Abstract: An ultraviolet optical isolater which utilizes a KDP-isomorph crystal as optical element is disclosed.

Abstract: A channel bank unit for interfacing baseband user signals with a PCM carrier communications channel. The channel bank unit includes a circuit allowing verification of the transmission interity between the channel bank unit and external equipment having two-way communication with the channel bank unit. The circuit includes a first portion for evaluating the reception integrity of signals received from the external equipment and a second portion for imposing a parity sense on the signals transmitted to the external equipment that is related to the evaluation results of the first portion.

Abstract: A reduction in idle channel noise and crosstalk in a mid-riser-biased successive approximation encoder is achieved through the use of two polarity decisions. Encoder (401) assigns a sampled analog input signal to the closest one of a multitude of discrete signal levels or code steps. A comparator (109) provides this assignment by successive comparisons of the sampled signal with a series of reference signals (110). Each comparison produces a binary digit. The first comparison, or polarity decision, is not transmitted and instead coupled to feedback circuitry (401) to reduce any dc component in the analog input signal to substantially zero. A second polarity decision is then made using a non-zero offset reference signal (402) corresponding to an intermediate position on a code step, typically the midpoint. The non-zero offset reference signal is applied along with subsequent reference signals to the comparator to determine the closest code step.

Abstract: A data link is additionally provided in a digital channel bank type transmission system without displacing or degrading any present voice or signaling channel capacities. The additional data channel is obtained by "borrowing" a major portion of the signaling subframe channel. A transmit circuit (FIG. 3 and FIG. 8) serves to time division multiplex a data channel into the signaling subframe channel by transmitting the signaling framing pattern in an intermittent periodic manner with preselected data bits interposed therebetween (waveform TDATA of FIG. 5). At the remote receiving terminal, a subframe recovery circuit (FIG. 7) serves to recover the signaling framing pattern embedded in the multiplexed subframe channel. A receive circuit (FIG. 4) at the remote terminal is responsive to a signal from the subframe recovery circuit to separate out the data bits in the multiplexed subframe channel.