07. Radio Transceiver Range

Transmission range depends on many factors. In some cases the range on the original equipment (outdoor sensor and weather station/display) cannot be achieved with a home-made receiver.

In Issue #14 - Calibrate from CC1101?, it was suggested to provide a means to calibrate the CC1101 transceiver's frequency offset.

Sometimes it helps to move the receiver a few centimeters to a different position or to change the antenna's orientation. You can also try a different type of antenna - wire antenna vs. helical coil antenna. Unfortunately there does not seem to be a CC1101 board with a proper antenna connector.

The YouTube video #182 ESP32 Lora Boards: What you need to know before you buy (incl. Antenna knowledge) by Andreas Spiess also suggests that some antennas out there are not as good as you could hope for...

I also noticed that radiated emissions from other electronic devices (PC, other microcontroller boards, ...) near the receiver had significant influence on signal quality. I even noticed that the power supply had some influence (USB power from my notebook was bad, USB power from my desktop PC or wall adapter was fine).

BUT - I got almost rock solid reception when I changed to the Adafruit RFM95W LoRa Radio Transceiver Breakout with a proper antenna (Delock LoRa 868 MHz Antenna SMA plug 3 dBi omnidirectional with tilt joint black in my case). I don't know if this is due to better chip design, better PCB design or just the antenna.

For a deep dive into this topic, see the TI Application Notes Achieving Optimum Radio Range (Rev. A) and AN058 -- Antenna Selection Guide (Rev. B).