My DIY battery-powered wireless driveway visitor detector, take 3! A much harder problem than I anticipated. Attempt 1 was using a cheap and low power PIR sensor. Too many false alerts. Attempt 2 was a radar presence detector. Doesn't work outdoors, way too many false alerts. This one uses a commercial outdoor PIR sensor, which seems to work quite well so far. On the down side, it uses quite a bit of power (20mA continuous), so I've had to add a lithium battery with solar charger. Nice thing about a LiFePO4 battery is that I don't need a fancy solar charge controller, I just use a buck converter set to about 14V. The grey box houses a microcontroller with a LoRa transmitter, mounted on an aluminium bracket that I can hang on my driveway pre-cast wall, so that the PIR sensor looks across the driveway. I put the battery and charger into an ice cream container and placed a roof tile over it to protect against rain and sun. The receiver side is an ESP32 connected to a LoRa receiver and buzzer that plays a ding-dong chime and also sends an MQTT message for futher automation. #diy #lora #pir #motion #sensor

"This means in two to five years we may be able to surf the internet or talk on our 900 MHz phones while walking down the sidewalk in nearly any city whose occupants own Amazon or other competing devices."

We may Soon have City-Spanning 900 HMz Mesh Networks
http://cheapskatesguide.org/articles/900mhz-mesh.html/

"These all use some form of local radio signal. Some, such as Briar, may use short-range Bluetooth and Wifi, while others use radios such as LoRa that can reach several miles with low power. ... Every item on this list uses full end-to-end encryption" #offline #messenger #lora #meshnetwork

Roundup of Secure Messengers with Off-The-Grid Capabilities
https://changelog.complete.org/archives/10205-roundup-of-secure-messengers-with-off-the-grid-capabilities-distributed-mesh-messengers