ReiBot.org

2 Watt Lora Range Test

Recently I noticed NiceRF selling 2 watt lora radios. With my last range test years ago getting 4+ miles of range on 100mW. I decided to try again with these higher power modules. Spoiler – at ~45 miles, I could reliably transfer packets with receiver RSSI of -120 to -123dBm with the base station’s link limit rated for -139dBm (based off module datasheet). I’d love to find out at what point this link drops out, but ran out of time.

ESP32 dev board – I designed it to be a somewhat generic dev board with a qwiic connector. Main notable part is supports input voltage range of up to 36V, 2A 5v buck, 600mA 3.3v linear reg. Didn’t spend much time optimizing PCB space/layout.

Antenna for the base station – blindly designed and 3d printed using a yagi-uda antenna calculator. Elements were coated with copper tape. Dipole with balun for the active element. Antenna impedance was sanity checked with a nanoVNA. Base station reported telemetry via Blynk and a wifi connection to provide Lora connection details over the internet to my phone. Antenna tripod was ~3 stories high on a grain silo stairway. I have no clue how ‘good’ this antenna is.

Since this test took place in the midwest, line of sight sucks. I used my FlyWoo explorer LR to elevate the transmitter to an altitude that allows for line of sight to the base station. I used a generic 2dBi whip antenna. My drone uses TBS Crossfire lora which hops around 900-915MHz for uplink/downlink. This likely bled a bit into my board’s 925MHz lora radio test. I made sure antennas are 90deg apart to help reduce this.

Range was about 45miles. Yep might be closer to 44 or 43 since this isn’t a linear path.

I’m going to keep this post brief. Here’s the main piece that you may be wondering – What were the secret sauce lora configs? Radiolib library used: BW=62.5, SF=12, CR=8, preamble was increased when testing lower BW, but don’t think it’s needed for utilized BW. Note that this is SLOW. Like 4-5 seconds to send a 25byte payload. While this isn’t practical for many applications: this was a range test, practicality depends on the application and there is no application here. I’m not posting schematics since there isn’t much here. Just an esp32 and lora module with some regulators.

I’d love to sell these boards, but would have to sell at ~70$ each. If there’s interest I can whip some up for anyone and throw them on Tindie with code/schematics, but that’s a bit steep in today’s world of low cost boards.

LoDuino – Low power Arduino with FCC Certified Lora radio

Thought I’d throw up something I’ve been meaning to sell for a while.

LoDuino is an adorable low cost 8Mhz 3.3v ATMEGA328 Arduino with Lora radio, it’s breadboard friendly footprint makes it great for quick prototyping. Applications that utilize good power conservation practices can run for years on a small 1000mAh battery.

Features

• FCC Certified Lora radio for 915Mhz ISM — this radio does not have a managment IC like the RN2903 which removes limitations and offers lower power consumption.
• 4+ miles Line-Of-Site communication range when using low bandwidth Lora. Modulation type and bandwidth settings greatly impact range. Need more range? Consider the U.FL version which allows you to use high gain/directional antennas.
• Lipo charger with charging status indicator fed into the Arduino.
• Built in battery voltage reading.
• Optimized for battery applications <30uA standby current. This can be much further reduced to ~5uA by disabling the brown out detection and shutting off timers.
• Two 3.3v regulators: One that’s always on powering Arduino and radio. The second is controlled by the arduino allowing the user to shut it off in case sensors that can’t sleep or sleep at a high standby current are being used.
• Two 1.5 amp fuses. One on the 5v charging breadboard output and one on the battery input. Just to help protect in case you’ve got it installed somewhere and a short is introduced from vibrations or other malfunction.
• U.FL version for high gain or directional antennas. The U.FL connector also lets you run a u.fl -> sma out of your project box for a professional look.

Leave a comment for purchasing, it will not be posted on the site.

Do you need FCC certification?

Read up on this document. If it’s for personal/non business use: probably not.

Other things to keep in mind

• If you’re needing the FCC certification then FCC ID 2AD66-LORAV2 must be placed in a visible area of your device. FCC rules/regulations must be followed within your software.
• Code uploaded through FTDI cable or equivalent.
• U.FL version is not fcc certified due to changing antenna and adding coaxial cables.

Included
Comes with headers and JST battery connector — not soldered since lipo batteries change up polarity on JST pins

Setup procedure:

1) Download the Arduino IDE in zip format

2) Extract the IDE, find Boards.txt for editing

3) Edit these two highlighted lines. When uploading to the LoDuino board, use the ‘Arduino Uno’ board option

4) Download ArSpayce Radiohead library

5) Extract radiohead to your new arduino libraries folder.

6) You’re done! Dont forget to check out the schematic

LoDuino Schematic

Code examples coming soon

Lora Range Test

Lora Pager

Aright So I designed those awesome Lora pagers mentioned in my previous post based off some SX1276 modules. How far can they really go? Here’s a graph with a quick test to find out. Red line represents the Lora module broadcasting its GPS position back to the base-station. Blue line represents my phone’s GPS record (to show where I was actually driving). Yellow thumbtacks represent base station. Unfortunately my  apartment is at a low altitude with roads on giant dirt hills around the base station: this killed range testing in most directions. Be sure to check out my Lora development boards that use the same radio

4.27 miles! yellow line represents base station to tag largest distance

Remember that this is with a 5dbi antenna on the base station located on the second floor of my apartment, and a free 2-3dBi antenna on the GPS tab sticking out of the sunroof on my car. Transmission power was 20dB. Zooming into that largest distance:

Zoom into the industrial area from previous image — Found the line of sight path!

Not bad for the pager’s 13mm! bad antenna. Definitely blows every other 100mW radio <10$ I’ve tested out of the water. It’s also awesome that it can sleep for only a couple microamps which brings the whole pager to ~50uA when on standby.

Pager with gps attached in car

How to do this on your own: save the pager’s Lat,Long in csv format then upload to gpsVisualizer and export as google earth (kmz format). For the phone use Geo Tracker (android) to record positions then share as a kmz and email yourself the kmz file. Then just open both files in google earth. I couldn’t figure out how to open these files in google earth for web browser, it’s very easy with the full install.