Compensating for the Loss or Gain of External Cables, Attenuators, and Preamps

Compensating for the Loss or Gain of External Cables, Attenuators, and Preamps
The insertion loss of the test cable and high power attenuator must be compensated for to obtain accurate W-CDMA or W-CDMA (with HSDPA) power measurements, such as channel power. This process is called normalization and is described in "Measuring Two Port Insertion Loss"
The insertion loss of the test cable/attenuator combination is accounted for as the RF In Loss, which is an offset applied to the power measurements by the test set.
Similarly, the insertion gain of an external preamp must be compensated for to obtain accurate W-CDMA or W-CDMA (with HSDPA) measurements.Although an external preamp produces a gain rather than a loss, this is also compensated for using RF In Loss. To enter a gain figure for a preamp, you must enter a negative loss figure. For example, to enter a gain of 20 dB, you must enter "-20 dB" here.

Step
Notes

1
[RF IN Loss]

2
Enter the RF In loss using the numeric keypad. Enter a negative number to indicate a gain.
If you are using a cable and attenuator connected to the base station power amplifier, enter the combined cable and attenuator RF In loss here. The RF In loss can be obtained by measuring the Insertion loss. See "Two Port Insertion Loss"
If you are using an external preamp and need to make an allowance for the preamp's gain, enter the gain by using a negative number.
Example of a loss: if you have to account for an external attenuation of 20 dB, enter "20 dB" here.
Example of a gain: if your preamp has a gain of 12 dB, enter the negative figure "-12 dB" here.

Note: If data had been previously entered in [RF IN Loss], that data will be lost and replaced by the value you enter here.

3
[dB]


	Step	Notes
1	[RF IN Loss]
2	Enter the RF In loss using the numeric keypad. Enter a negative number to indicate a gain.	If you are using a cable and attenuator connected to the base station power amplifier, enter the combined cable and attenuator RF In loss here. The RF In loss can be obtained by measuring the Insertion loss. See "Two Port Insertion Loss" If you are using an external preamp and need to make an allowance for the preamp's gain, enter the gain by using a negative number. Example of a loss: if you have to account for an external attenuation of 20 dB, enter "20 dB" here. Example of a gain: if your preamp has a gain of 12 dB, enter the negative figure "-12 dB" here. Note: If data had been previously entered in [RF IN Loss], that data will be lost and replaced by the value you enter here.
3	[dB]