OTA (over-the-air) testing provides field technicians with the ability to monitor hard-to-reach pole-top base stations. Traditionally, the repair process for pole-top base stations entailed pulling down the failed base station, then installing a new one. The failed base station was then returned to the manufacturer or repair depot for service. If a base station was determined to be healthy (a no trouble found (NTF) event), then the cost of the process was incurred unnecessarily. OTA testing provides information about the health of the base station, thereby improving the likelihood that a correct decision will be made with regard to the base station. The result is fewer NTFs and elimination of their associated costs.
If you choose to measure EVDO performance over the air with an antenna, then additional setup is required, as explained in the setup section. The instrument needs a timing reference in order to determine PN Offset and timing errors. This reference comes from the base station GPS when it is connected to the instrument, or it can be recovered from GPS when a GPS antenna is connected.
To make EVDO OTA measurements, connect the instrument to the base station and perform the following setup procedure:
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Press Freq main menu key then press the Channel submenu key and use the Up/Down arrow keys, the keypad, or the rotary knob to select a channel number for the selected signal standard. The center of the channel is tuned to the center of the display.
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Press the Setup main menu key to open the Setup menu.
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Press the Setup main menu key then press the Walsh Codes submenu key to toggle between 64 codes and 128 codes depending upon the transmitting signal.
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64 Walsh Codes can be displayed when the unit is in 128 code mode. The Walsh Codes will be repeated on the measurement screen.
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Press the Measurements key to open the measurements menu.
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Press the OTA submenu key to activate Over-The-Air measurements.
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From the OTA menu, press the Pilot Scan submenu key to display the nine strongest pilots, the PN codes, Ec/Io, Tau, Pilot Power, Channel Power, and Pilot dominance (Figure: “EVDO OTA Pilot Scan”).
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From the OTA menu, press the Multipath submenu key to display six channels of multipath parameters, including Ec/Io, Tau, Channel Power, and Multipath Power (Figure: “EVDO OTA Multipath”).
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