|
The MMM-4680 and
MMX-4680 are part of a family of data transcoders for converting between the
commonly used MPEG2 Transport Stream formats for video distribution in the
broadcast industry.
With the MMM-4680 up
to four ASI and one RS232 data signal can be combined together and converted
into a 155Mb/s G.703 (STM‑1) electrical signal.
The sum of the ASI
input payload rates can be anything up to 148 Mb/s. Inputs may be 188 or 204
byte packet length, burst or continuous, and may have energy dispersal
scrambling, interleaving and/or Reed Solomon bytes included. An individual
input may be up to 148Mb/s if the other inputs are unused.
The MMX-4680
separates the 155 Mb/s G.703 signal back into the original four ASI
signals (at their original rates) and the RS232 data signal. The ASI outputs
are suitable for Single Frequency Network use, in that there is no data rate
conversion or PCR restamping of the ASI streams. |
Inputs are
automatically equalised for lengths of up to 250m of Belden 8281 or equivalent
cable.
RS232 uni-directional
data may also be sent on the same link. It can pass rates up to 38kb/s with any
combination of start/stop & parity bits. The data rate does not affect the
payload available for the ASI streams.
Front panel
indication and relay alarm on the MMM‑4680 transmitter shows if there is an
input data rate violation. Corresponding alarm on the MMX‑4680 receiver shows a
loss of STM-1 input.
The MMM-4680 and
MMX-4680 are designed to fit IRT’s standard Eurocard frames and may be used
alongside any other of IRT’s analogue or digital Eurocards.
|
