Methods I Rejected: Time Domain Reflectometry

Methods I Rejected: Time Domain Reflectometry

Soil Moisture Sensor Project

Time domain reflectometry

After rejecting any method that requires you to electrocute worms by running electricity through their home, the next method I research and rejected was time domain reflectometry.

Time domain reflectometry is a fancy system of measuring how electrical waves move. Firstly, you send a pulse of energy down a cable. You then measure the size of any reflected pulses and how long it takes for those pulses to return. I did start reading something about how moist soil and dry soil affect pulses of energy in different ways. When I went to look at how time domain reflectometry works I saw lots of pictures of oscilloscopes and read….

“The physics behind this method can be pretty complex (single equations that take up half a page)…”

https://www.allaboutcircuits.com/projects/build-your-own-time-domain-reflectometer/

“Usual TDRs need expensive high-speed components.”

“I have built a prototype. The parts cost less than 50 Euro, even in single quantities.”

http://www.eevblog.com/forum/projects/building-a-poor-man’s-time-domain-reflectometer/?PHPSESSID=c057a5749b45d8745d5d208af924b567

As a result, I decided that this method was not the simple but effective method of measuring soil moisture content that I needed for my home garden. So let’s move on to low pass filters, capacitor charging time, or  microchips that measure capacitance.

Go back to review of previous sensors, or main page.

 

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