Keysight E6610A, Руководство пользователя и программирования

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Appendix A: Selecting Attenuation and Power Levels
So, for the example set-up shown above, assume that the RRH is tested at 2 downlink
powers of +30 dBm and +47 dBm. There is 30 dB + 20 dB attenuation in the path from
the RRH antenna port to the RF RX inputs. Therefore, the power presented at the
E6610A’s RX input will be -20 dBm and -3 dBm.
For testing the uplink path of the RRH, there is 30 dB of attenuation from the E6610A's
Tx output ports to the RRH's antenna port. Therefore, the range of CW power levels
that the RRH’s UL could be tested at would be:
Maximum CW output power of +10 dBm – 30 dB attenuation = -20 dBm
Minimum output power of -55 dBm – 30dB attenuation = -85 dBm
To allow some margin for cable and circulator losses, the maximum power level
should be reduced by about 1-2 dB.
In order to obtain the best signal-to-noise level at the RRH for uplink testing, it is best
to operate the E6610A transmitter at as high a power as possible and to have a large
attenuator connected directly to the RRH. Similarly for best SNR in downlink testing,
the minimum possible attenuation on the E6610A’s RX input path should be used.
If interference is encountered on uplink measurements, the SNR of the signals
presented to the RRH’s uplink can be improved by increasing the attenuation of the
loads on the RRH’s antenna. For example, if these are increased from 30 to 40 dB,
then the E6610A will transmit a signal 10 dB higher in power, which would increase
the SNR by 10 dB for a fixed level of interference.
This 10 dB improvement in UL SNR has to be balanced by the fact the maximum RSSI
test level would be reduced by 10 dB to -35 dBm.
100 Keysight E6610A User and Programming Guide