Troubleshooting Setting Power Levels

How Do the Amplitude Offset Settings Impact Mobile Station Tests?

The maximum amplitude offset allowed is +/-100 dB. However, the practical limit for external loss (negative amplitude offset) is set by the minimum channel power measurement and maximum signal generator output.

For example, the test set's signal generator can provide a maximum of -13 dBm /1.23MHz (CDMA modulated) and the channel power measurement minimum input is -69 dBm /1.23MHz. So the practical amplitude offset limit for performing TIA/EIA-98-E 4.4.6 Minimum Controlled Output Power (see Testing 4.4.6 Minimum Controlled Output Power ) and 3.5.1 Receiver Dynamic Range (see Testing 3.5.1 Receiver Sensitivity and Dynamic Range ) tests is -12 dB. This is dictated by the maximum RF Signal Generator output level of -13 dBm /1.23MHz with CDMA modulation (see Range of Power Levels ). The minimum power and dynamic range tests require a -25 dBm /1.23MHz CDMA modulated input to the mobile station's receiver, so the maximum external path loss for these tests is 12 dB (an amplitude offset of -12 dB).

CDMA tests that do not require a high forward link (signal generator) power or measuring a low mobile TX level can use higher amplitude offset values. The Demodulation of Forward Traffic Channel in AWGN test is a good example (see Testing 3.4.1 Demodulation of Forward Traffic Channel in AWGN ). In this case the test requires a -55 dBm /1.23MHz CDMA modulate signal and a -54 dBm /1.23MHz AWGN signal into the mobile station's receiver. The test set can provide a maximum of -13 dBm /1.23MHz CDMA modulated signal and a maximum of -20 dBm /1.23MHz AWGN signal (with overrange to -15 dBm with reduced unspecified performance). Therefore, the maximum external path loss for this test is 32 dB (an amplitude offset of -32 dB) since AWGN range is narrower (-34 dB, that is -54 dBm minus -20 dBm) than CDMA modulated signal (-42 dB, that is -55 dBm minus -13 dBm).

In summary, for all CDMA mobile tests the external path loss must not result in requiring more than -13 dBm/1.23MHz from the test set's signal generator or measuring less than -69 dBm /1.23MHz with the channel power measurement.

It is very important that the external path loss value be entered into the RF IN/OUT Amplitude Offset table on the system config screen (see Amplitude Offset ). If the external path loss is not entered into the table, the test set will not range properly and unstable performance will result.