Tag Archives: radio

Wireless Home Monitor System

Over the past five years or so, I’ve been tinkering with wireless monitoring in my home. One of my first projects in 2010 was the Remote Fuel Oil Gauge that used the OnShine RX/TX pair at 433 MHz.

Shortly after this, I began to explore home environmental sensing, using a new internet service called Pachube (then Cosm, now Xively). I built an internet-linked environmental sensor that’s now installed in my office at NSCAD.

Next step was to build sensors that could wirelessly send data to a base station that would relay it to a central repository on the internet. To do this, I used Jean-Claude Whippler’s JeeNode library that enables the Hope RF12 and RF12B to communicate with each other and a base station JeeLink that can connect directly to a Raspberry Pi using its built-in USB.

Home Sensor Configuration
Home Sensor Configuration

The basic configuration is comprised of the RPi and Python control and communication software that accepts the data from the JeeLink, does some conversions, and then sends it along to Xively. Xively handles the graphing.

Sensor Units

  • Basic Temperature only unit using DS1820
  • Basic Temperature and Humidity unit using DHT22
  • Garage unit: one DHT22 for garage, another DHT22 for “worm box”—Dorothea gives food scraps to worms, which process the scraps to good soil for the garden—plus a carbon monoxide sensor and a garage door open sensor
  • Office unit: one DHT22 plus a PIR sensor to detect activity in the office
  • Kitchen sensor unit: one DHT22. Solar powered.
  • Backyard Shed sensor unit: one DHT22. Solar powered.

Display Unit

There’s one LCD display on the kitchen refrigerator door that displays data from the Garage unit; if the garage door is open, a redLED blinks at .5 Hz.

More on various aspects of the system… later.

Military Room Escape Movie Prop

Well, hello there. It was a long, dreadful, record-breaking winter here in Nova Scotia. Although most of the snow has melted, it’s still unseasonably cold. I heard on local radio today that people are calling it “springter”. My last post was in October, and since then I’ve been occupied with teaching, promoting NSCAD programs in China and chairing an academic department; things that are either not blog-worthy or worth repeating publicly.

Weather Sensing Invention

Around the time of my last post, I had stumbled upon what I think might be a new invention relating to weather sensing. With the help of Kevin Buchan, NSCAD’s research consultant, I issued a proposal to Innovacorp for an Early Stage Commercialization Fund grant to help develop a working prototype. I heard at the end of February that I didn’t get the grant, so that’s off the table for the moment. By the way, my friend and colleague Sol Nagler received funding for his “Narratives – A Geolocative Interactive Storytelling Mobile Application” project. At least, I thought he was my friend. 😉


Over the past number of years, I’ve been utilizing tiny RFM12 and RFM12B 434 MHz radio units to send and receive sensor data around the house. These units use Arduino ATMEGA 328 microcontrollers and the Jeenode Library. I hope to talk more about this long-term project in future posts.

The more I worked with these magical devices, the more interested I became in their inner workings. Specifically, I wanted to know:

  • how to get the RF energy from the little circuit out to the world
  • what kinds of environmental factors affect the propagation of the RF energy
  • how to maximize and direct the RF energy from the sensor to a base receiver

However, in my research I was confronted with a wall of my own ignorance; as I searched for answers, more questions kept popping up. So I decided to undertake a long-term study, and as part of that plan I applied for my amateur radio license. I took the test on March 31 and received my Basic with Honours license, which allows me to use all of the HF, VHF and above amateur radio bands using standard commercially-designed and built radios. I want to be able to design and build my own transmitters, but that will have to wait until I can pass the Advanced license test. My callsign is VE1LEB. The VE1 prefix indicates my location as Nova Scotia, Canada.

Changshu K-4 Heavy Key
Changshu K-4 Heavy Key

So what’s the “Military Room Escape Movie Prop”? It comes from the AliExpress listing for a Chinese Army Changshu K-4 morse code key that I received in the mail yesterday. These keys have been in service in the Chinese military from the early 1960’s. It weighs one kilogram and it’s a thing of beauty! Morse code hasn’t been a requirement for amateur radio licensing in Canada for ten years, but I’m learning to send and receive anyway and hope to take the 5 wpm test in the Fall to get this function added to my certification.

So until next time, 73!