Beacon & Reciever

[yuval]

Hi,

i got a project which i need to know if a person put an object in it's place.

The project got 2 elements:

1) Beacon transmitter (@ 0 dbm) attached to the object.

2) NRF832 receiver (SDK11)

I try to see if the beacon is in 0 - 15 cm from the receiver.

When i look on the RSSI of the beacon i see strange things:

The RSSI changes from time to time without moving anything: When the beacon is about 10cm from the receiver - The readings can be around -40dbm for half a minute  and after that the readings somehow changes to -55 and even -60dbm and then after a while it changes again....

What can be the reason?

Any idea how to solve this ?!

B.r

Yuval.

[Kaja]

Hi, 


our expert on this is out off office today, be will be back tomorrow, so he will get back to you in the coming days. 

Best regards,
Kaja

[yuval]

BTW:

!) I put my beacon about 50cm from my android phone (without moving it) and this is the RSSI i got. It seems that it changes peak to peak about     10dbm and sometimes even more. is there something to do about it ?!

2) Is the RSSI measurement and the receiver in the NRF52832 are effected from other RF transition from another sources in the area ?!

B.r,

Yuval.

[yuval]

I put the beacon even closer (20-25cm) from my android phone without moving them and this is the RSSI i got.....

Is there something to do about it ?!

[Jared]

Hi there,

First, I would like to specify that RSSI can not be used as an accurate measurement for calculating the distance since it's dependent on several external factors as mentioned here and here. RSSI samples is also only valid between -20 dBm and -90 dBm. Other external activity on the sampled channel will also affect the RSSI. A way of mitigating the variation is to take several samples and take the average of them. That should at least give you a better estimate that can be used to calculate the distance. 

regards

Jared