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The matched-filter NTDS receiver on the Jentech Dual E board provides enhanced sensitivity for weak signals as well as enhanced filtering and rejection of signal distortion components.  The high fidelity LLS NTDS transmitter provides full MIL-STD-1397C specification compliance.  The full set of System Integrity Features (SIF) is provided as well as parity enable/disable, single word transfer, burst transfer, word timeouts, buffer timeouts and NTDS data rates at the theoretical limits. 

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:

Source timeout

Sink timeout

Sink parity

Sink timing

Sink illegal condition

Control frame validation

In addition the Dual E board provides full Type E functionality including:

Priority for EIs and EFs over INs and OUTs

Forced EFs

Immediate EFs

Multiple Forced EIs without loss

Parity Enable/Disable

Single word transfers (SWT)

Burst Mode transfers 

Buffer and Word Timeout - Performed in Real-time

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:

Single Word Transfer
Data Rate:

200 kwords/sec (based on 32 bit words)

Burst Mode Transfer
a Rate :

300 kwords/sec (based on 32 bit words)


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