Release 1
DAMS-NT DigiRIT Operation Manual
12/14/2012
Microcom Design, Inc.
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components. The raw DCS spectrum is located 450 kHz above the LRIT signal at 1694.450
MHz.
Generally speaking, the DigiRIT’s 70 MHz IF Input is intended to be utilized with Microcom’s
standard DRGS front-end, which allows a single satellite dish to provide an input to both the
LRIT DigiRIT Receiver and a local DCS DRGS. The 140 MHz input is generally utilized in a
stand-alone LRIT configuration. A DCS DRGS receiver typically requires a satellite dish in
excess of 3.5 meters in diameter, while the LRIT signal can be reliably received with a dish as
small as 1.2 meters.
In Microcom’s standard DRGS configuration, the DCS IF is at 74.450 MHz and the LRIT signal
is at 74.000 MHz. In a standalone LRIT receive system, Microcom typically utilizes a more
compact front-end that better fits on the smaller dish; this front-end provides the LRIT signal at
137.500 MHz.
Once the DigiRIT has acquired the LRIT signal, it will extract the DCS messages from the LRIT
stream and forward them out the DCS TCP/IP network connection as they are received. The
receiver’s DCS interface is compliant with the “DAMS-NT Network Interface Specification
V8.1”. However, only the “DCP Message Interface” socket is implemented. Since the “Event”,
“Real-Time Status”, and “Configuration” interfaces are more geared toward a DRGS, these
interfaces are not applicable to an LRIT DCS receiver.
A complete the LRIT DCS system requires a computer or server hosting a DAMS-NT
compatible Client application. Since the DigiRIT Receiver utilizes TCP/IP network
communications, no special hardware is required for the Client computer to ingest DCS
messages. While Microcom has its own DAMS-NT Client software, use of the DAMS-NT
interface socket means the DigiRIT Receiver is compatible with other DAMS-NT Client
applications. As such, the computer/server and host application can be provided by the end user.
For this reason, the standard Microcom DAMS-NT DigiRIT Receiver system does not include a
computer nor any application software; although these can be optionally provided.
Note that while Figure 2 only shows a single computer, the DigiRIT Receiver can support up to
three DAMS-NT Client connections. These Client connections can be separate computers
hosting unique applications, a single computer hosting multiple Client applications, or a
combination of these provided the total number of socket connections is limited to three.
Finally, it should be emphasized that since the DCS re-broadcast provides complete channel
coverage and since the LRIT stream is transmitted to both satellites, a single satellite dish
pointed at either the East or West spacecraft is sufficient to collect all DCS messages routed
through the GOES system and received by NOAA. To a yield a similar result utilizing a
traditional DRGS not only requires two satellite dishes and accompanying front-ends, but also
requires a substantial amount of additional hardware and software to receive all of the more than
200 active DCS channels (soon to double to more than 400 in the coming years). In other words,
a simple, low-cost LRIT DCS system pointed at just one GOES satellite, as is possible with the
Microcom DigiRIT Receiver, can yield total GOES DCS message reception at a fraction of the
complexity and cost of a complete DRGS.
On the other hand, while it is not necessary to get the LRIT stream from both spacecrafts, there is
one distinct advantage to utilizing two DigiRIT systems, one for GOES-East and one for GOES-
West; specifically, redundancy. Adding a second DigiRIT antenna and receiver to get the LRIT
