Category: Sensors

Smarthome-type Candidate Networks

Posted on by CBMalloch

  • Long-range off-the-grid communications

    • Meshtastic

      • LoRa sub-GHz radio band, e.g. 915MHz in the US
      • mesh, broadcast, forwarding, max 7 hops
      • normal use case – short text messages

    • MeshCore

      • LoRa sub-GHz radio band, e.g. 915MHz in the US
      • mesh, using path learning
      • AES encryption
      • devices have fixed roles: companion radio, repeater, room server, stand-alone device
    • Reticulum
    • LoRa and/or HAM
      • APRS – Automatic Packet Reporting System “Packet Radio”
        • Digipeaters
        • aprs.fi

  • Wireless Personal-Area Networks

    • BSR X-10

      • power line transmission

    • XBee

    • Zigbee

      • 6LoWPAN/IEEE 802.15.4
      • 2.4GHz, sub-GHz, e.g. 915MHz radio bands
      • 10-100 meters, line-of-sight
      • star, tree, mesh
      • Zigbee coordinator (ZC), router (ZR), end device (ZED)
      • encryption
      • optimized for battery-operated devices
      • network layer, application layer, Zigbee device objects (ZDO), manufacturer-specified application objects

    • Z-Wave

      • sub-GHz radio band, e.g. 915MHz in the US

    • painlessMesh

    • Thread

      • 6LoWPAN/IEEE 802.15.4
      • 2.4GHz radio band
      • can be run on ESP32, perhaps on ESP8266
      • IP-addressable
      • cloud access
      • AES encryption
      • optimized for low-power and battery-operated devices
      • open-source implementation OpenThread via Google
        • OpenThread network simulator

    • Tasmota

      • Protocol for ESP devices
      • Supports Matter, but only (so far) over WiFi

    • Matter

      • Lives atop Thread; can also live atop WiFi

Evaluation of Occupancy / Motion Sensors for Perimeter Security

Posted on by CBMalloch

— Work in Progress —

I am evaluating range, sensitivity, immunity from false triggering, and power requirements, for various projects around the house. In particular, I would like to be notified when a person or a vehicle comes down my driveway, so I can light the way if it’s dark.

Sensors Considered

  1. Passive Infrared (PIR)
    1. AM312 3.3 or 5V, active low
    2. SB0072 Futurelec MINI_PIR_MOD_B 5-20V, adjustable delay time
  2. Microwave Doppler
    1. RCWL-0516
    2. RCWL-9192
  3. Ultrasonic (SONAR)
    1. RCWL-1655 board and waterproof ultrasonic distance sensor

TLDR;

PIR produces many false triggers with sunlight and moving foliage.

Microwave Doppler is pretty short-range

Ultrasonic is pretty short-range

Testing

Passive Infrared (PIR)

Microwave Doppler

Ultrasonic (SONAR) – RCWL-1655

Range: Quoted as up to 5 meters; detects humans up to about 1.5 meters

Immunity from false triggering: Once I filtered out zero-responses, I only see false triggering when there is a target too small or too far away to reliably register.

Power requirements: Currently testing with a 1500 mAh LiPo battery; started the test on 2024-09-22 at 21:00 or so.

Test routine:

  • take a reading “ping”
  • if result is different than before, take repeated readings until two in a row match within 10%
  • if this new “clean” reading is different than before, report it with a JSON message transmitted via LoRa
  • sleep for 0.25 seconds (originally 1 second). Since the processing takes 120ms or so, sleeping for 250ms cuts power consumption by perhaps two thirds.