nRF24L01 range test part 2 (arduino)

[@RWBHere]

Those antennae show you how lossy the rubber duck is. Those packet size vs data rate results are interesting. Thanks for the tests. A few thoughts, and typed as I thought about them, so please accept my apologies for the length of this, and the somewhat random order. It's how my simple mind works. EDIT: TL;DR, so as a précis: Check your radio bandwidths. Check the Arduino internal bandwidths. Check data rates. Check for signal collisions due to latencies. Now, in full: As you approach 16 bytes, are you experiencing transmit/receive collisions? It would explain the sudden jump to 'normality from 17 bytes onwards. Furthermore, the plateau at up to 8 bytes and the cutoff from 24 bytes bear consideration, since the three relevant figures are multiples of 8 bytes. Maybe the circuitry is hitting internal conflicts at those multiple, and running into a throughput wall at 24 bytes? You might also want to look at transmitter and receiver latencies as possible sources for more clues. Even a clock or data frequency change can be tried, to see whether, for instance, switching to 512 k instead of 256 k might yield different results. Where I'm coming from with clock frequencies is the bandwidth needing to be at least twice the data rate for transmission to be possible. Thus, 8 bytes = 64 bits, needs a minimum of 128 bits of bandwidth, but if you're sending, for example, 256 packets per second, you’ll need a bandwidth of at least 32,768 kHz to send those 8 bit packets. At a packet size of 24 bytes, you'll need a theoretical transmitter channel bandwidth, and a receiver with an internal passband of at least ~100kHz, plus a margin for bandwidth edge effects, such as phase angle errors. That's stretching things for most cheap commercial equipment. O.K., I'm not an Arduino fan (code is like Mandarin to me), and am making some assumptions, so might be talking garbage, but how many bits of data are required for an Arduino to produce the required packets at the throughput rate in use? I'd hazard that it's a multiple of the output signal, such as 2, 4, or even 8. That would go some way towards explaining the maximum claimed packet size being limited to 32 bytes. In other words, maybe p 32x8 bits, times the number of packets per second, times the number of bits needed for the code to generate the output, times 2 ; the bandwidth needed for the signals to pass through the device. In my assumed worst case, that's (32 x 8 x 256 x 8 x 2) Hz = approximately 1.07 MHz needed inside the Arduino. As said, possibly wrong, but you can begin to see why the limitations are there, by using the figures which you know. My guess is that your main limitations are the transmitter and receiver bandwidths. Transmission theory is a subject in itself, and there's no point in typing reams of text here, so we'll atop now!

[@fil9625]

what are these antennas are called? Can you do a video about how to make them?

[@farazshah4484]

your videos are very informative. i have watched almost all. and i am planning to buy an arduino are the nrf24l01 radio modules to function them on RC plane. what u say? how much maximum range i can get with these components? i am doing this because the ready made RC transmitter radios and receiver are quit costly here in pakistan.

[@iforce2d]

Faraz Shah kzbin.info/www/bejne/naWwaWZoj5WooKc

[@adrianokuma7943]

Nice video man. I would validate the data you are receiving sending some specific data and validating it in the receiver, because maybe you were receiving data from a remote control or another device using the same module near you... just guessing

[@frankrivers4653]

Dunno if it's applicable to your setup, but I've noticed that when using commercial radios (futaba, JR, etc) if the transmitter is too close to the receiver (within one metre) the receiver is "swamped", and the transmitter will report loss of signal. The solution is to move the tranny a bit further away and everything is okay again. With your throughput testing I'm wondering if the RF24s might have been too close to each other?

[@ckbne]

you have inspired me to build my own CA quad. really enjoying your videos, i was thinking back to your return to home testing. What if you tried your own home brew Differential GPS. Grab another receiver sample its static location and calculate the drift of the GPS constellation. Send the differential DMS to the quad via your radios and offset it from the received data on the mobile unit. presto wobble free gps constellation. I intend to try this in the new year when i get some vacation time. Thanks.

[@iforce2d]

That sounds like an interesting project!

[@shadow7037932]

Two questions: 1. Which RF24 library are you using? 2. Which SPI library are you using? Built in one?

[@iforce2d]

This RF24 library: maniacalbits.blogspot.jp/2013/04/new-rf24-driver-release-fork.html and the normal SPI library.

[@KAFA2020]

Great video. Please could you help to make wide range Audio video Tx/RX using Arduino

[@ReinkeDK]

Nice video Do you know if it would make sense to have such an cloverleaf antenne on the master station, and just the build in antenne on the sending stations? I am working on a measure temperature and other stuff system for my new house. p.s. where did you buy those antenna you test today?

[@iforce2d]

As far as I know, circularly polarized antennas will not play so well with the linear polarized ones. You would probably be better off using a rubber duck/whip one with the PCB antenna. I got them from Banggood: www.banggood.com/2_4G-3-Leaves-Omnidirectional-Gain-Antenna-For-Transmitter-p-76956.html Hmm... seems like they don't stock the skew planar anymore.

[@ReinkeDK]

***** Thanks a lot for your quickreply, I'll stick to a rubber duck version for the base station :)

[@retromelon123]

I'd be interested to know how you measure distance between your controller and the quad. Is this a built in feature of the radio module? :)

[@iforce2d]

There is a GPS module on the transmitter, and I'm calculating the distance to the starting point. I didn't show any of it in this video, but the previous video mentions a bit more about it.

[@retromelon123]

***** Ah, interesting - thanks for the quick response! I should probably not be watching the videos in reverse order, haha.

[@rcsaz3039]

is it possible to reach 200m with this chip? and with low cost simple wire antena?

[@mayankanand1379]

hey is there a way i can shield my nrf module...

[@sirdimka]

Very strange results after 25 bytes. I'm sending 31 bytes packets and it works well. I was just using a simple chat sketch from here - forum.arduino.cc/index.php?topic=183961.0 Sometimes it loses the packets, but that sketch always swaps pipes when it sends data and I thought that the packet loses might be because of that. There are a few differences with your code, for example. that chat doesn't use the acknowledge payloads, it specifies CRC length and retries. Not sure what the default values for those parameters are.

[@iforce2d]

Yeah, I seem to vaguely recall having sent 32 byte packets in the past too...

[@muh1h1]

that video is very quite for me, does anybody encounter simular problems?