LAUNCHXL-CC3235SF: TX signal strength weakness in 5GHZ AP Mode

Hi Mehmet, thank you for your question.

In general, 5 GHz band will be weaker than 2.4 GHz band due to shorter radio waves, although your 26 dBM gap is quite large.

Could you describe how you are getting these RSSI values?

Actually, I got the rssi values in a very simple way. I have a device with a cc3235sf. I'm running a rssi scan here. These are the values measured by this device. 2.4 ghz and 5ghz device broadcast from the same device and the same location. And the scan results from the other device are like this.

Does your CC3235SF project interact with radio_tool.h (file name may vary based on SDK) functions at all?

I don't understand exactly what you mean. Could you give me more details?

If you look at an SDK compatible with CC3235SF, you will find a network terminal example (feel free to follow this exercise as well) where you can set a device as an access point and analyze RSSI values as well. The example code itself has a radio_tool.h file and I was wondering if your project uses similar functions.

Yes, I use the functions there. As I said, the broadcast at 2.4 GHz is much more powerful. There is a serious difference.

Hi,

Do you use own hardware or LaunchPad? If you are using own hardware, was your antena path validated at VNA and properly optimised? If your RF desing was not properly calculated and validated it can be reason for a poor RF performance. Can you compare RSSI from your design with LaunchPad? What type of antena do you use?

Jan

Yes, I use the functions there. As I said, the broadcast at 2.5 GHz is much more powerful. There is a serious difference.

Hi,

Your design may to work at 2.4GHz but it can be totaly wrong for 5GHz. Who knows. I think first step is comparsion same code at your hardware and LaunchPad. If your hardware will be significantly diferent, you can start search what is wrong with your hardware.

Jan

No, I've already been experimenting with Launchpad. And I got these results in those experiments.

Hi,

If results with your hardware and LaunchPad are same, it is likely your hardware correct. If your hardware is equiped by antenna connector (eg. uFL) you can check TX power with spectrum analyser and compare with datasheet.

Inside your code make sure that you have set TX power to max and you have set right country code. That is all what you can do. Maybe you can try set TX power offset by Uniflash, but be carefuly to not void regulatory requirements.

Jan

I set the TX power parameter to 0. I also entered the correct country code. But as I said, there is a significant difference between 2.4 GHz and 5 GHz.

Hi,

RSSI diference between 2.4G and 5G is expected as was said by Brandon before. Unfortunately you not answare previous questions, from this reason is hard to get you any clue.

Jan

Hi Mehmet, where are you setting the power parameter to 0? Are you doing it in an actual radio tool GUI, Uniflash, or the file as I described which can be found in the network terminal?

I adjust it both in the software and via uniflash, but the result does not change.

How are you adjusting it in software? Can I see how you are passing in the power level?

I do it with this command 

    unsigned char maxTxPower  = 0;  

retc = sl_WlanSet(SL_WLAN_CFG_GENERAL_PARAM_ID, SL_WLAN_GENERAL_PARAM_OPT_AP_TX_POWER, 1, &maxTxPower);
if (retc != 0) {
Display_printf(display, 0, 0, "[WiFi Config] TX power set failed (ret = %d)", retc);
} 

Can you describe your process in such a manner that I can attempt to replicate what you are doing? I want to see if I need to experiment with your setup to determine what is going on and pinpoint the issue.