How to run the Spectrum Analyser on PMP450x AP/BHM and SM/BHS

Problem:

How to run and interpret the Spectrum Analyzer on PMP450x AP/BHM and SM/BHS.

Solution:

The integrated spectrum analyser can be very useful as a tool for troubleshooting and RF planning. However, the integrated spectrum analyser is not intended to replicate the accuracy and programmability of a high-end spectrum analyser, which sometime can be used for other purposes.

Below is the step by step procedure to run the spectrum analyser on the AP/BHM and SM/BHS:

Step 1:

Login to the AP UI and navigate through Tools > Remote Spectrum Analyser, select the particular SM and enter the duration (60 sec recommended) in Timed Spectrum Analyser Tab, then click on Start Timed Sector Spectrum Analysis as shown in the below screenshot.

Keeping the 5 MHz channel bandwidth will allow the radio to scan all the frequency channels of a particular channel band.

Remote spectrum step 1.png

In the older software version 15.2.1 or earlier, we had  to run the spectrum on the AP and SM at the same time to get the proper results from the external sources; however, from software version 16.x, we have to run the spectrum analyzer on the AP and the SMs will go on a spectrum mode automatically and the results will  be displayed on AP UI>>Tools>>remote spectrum analyzer.

When the Spectrum Analyser starts on a module, it enters a scan mode and drops any RF connection it may have had. When choosing Start Timed Spectrum Analysis, the scan is run for a specific amount of time set in the Duration configuration parameter.

When choosing Start Continuous Spectrum Analysis, the scan is run continuously for 24 hours, or until stopped manually (using the Stop Spectrum Analysis button)

Step 2:

After the above step, navigate to AP UI>>Tools>>Spectrum analyser, enter the duration (90 sec recommended) in Timed Spectrum Analyser Tab, then click on Start Timed Sector Spectrum Analysis as shown in the below screenshot.

Spectrum analyser AP.png

The above procedure causes the SM/BHS to drop any active RF link. If a link is dropped when the spectrum analysis begins, the link can be re-established when a set duration has elapsed, or the spectrum analyser feature is disabled. (See the below screenshot)

Start time on remote spectrum.PNG

Step 3: Once the spectrum analyzer on the AP/BHM finishes scanning, you can get the spectrum analysis.xml report or see the spectrum graph results as shown in the below screenshot:

Main AP interference new .png

Step 4: Once the spectrum analyzer on the SM/BHS finishes scanning, you can see the spectrum graph results or get the spectrum analysis.xml report as shown in the below screenshot:

Interference main spectrum on SM.png

Step 4: Once the spectrum analyzer on the SM/BHS finishes scanning, you can see the spectrum graph results or get the spectrum analysis.xml report as shown in the below screenshot:

Interpretation of spectrum graph:

Spectrum colors.png

The best channel will be the one which has a low interference level that is close to -90 dBm. We will need to consider the edge frequencies as well while checking the interference level on the operating carrier frequency.

For example:

Suppose you configure the radio with the carrier frequency such as 5800 MHz and channel bandwidth of 40 MHz, the Lower (FL) and higher frequency (FH) should be 5780 MHz and 5820 MHz respectively. We will have to check the interference power level on these frequencies as well, so that if there is a high interference level on the edge frequencies, we can reduce the channel bandwidth to improve the link reliability.

Center frequency.png

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