So I have some LoRa Ra-01 modules (here) and a couple ESP32's
I've used both RadioHead and Sandeep's LoRa library but range is sub 100m. Prob about 30m to be honest. I cannot for the life of me get these to work at distance. I've tried many different settings and seem to get about the same distance. I've tried adding a wire antenna to one and it was worse.
At 1m apart the receiver reports an RSSI of -100 or less. I'm at a loss as to what it could be.
How busy is the 433 MHz band?
Do you have line of sight between the modules?
What exact modules are you.using? (Link)
Hey there. There is a link in the original post
As for how busy the band is, it should be very quiet. I'm on a farm in the middle of no where and have line of sight
I have great results using this 2x this antenna, but I cannot find my RSSI readings I did a few years back.
Hmm yea I was hoping to not have to try to modify these to take such an antenna. It would be quite tricky to do on these boards. I need to it go sub 500m and I'd have thought these would out perform the HC-12 which can actually achieve that
Nothing wrong with your code at first glance. I've done a basic test recently with two RFM9x (933Mhz) just using whip (Wire) antennas measure to exact length. I was able to test 2km (probably more if I had tested it) just using a whip antenna. There are youtube clips from Andrea Spiess (worth a look if you are playing with LoRa) talking about dodgy RF models? He also has several great clips on Antennas.
Like i said for me just a wire antenna cut to length gave a strong RSSI. I was able to control a motor and vary the speed accurately at the other (base) end.
Apart from that check the power is good and as others suggested perhaps interference. My guess would be its your antenna or dodgy module.
Below shows the base station with whip antenna (Red wire going no where with tape on the end) I used an RFM Module (Small Blue PCB)
Below shoes the transmitter end using an Adafruit with the RFM onboard and again just a whip antenna. 2km tested with RSSI still within the range i was looking for. These are just test boards for another bigger project.
Cheers Chris. Thanks for the info. I had some doubts about using a breadboard to power the module and ESP32 and was considering soldering up a couple boards but don't think it would really be a problem. Similar setup to yours really.
Thats almost clasic symptoms of damadged modules that have gone very low power output.
Were they at any time operated in transmit mode with no antenna connected ?
I've seen this mentioned elsewhere as well but seeing as they came with the antenna installed and in a sealed packet I'd assume they were ok. One had a bit of a dry solder joint but fixing that didn't help. I have 3 total so have removed that one from the equation.
I'm starting to lead towards possible faulty boards, just hard to believe being brand new
That would not be at all common for LoRa modules, very rare really.
The primary troubleshooting step is to setup LoRa for a packet lasting a few seconds and measure the actual RF output power.
As for antennas, there a lot of stuff out there on good\bad antenna most of which in practice you can ignore. For a 433Mhz LoRa module a simple 17cm wire is more than adequate for most all purposes.
On simple 17cm wires, I would expect RSSI to be -40dBm or maybe -30dBm under those circumstances with RF power set at 10dBm. So you would appear to have circa 60dBm missing.
A quarter wave whip is the absolute best possible antenna you will get short of some serious design effort. It will work better with one or more ground radials attached to the antenna ground point (cut 5% longer than the whip).
Substantially better than the short stub and all the more if the stub is missing the radials.
reset is on 14 as you can see from the sketch above.
Aside from these connections I have the 3.3v regulated power coming from a 18650 holder to a breadboard that powers the esp32 via 3v3 pin and the ra-01 module powered from the breadboard too. I had a 100uF decoupling cap on the breadboard. Tried with and without
I may as well try some wire on the antenna of the other modules.
Hi,
Can you please post some images of your project so we can see your component layout?
Can you please post a circuit diagram?
An image of a drawn schematic would be fine.
That spring antenna looks like complete junk. That's the first thing to fix. Proper spring antennas have the turns spaced out, but any antenna needs to be resonant at the correct frequency or will perform very poorly indeed. Also the smaller the antenna (below 1/4 wavelength), generally the weaker it is. Start with a 1/4 wavelength wire antenna (against a ground plane if possible). Or any commercial antenna with a datasheet.
1/4 wavelength at 433MHz is about 17.3cm - normally a 1/4 wave antenna would be slightly shorter than that, say 17.0cm.
Note there is a lot of hype about LoRa range, and the multi-km ranges require clear line-of-sight paths and high gain linear antennas (collinear arrays are often used). You have to use the lowest baudrate for longest range as well.
One wet tree in the path and the range will drop massively, as this is the UHF band.
With 17cm wire antennas a 433Mhz LoRa transmitter running at 10dBm power output should be received by a receiver that is 1m away at around -27dBm.
If your only receiving at -100dBm then you have a link that has has only about 1/5,000th of the performance\range it ought to have. Be surprised if that is down to antennas or wiring.
Dodgy wiring could lead to the voltage dropping so low that the transmitter output colapses, but then you would not receive a packet.
That an RSSI is recorded suggests that packets are getting through, but I cannot think of a wiring problem that could result in the transmitter functioning correctly but with output power level dropping by almost 70dBm.
Note - This isn't my setup. Mine are not soldered however and am using standard jumper wires
Dodgy wiring could lead to the voltage dropping so low that the transmitter output colapses, but then you would not receive a packet.
That an RSSI is recorded suggests that packets are getting through, but I cannot think of a wiring problem that could result in the transmitter functioning correctly but with output power level dropping by almost 70dBm.
Yea this is why I will start from scratch with all new jumper wires. One poor connection would bring the whole system down. Jumper wires certainly are thin, but normally do the trick when prototyping.
Only other possible cause is operating them without antennas and causing damage. This certainly hasn't happened in my hand however
Big problem.Solder the connections (or solder header pins and use Dupont connectors) to the radio module, and your problems, which are caused by intermittent connections, will go away.
Of course that won't repair the damage previously done to the radio modules by failing to solder the wires or header pins to it.