Trouble Shooting Guide

Axxcelera Broadband
Troubleshooting-Installing an RF link - 31 - Issue: 5.3.x
Rev 2
FCC High-Band = +14dBm (+14dBm for AB-Extender)
FCC Mid-Band = +8dBm ( +4dBm for AB-Extender)
FCC Low-Band = +1dBm ( -2dBm for AB-Extender)
The nominal TX power value also takes into account any deviations from the standard FCC limits, such as
a System Backoff adjustment or a non-FCC power scheme. Nominal TX power can therefore be used to
see if the AP and SUs in a sector are using the same power scheme, e.g. a difference between the AP’s
nominal TX power, and the SU’s actual (AP) TX power indicates that the units have been incorrectly
configured.
10.1.6 actual TX power
Actual TX power is the actual power level (dBm) being transmitted from the AP radio. It should be very
close to, but slightly below, the nominal TX power. The difference between the nominal and actual TX
powers represents the error in the transmit power level. A large difference indicates that the unit is
transmitting at the wrong power level, and is likely to cause RF problems. Because the actual TX power is
calculated from calibration data, the accuracy of the actual TX power calculation is dependent on the
accuracy of the calibration data.
SU Modem Txpower
192.168.3.254 hmm> modem txpower
corrected FCC backoff tx attenuation +18.494 dB
AGC: RX pointer is 8, TX pointer is 9
nominal TX chain attenuation 18 dB
actual TX chain attenuation +19.000 dB
digital baseband attenuation +1.904 dB
nominal (AP) TX power +1.000 dBm
actual (AP) TX power +1.000 dBm
actual TX power -1.410 dBm
rssi at SU -72.638 dBm
path loss to AP -73.638 dB
valid rssi range at AP -78 dBm to -71 dBm
Offset to fix uplink cell errors +0.000 dB
estimated rssi at AP -75.048 dBm (OK)
Of the fourteen numbers reported by “hmm modem txpower” on an SU, only five are of any real value for
debugging RF problems : “actual TX chain attenuation”, “nominal (AP) TX power”, “actual TX power”,
“rssi at SU” and “estimated rssi at AP”.
10.1.7 corrected FCC backoff tx attenuation
Corrected FCC backoff tx attenuation is the amount of attenuation required in the transmit path to keep the
transmit power at or below the FCC limit for that channel/polarization.