Trouble Shooting Guide, Advanced
4/00021-3/FEA 209 544/25 C
Ericsson Mobile Communications AB
52(78)
15 Calibration Intermediate Power
15.1 What is Intermediate Power
“Intermediate Power” is a calibration, which is necessary to fulfil the demands of the GSM-
specification for the up- and down ramping of the power, and to minimise the transient
spectra.
The up- and down ramping, of the control voltage to the power amplifier, does not change
momentarily from zero-to-max/max-to-zero.
That would cause a large number of over tones due to the switch.
The up- and down ramping of the control voltage are instead performed with two help steps.
The control voltage then passes through an exponential amplifier and a Bessel low pass filter
in N700 where the transient disturbance is reduced.
This gives a control voltage without the straight, vertical edges and the sharp corners that
produces the over tones.
The two help steps in the up- and down ramping of the power are called Intermediate Power
level.
Fig. 15.1 below shows the up ramping of the control voltage before it passes through the
exponential amplifier and the low pass filter, i.e. what the up-ramping steps looks like.
Fig. 15.1
The three power steps, Low Intermediate Power level, High Intermediate Power level and
Full Power level, are set by the power level DAC in N500 and are amplified and filtrated in
N700.
The intermediate power levels are tuned with DAC 2/DAC 3 (low/high) and is measured on
mid channel at the antenna connector. The value should be tuned until the output power is
better than high limit that corresponds to the intermediate power level (Table 15.1).
Parameter
Max
Units
-10
µ
s/P1 5
-6
dBc
-18
µ
s/P1 5
-30
dBc
-10
µ
s/P1 9
-6
dBc
-18
µ
s/P1 9
-30
dBc
-10
µ
s/P1 19
-1
dBc
Table 15.1