RPT-83

The RPT-83 has the following features including Automatic ALBO Function;Cloek-tihutdown Circuit (RPT B3);Low-Power Operation (100mW);Pin Compatible with XR-C277.

The RPT-83 is integrated circuit that perform the active functions required for regenerative PCM repeaters. They can operate from less than 100kHZ to greater than 3MHz. In PCM systems, information is transmitted by the presence or absence of bipolar pulses in specified time slots. The RPT-83 repeaters automatically adjust gain to optimize signal levels, determine if a pulse is present or not, and retransmit the reconstrutted pulses.Bipolar-pulse transmission, the transmission of alternately positive and negative pulses, is used on repeater lines to remove the DC component present in unipolar PCM pulse trains. This also places the principal energy components  in the 0-1.544MHz band, as opposed to the 0-3.088MHz band for unipolar pulse trains. The absence of a DC component in bipolar pulse trains permits the repeater to be transformer-coupled to the repeater line and helps prevent time-shifting of the regenerator firing levels with variations in input pulse density.

The preamplifier stage amplifies the input signal and applies it to the three comparators labeled data detector, clock detector,and peak detector, respectively. Each comparator provides an output whenever the signal exceeds the trip point on both positive and negative pulses. Each comparator trips at a different threshold. The data detector is set to trip at the 54% point;the clock detector trips at the 73% point; and the peak detector trips at peak amplitude. Current pulses from the peak detector are integrated by the capacitor in the ALBO filter. This causes a relatively constant current to flow through the emitter follower and D1. In the RPT 83, a low voltage at the ALBO filter enables the clock-shutdown circuit when there is no input signal. The clock-shutdown circuit turns off the clock amplifier so that neither the regenerated clock, nor the strobe outputs, are sent to the flip-flops. This prevents the RPT-83 from sending noise or crosstalk outas valid-appearing data pulses when the incoming data level is too low.