BDA Filter Configuration Test
Cleaned Lesson Transcript / Study Notes
The final commissioning test is the BDA Filter Configuration test.
This test verifies that the BDA filters are programmed correctly and that the expected uplink and downlink frequencies are being amplified properly.
The test is performed in two parts:
- Uplink filter configuration
- Downlink filter configuration
1. Start with the Uplink Filter Configuration
Begin with the uplink side of the BDA filter configuration test.
The guided image shows how the test equipment should be connected.
The setup includes attenuators to protect both:
- The test equipment
- The transmitter
The attenuators are important because the BDA can output high RF power, and the test equipment must be protected from excessive signal levels.
2. Review the Test Configuration
From the configuration, verify the following:
- Programmed filters
- Start frequency
- Stop frequency
- Resolution bandwidth
- Scanner attenuation
- Signal source power level
- BDA gain
- Any AGC/ALC impact
If AGC is being engaged during the test, that must be accounted for in the grading parameters.
The start and stop frequencies are important because they must match the step frequencies used by the signal generator.
3. Configure the Signal Generator
In the Signal Hound vector signal generator, also referred to as the VSG, configure the same start and stop sweep used in the test setup.
This is a step sweep.
That means the signal generator starts at the beginning frequency and generates a CW signal at each step until it reaches the stop frequency.
In this example, the uplink sweep starts at:
798.98125 MHz
The signal generator then creates a CW signal every:
12 kHz
The sweep continues through the configured stop frequency, which is above:
805 MHz
The step size should match the resolution bandwidth used in the test.
The dwell time controls how long the CW signal remains at each frequency step.
4. Verify the Step Sweep
Before testing through the BDA, the transmitter can be connected directly to the IBflex to demonstrate what the step sweep looks like.
This shows the CW signal stepping through the band every 12 kHz.
Once the signal is passed through the BDA, only the frequencies within the BDA passbands should be amplified. Frequencies outside the programmed filters should be rejected or greatly reduced.
The amplified passband signals should fall between the configured high and low limits.
5. Run the Uplink Filter Test
Reconnect the test setup through the BDA.
Begin the actual uplink filter configuration test.
If the signal generator is turned off and then back on, the sweep will restart from the beginning.
The sweep begins transmitting from the low side of the band and moves left to right across the frequency range in 12 kHz steps.
As the sweep progresses, the BDA filter responses appear.
In this example, two filters are visible.
Add the uplink filter test result to the report.
6. Review Uplink Results
After the uplink test is added to the report, review the results table.
The table shows whether each configured filter passed.
In this example, both uplink filters passed.
The results table also shows the measurements for the other frequency bins that fall inside the filters.
This confirms that the programmed uplink filters are amplifying the intended channels and rejecting frequencies outside the passband.
7. Run the Downlink Filter Configuration
The downlink test is similar to the uplink test, but the equipment setup changes.
The guided image changes to show the correct downlink configuration.
For downlink testing:
- The measurement is taken on the downlink side
- The signal is generated toward the donor side
The downlink frequencies are adjusted using the appropriate offset.
In this example, a:
30 MHz offset
is applied.
8. Begin the Downlink Test
Select the test point.
Begin the downlink filter configuration test.
The sweep runs across the configured downlink frequency range.
As with the uplink test, the filter responses appear as the sweep reaches each programmed passband.
Once the filters are captured, add the result to the report.
9. Review Downlink Results
The downlink results are reviewed the same way as the uplink results.
The report shows:
- Channel power measurements
- Power measurements for selected frequencies
- Filter pass/fail status
- Any frequency bins inside the filters
This verifies that the downlink filters are configured properly and that the correct frequencies are being amplified.
Final Result
The BDA Filter Configuration test confirms that the BDA is programmed correctly on both uplink and downlink.
This test documents:
- Uplink filter response
- Downlink filter response
- Start and stop frequencies
- Step sweep settings
- Resolution bandwidth
- Signal source power
- Scanner attenuation
- BDA gain
- AGC/ALC considerations
- Channel power measurements
- Pass/fail results
In this lesson, both uplink and downlink filter configuration tests were completed and added to the report.
This concludes the BDA commissioning process.