What are the options for communicating sensor data to a central point in a medium size building?

I want to build a cheap centralized temperature control. In each room there are about 4 radiators which I want to equip with a few sensors like temperature, light, sound level, and with a radiator valve actuator. Let's say the building has 50 rooms with a wireless network available.

The main requirements are low costs (for the project as a whole), and it should be relatively easy to design and implement. I have some experience with PCB design and micro controllers, and I can ask help of more experienced people. I'm not bound to specific sensors or actuator.

I guess power for the sensors and for the actuator come from a power outlet. Maybe the signal can also travel over the power net.

P.S. As newbie, I feel I could use some help to improve this question. All help is appreciated.

  • \$\begingroup\$ Can you explain whats electronic knob ? \$\endgroup\$ – rahulb Mar 13 '14 at 10:13
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    \$\begingroup\$ Have you worked on electronics projects before? This is quite ambitious, and will likely be relatively expensive. \$\endgroup\$ – Polynomial Mar 13 '14 at 10:14
  • \$\begingroup\$ @rahulb I found the word: radiator valve actuator. \$\endgroup\$ – sjdh Mar 13 '14 at 10:15
  • \$\begingroup\$ @Polynomial I didn't do big projects before. If I go on with this I will ask help of an experienced engineer. First I would like to get a better idea of the options. \$\endgroup\$ – sjdh Mar 13 '14 at 10:17
  • \$\begingroup\$ I think the added questions about sensors is beyond the scope of the original question and you'll probably get better answers raising this as a new question just focussing on the sensors. \$\endgroup\$ – Andy aka Mar 13 '14 at 11:14

Power line transmission is a good option for this. The chip-sets do seem to be able to handle "decent" data rates with a good degree of reliability. The 100kHz band looks probably the most attractive and is, as far as I know, dedicated to this sort of thing. This document from NXP (entitled AN10903, TDA5051A ASK power line modem) is a good reference for what you have to do. It contains a wealth of knowledge on how to couple to the AC lines and how to impedance match etc.. The chip-set is good for 1200baud and I think this would be good enough for what you are looking to achieve. Remember one thing, faster data rates = wider bandwidth = more received noise = less sensitive receiver.

Here is the data sheet for the chip and below is a diagram in that document: -

enter image description here

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  • \$\begingroup\$ This is an interesting option. Could you comment on the other hardware needed? I think at leas a microprocessor, right? And on the cost? \$\endgroup\$ – sjdh Mar 13 '14 at 10:47
  • \$\begingroup\$ See also these links about the TDA5051A ukessays.com/essays/information-technology/… and digikey.com/en-US/articles/techzone/2011/mar/… \$\endgroup\$ – sjdh Mar 13 '14 at 10:47
  • \$\begingroup\$ Other hardware? Not sure what you want to know other than they are fairly cheap and off-the-shelf parts used in the design and yes a small MCU is needed and then you'll need to consider the interface to the various sensors but to answer fully this becomes a mammoth task. Your 2nd comment mentions "these links" - I don't see any. \$\endgroup\$ – Andy aka Mar 13 '14 at 10:50
  • \$\begingroup\$ I see, that is all I wanted to know: this chip works with the cheapest sensors and the cheapest MCU's. TDA5051A costs about three dollars only, so this is a good option. \$\endgroup\$ – sjdh Mar 13 '14 at 10:54
  • \$\begingroup\$ @sjdh 1200bps is not too slow for you? Bear in mind that you will need to packetize data into a frame that would need to have an error checking and data repeat request functionality to ensure things are not switching on and off randomly - this is why these things can be so troublesome but it's the same for radio!! \$\endgroup\$ – Andy aka Mar 13 '14 at 11:05

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