User guide

Configuring a Point-to-
Multipoint Link for Te
Testing the Components
204
pmp-0229 (Mar 2013)
If the number of sessions is significantly greater than the number for other SMs, then this may
indicate a link problem or an interference problem.
Reg Count
When an SM makes a registration request, the AP checks its local data to see whether it considers
the SM to be already registered. If the AP concludes that the SM is not, then the request
increments the value of this field.
Re-Reg Count
When an SM makes a registration request, the AP checks its local data to see whether it considers
the SM to be already registered. If the AP concludes that the SM is not, then the request
increments the value of this field. Typically, a Re-Reg is the case where both
• an SM attempts to reregister for having lost communication with the AP.
• the AP has not yet observed the link to the SM as being down.
A high number in this field is often an indication of link instability or interference problems.
RSSI, Jitter, and Power Level (Avg/Last)
The Session Status tab shows the received Power Level in dBm and Jitter. Proper alignment
maximizes Power Level and minimizes Jitter. As you refine alignment, you should favor lower
jitter over higher dBm.
For example, if coarse alignment gives an SM a power level of −75 dBm and a jitter measurement
of 5, and further refining the alignment drops the power level to −78 dBm and the jitter to 2 or 3,
use the refined alignment, with the following caveats:
• When the receiving link is operating at 1X, the Jitter scale is 0 to 15 with desired jitter
between 0 and 4.
• When the receiving link is operating at 2X, the Jitter scale is 0 to 15 with desired jitter
between 0 and 9.
However, Jitter is not calculated and reported in the PMP 400 Series OFDM AP. The Session
Status tab also shows a historical RSSI, a unitless measure of power. Use Power Level and ignore
RSSI. RSSI implies more accuracy and precision than is inherent in its measurement.
In both an FSK and an OFDM module, the spectrum analyzer measures and displays the detected
peak power level. This is consistent with the received Power Level that various tabs in the FSK
modules report. However, it is inconsistent with received Power Level indications in OFDM
modules, which use this parameter to report the detected average power level. For this reason, you
will observe a difference in how the spectrum analyzer and the Power Level field separately report
on the same OFDM signal at the same time.