1xEV-DO Power Measurement Solutions
Agilent EPM-P series power meters (E4416A single channel and E4417A dual channel) along with the E9320A family of peak and average sensors simplify development, verification, and manufacturing of 1xEV-DO wireless systems. Using the E9322A sensor, the EPM-P series power meters provide peak, average, peak-to-average ratio, and time-gated power measurements. The E9322A sensor (50 MHz to 6 GHz) provides a 1.5 MHz video bandwidth, ideal for 1xEV-DO power measurements, and maximizes the dynamic range. Real-time markers allow close analysis of the signal under test and 'analyzer' software, operating in a PC or laptop environment, provides pulse and statistical analysis for complete power and timing characterization for testing TDMA and CDMA parameters and system performance.
Setting-up the EPM-P series power meters for 1xEV-DO measurements
The following power meter configuration provides
- average power measurement in a 1xEV-DO burst (one half slot).
- peak-to-average ratio in an 1xEV-DO burst
- a trace display of the burst profile
Sensor: The recommended sensor is the E9322A. The 5 MHz video bandwidth sensor, the E9323A, may also be used but with a reduced peak power dynamic range.
Frequency: 1900 MHz. Set the frequency in the EPM-P series power meter to the frequency of the signal under test to ensure that the correct calibration factor is automatically downloaded.
Measurement: The measurement is started by detecting the 1xEV-DO RF burst using the internal RF level trigger. Time-gating is used to measure the average power and the peak-to-average ratio in the RF burst.
Time-gating: The aim is to measure the average power in one half active slot. An active half slot lasts for approximately 833 us and the rise time lasts for less than 7 us. We cannot absolutely guarantee the point in time where the EPM-P power meter will trigger, therefore the measurement (Gate 1) is set to start 10 us after measurement is triggered, and to last 810 us. Power measurements in an idle slot can also be measured. The idle slot lasts for approximately 180 us.
Note: Four independent time-gates are available.
Triggering: Triggering is set to occur on the rising edge of the RF burst. For 1xEV-DO, set the internal trigger to be auto-level triggered.
- Trigger hold-off is the period of time for which the trigger must have been inactive before another trigger can be accepted; trigger events closer together than the hold-off period will be ignored. This can be set to 1 ms, which prevents the power meter from re-triggering until the current active timeslot is measured.
Measurement display: To view the pulse shape and also the average and peak-to-average ratio power measurement in an active slot, set up trace display in the upper window and a dual numeric display in lower window.
- Max power: +20 dBm
- Min power: -35 dBm
- Start: -40 us
- Length: 1 ms
- Filtering is set to Auto, as this allows the meter to determine the optimum number of averages for that power level. If faster measurement is required, averaging could be set to Manual and the number of averages reduced. Similarly, if measuring at lower levels or if extremely stable measurements are required, the averaging number could be increased. Note that this will slow down measurements.
- Video Averaging is OFF because display is being used to give quick visual feedback on the shape of the pulse. It is not essential to average the pulse captures together to get a smooth trace