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### Topic: How many Decibels nRF24L01 uses? (Read 984 times)previous topic - next topic

#### duinoWorld

##### Aug 16, 2017, 05:48 am
I am working on a project which an nRF24L01 (Receiver) will need to receive from another nRF (Transmitter), to determine the transmitter's distance/range(In meter if possible), dB (if possible), to locate the transmitter.

I've seen that if nRF24L01 wants to get the dB, it requires RPD.
Is it correct?

Quote
bool RF24::testRPD(void)
{
}

#### jremington

#1
##### Aug 16, 2017, 05:55 amLast Edit: Aug 16, 2017, 05:56 am by jremington
Quote
to determine the transmitter's distance/range(In meter if possible), dB (if possible), to locate the transmitter.
This idea comes up at least once a week in this forum, and it is not possible.

Received signal strength depends on many factors, most of them more important than the distance between transmitter and receiver .

#### duinoWorld

#2
##### Aug 16, 2017, 06:19 am
But i just want to calculate the distance between them. Do you have any ideas?

#### jremington

#3
##### Aug 16, 2017, 06:43 am
Quote
Do you have any ideas?
A measuring tape, laser distance sensor, etc. (anything but radio signal strength).

#### Robin2

#4
##### Aug 16, 2017, 09:23 am
But i just want to calculate the distance between them.
Why?

If you tell us that we can probably give a more useful answer.

I have had a pair of nRF24s (the low power ones with the PCB antenna) working at 110 metres distance outdoors.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

#### duinoWorld

#5
##### Aug 17, 2017, 07:06 am
I am trying to use my NRF (Receiver) to detect where the Transmitter would be. Even when it is moved to another places. I just want to know any way to detect the exact place, or calculate the distance through any formula. But NOT using measuring tape or laser distance sensor. Just using the NRF24L01

#### Robin2

#6
##### Aug 17, 2017, 10:10 am
I am trying to use my NRF (Receiver) to detect where the Transmitter would be.
That won't work.

You could put a GPS on each device and use the nRF24 to exchange the position data from the GPS.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

#### MaHa76

#7
##### Aug 17, 2017, 01:20 pm
only theoretical

You could try to Count the timer for Signal- send ping - receive answer and compare it with time fpor processing...

Signal will take 300m per millis... so you Need to make your System realy stable and solid...

(sorry for my poor english)

#### Robin2

#8
##### Aug 17, 2017, 01:48 pm
only theoretical
Too theoretical to be useful.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

#### Whandall

#9
##### Aug 17, 2017, 05:35 pm
Signal will take 300m per millis...
299.792.458 m/s means 300m per micro second, or 18.7m per cycle (with 16MHz).
Ah, this is obviously some strange usage of the word 'safe' that I wasn't previously aware of. (D.Adams)

#### DaveEvans

#10
##### Aug 18, 2017, 12:00 am
299.792.458 m/s means 300m per micro second, or 18.7m per cycle (with 16MHz).
Um, no.  300 m/s (or 343 m/s or whatever) is equivalent to:

3x10^2 m/s

...times 10^-6 s/us = 3x10^-4 m/us

...times 10^3 mm/m = 3x10^-1 mm/us

or, simply, 0.3 mm/us

#### jremington

#11
##### Aug 18, 2017, 03:16 amLast Edit: Aug 18, 2017, 03:19 am by jremington
Quote
Um, no.  300 m/s
is very roughly the velocity of sound in air, not light (the topic of this thread and correctly discussed by Whandall).

#12
oops!

#### el_supremo

#13
##### Aug 18, 2017, 04:21 am
Even if you could accurately measure the distance to the transmitter, you still don't know the direction to its new location.

Pete
Don't send me technical questions via Private Message.

#### MaHa76

#14
##### Aug 18, 2017, 07:08 amLast Edit: Aug 18, 2017, 07:09 am by MaHa76
@Whandall: You are right - there Aare 3 Digits missing... 300 per micros...

So maybe it would be possible to add an Sonar- Module to each Note - start a Ping and Count time till it recieves on other Note...

Start Event could be shared between Notes via nrf24.

For Location more Notes are Need to compare different running times...

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