RAD DATA COMMUNICATIONS
=======================

   MTM-20 (X.21, DC POWER)

   Card Type         Modem (synchronous)                          
   Chipset           Unidentified                                 
   Transfer Rate     32/64Kbps                                    
   Data Modulation   QAM                                          
   Data Bus          Serial                                       

<gopher://bitreich.org/I/th99/t/P-R/53671-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   |       Function       | Label |      Function       | Label |
   |----------------------+-------+---------------------+-------|
   | DC power in          |  CN1  | Analog loopback     |  SW2  |
   |                      |       | test switch         |       |
   |----------------------+-------+---------------------+-------|
   | X.21 serial port     |  CN2  | Remote digital      |  SW3  |
   |                      |       | loopback test       |       |
   |                      |       | switch              |       |
   |----------------------+-------+---------------------+-------|
   | Line out (see pinout |  SC1  | Test pattern switch |  SW4  |
   | below)               |       |                     |       |
   |----------------------+-------+---------------------+-------|
   | Local digital        |  SW1  |                     |       |
   | loopback test switch |       |                     |       |
   |------------------------------------------------------------|
   |      Note:Modem can be made to perform self-test by        |
   |      holding down SW2 and SW4. The DCD, TEST, and SQ LEDs  |
   |      should go on, and the RD LED should go off.           |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                         SC1 PINOUT                         |
   |------------------------------------------------------------|
   |    Function     | Terminal |      Function      | Terminal |
   |-----------------+----------+--------------------+----------|
   | Ground          |    1     | Not used           |    5     |
   |-----------------+----------+--------------------+----------|
   | Not used        |    2     | Transmit line      |    6     |
   |-----------------+----------+--------------------+----------|
   | Receive line    |    3     |   Transmit line    |    7     |
   |-----------------+----------+--------------------+----------|
   | Receive line    |    4     |                    |          |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |                Setting                 | Label | Position  |
   |----------------------------------------+-------+-----------|
   |>> | DCD forced high                    |  JP3  | Pins 3 &  |
   |   |                                    |       | 4 closed  |
   |---+------------------------------------+-------+-----------|
   |   | DCD normal                         |  JP3  | Pins 1 &  |
   |   |                                    |       | 2 closed  |
   |---+------------------------------------+-------+-----------|
   |>> | Signal ground connected to chassis |  JP4  | Pins 1 &  |
   |   | ground                             |       | 2 closed  |
   |---+------------------------------------+-------+-----------|
   |   | Signal ground not connected to     |  JP4  | Pins 2 &  |
   |   | chassis ground                     |       | 3 closed  |
   |---+------------------------------------+-------+-----------|
   |>> | Line speed set to 64Kbps           |  SW5  | Position  |
   |   |                                    |       |     4     |
   |---+------------------------------------+-------+-----------|
   |   | Line speed set to 32Kbps           |  SW5  | Position  |
   |   |                                    |       |     3     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                       TRANSMIT LEVEL                       |
   |------------------------------------------------------------|
   |   Setting   |  JP5/A  |  JP5/B  | JP5/C  | JP5/D  | JP5/E  |
   |-------------+---------+---------+--------+--------+--------|
   |>> |  0dBm   | Closed  |  Open   |  Open  |  Open  |  Open  |
   |---+---------+---------+---------+--------+--------+--------|
   |   |  -3dBm  |  Open   | Closed  |  Open  |  Open  |  Open  |
   |---+---------+---------+---------+--------+--------+--------|
   |   |  -6dBm  |  Open   |  Open   | Closed |  Open  |  Open  |
   |---+---------+---------+---------+--------+--------+--------|
   |   |  -9dBm  |  Open   |  Open   |  Open  | Closed |  Open  |
   |---+---------+---------+---------+--------+--------+--------|
   |   | -12dBm  |  Open   |  Open   |  Open  |  Open  | Closed |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                        CLOCK SOURCE                        |
   |------------------------------------------------------------|
   |          Setting           |              JP1              |
   |----------------------------+-------------------------------|
   |>> |        Internal        |       Pins 1 & 2 closed       |
   |---+------------------------+-------------------------------|
   |   |        External        |       Pins 3 & 4 closed       |
   |---+------------------------+-------------------------------|
   |   |        Received        |       Pins 5 & 6 closed       |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                        LINE LENGTH                         |
   |------------------------------------------------------------|
   |                Setting                |        JP2         |
   |---------------------------------------+--------------------|
   |>> |              0-10Km               | Pins 3 & 4 closed  |
   |---+-----------------------------------+--------------------|
   |   |              7-13Km               | Pins 1 & 2 closed  |
   |---+-----------------------------------+--------------------|
   |   | Auto select (not yet implemented) | Pins 5 & 6 closed  |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     DIAGNOSTIC LED(S)                      |
   |------------------------------------------------------------|
   | LED  | Color  |  Status  |            Condition            |
   |------+--------+----------+---------------------------------|
   | PWR  | Green  |    On    |           Power is on           |
   |------+--------+----------+---------------------------------|
   | PWR  | Green  |   Off    |          Power is off           |
   |------+--------+----------+---------------------------------|
   | RTS  | Yellow |    On    |       RTS signal is high        |
   |------+--------+----------+---------------------------------|
   | RTS  | Yellow |   Off    |        RTS signal is low        |
   |------+--------+----------+---------------------------------|
   |  TD  | Yellow |    On    |    DSU is transmitting SPACE    |
   |------+--------+----------+---------------------------------|
   |  TD  | Yellow |   Off    |     DSU is not transmitting     |
   |------+--------+----------+---------------------------------|
   |  TD  | Yellow | Blinking |    DSU is transmitting data     |
   |------+--------+----------+---------------------------------|
   |  RD  | Yellow |    On    |     DSU is receiving SPACE      |
   |------+--------+----------+---------------------------------|
   |  RD  | Yellow |   Off    |      DSU is not receiving       |
   |------+--------+----------+---------------------------------|
   |  RD  | Yellow | Blinking |      DSU is receiving data      |
   |------+--------+----------+---------------------------------|
   | DCD  | Yellow |    On    |     Carrier signal detected     |
   |------+--------+----------+---------------------------------|
   | DCD  | Yellow |   Off    |   Carrier signal not detected   |
   |------+--------+----------+---------------------------------|
   | TEST |  Red   |    On    |       DSU is in test mode       |
   |------+--------+----------+---------------------------------|
   | TEST |  Red   |   Off    |     DSU is not in test mode     |
   |------+--------+----------+---------------------------------|
   |  SQ  | Yellow |    On    |     Signal quality is good      |
   |------+--------+----------+---------------------------------|
   |  SQ  | Yellow | Blinking | Signal quality is poor or test  |
   |      |        |          |     pattern contains errors     |
   +------------------------------------------------------------+