3-Level partial-response signalling for voice-grade circuits
Joydeep Das, Suman Rakshit · Electronics Letters · 1978
Contrary to present practice, data transmission through voice-grade circuits becomes more efficient when p.r.s. codes are used. It is shown that 3-level and higher-level p.r.s. codes can achieve data rates up to 7.2 kb.p.s. when suitable delay equalisation of the bandpass channel (300–3400 Hz) is provided. Satisfactory eye pattern and error rates have been obtained.