34
G.703 CODIRECTIONAL CONVERTER
The Converter is also capable of operating opposite any 511 BERT tester.
When you use one Converter opposite another, either with one or both PATT
buttons depressed (see Figure 4-2 below) or with an external BERT
transmitting the same V.52 (511-bit) pattern, you can test the complete link.
To activate the BERT, depress the PATT button. The ERR LED will light
momentarily, just to confirm that the LED is working, and then the test will
proceed. If errors are detected, the ERR LED will be continuously lit (if the
errors are continuous) or will blink (for intermittent errors).
NOTE
While PATT is depressed, the data-communications interface is
functionally disconnected.
4.3.1 T
HE
M
ODEM
S
ELF
-T
EST
To verify that the G.703 Codirectional Converter itself is operating correctly,
initiate the modem self-test by depressing the PATT and ANA buttons (refer
to Figure 4-3 on the next page):
1. Press ANA to start local analog loopback. The TEST LED should light.
2. Press PATT to begin test-pattern transmission. Verify that the TEST LED
is still lit and that the ERR LED lights briefly.
3. If the ERR stays lit or continues to flicker after the initial flash, the
Converter is faulty; call Black Box to arrange for repair or replacement.
Otherwise, the Converter passes the test; restore all of the buttons to
their normal positions.
Figure 4-2. Two Converters doing end-to-end BERT.
PATTERN
GENERATOR
PATTERN
TESTER
ERROR
PATT
DEPRESSED
PATTERN
GENERATOR
ERROR
PATT
DEPRESSED
(DISCONNECTS
EXTERNAL DTE)
PATTERN
TESTER
RCV
DTE
XMT