. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. 616 BELL SYSTEM TECHNICAL JOURNAL protection. All outside connections to the panel are made through the terminal block in the lower right-hand corner. Wires supplying power, together with those which are at a low potential with respect to ground, are run in a cable, while wires at a high potential are run directly from point to point in as short a path as possible in order to reduce losses resulting from the capacity of these wires to ground. Demodulator an
. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. 616 BELL SYSTEM TECHNICAL JOURNAL protection. All outside connections to the panel are made through the terminal block in the lower right-hand corner. Wires supplying power, together with those which are at a low potential with respect to ground, are run in a cable, while wires at a high potential are run directly from point to point in as short a path as possible in order to reduce losses resulting from the capacity of these wires to ground. Demodulator and Receiving Oscillator. The circuit of the demodu- lator shown in Figure 35 is in many respects similar to that of the Oubpul. P Incut H30' HSO' -24" i -22-5' -2V Figure 35—Schematic of demodulator circuit and receiving oscillator modulator. The function performed by the demodulator is also similar, being a translation from a high-frequency band to a lower instead of the reverse. The oscillator which supplies the carrier to the demodulator is of the same type as the modulator oscillator, and has been discussed in connection with that circuit. No adjustable feature for balancing the carrier is required in the demodulator circuit. The carrier sup- pression needed in addition to the suppression inherent in the balanced circuit is provided by the low-pass filter at the output. If the carrier is not sufficiently suppressed, it will pass into the voice circuit or across the hybrid coil into the associated modulator, causing in some channels an objectionable beat tone. The transmission stability of the demodulator is obtained by the same methods used in the modulator since the performance of the two circuits is similar, and the transmission quality requirement is essentially the same for both units. A typical demodulator charac- teristic is shown in Figure 36. This characteristic at the higher frequencies is controlled by the low-pass Please note that these images are
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