Patton electronic 2073 - Manual (Page 10)

5.3.2 Operating Remote Digital Loopback (RDL)
The Remote Digital Loopback (RDL) test checks the performance
of both the local and remote Model 2073s, as well as the communica-
tion link between them. Any characters sent to the remote Model 2073
in the test mode will be returned back to the originating device (i.e,
characters typed on the keyboard of the local terminal will appear on
the local terminal screen after having been passed to the remote
Model 2073 and looped back). See figure 7 below.
Figure 7. Remote Digital Loop
To perform an RDL test, follow these steps:
1. Activate the RDL by moving the front panel toggle switch
DOWN to remote.
2. Perform a bit error test (BERT) using the internal V.52 gener
ator (as described in Section 5.4), or using a seperate BER
Tester. If the BER test indicates a fault, and the Local Line
Loopback test was successful for both Model 2073s, you may
have a problem with the twisted pair line between the
modems. You should then check the twisted pair line
for proper connections and continuity.
5.3.3 BIT Error Rate (V.52) Diagnostics
The Model 2073 offers a V.52 Bit Error Rate (BER) 511 test pat-
tern. This test pattern may be invoked along with the LAL and RDL
tests to evaluate the unit(s) and the communication links.
When a 511 test is invoked, the 2073 generates a pseudo-random
pattern of 511 bits using a mathematical polynomial. The receiving
Model 2073 then decodes the received bits using the same polynomi-
al. If the received bits match the agreed upon pseudo-random pattern,
then the 2073(s) and the communication link(s) are functioning proper-
ly.
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511 Initiates a built-in 511 bit pseudo-random
pattern generator and detector.
511 with Errors Initiates a built-in 511 bit pseudo-random
pattern generator and detector. The test
pattern generator also injects
intentional
errors approximately once per second,
causing the Error LED to blink.
To perform a V.52 BER test, follow these steps:
1. Locate the toggle switch group on the right side on the front
panel and place it in the middle where it is marked “Normal”.
This acti vates the V.52 transmission and reception of the
selected test pattern. If there are errors in the received patt
ern, the error LED will blink accordingly.
2. If the above test indicates no errors are present, move the
toggle switch UP to 511/E, activating the BER test
with intentional errors. If the test light is working properly,
the local modem’s red error LED will blink approximately once
per second.
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NOTE: The above V.52 BER tests can be used independently
of the Remote Digital Loopback tests. This requires two opera-
tors: (1) to initiate and monitor the tests at the local Model 2073,
and (2) to do the same at the remote Model 2073. In this case,
the test pattern sent by each Model 2073 will not be looped back,
but will be transmitted down the line to the other Model 2073.
While one operator initiates test, the other monitors for errors.