Nokia RH-57 Series Troubleshooting Manual page 46

2112 (RH-57)
Troubleshooting - RF
Tuning Title
Tx Gain Comp
TN G_Offset
Tx Limiting Cell
Rx IF AGC Rx dB Ctr
LNA Gain
Page 46
Description
This tuning ensures that the value of
TxdBCtr correctly corresponds to the
absolute Tx output power. On the mid
channel, with TxdBCtr set to a specified
value, G_Offset is adjusted so that the
output power is -8dBm, and that value
of G-Offset is recorded (which is an
absolute value) in the next tuning. The
output power in dBm is recorded in this
tuning.
See description of previous tuning. This
step reports G_Offset.
This tuning provides an upper limit on
the transmit power while in Cell IS95
mode. The reason for this is to ensure
that the phone never goes above the
maximum transmit power level. After
this is done on the mid channel, the
channel is changed to each of the other
channels, and detector offset is
reported.
This tuning calibrates the Rx IF AGC
curve. The tuner injects three known
signal power levels into the phone's
receiver, and for each one the phone's
AGC algorithms, adjusts the RX_IF_AGC
to get the same amplitude at the output
of Yoda, although different amplitudes
are going in. From these three points,
curve fitting is used to interpolate
between measurement points.
This tuning records RxdBCtr (which is
automatically adjusted to produce the
same amplitude on the receiver output
no matter what the input is) for the
receiver with the LNA in high gain mode,
and again with the LNA in low gain
mode.
©2004 Nokia Corporation
Nokia Customer Care
Troubleshooting
Set the phone to local mode and program it
to Cellular CDMA Rx/Tx mode on channel
384, using the Main Mode window. Using
the Phoenix RF Tuning window, choose
mode = RF Tuning, and choose this test.
Adjust G_Offset in the "Values" dialog box
line until the Tx output power (measured on
the RF connector with a spectrum analyzer)
is equal to -8.0dBm +/- 0.5dB. Use the
G_Offset limit range as a guide to which
values to enter.
If G_Offset is not within the limits, trouble-
shoot the Cell Tx.
If the maximum cannot be reached, either a
component in the transmitter has too much
loss, or not enough gain. Troubleshoot the
transmitter, with the phone set to the same
channel as the failed channel. Once this is
done on the center channel, change to each
of the other channels, and record the power.
Do not adjust G_Offset on the other chan-
nels, just record the power. It should be
within the limits listed in the tuning results
file.
Channel Cell
Low 1013
LowMid 125
MidLow 225
Mid 384
MidHigh 558
HighMid 750
High 777
While injecting a signal into the receiver,
check the values of RX_IF_AGC PDM value
and, if needed, voltage. RSSI should be
within +/- 2 dB of the actual power in dBm
on the RF connector. The AGC will try to
keep the same amplitude on Yoda output;
therefore, if the AGC value is larger than
normal, then the AGC is compensating for
loss in the chain prior to the variable gain
amplifier.
Check Alfred and supporting components.
Company Confidential
Power
22.86-23.06
23.61-23.81
24.16-24.36
25.03-25.23
24.83-25.03
24.60-24.80
24.57-24.77
Issue 1 07/2004