Testing a microwave radio system over-the-air (OTA) involves verifying the proper functioning of both the transmitter (TX) and receiver (RX) components. OTA testing is essential to ensure that the system meets performance specifications and operates correctly in real-world conditions. Here are some steps to test a microwave radio system OTA:
Equipment and Setup:
- Ensure you have the necessary testing equipment, including a spectrum analyzer, signal generator, power meter, and appropriate antennas for both TX and RX.
- Set up the testing environment in an open area free from obstructions to minimize signal interference.
- Place the TX and RX equipment at specific distances from each other to simulate the expected operational range.
Signal Generator and Transmitter Testing:
- Connect the signal generator to the transmitter input and set it to produce the desired signal at the appropriate frequency and power level.
- Verify that the transmitter is emitting the correct signal and the power output is within the specified range for the radio system.
Spectrum Analyzer and Receiver Testing:
- Connect the receiver output to the spectrum analyzer to monitor the received signal.
- Set the spectrum analyzer to the appropriate frequency range and resolution bandwidth to capture the transmitted signal.
Signal Reception and Quality:
- Monitor the received signal strength and ensure it is within the expected range for the given distance between TX and RX.
- Check for any signal interference or noise that could affect the system's performance.
- Assess the signal quality metrics, such as signal-to-noise ratio (SNR) and bit error rate (BER), to determine if they meet the required specifications.
Antenna Alignment and Polarization:
- Check the alignment and polarization of the antennas to ensure optimal signal transmission and reception.
- Adjust the antenna alignment if needed to achieve the best signal strength and quality.
Range and Link Performance:
- Gradually increase the distance between the TX and RX to test the system's performance at different ranges.
- Observe how the signal strength, quality, and link stability change as you move further apart.
Fade Margin and Rain Attenuation:
- Test the system under adverse weather conditions, such as heavy rain, to assess its performance during fading and attenuation events.
- Calculate the fade margin to ensure the link remains reliable under challenging environmental conditions.
Interference and Coexistence Testing:
- Assess the system's susceptibility to interference from other wireless devices operating in the same frequency band.
- Test the coexistence of multiple microwave radio systems to avoid performance degradation due to interference.
Documentation and Reporting:
- Record all test parameters, results, and observations during the OTA testing.
- Generate a comprehensive test report that outlines the system's performance and compliance with specified requirements.
It's important to follow safety guidelines and use appropriate testing equipment while conducting OTA testing to avoid exposure to high-power microwave signals. Additionally, make sure to comply with local regulations and obtain any necessary permissions for testing in certain frequency bands.