B-L072Z-LRWAN1: improving the reach

[Mikhail Soloviev]

Posted on November 16, 2017 at 23:52

I purchased three B-L072Z-LRWAN1 nodes yesterday and started my long awaited experimenting. The distance while maintaining stable communication between two B-L072Z-LRWAN1 nodes is a bit of a dissapointment. After having used nRF24 + PA + LNA and reaching up to 1km, I was now hoping for a miracle in a tiny pack

While the LoRa community claims >15km, I can barely get 1km with these units. I presume 15km is an extrem. However I hope things can be done better (at least up to 5km).

Some obvious concerns are the antenna supplied in the box. It is a 4cm one. Another concern is antenna imedance matching. As it says on the schematics, temporarily replaced by 0Ohm resistors. Does anyone have an idea what this means? Has anyone tried to populate those pads with macthing components? Did it help?

Please share your thoughts on improving distance with B-L072Z-LRWAN1

#b-l072z-lrwan1

[Tesla DeLorean]

Posted on November 17, 2017 at 15:05

About 1KM is about what one might expect within an industrial park like setting. Line-of-sight (LoS) is the primary limitation. Can get 3KM without issue at the highest speed settings where LoS between antennas exist, power/gain less helpful without this.

A beacon using the stock antenna and lowest speed settings, and inside a building, was receivable on a second unit with a 7 dBi antenna (5/8 over 5/8 over 1/4) mounted on a truck 11KM away. I would expect if I put the stock unit on top of a 100ft tower I'd get a lot further. I'm in a place that's rather flat, so no opportunity to place devices on geological high points (large hills, mountains).

Getting the 20 dBm setting on the SX1276 requires software changes related to the current and power registers, otherwise you'll be limited to 17 dBm or less.

The are LoRa implementations using an LNA to improve receive sensitivity, which do seem to get much better RSSI numbers. The Murata module is basically just an STM32L0 + SX1276