Communications: electrical – Continuously variable indicating – Using a particular modulation
Patent
1979-11-08
1981-10-20
Caldwell, Sr., John W.
Communications: electrical
Continuously variable indicating
Using a particular modulation
34087029, 34087043, 328162, 328173, 375 26, G08C 1916, G08C 2500
Patent
active
042964121
ABSTRACT:
Differential pulse code modulation (DPCM) is used for a fast digital transmission of the analog input signal. In the DPCM modulator, a difference is built between the scaled input signal and the output of a digital/analog converter, which is controlled by a digital integrator. Comparator means generate a DPCM signal with values corresponding to "no change", "up-" or "down-integration" in dependence on the amplitude and polarity of the mentioned difference. The zero-crossings of the input signal itself are detected separately and are converted into a one-bit PCM signal, having the value "reset". The DPCM and PCM signals are combined into a multi-value control signal, which is fed to the integrator and causes it to follow-up the input signal and make a reset at each zero-crossing. The multi-value control signal is coded, transmitted to the receiver side of the link and decoded. The different decoded values control an integrator in the demodulator in the same way, as in the modulator. The input signal is reconstructed by digital integration of the DPCM. The periodical reset of the receiving integrator avoids a dc offset of its output, caused in any conventional DPCM system by the initial conditions of the integrator, by transmission errors, by an offset of the modulator and so forth.
REFERENCES:
patent: 3173092 (1965-03-01), Meschi
patent: 3678413 (1972-07-01), Wakeling
patent: 3927309 (1975-12-01), Fujiwara et al.
patent: 4151517 (1979-04-01), Kelley
patent: 4161628 (1979-07-01), McRea
"Military Standardization Handbook", 9-20-74; Mil-HDBK-217 B, pp. 2.1.1-1, 2.1.5-5, 2.1.7-1, .7-2, .7-11.
BBC Brown Boveri & Company Limited
Caldwell Sr. John W.
Crosland Donnie Lee
Kleeman Werner W.
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