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 (no trouble found, or NTF), 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 condition. The result is fewer NTFs and elimination of associated costs.
If you choose to measure CDMA performance over the air with an antenna, then additional setup is required, as explained in the following sections. The instrument needs a timing reference 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.
The Over-The-Air (OTA) Measurement option consists of Pilot Scan, Multipath, and Limit Test.
2. Press the Setup main menu key then the Walsh Codes submenu key to choose 64 codes or 128 codes depending upon the transmitting signal.
3. Press the Measurement main menu key to open the Measurements menu.
4. Press the OTA submenu key to activate Over-The-Air measurements.
Pilot Scan Setup
From the Over-The-Air 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: Over-The-Air Pilot Scan Measurement).
Over-The-Air Pilot Scan Measurement
Multipath Setup
From the Over-The-Air menu, press the Multipath submenu key to measure and display multipath parameters.
Over-The-Air Pilot Multipath Measurement
Limit Test Setup
1. Press the Limit Test submenu key to display the Limit Test measurement and list the Limit Test window. Set the Rho Limit, Adj Rho Limit, Multipath Limit, Pilot Dom Limit, and Pilot Pwr Limit by pressing their respective submenu key.
2. Start or restart the measurement by pressing the Start/Restart Measurement submenu key. The test takes ten measurements and displays pass or fail status for each measurement. After the ten measurements are taken, the average for the five parameters is calculated and a pass or fail status is displayed.
3. To set new limits from the current limit average values, press the Set Avg Measured Values as Limits submenu key.
