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Years of field experience have shown that user environments (either on-shore laboratories or shipboard) can vary widely and the Dual E NTDS transceiver has been custom designed for optimum performance under a range of conditions. The combination of Jentech's wide bandwidth receiver and low bandwidth transmitter help to minimize signal reflections within any given system. The Receiver: Enhanced sensitivity for weak signals is provided by the matched-filter receiver and becomes extremely important in installations using long cable lengths. Enhanced filtering and rejection of signal distortion components is particularly important in installations using electrical or mechanical switching systems. In addition, the wide bandwidth of the Dual E board receiver minimizes signal reflections that could interfere with or confuse equipment linked at the other end of the interface. The Transmitter: The Dual E board transmitter is fully MIL-STD-1397C specification compliant. Zero crossing accuracy (timing) is held to within +(-)3 ns accuracy as required of the Manchester data. The voltage level is near the top for any marginal receivers which may be at the end of a long cable but still within the limits of 500 to 750 mvolts (peak). The Dual E board meets the residual distortion and noise level requirements when not transmitting. Bandwidth (rise and fall times) is limited in order to minimize reflection at the remote receiver. The rise and fall times of the Dual E board adhere to the 50 to 180 mvolts per ns required. By maintaining the rise time to within required specification limits, Jentech has effectively limited the bandwidth. The full set of System Integrity Features (SIF) for Type E interfaces as called out in Section 5.4.7 of MIL-STD-1397C are supported and are summarized below:
In addition the Dual E board provides full Type E functionality including:
As noted in MIL-STD-1397C Figure 67, actual Type E NTDS data rates vary as cable lengths increase. With this limitation in mind, the Jentech Dual E board is capable of supporting NTDS data rates at the theoretical limits as called out below:
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