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CC8520: Established design with sudden field complaints, Adaptive Frequency Hopping is not working as advertised.

Part Number: CC8520
Other Parts Discussed in Thread: CC2590

We have had a an audio transmitter/receiver design on the market for a number of years. Each node uses a CC2590 + CC8520. For the first few years we had very few field complaints regarding audio dropouts or connectivity issues. However, over the last year or two the number of dropout complaints have increased significantly.

After performing deep investigations into possible changes to PCB fabrication, components, etc. and finding nothing, we made an accidental discovery in our own QC environment where dropouts were suddenly appearing. A new WiFi router had been installed in the vicinity of our test area and by analyzing the RF spectrum we discovered that CH1 was being significantly polluted with high signal levels from multiple sources.

As is the case these days, many WiFi router firmware updates will allow for increased RF power levels, and the proliferation of mesh networks is another concern.

Using a controlled experiment where we enabled and disabled additional WiFi sources set to CH1 in a polluted environment while monitoring the PurePath Adaptive Frequency Hopping, we discovered that the system was regularly hopping to the CH1 RF band, regardless of the amount of pollution within that band. My understanding of how the system is supposed to work is that the next band to move into is monitored for pollution and will be SKIPPED if it is determined to be overcrowded or overloaded with signal. This is not what we are seeing.

I'd like someone on the wireless design team to get in touch regarding this issue, if possible.

Thank you,


  • Hi Andrew,

    Please refer to Section 2.3.4 and 3.4.5 of the CC85XX User's Guide and Application Report SWRA487.  Has any Frequency Planning already been performed, either through the PurePath Wireless Configurator or NWM_SET_RF_CH_MASK EHIF host commands?  This will preemptively avoid known interference channels but also limit the options of available channels to actively use in the hopping mechanism.  If there are multiple interferers across several 2.4 GHz channels then the frequency hopping algorithm may not have a choice other than to use sub-optimal channels.  SWRA487 provides tips on changing the LBT algorithm alongside other recommendations.