About the antenas, it makes a lot of sense to have omnis instead of directional for the relays, and making DIY antenas would actually be ideal (lowest price, and ready materials). @PA7John do you have any resources on building such dipole antennas? Are there any other antennas we could DIY?
About energy/solar, that’s a great point about the 10W at 12V, I’m looking now at this 5W 5V panel, but it has the same price as the 10W, is it worth it? To use the 10W I’d need a step-down and probably worth doubling the batteries, is that right?
The 100Km were with a line a sight I assume, right?
You’re all very awesome, thank you once again for sharing your knowledges and experiences!
Hi @luandro – I really dig this project! I’m eager to help think things through if I can, as your project has a lot of overlap with projects I’m hoping to try out myself …
I don’t have any particularly useful input yet I don’t think – but, if you haven’t seen Andreas Spiess’ stuff on Youtube, it’s all really nicely done, and he has all sorts of useful tutorials around LoRa ranges, antenna design, etc …
Found that 5v panels are usually more expensive then 12v in my area.
Looking at your 5v panel it has a build in usb convertor, that will need some waterproofing!
There are panels that output 5-6 volts directly
Considering the remote location in general you want as few points of failure as possible, or as few components as possible?!
The Swiss guy has some good video’s, personally I’m looking into pcb dipoles atm
Many DIY can be googled “868mhz, Lora antenna, etc” have a look and see if there is something that suits the project, also omi directional builds
Very good point @PA7John. Any tips for waterproofing? Silicon around it?
For antennas I’ve been looking at this tutorial for building omnis. I’m guessing they would be the ones with most gain, is that right? Seems like an art, but with enough practice I think we can do it.
Frequency 915 MHz
Latitude -8.39175535 °
Longitude -47.74225488 °
Latitude 08° 23’ 30.32"S
Longitude 047° 44’ 32.12"W
QRA GI61DO
UTM (WGS84) 23L E197990 S9071337
Elevation 272.5 m
Base Antenna Height 1 m
Base Antenna Gain 3.5 dBi
Base Antenna Type omni
Base Antenna Azimuth 0 °
Base Antenna Tilt 0 °
Mobile Antenna Height 2.0 m
Mobile Antenna Gain 3.5 dBi
Tx Power 0.01200 W
Tx Line Loss 0.0 dB
Rx Line Loss 0.0 dB
Rx Threshold 0.220 μV (-120.2 dBm)
Required Reliability 60%
Strong signal margin 10.0 dB
Weak signal field 12.8 dBμV/m
Strong signal field 22.8 dBμV/m
Weak signal covered area 502 km2
Strong signal covered area 220 km2
Weak signal population reached 1032 pop
Strong signal population reached 454 pop
Landcover used Yes
Two rays method used Yes
Radio coverage ID RM7FEA1377749C_2
Generated on 9/1/2020 4:36:06 PM
I probably gave up on 915MHz. And I chose a lower frequency, not higher than 433 MHz. Without very high-quality and sophisticated equipment, you will not get a normally working antenna in a frequency of 915 MHz and all the energy will simply heat the equipment instead of flying in the right direction. At 433 MHz, there is a hope that you will buy or make a working antenna. And of course you need to raise the repeaters as high as possible, the trees absorb these frequencies very efficiently.
@skyde that’s interesting. It seems I can find LoRa boards on 433Mhz as easily as I can find 915Mhz here, would just make the T-Beams I already have useless for this specific experiment.
This would be a big change of plans, can someone else confirm changing to 433mhz would be a better idea? @geeksville@PA7John@dafeman@sam_uk
This will happen in a savanna region, so I’m hoping trees won’t be a huge problem for now. But in the future I intend to implement such networks in the amazon, which will have big problems with trees.
50km is quite achievable with direct line of sight. In your settings you have your TX power set too low. It should be 0.10000W. Rx Threshold can be set to 0.035uV to correspond with -136dBm. Your base antenna will likely be higher than 1m (up on a pole I assume) and if you get those big collinear antennas they are 5.8dBi.
I’m thinking on a good day with EByte E22-900M-22S radios, 5.8dBi antennas and direct line of sight we will see 150km+.
I’ve never used 433MHz to compare to 900MHz sorry. I guess on paper it should achieve better results. However there is greater abundance of 900MHz products around.
The Heltec I was looking at uses a XS1278 radio, also found this TTGO LoRa V1 which uses the SX1276.
Update: These TTGOs with Lora+Gps+baterry just showed up. I’m guessing they are always the best choice? With these and a 5w 5V panel I have a kit ready for deployment, correct?
I can’t say for sure. I’m starting to think we should work on a device spreadsheet in the wiki.
In some cases there will be a trade off between low power and higher transmit range.
In some areas there are rules on transmit power, that may or may not be enforced. Each use case will be different. Maybe in a remote area with little risk of interference (especially if you are likely the only one operating devices in that freq range) transmitting higher than what is legal may be worth it to make a repeater reach remote areas but I strongly suggest using that as an option of last resort.
The LoRa SX1262 based modules are the latest offering with higher TX power, better RX sensitivity and lower RX current. There aren’t many devices being offered with them yet however. The TBeam SX1262 is one option. You will still have good success with the current offering though.
At a minimum, you need to tune your antennas. 99% of antennas need tuning. Try to find someone who has a vector analyzer and can help you tune the antennas. this is key and try to raise the retanders as high as possible. use directional antennas where possible.
This was the expected reach using the simulation. Unfortunately I didn’t have the map with me to check exactly where we’d could have signal in the closest town (Alto Paraíso de Goiás), so I drove to the wrong places to test.
But I was very surprised with these results, I was expecting to climb a hill to get a message through, but from inside the car messages were being sent no problem (using the maximum range/lowest speed settings). Within the village I got a connection everywhere.
Based on the simulation for the Krahô territory I’ve decided to change strategies, and go for the best spot on the whole territory, making possible for all villages to connect. The trick here is to either have a really good omni:
Or place two nodes at this hill, each one with a yagi, which might be more guarateed to work, but would require placing more nodes at the center in case villages in the other directions want join the network:
Any other ways to tune antennas?