Trango Systems TrangoLINK APEX 18 User Manual page 42

LOCK: Once lock is achieved, the radio can pass traffic. If the lock is not "1", there are
problems with the link setup that need to be evaluated.
RSSI: The receive signal level in dBm. This value should be compared to the expected
signal level determined during the design phase of the project. Signal levels low by 20
dBm are typically associated with antenna misalignment (one antenna is aligned to a
side lobe) Signal levels low by more than a few dB may indicate obstructions in the
Fresnel zone. Make sure that your target RSSI is set correctly when evaluating RSSI
readings.
THE RSSI SHOULD NOT EXCEED -25dB. EXCEEDING THIS FOR EXTENDED PERIOD
!
OF TIME MAY CAUSE DAMAGE TO THE UNIT
MSE: Mean Square Error is calculated and displayed in dB. MSE is similar to Signal to
Noise Ratio (SNR) except that is accounts for distortion and interference in addition to
noise power.
BER: Bit Error Rate (BER is calculated on the RF link.) The BER is displayed in 0.00E-
00 format and measures the number of uncorrected bit errors divided by the number of
bits transmitted. The BER value displayed in the linktest command is the instantaneous
value of the BER for 1sec duration. Telephony circuits (T1/E1) can tolerate BER of 10
but for IP traffic and reliable telephony traffic the BER should be no greater than 10
Substandard BER performance is difficult to isolate and generally requires careful fault
isolation using the loopback feature of the radio.
The linktest command can be executed by typing the command "
the number times to display results.
The example below displays the linktest command and 5 lines of data. Please note that
once the command is launch the linktest cannot be interrupted.
TX/RX: TX/RX is the current modulation the radio is transmitting and received. If you
have ACM enabled the modulation may change due to atmospheric or interference
conditions.
Example:
(trango-view)# linktest
(trango-view)# linktest 5
LOCK
1> 1 -42.00 dBm
2> 1 -42.00 dBm
TrangoLINK Apex™ 18 User Manual Rev. 1.0
[0-99]
RSSI MSE
-33.00 dBm
-33.04 dBm
Section: Chapter 3 - Configuration
linktest"
BER TX
0.00E+00 QAM256
0.00E+00 QAM256
-3
,
-6
.
followed by
RX
QAM256
QAM256
Page 40