Transmit information on AC 220v 50Hz Wire - Help - Page 1
Forum section: electronics / beginners

author: igorbog
author_rank: Contributor
timestamp: February 14, 2012, 04:39:35 pm
content: Hi.I want to send information(Temperature) from one avr to another by using home ac network. I thought to design mixer with modulator and transmit my data on 100kHz, while ac network is 50Hz. Can any body help with this issue? how to do it?

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 14, 2012, 05:11:24 pm
content: This seems easy at first, but is a fairly complex problem. You run into tons of devices making your power line/signal bus really noisy. A noise dimmer or CFL bulb can make your data unreadable.There are established standards such as X10. This is a low speed protocol, but most likely fast enough to do what you need. You can also look at the Arduino X10 libraries for how to interface with modules. Then a $20 module on each side connects them.http://www.x10.com/automation/x10_pl513.htm

author: kripton2035
author_rank: Super Contributor
timestamp: February 14, 2012, 05:41:21 pm
content: there is also the universal power bus, which is free and more documented than x10an implementation here :http://mrx23dot.blogspot.com/2012/01/cloning-upb-home-automation-system.html

author: cybergibbons
author_rank: Frequent Contributor
timestamp: February 14, 2012, 07:19:45 pm
content: I'd stick to RF - easier, safer, lower power.

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 15, 2012, 02:06:25 am
content: Quote from: cybergibbons on February 14, 2012, 07:19:45 pmTechnically, if you are hooked to the power line already, lower power isn't really a problem. However, I agree. If you are within wireless range, that will be much easier.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 15, 2012, 02:54:58 am
content: this is a skeptic to me. how are you going to inject signal from a finite impedance source into almost zero impedance high powered line (mains)? let alone the noise sachejj mentioned. i will not bother to answer even i'm an expert. OP did not give complete description imho.

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 15, 2012, 03:10:57 am
content: Quote from: Mechatrommer on February 15, 2012, 02:54:58 amThe two protocols mentioned have two things going for them: slow bit rate and know position in the existing wave to send or receive (minimizing the noise issue.)For example, the X10 uses a 1 ms 120 kHz burst at zero crossing for 1 and lack of a burst for zero. This allows you to filter out noise by using a band pass on 120 kHz. This also filters out the mains frequency. However, with only at zero crossing, you have 120 Hz or 100 Hz bit speed. Less with collision and error correction. Injecting the signal isn't an issue, because you are only using the power lines like a transmission line. The frequency burst doesn't have to be 115-230 V. It just exists on the same line.Universal Powerline Bus uses a voltage spike at 1 of 4 known positions in a half cycle, rather than just the zero crossing. This allows values of 0-3 (2 bits) in each half cycle. So you get double the bandwidth of X10, 240 Hz or 200 Hz. The voltage spike is usually created by dumping a capacitor into the line at the right time.

author: Jimmy
author_rank: Regular Contributor
timestamp: February 15, 2012, 12:28:06 pm
content: for a good hint look at the mamba shieldhttp://dlnmh9ip6v2uc.cloudfront.net/datasheets/Dev/Arduino/Shields/MambaSch.pdf

author: Unknown
author_rank: Unknown
timestamp: February 15, 2012, 08:55:36 pm
content: Quote from: Mechatrommer on February 15, 2012, 02:54:58 amThe mains impedance at f >> 60 Hz (eg. the 120 kHz that sacherjj mentions) will be far from zero.