BLE beacon RSSI issues?

RE: BLE beacon RSSI issues?

PKSHER — Wed, 03 Jul 2019 07:07:05 GMT

Thank you and Mttrinh for your coperation adn support.

Your suggestions will be indeed helpful.

RE: BLE beacon RSSI issues?

awneil — Fri, 28 Jun 2019 15:09:18 GMT

You need both!

RE: BLE beacon RSSI issues?

PKSHER — Fri, 28 Jun 2019 14:44:44 GMT

SO, Its mean RSSI is the one I should care abount since I am scanning beacons and determining near or far.

RE: BLE beacon RSSI issues?

awneil — Fri, 28 Jun 2019 14:24:42 GMT

Think about it:

The value tells you how "loud" the beacon itself is;

How "loud" your device "hears" it will depend on both how "loud" the beacon is and how far away it is....

RE: BLE beacon RSSI issues?

PKSHER — Fri, 28 Jun 2019 14:17:32 GMT

OK now I get it. But can signal power be used to determine near or far, because its embedded in the ibeacon format as it is more stable than RSSI.

RE: BLE beacon RSSI issues?

awneil — Fri, 28 Jun 2019 14:12:31 GMT

As Mttrinh already said, the raw RSSI depends on very many things - including your particular hardware design.

So it is impossible to just give a universal formula.

You are going to have to work it out empirically.

RE: BLE beacon RSSI issues?

PKSHER — Fri, 28 Jun 2019 14:09:52 GMT

Yes I saw the reply.

OK near or far, but how?

RE: BLE beacon RSSI issues?

awneil — Fri, 28 Jun 2019 14:02:26 GMT

Did you see my other reply?

From that description, it sounds to me that the 'signal' value is a constant for the particular beacon ?

in other words, it tells you how "loud" the beacon is.

[quote userid="80472" url="~/f/nordic-q-a/49051/ble-beacon-rssi-issues/195387"]How do we determine the approx distance[/quote]

As Mttrinh already said, you really can't determine anything more than just "near" or "far".

RE: BLE beacon RSSI issues?

PKSHER — Fri, 28 Jun 2019 13:49:54 GMT

Ok Thanks. So its mean for distance measurement, we need to focus on the last byte i.e. signal power rather than RSSI. And yes I have observed RSSI keeps on changing whereas signal strength is same when we donot change beacon location.

So I am going to use signal power and this brings me to rephrase my last part. How do we determine the approx distance if say (29) is what we get as signal power.

RE: BLE beacon RSSI issues?

awneil — Fri, 28 Jun 2019 10:20:12 GMT

[quote userid="80472" url="~/f/nordic-q-a/49051/ble-beacon-rssi-issues"]Ibeacon format says the last byte is signal signal, is it RSSI[/quote]

This page says,

"power level in 2's compliment, indicating the signal strength one meter from the device. This number must be calibrated for each device by the user or manufacturer"

RE: BLE beacon RSSI issues?

Mttrinh — Fri, 28 Jun 2019 10:02:44 GMT

Hi,

1. Yes, the last byte of a iBeacon packet structure are signal power. What is the difference between the two?

2. RSSI signal is too unreliable for any accurate distance measuring. The RSSI just gives you a number for the signal strength. There will always be too many variables affecting the measured RSSI, like radio interference, signal/multi-path reflections, and loss in the antenna layouts. Typically the RSSI can be used to indicate a rough estimate(for instance: far away or close).

There have been many discussions on the forum regarding this topic, you can find more here.

[quote user=""]what does it mean RSSI at 1m is -77 dbm (say)[/quote]

Have a look at this.