How can I find out which frequency they are made for?
You can distinguish by whether have these two capacitors. If there are two capacitors, it is 868 version, if not, it is 470 version.
Thank you! So my suspicion was right, my reseller sent me 2x433 and 1x868 instead of 3x868…
Oh sorry, I was wrong. First, I misread you and meant that two capacitors mean I got a 433, but it’s the other way around. I also opened the working 1th module… it looks exactly the same as the other two regarding hardware:
#1 can communicate form the air raid shelter to the sensors gateway in our main building 200m away. With number 2 and 3, I can’t even get a connection to the gateway from the lower floor in the same building with exactly the same firmware.
So I did a test now. I used a LoRa 32 as a ping pong base station, a fixed antenna for the cubecells and 5dBm, 868MHz, SF5, BW125, CR4/5 on both sides, distance 2m. These are the results (RX RSSI on the ESP32 side/RX RSSI on the cubecell side):
CubeCell #1: -101/ -98 //WITHOUT ANTENNA CubeCell #1: -71/ -51 CubeCell #2: -100/ -45 CubeCell #3: -93/-102 //WITHOUT ANTENNA CubeCell #3: -93/ -51
Number 2 I could not do any test without antenna, as I soldered a 86mm wire instead of the IPEX connector.
So I think antenna switching is broken on modules 2 and 3, but I can’t see anything wrong under the microscope (well, it’s not the nicest soldering, but nothing shorted or open). I drown everything in flux and hit it with hot air. I’ll report back…
Nope, same problem as before. Any ideas? I measured also (with an oscilloscope) the signals at the collector and the base of Q5 as well as Pin 4 and 6 of U2. Everything looks fine…
You can use cubecell No. 1 to do pingpong test with cubecell No. 2 and No. 3 respectively, and observe the experimental results.
@shaffer It’s about the same picture:
CC1/CC2: -87/ -38 CC1/CC3: -89/ -49 CC2/CC3: -89/ -88