Difference in RSSI value while using SCANNER code in NRF DK and BT840

[NIkhilS]

Hi Sir

We are scanning nearest BLE using NRF Scanner example using 1-  NRF52840-DK and 2. BT840 .

We are getting good RSSI value using 1 but very poor RSSI values when we are using the SAME SCANNER CODE on 2 ie BT840 module .

Kindly help us in this .

Thanks and regards

[Henry_Chou]

Maybe the BT840 module hardware with the PA,LNA front-end chip or RF switch circuit ,so that you have to control LNA switch or RF in/out in the code. The example code is not include the front-end chip & double-end RF pin control. However, the PA switch can be control by hardware pin, so you don't need to control it.How about the RSSI value bewteen two kits in advertising? May you show that?

[NIkhilS]

Hey Henry

We are using base model for BT840 , it doesnt have PA,LNA front-end chip or RF switch circuit .
RSSI is advertising is ok in both DK and BT840 ....

[Henry_Chou]

My old project is above. Using the DK(832DK) circuit rssi about -50~-75dbm within 5~10 meters.

But in our production board add on nordic FEM (PA& LNA) chip is around -40~-65dbm(not BT840).

You may check your case. 

If it's not the hardware issue, I think that it must be some TX power or RX sensitivity configuration case. 

[NIkhilS]

Hey Henry
Thank you for sharing this insight .
We changed scanning interval and can get good Rx sensitivity now.
Keep it up the good work Henry ..
My best wishes .