopiers; voiceband modem signals; Code standards; Data communication; Data compression; Detection algorithms; Digital signal processors; Frequency; Modems; Quantization; Radio link; Speech;
Conference_Titel :
Vehicular Technology Conference, 1990 IEEE 40th
Conference_Location :
Orlando, FL
DOI :
10.1109/VETEC.1990.110341
