(under subclass 24) Networks with attenuation or attenuation and phase distortion characteristics which vary over a frequency range for use in a wave transmission system for modifying the attenuation or attenuation and phase characteristics of the wave energy as a function of frequency, and systems within the class definition which include such networks.
(1) Note. Equalizer networks are used to reduce the attenuation or attenuation and phase distortion characteristics which the wave energy in a long line transmission system would have in the absence of the network. The network may be used for predistorting so that the distorting effect of the long line will be corrected.
(2) Note. A filter is distinguished from an equalizer in that a filter is intended and designed to transmit a frequency or one or more bands of frequencies without modification while undesired frequencies are attenuated to a low value so that the desired frequency or frequencies are transmitted by the filter and the undesired frequencies are substantially blocked, while the equalizer has the function of changing the relative amplitudes of the waves of different
frequency over the range of frequencies transmitted by the equalizer.
(3) Note. Included are tone control networks which involve only passive elements and which vary the attenuation or attenuation and phase distortion characteristics over a range of frequencies. Included are such networks as are used for "bass boosters", "treble boosters", "treble cut systems", etc.
SEE OR SEARCH THIS CLASS, SUBCLASS:
18, for this subject matter where the equalizer is provided with automatic control means. 20, for wave shaping systems.
81, for attenuator networks within the class definition composed entirely of resistive elements.
138+, for phase control or delay networks, per se.
SEE OR SEARCH CLASS
323, Electricity: Power Supply or Regulation Systems, appropriate subclasses for miscellaneous impedance and transformer systems, and for phase control systems.
109, 120, 122, 154, 157+, 185+, 192+, and 304, for amplifier systems combined with an equalizer network.
332, Modulators,
107, for distortion control in pulse modulators, subclasses 123+ for distortion control in frequency modulators, subclasses 144+ for distortion control in phase modulators, and subclasses 159+ for distortion control in amplitude modulators.
381, Electrical Audio Signal Processing Systems and Devices,
98+, for audio signal processing devices and systems having frequency control.
455, Telecommunications, 267, for radio receivers with tone control networks.
