NRF24L01+ range of only few meters

[sven]

@epierre
petewill propose full wave antenna, please look here: http://forum.mysensors.org/topic/775/8-lamp-outlet-smart-plug-module/67

[epierre]

@sven I did ad a home made half wave on a 433Mhz device (Imagitronix), and also added a quater wave on the RFXTRX to improve the range.

Frequency = 868 MHz
Quarter Wavelength: 82.2 mm = 3.235 inch
Half Wavelength: 164.3 mm = 6.470 inch

so it is a quarter Wave as the amplified version propose

[sven]

@epierre
The NRF24L01+ is working on an other frequency, it is 2400 MHz and not 868 MHz. I think to post http://forum.mysensors.org/topic/775/8-lamp-outlet-smart-plug-module/67 might be correct.

[epierre]

@sven on the video he shows 83.38 ?? you are right, it is 2.4GHz

1/4 wave antenna is 31.25 mm long
1/2 wavelength is 62.5mm.

so why did he mesured 83.38 ? was it inches ? (imperial non universal?)

[Anduril]

@HenryWhite yeah I have caps at all my nrfs. Will try with a different power source, as mine is attached to my pc usb as well. At least for testing it should work on batteries.

[mfalkvidd]

@epierre said:

@sven on the video he shows 83.38 ?? you are right, it is 2.4GHz

1/4 wave antenna is 31.25 mm long
1/2 wavelength is 62.5mm.

so why did he mesured 83.38 ? was it inches ? (imperial non universal?)

As Pete explains in the video, you need to add 83.38mm to the pcb antenna to get a full wavelength.

[epierre]

@mfalkvidd said:

83.38mm to the

I'd like to understand @petewill

[HenryWhite]

@Anduril said:

@HenryWhite yeah I have caps at all my nrfs. Will try with a different power source, as mine is attached to my pc usb as well. At least for testing it should work on batteries.

If that doesn't help try exchanging the Gateway Radio module.

[nunver]

Basically, from what I understand, a few meters of range is abnormal, and there is something I am doing wrong (a lot of which you outlined above and elsewhere). I understand that if powered correctly and fitted with capacitors and, if need be, some home made antennas, they should communicate through concrete walls up to 10-20 meters.

Do you confirm? Only then I will have the stamina to go back and spend another weekend crouched on that desk. :wink:

[mfalkvidd]

The nrf should have about the same range as regular wifi. So if regular wifi works in that room, you should be able to get the nrf working. If wifi doesn't work, you are not likely to get the nrf working either. In that case you'll probably be better off using ethernet (place an ethernet gateway in that room, with wired access to your home network) or use rs485.

10-20m solid concrete is going to be tough (for almost any type of radio signal), but with regular walls you should get at least 10m, probably 20-50.

[petewill]

@epierre my notes are in inches so forgive me not converting it here. My thinking was to make a full wavelength antenna using the existing pcb antenna. A full wavelength antenna for 2.4GHz is 4.92 in. I measured the existing pcb antenna on the nRF and it was 1.64 in. So, 4.92 - 1.64 = 3.28 in. (or 8.3312 cm). I'm not claiming to be an expert at all (an other people have said this shouldn't work) but it has worked well for me so I keep doing it. :) Others have reported success too so hopefully it will help you.

(thanks for your help @mfalkvidd)

@nunver Have you changed the PA level to MAX in myconfig.h?

[VooDooX]

Have you tried changing #define RF24_DATARATE in MyConfig.h from RF24_250KBPS to RF24_1MBPS or RF24_2MBPS?

That helped in my case. But you have to recompile gateway and node(s).

[Anduril]

@HenryWhite I tried with my ESP on battery and only get few meters range, too.
Also changing radio did not change anything. But my radios are from the same seller, even if my second batch was ordered months after the first. So maybe still same typ of radios.
I will check for @VooDooX hint and change datarates. I will report back...

[epierre]

@petewill when you solder you are at the end of the existing antenna, so you should add both length right ? and yes using imperial unit is well... non international ;-)

[petewill]

@epierre Yep, 1.64 + 3.28 = 4.92in is that what you're referring to?

[Igor Katkov]

I also have a poor range. With all the tricks:

• pairs of electrolytic+ceramic capacitors

• short leads

• max out emittance power

• lowered KBS to 250

• increased retries and delays

• free of wifi interference freq

• lowered payload to 4 bytes

• powered usb hub for gateway

• laptop USB powered arduino for sensor

• what I did not try - is separate step down regulator for radio

I got 10m at most through couple of walls. These are plain wood frame + drywall + insulation walls.
Even that was only possible with max power output on both sides and 250KB/s speed + 4bytes payload. I'm not sure if mysensor serial protocol allow to change payload size. I had to go down to roots of nrf24 programming to debug my poor reception.
Payload size was the greatest impactor by the way I had to make my own test hardware+software to do these range tests (simple echo server, sending time back, thus 4 bytes payload)

I've almost give up on nrf24 and ordered 4 hopeRF 483MHz transceivers for testing.

[mfalkvidd]

@Igor-Katkov did you get better results with higher output power? I am no radio expert, but most stuff I have read says that higher output often results in worse signal to noise ratio.

[Igor Katkov]

@mfalkvidd Yes, a few more meters with PA_MAX.
Here is my best performing code

  radio.setPALevel(RF24_PA_MAX);
  radio.setDataRate(RF24_250KBPS);
  radio.setPayloadSize(4);
  radio.setChannel(2);
  radio.setRetries(15, 15);

Full code https://gist.github.com/ikatkov/6df540838bd4d3ea8b57

[mfalkvidd]

@Igor-Katkov interesting. Thanks for sharing!

[Igor Katkov]

It appears that I was quite foolish expecting FTDI adapter board to power my nrf24 :-(
datasheet says it can provide at most 50mA.

I'll try 2AA batteries and a step up regulator