INSTALLATION AND MAINTENANCE MANUAL
E1 FAMILY
LICENSED & SPREAD SPECTRUM RADIOS
JUNE 2001
SECTION 2: PRODUCT DESCRIPTION
PAGE 3-71
3.13.2
Loopback/BER Testing
When a pair of
Lynx
radios are installed and communicating with each other, a loopback or BER
test can be performed to evaluate the link performance.
The
Lynx
uses an internal test signal for loopback. Alternatively, an external test signal can be
injected, as described in Section 3.12.4. Any E1 test pattern may be used to make measurements
at one end of the link, provided the test sequence contains adequate 1’s density, which is no more
than 15 consecutive zeros.
A 2
15
-1, QRSS or 3 in 24 test may be used. However a 2
23
-1 test
will violate the 1’s density requirement.
To loop around the far-end radio, press ENABLE and hold for approximately 3 seconds. then
release the Loopback ENABLE button on the front panel of the near-end radio. The ENABLE LED
should now be blinking.
If the ENABLE loopback button LED is illuminated and not
blinking, this means the far-end radio has initiated loopback
(either manually or through the DIAGNOSTICS port).
When loopback is enabled using the internal test signal, the ERROR LED should not illuminate if
the path is operating error-free. If the ERROR LED illuminates, this means that at least one bit error
has occurred.
The DATA LOSS LED will illuminate if the external test signal mode has been selected (see
Section 3.12.4) and there is no external test signal present at any of the CEPT-1 ports. When using
external test mode and an external test signal, the ERROR LED function does not apply. In external
test mode the ERROR LED will not illuminate, even when errors are present.
