Scan Duration

[Lexi]

Hello, 

I am using nRF52480, s140 , SDK_15.0 and using a rscs central example. I used 

uint32_t current_time = app_timer_cnt_get();
NRF_LOG_INFO("current_Tick: %02d", current_time); 
uint32_t CurrentTIME = current_time/32.768;
NRF_LOG_INFO("current_time: %02d", CurrentTIME); 

at  BLE_GAP_EVT_ADV_REPORT event to print current tick and current time in milisecs , I set :

#define SCAN_INTERVAL 0x00F0
#define SCAN_WINDOW 0x0050  

#define SCAN_DURATION 0x0000 
#define SCAN_DURATION_WITELIST 10000

I am going to just scan some beacons around to print a log file with time and RSSI from all around beacons with HTerm terminal on com port. 

I want to scan be contentiously until it is disconnected. but when I plot current_time vs RSSI for one beacon about one hour scanning,  current_time start from 0 till  512000 about 4 times! 

I could not understand why it is look like this? should I change any duration? 

Thanks

[Kenneth]

Hello,

The RSSI is heavily influenced by the antenna, an since there is no perfect omni-directional antenna with a flat gain over the 2.4GHz, then you typically end up with an antenna that have different gain over the 2.4GHz band, and with different gain depending on rotation of the antenna. Overall it looks like this is what you can expect. Several dB difference is normal. It may also look as you have a noise source in the upper 2.4GHz band (e.g. WIFI?) that prevent you from receiving much advertisement packets there.

Best regards,
Kenneth

[Lexi]

Hi Kenneth, thanks for your reply, but still I can not get it why it stop at 512000??, it is 2.4Ghz BLE on 3 different advertising channel. 

[Kenneth]

Maybe it is related to this:

https://devzone.nordicsemi.com/f/nordic-q-a/19621/rtc1-counter-return-to-0