Wireless Remote Weather Station (without WiFi)

We have chickens at our place and in the heat of summer and cold of winter their coop can get very hot, very cold, and very humid.     This changes how you have to care for them.

I built a wireless weather station so that my wife can have immediate access to real time temperature and humidity information whenever she wants and wherever in the house that she wants.

The project has two pieces:

• Transmitter
• Receiver

The transmitter will be powered by a connected cable.   The receiver will be powered by a battery pack.

Since we're doing wireless transmission of data, we'll need a decent protocol to send data that has enough error correction to make data transmit reliable.   I found the Radiohead ASK library (Amplitude Shift Keying) library which seems well suited to the task.

http://www.airspayce.com/mikem/arduino/RadioHead/classRH__ASK.html

I spent a fair amount of time working with two Arduinos and the Spectrum Analyzer to get the data transmission locked in.   I had ordered some very cheap RF modules from China which didn't come with any documentation.

I figured that since I had the spectrum analyzer that even if I didn't have docs, I could figure it out.

I found that 315 Mhz is where the transmitter lives.

For best transmission you want the antenna to be tuned to resonance for your proper frequency.   That's wavespeed / frequency (in Mhz).   If you have some background in RF, this is easy.   If you don't, look up an antenna calculator and fill in the frequency and that you want a quarter wave vertical (think car antenna).   The calculator will give you a length that is good enough.

Transmission happens very quick, so it's difficult to tell sometimes if you're really catching the broadcast in the receiver or not.

Now that I had two Arduinos talking to each other, it was a simple job of connecting sensors and displays. 

The transmitter does need to live in a weatherproof box which I found at Home Depot. 

You'll note that there's a boost convertor in the picture and a relay behind.   This was for the light system.   They are installed but not powered.

It also requires some wiring inside the chicken coop in order for the sensor to be valuable.   Additionally the birds will tend to pick at things that are new, so it needs to be protected initially.

I put lights in the tube as a way of increasing egg production in the winter.   It didn't seem to make any realistic effect, so I turned them off.

I tested the range out once I got it all wired up and found that I can go a couple hundred feet away and get a very good signal.

The transmission is very reliable and has run all winter without any reboots.

An interesting gotcha is that the my cheap transmitter/receiver pair were labeled that they performed properly at 3.3v.    I found that this wasn't the case after a couple hours of troubleshooting and started running them at 5v.

Overall, a fun and interesting project.

Note: I picked up all my parts at Doug Rich's store here:

https://squareup.com/store/just-for-fun-6

When I've wanted strange one-off parts, he's been able to track them down at a very affordable rate.