Which ExpressLRS Receiver Should You Buy?
Disclaimer:
I am completely independent from any manufacturer of FPV products or company in the fpv space. These are my personal recommendations based on my experiences. I do not receive any compensation for these recommendations. I am not responsible for any damage or injury that may occur from following my recommendations. Please use common sense and be safe.With such a massive variety of ELRS receivers, choosing the right one can be an overwhelming task.
In this guide I will break down the individual aspects you should consider when buying the receiver for your next build or pre-built quad.
Don’t wan’t to read the whole guide? Click here for some recommendations.
Decision Factors
Frequency
Deciding on a frequency will be the first and most important step to finding the right receiver. You can choose between 2.4GHz and 900MHz. (915MHz FCC, 868MHz rest of the world). The hardware is not compatible between frequencies meaning a 2.4GHz transmitter can’t talk to a 900MHz receiver and vice versa.
Generally you would choose 900MHz for maximum range and penetration and 2.4GHz for maximum responsiveness. However, even at 2.4 GHz, ERLS has exceptional range and penetration and will most certainly surpass the range of your video transmission.
Some people say that the selection of hardware is much larger for 2.4GHz. In my opinion this is mostly outdated information. The selection has gotten a lot better. You will find everything you would want for 900MHz.
Range, Penetration, Diffraction
If your neighbors ever blasted music in the middle of the night, you’ll know that lower frequencies (the bass) will travel further and through your walls, while the higher frequencies are cut off.
This holds true for radio frequencies. 900MHz will travel further (range) and more easily through walls (penetration) than 2.4GHz.
One aspect that is rarely mentioned is diffraction. This phenomenon describes radio waves kind of “bending” around obstacles. I had more than one instance in which I lost video on long range behind a big rock but still had control over the drone which ultimately saved my quad more than once. I was on 900MHz in these instances (because I use 900MHz for long range) but I don’t know if 2.4GHz would have had the same effect.
Responsiveness
900Mhz offers 250Hz for highest refresh rate. It means that your transmitter can send out the stick positions 250 times per second. While that is enough for most pilots, 2.4GHz offers up to 1000Hz.
The higher the refresh rate, the more responsive the drone will be in the air. In my opinion it doesn’t matter as much. 250Hz means you have a maximum latency of 4ms. 1000Hz will have 1ms. That can mean a difference for racing pilots but I think most freestyle pilots will be good with either.
Antenna size
Image description:
The 900MHz receivers are significantly bigger than the 2.4GHz receivers.As 900MHz is a much lower frequency and therefore has a longer wavelength so the antennas will be bigger.
This offers more mounting options for 2.4GHz antennas.
There are also so called „Minimortal“ or „Mini-T“ antennas for 900Mhz. Note that these have significantly worse reception and you will be better off using a 2.4GHz receiver in these scenarios where you need a small form factor.
In my opinion this is the biggest advantage of 2.4GHz.
Number of pilots in the air
2.4GHz has a much wider frequency range than 900MHz and therefore more space to fit in a lot of pilots at the same time. Especially at high output powers interference will decrease performance for everyone around. So if you plan to fly with more that 3 others, you might want to consider using 2.4GHz.
Antenna Type
Image description:
The T-antenna on an ELRS receiver.
Image description:
The SMD antenna on an ELRS receiver.Basically there is the known T shape antenna and antennas soldered directly on the receiver board (SMD antenna).
This is primarily a size/weight vs. range/penetration compromise. If you need a small lightweight receiver you will use an SMD antenna. Otherwise you won‘t. SMD antennas will still offer exceptional range so you don‘t have to be scared that you will loose radio signal before video.
BetaFPV offers a new type of SMD Antenna called “flat antenna”. Supposedly this has a better reception. It will however give you an even smaller form factor than the “tower” style SMD antenna.
900MHz only offers the T shape antenna and it will be significantly bigger than the 2.4GHz T antenna. TBS Crossfire (which is 900MHz as well) always had the option of an L antenna. I haven’t seen one for ELRS but it would probably work to just use a Crossfire antenna.
Size/Weight
ELRS receivers come in 3 different sizes. Manufacturers will deviate a little bit from these but not a lot. Only the bigger receivers that include additional features have more unusual sizes.
The sizes are called PP (yap actually), Nano and Matek.
Most builds will be fine with a PP receiver. Bigger receivers usually have more features though.
Telemetry Power Output (PA/LNA)
On some receivers you can find a PA/LNA Chip. This will increase the gain of the received signal as well as increase the power of the telemetry output.
Telemetry output can be really useful. If you have a gps on board you can always find your quad when it goes down. The radio can show the last gps location and if you still have connection, the current position. This is much more reliable than the VTX OSD.
For most usecases the telemetry power output without PA/LNA will be enough though. The telemetry is usually not too important for FPV pilots because we have our OSD in the goggles. Unless I’m building a long range quad, I wouldn’t worry about telemetry power.
TCXO
TCXO stands for Temperature Compensated Crystal Oscillator.
In order to generate an RF signal a radio needs an oscillator. Usually, RF chips will have an oscillator (XO) onboard but if the chip heats up or is exposed to very high or low temperature environments the XO can deviate from the original frequency, which can result in signal loss. Now this is an unlikely scenario as ELRS has some amount of tolerance for this but if you want to be absolutely sure, you can choose hardware with a TCXO.
A TCXO is an external circuit on the receiver and will be much more accurate than the internal XO. Even at difficult temperatures.
Most hardware nowadays comes with a TCXO but there is no need for one in most scenarios. You can safely buy a receiver without a TCXO. However, if you like the extra peace of mind a TCXO will certainly help.
Diversity
Image description:
A true diversity receiver that can be recognized by the two chips on the receiver.Some receivers have dual antennas. This is a very neat feature if you are going for long range builds as the second antenna can pickup the signal if the first one hits a dead spot.
There are two types of diversity receivers.
Antenna diversity means, that the receiver will switch between antennas using the one that has better signal strength. Stronger signal does not always mean better link (in general it does though) so that’s where true diversity comes in.
True diversity means, that the receiver will actually decode signals of both antennas. This will eliminate the chance of the receiver accidentally choosing the wrong antenna.
Recommendations
Racers, Tinywhoops
2.4GHz PP RX with SMD antenna
Radiomaster RP2:
BetaFPV Lite Flat:
Freestyle
2.4GHz PP RX with external antenna
Radiomaster RP1:
Long Range
900MHz with diversity
Radiomaster BR3 (antenna diversity, 500mW):
BetaFPV SuperD (true diversity, 100mW):
or 2.4GHz with diversity
BetaFPV SuperD:
Radiomaster RP4TD: