OPT014-1 BDA Testing 4
Signal to Building Test
Cleaned Lesson Transcript / Study Notes
This lesson covers the Signal to Building test used during BDA commissioning.
The purpose of this test is to evaluate possible donor antenna locations and determine which location provides the best usable signal from the public safety radio system.
1. Start the Signal to Building Test
Begin by opening the Signal to Building test.
This test is used to measure signal strength and signal quality at possible donor antenna locations.
These test points represent candidate locations where the donor antenna may be installed.
2. Test Point 1
Start with Test Point 1.
At this location, the scanner is decoding the public safety control channel.
The measurement is added to the report.
In this example, Test Point 1 barely passes the required threshold.
The signal is around:
-94 dBm
This is close to the pass/fail limit, so it is considered a marginal result.
3. Test Point 2
Move to Test Point 2 and repeat the measurement.
This location produces a much better result.
The measurement is added to the report.
Test Point 2 provides stronger and more reliable signal performance than Test Point 1.
4. Test Point 3
Move to Test Point 3 and repeat the same process.
Take the measurement and add it to the report.
In this example, all three test points initially pass the configured criteria.
5. Adjusting the Threshold
The pass/fail result depends on the configured threshold.
In the example, the original threshold is set around:
-95 dBm
When the threshold is changed to:
-90 dBm
Test Point 1 now fails because its measured signal level is weaker than the new requirement.
The result becomes:
- Test Point 1: Fail
- Test Point 2: Pass
- Test Point 3: Pass
This shows why the threshold setting matters and why the test configuration must match the AHJ or radio system requirements.
6. Selecting the Best Donor Location
Based on the results, Test Point 2 appears to be the better donor antenna location.
It has a stronger signal than Test Point 1 and provides a better margin above the pass/fail threshold.
When choosing a donor location, look for the point that provides:
- Strong signal level
- Reliable control channel decode
- Good signal quality
- Margin above the minimum threshold
- Low interference or out-of-band noise
7. Capture a Spectrum Analyzer Screenshot
After identifying the stronger donor location, return to that test point and capture a spectrum analyzer screenshot.
In this example, the spectrum analyzer is used at Test Point 2.
The purpose is to look for out-of-band noise that could potentially create problems for the BDA.
Out-of-band noise may indicate interference or nearby RF energy that could affect system performance.
Use the screenshot capture icon to save the image to the test.
The captured image becomes part of the donor location test documentation.
8. Why This Test Matters
The Signal to Building test helps confirm that the selected donor location is suitable before installing or commissioning the BDA.
A poor donor signal location can cause problems such as:
- Weak downlink signal into the BDA
- Poor signal quality
- Reduced system reliability
- Increased risk of interference
- Incorrect donor antenna placement
- Failed commissioning results
A strong donor location improves the chances of successful BDA performance.
Final Summary
The Signal to Building test evaluates candidate donor antenna locations.
The technician measures the public safety control channel at each test point, adds results to the report, and compares the signal levels against the required threshold.
In this example:
- Test Point 1 barely passes at approximately -94 dBm.
- Test Point 2 performs much better.
- Test Point 3 also passes.
- When the threshold is tightened from -95 dBm to -90 dBm, Test Point 1 fails.
- Test Point 2 is selected as the better donor location.
- A spectrum analyzer screenshot is captured to document possible out-of-band noise.
This test helps ensure that the donor antenna is placed in the best available location for reliable BDA operation.