Release 1
DAMS-NT DigiRIT Operation Manual
12/14/2012
Microcom Design, Inc.
9
5.
70 MHz IF Test Point
BNC
6.
140 MHz IF Test Point
BNC
7.
Cooling Fan
N/A
8.
140 MHz Antenna IF Input Connector
SMA
9.
140 MHz Front End DC Power Indicator LED
N/A
10.
140 MHz Antenna IF Output Connector
SMA
11.
70 MHz Antenna IF Input Connector
SMA
12.
70 MHz Front End DC Power Indicator LED
N/A
13.
70 MHz Antenna IF Output Connector
SMA
14.
Raw LRIT/HRIT Network Connector
RJ-45
15.
DCS Message Network Connector
RJ-45
16.
IRIG-B Timing Input
BNC
17.
AC Power Input with On/Off Switch
IEC320-C14
18.
Power Indicator Lamp
N/A
19.
Ground Lug
Stud
1.3.2.
DAMS-NT DCP Message Interface
While complete details of the “DCP Message Interface” can be found in the “DAMS-NT Network
Interface Specification V8.1”, this section provides a brief overview of this interface and
addresses some minor deviations from the specification.
The DCP Message Interface provides a mechanism for multiple clients to receive DCS messages
from the DigiRIT unit. While multiple client connections are supported by the DigiRIT
Receiver, the maximum number of Client connections is limited to three (3). The DCP Message
Interface is a one-way stream of DCS messages. After a client establishes a connection, the
DigiRIT immediately begins to send DCS messages as they become available, i.e. the DAMS-
NT Client does not poll for messages.
If no DCS message is received via the LRIT stream for more than 10 seconds since the last
message was sent to a client, the DigiRIT will send the keyword “NONE” followed by a CR/LF
to allow clients to detect the difference between a dead socket and the case where no new data is
available, as often happens in the LRIT DCS re-broadcast while LRIT system is transmitting
another product.
Each DCS message is sent the connected Clients after it is received via the LRIT stream and
after the message has been validated. Valid DCS messages are translated from their native LRIT
DCS structure and are re-formatted per DAMS-NT DCP Message Interface. This format
includes a 55-byte header, followed by the actual message data, followed by a CR/LF, and
possibly followed the V8.1 carrier times.
1.3.2.1.
DAMS-NT Message Header
The DigiRIT creates a 55-byte header compatible with the DAMS-NT format, which is
summarized in the table below. However, minor deviations from the specification imposed by
limitations in the raw LRIT message format are discussed below. All fields, including the
StartPattern, in the header are in ASCII without any parity.