We have been working on communicating two RAK3172 modules in P2P mode for a while.
At first we worked with 868 MHz and after 300-400 meters communication between modules was lost.
Then we decided to set the frequency to 433 MHz. We connected 433 MHz antennas with 5 dBi power to our RAK3172 modules. And then in the final test we did today, we were able to reach 400 meters in the city (the RSSI was around -115 and -120 at that moment). We couldn’t get any data after 400 meters.
The transmitter (TX) RAK3172 from the modules was located on the terrace on the top floor of the building where I was located. The receiver (RX) module was located in a car 400 meters away. This was the maximum range we were able to reach during testing.
The parameters we applied in the communication test:
I can’t understand why the distance is so low. Are we doing something wrong, or can we communicate with the RAK3172 5 dBi antenna and the above parameters for a maximum of 400 meters?
The RF path inside the RAK3172 is matching for either 800-920 MHz (RAK3172-H) or ~400MHz (RAK3172-L). When using our RUI3 firmware, you cannot set a frequency lower than 800 MHz on the RAK3172-H module. What firmware are you using? If you are using a custom firmware created with STM32CubeIDE, are you adjusting the LoRa part as described in our Low-Level-Development tutorial?
If not, the STM32WL5E will not work as expected, which could explain the short range.
I’m using latest firmware and editing code at Arduino IDE. For setting low freq. mode, i pulled down PB12 and set frequency with code and with AT+PFREQ=433000000 command.
Why do you say the RF path is not matched for 433 MHz? The module I have, does not say RAK3172(L) or RAK3172(H). What would prevent me from using it for 433 MHz?
Yes, I tested it in the city. Although I do not insert a building directly between the two modules, buildings, trees, etc. within 400 meters. exists.
That’s how my module looks like (No “H” or “L” indicator):
If you look into antenna matching, you will learn that the R/C/L matching between the antenna and the RF pin of the STM32WLE5 has to match with the frequencies it should work with the best efficiency.
The values of all marked components are different between the H and the L version.
Yes, the LoRa transceiver can be set to 150Mhz to 960MHz. But that is INSIDE the chip. It still needs a RF path matching and correct frequency antennas to get a usable range.
I ask one more time.
What is the test environment?
When I go out with a mapper from my house, I get signal until the end of my street, as soon as other buildings are between the node and the receiver, I loose the signal. In some spots with less structures between the two devices I can get 700m, in some spots I get no connection at all.
This is a heat map when I tested the device. As you can see there are many areas where the device could not reach the gateway.
1-) How did you decide that my RAK3172 module is a -H version, even though there is no “H” or “L” phrase on it as it says in other modules?
2-) If in the features section (150- 960 MHz) is written, is it an empty expectation to be able to communicate at the frequency I want in this frequency range without saying “fake etc.”?
No -H on the label means H version.
-L on the label means L version.
(I) on the label means it has IPEX connector
no (I) on the label means it has no IPEX connector.
City environment can mean anything. The picture makes it clear. If there is direct line of sight, the range is too less. I get more with our small PCB antennas that we use for evaluation.
So you are saying that 400 meters is the maximum range I can get, unless I position the antennas as indicated in the image below (ie, as long as there are buildings etc. in between). Do I understand correctly?
Buy a proper antenna as it’s very important and most of “Alixexpress” ones are quite terrible and not for frequencies indicated on it !
I get few kilometers range easily with RAK3172 and a proper 2.3dB antenna (one from RakWireless with proper cable too).
Influential. What is your test environment? Is there a direct line of sight between the receiver and transmitter modules? Or are there buildings in between?
