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Mounting in order to reduce the error in the regulators of level gradual pilots comprising of the discriminators of voltage as a measuring detectors, in particular for telecommunication systems with carriers multichannel
Mounting in order to reduce the error in the regulators of level gradual pilots comprising of the discriminators of voltage as a measuring detectors, in particular for telecommunication systems with carriers multichannel
1,048,100. Automatic volume control. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. March 3, 1964 [March 14, 1963; Dec. 5, 1963], No. 8900/64. Heading H4R. In a pilot controlled automatic volume control system, particularly for multi-channel carrier systems, e.g. of Specification 1,009,064; in which variations of the pilot signal level from a standard level in one direction or the other are detected by a respective one of two voltage discriminator two-state devices, e.g. Schmitt triggers, which control the stepping direction of a gain adjusting device including a thermistor, the effects of the back-lash, or hysteresis, in the operating potential of the voltage discriminator two-state device is reduced by feeding them via a temperature compensated comparison amplifier of relatively high gain. Fig. 1 shows an embodiment in which the rectified pilot voltage, applied to terminal Up, is compared with the voltage developed across Zener diode D 1 to control the input voltage to the low and high level voltage discriminator Schmitt trigger stages ST 1 and ST 2 . The arrangement is independent of temperature if the temperature coefficient of transistor Ts 1 is equal and opposite to that of diode D1. Alternatively the Zener diode may be connected in the base circuit of one of a pair of transistors connected as a differential amplifier with the rectified pilot signal applied to the base of the other transistor, Fig. 2 (not shown). An additional diode may be connected in one or the other base circuits of the differential amplifier to compensate the temperature coefficient of the pilot rectifying diode, Figs. 3 and 4 (not shown).
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