MDT-3670: ASI to ASI & G.703 Network Interface Adapter.


      Wide range of ASI to ASI & G.703 conversions.
      Reed Solomon encoding.
      Packet length indication.
      Selectable 188 to 204 byte conversion.
      Packet stuffing with or without PCR restamping.


User Manual  


The MDT-3670 is part of a family of data transcoders for converting between the commonly used MPEG2 Transport Stream formats in the broadcast industry for video distribution.

The MDT-3670 can operate at ASI rates from 2 Mb/s to 50 Mb/s. The input ASI stream can be rate adapted (and optionally PCR restamped) to an E3, DS3 or framed DS3 rate. Front panel switches allow Read Solomon encoding, Interleaving and Scrambling (energy dispersal). The input signal can be converted from 188 byte packet size to 204 prior to encoding.

After encoding, two outputs are provided. An ASI output and a G.703 output, which may be at E3 or DS3 (framed or unframed) rate for interfacing to Telco type of systems.

There are several industry modes of encoding that can be performed by the MDT-3670. They are loosely classified as follows:
          Standard: Full rate [no rate adaption]
          Upstream: Rate adapted input (PCR restamping)
          Downstream: Packet stuffed [no PCR restamping]
          Compatible: 9 bit encoding, IRT MFC-3465

This range covers most of the ASI/G.703 transmission methods from both IRT and most other equipment manufacturers.

Front panel switches allow Reed Solomon encoding and the addition of interleaving and scrambling (energy dispersal). On board switches allow 188 to 204 byte conversion and framing for DS3 signals.

The MDT-3670 is fabricated in IRT's standard Eurocard format and may be housed in a variety of IRT's frames.


1 x ASI-C 75 Ω, 800 mVp-p, BNC connector.
2 to 50 Mb/s.
Automatic, better than 250 metres at 270 Mb/s for Belden 8281 or equivalent cable.

Type 1
1 x ASI-C 75 Ω, 800 mVp-p, BNC connector.

Type 2
1 x G.703, 75 Ω BNC connector.
G.703 Rate
E3 (34.368 Mb/s);
Framed or unframed DS3 (44.736 Mb/s).

Relay NO/NC link selectable,
(Relay energised when Input Sync is obtained).
Relay NO/NC link selectable,
(Relay energised when there are no G.703 output rate errors).

Power Requirements:
28 Vac CT (14-0-14) or 16 Vdc.
Power consumption
< 5.5 VA.

Temperature range
0 - 50°C ambient.
Suitable for mounting in IRT 19" rack chassis with input, output and power connections on the rear panel.
Finish:             Front panel
Grey background, black lettering & red IRT logo.
                       Rear assembly
Detachable silk-screened PCB with direct mount connectors to Eurocard and external signals.
6 HP x 3 U x 220 mm IRT Eurocard.

Supplied accessories
Rear connector assembly including matching connector for alarm output.


Due to our policy of continuing development, these specifications are subject to change without notice.