I've finally made a little progress over the last two days. Lots of background reading on the excellent SX12XX library and some tinkering to make a portable radio modem for future testing

Here's the transmit end soldered up to a little bit of prototyping board I had lying around, which it turned out was the perfect size to fit the E28+breakout, Arduino Pro Mini, and voltage reg! All powered off a tiny 2S LiPo at the moment. The antennas are external Happymodel ELRS-intended and are supposedly 5dB...

The voltage divider is included for battery monitoring. I modified the 'varying power' library examples (numbers 10/20) to include sending one battery voltage packet per test and print serial bytes in a slightly more interpretable format for a python script to read and save to csv.

Just as a proof of concept, I looked at how RSSI/SNR vary with Tx power and RF attenuation, see below:

• TC1 = line of sight, 3-4m separation
• TC2 = as TC1 but cross-polarised antennas
• TC3 = several brick walls of attenuation
• TC4 = as TC3 but cross-polarised antennas
  (and yes, the axes are intentionally the wrong way around since it's easier to fit the plots on a horizontal screen this way!)

Clearly something is working right as RSSI drops off linearly with Tx power! SNR performance leaves a bit to be desired but seems that @NeverDie had similar results. Not very exciting but showing the setup is correct for now and I can move on to some more interesting things.

Next up is to have a look at implementing the PA/LNA on the E28 modules and seeing what kind of difference I get in performance. Spotted the RX/TX_EN pins in the library documentation so I'll give those a go

@NeverDie Hi, I've just started playing with a pair of these modules that I've had kicking around for a while. Fascinating thread and I haven't finished reading through yet, thanks for being so thorough!

I'm using the same library. When it comes to enabling the TX_EN and RX_EN pins, can you clarify how? Is it done through the microcontroller script, or by setting the pin inputs to high (+3.3v)?

Thanks for letting me know, I'm going to play around with these over the weekend and I'll try to report back. Not too bothered about getting optimal performance since it's my first time messing with RF specifically in an arduino project, just want to do some basic testing. Some 868 modules are for sure on my list to check out next

I've finally made a little progress over the last two days. Lots of background reading on the excellent SX12XX library and some tinkering to make a portable radio modem for future testing

Here's the transmit end soldered up to a little bit of prototyping board I had lying around, which it turned out was the perfect size to fit the E28+breakout, Arduino Pro Mini, and voltage reg! All powered off a tiny 2S LiPo at the moment. The antennas are external Happymodel ELRS-intended and are supposedly 5dB...

The voltage divider is included for battery monitoring. I modified the 'varying power' library examples (numbers 10/20) to include sending one battery voltage packet per test and print serial bytes in a slightly more interpretable format for a python script to read and save to csv.

Just as a proof of concept, I looked at how RSSI/SNR vary with Tx power and RF attenuation, see below:

• TC1 = line of sight, 3-4m separation
• TC2 = as TC1 but cross-polarised antennas
• TC3 = several brick walls of attenuation
• TC4 = as TC3 but cross-polarised antennas
  (and yes, the axes are intentionally the wrong way around since it's easier to fit the plots on a horizontal screen this way!)

Clearly something is working right as RSSI drops off linearly with Tx power! SNR performance leaves a bit to be desired but seems that @NeverDie had similar results. Not very exciting but showing the setup is correct for now and I can move on to some more interesting things.

Next up is to have a look at implementing the PA/LNA on the E28 modules and seeing what kind of difference I get in performance. Spotted the RX/TX_EN pins in the library documentation so I'll give those a go

Thanks for letting me know, I'm going to play around with these over the weekend and I'll try to report back. Not too bothered about getting optimal performance since it's my first time messing with RF specifically in an arduino project, just want to do some basic testing. Some 868 modules are for sure on my list to check out next

@NeverDie Hi, I've just started playing with a pair of these modules that I've had kicking around for a while. Fascinating thread and I haven't finished reading through yet, thanks for being so thorough!

I'm using the same library. When it comes to enabling the TX_EN and RX_EN pins, can you clarify how? Is it done through the microcontroller script, or by setting the pin inputs to high (+3.3v)?