(under the class definition) Networks including a non-linear device for decreasing the amplitude range of the signal applied to the device, and a nonlinear device connected to receive the wave having the decreased amplitude range for increasing or restoring the amplitude range of the signal, and long line transmission lines in combination with such networks.
(1) Note. This subclass provides for amplitude compression and expansion systems even though the system includes an active element such as a vacuum tube type amplifier. See (3) Note below.
(2) Note. This subclass does not include devices which merely shift the amplitude level up or down merely to control
the peak amplitude without controlling the amplitude range. Neither does this subclass include the combination of a limiter or clipper and an amplifier which cuts off the higher amplitudes and then amplifies the remaining portion of the wave energy so that the output wave does not contain any variations in wave form above a certain amplitude level, and is not therefore a function of the input wave energy.
(3) Note. In the compressor portion of the compander, the input waves of smaller amplitudes may be increased in amplitude while the input waves of larger amplitude may be increased by a smaller ratio or decreased. All amplitudes of the wave may be decreased, the larger amplitudes being decreased to a smaller extent. The expander portion may operate in a similar manner except to increase the amplitude range.
SEE OR SEARCH THIS CLASS, SUBCLASS:
20, for miscellaneous passive type wave shaping networks which modify the amplitude time characteristic of the signal transmitted therethrough. 81, for the attenuator network in this class which reduces the energy of the signal passing therethrough.
SEE OR SEARCH CLASS
178, Telegraphy,
45, for loaded lines in combination with a compander.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems,
309+, for a miscellaneous limiter with an amplifying circuit.
330, Amplifiers,
96, 123 and 129+ for amplitude range compressors or expanders of the amplifier type where the input signal is applied to a control grid of an amplifier tube whose bias is controlled in accordance with the signal intensity to produce the necessary compression or expansion, and wherein the output signal is abstracted from the plate of the amplifier tube. Subclasses 143 and 144+ for compressors or expanders where a variable impedance element is included in the signal path and the variable impedance is controlled in accordance with the signal intensity. The combination of an amplitude compressor and expander (i.e., a compander) one or both being of the amplifier type is classified in this class, (333) subclass 14. However, where such combinations involve correction only of an amplifier condition and not a condition of the transmission line, classification is with amplifiers Class 330. Combinations of an amplifier and a limiter where the output more substantially conforms to the input wave form are
classified in Class 330. See Class 250, subclass 27, above.
369, Dynamic Information Storage or Retrieval,
133, for phonograph recording and reproducing systems involving amplitude range compression and expansion.
370, Multiplex Communications, 202, for a multiplex system which includes an amplitude compression or expansion means.
381, Electrical Audio Signal Processing Systems and Devices,
106, for one-way audio signal transmission having amplitude compression/expansion.
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression,
500+, for systems changing the frequency range of a band of audio signal frequencies, transmitting the energy at the changed range, and restoring the transmitted audio signal to its original frequency range.
