Title :
Linearity testing of multi-level transmitters for communication systems
Author_Institution :
British Telecom Res. Labs., Ipswich, UK
Abstract :
A method of testing multilevel transmitters is described which avoids the use of echo-cancellers but still uses a test signal which closely resembles random data with a wide spectral content, little autocorrelation, large excursions of running digital sum, and a rich selection of transmitted symbols of transitions. The transmit signal is based on a chirp coded to use only the allowable transmit symbols in a nose shaping coder. The chirp is modified to exhibit a spectral cavity, kept deep during the coding process by arranging a coincident noise minimum in the coder. Transmitter imperfections can be observed as they fill the cavity with distortion products. The method is assessed against a theoretical model of transmitter distortion, and measurements of an ISDN (integrated services digital network) basic rate 2B1Q transmitter are shown
Keywords :
ISDN; electric distortion measurement; electronic equipment testing; encoding; transmitters; ISDN basic rate 2B1Q transmitter; coded chirp; coincident noise minimum; communication systems; distortion products; linearity testing; little autocorrelation; multilevel transmitters; nose shaping coder; running digital sum; spectral cavity; test signal; transition symbols; transmit signal; transmitter distortion; transmitter testing; wide spectral content; Autocorrelation; Chirp; Distortion measurement; Echo cancellers; ISDN; Linearity; Noise shaping; Nose; Testing; Transmitters;
Conference_Titel :
Acoustics, Speech, and Signal Processing, 1991. ICASSP-91., 1991 International Conference on
Conference_Location :
Toronto, Ont.
Print_ISBN :
0-7803-0003-3
DOI :
10.1109/ICASSP.1991.150766