User Manual

INSTALLATION AND MAINTENANCE MANUAL
LYNX.sc E1 FAMILY
SPREAD SPECTRUM RADIOS
OCTOBER 1998
SECTION 4: TROUBLESHOOTING PAGE 4-23
4.10 BER (Bit Error Rate) Testing
Bit error rate (BER) testing is the preferred way to evaluate a radio link’s performance. It can be
performed from end-to-end or in loopback mode (which tests both directions of the radio path).
Figure 4-2 illustrates a typical BER test configuration for loopback testing (which may include the
radio’s path instead of in-line attenuators). Figure 4-2 illustrates a typical BER test configuration
for end-to-end testing.
When performing BER testing, make sure of the following:
- Disconnect all CEPT-1 inputs and outputs to both radios.
- Connect BER tester to bantam jacks or data in/output connector(s)
- Select external test signal for loopback testing using the DIP switches as defined in
Section 3.12.
- Verify all DIP switch settings.
- The BER test pattern chosen must contain adequate 1’s density
A 2
15-1
, QRSS, or 3 in 24 test pattern may be used.
The LYNX.sc uses HDB3 line coding.
If two BER test sets are used to measure the link performance
separately in each direction, frame slips will occur unless the BER
test sets are synchronized with one test set as the master and the
other as the slave.
BER testing may be performed on the bench, with two terminals back to back, or over the radio
path. Also, it may be performed from end-to-end (which requires two BER test sets over a link, the
far-end unit slaved to the near-end unit’s clock) or in loopback mode, as described in Section 4.9.
If BER testing indicates an unacceptable level of errors, follow the instructions in Section 4.6.2. or
perform a back-to-back test as described in Section 4.9.
Figure 4-2: End-to-End BER Test Configuration