Remote Temperature Monitoring (RF/Wireless etc?)

[LaurenceSachs]

Hello there,

Well I am a Mechanical Engineer with very limited experience with electronics and radio. So basically I have no idea where to start on this and how to go about it???? Please give me some advice, where i should look online for info etc.

I have a specific application where I have to monitor the temperature of a or several roaming (quite possibly over several hundred meters) assets in outdoor conditions like on farms. Essentially i need to be warned when the temperature spikes above/below a certain range.

So what I was thinking of was having the below:
Temperature sensor > RF/Wireless/GSM??? Transmitter >>>> Receiver > Computer/Beagle Board/Circuitry???? > Program that tracks the temperature and sends out alerts via sms/e-mail/ whatever when there is a temperature spike.


It all obviously needs to be quite environmentally hardy, and reliable of transmitting over outdoor terrain. Booster antennas may be necessary. I have seen the XBee wireless module and the Zig Bee module, what are they like?

Thank you for your input!!!

Regards
Laurence

 

[VEBill]

Radio range is the first question to be asked.

Many farms are located in areas outside GSM coverage. Not to mention having to pay $10-20 per month *per sensor* for direct network access would get boring fast.

If you just need high and/or low set points to trigger an alarm, then the simplest conceptual approach would be to think in terms of simply triggering an on-off discrete signal (as opposed to transmitting the actual temperatur value). This approach opens up a wide range of inexpensive long range on-off keyed transmitters of all sorts and types. Sending the actual temperature value over the radio link is an entirely different problem with fewer simple and cheap solutions.

 

[LaurenceSachs]

Thanks VE1BLL for the post,

Well the way I see it is that I have four areas i need to focus on.

1. Temperature sensing
2. Transmitting temperature value to base receiver
3. Monitoring/Trending the temperature of multi assets.
4. Alerting Manager of temperature spike.

I think the most challenging part is 2, what type of technology would be recommended for this, the rest can be worked around that?

Thanks again!

 

[IRstuff]

That should be the least of your problems. There are tons of RF solutionsm like:

http://www.digi.com/technology/wireless/products.jsp

You can search for "radio modem" and get lots of hits.

TTFN

FAQ731-376

 

[catserveng]

I have used equipment from B&B Electric for remote generators and engine driven pumps. Have used them for start/stop, montoring of fuel level, oil pres and water temp, etc.

Try this link,

http://bb-elec.com/product_multi_family.asp?MultiFamilyId=93&Trail=4&TrailType=Top

Hope that helps.

 

[itsmoked]

I still prefer VE1BLL's suggestion - hands down!

Do your data capture locally and only send a "temp problem" wireless signal. If you want trending data go out to these roaming whatevers and download the trend data once a month, a quarter, or a year. You would want some meager eyes-on of your data capture instruments occasionally anyway.


You aren't controlling these field temperatures over a distance and you don't need the immediacy of realtime temperature, so don't pay for it. The chances of you losing chunks of trending data is MUCH greater if you don't log it locally on each roamer. I don't know what your roaming power sources are but the energy requirements also go up dramatically for streaming data.

Also if you do the streaming method you will need a constantly running computer somewhere to log your incoming data. PCs doing that kind of job are not well suited. They need UPS's, have hard drives that fail, get messed with by people who don't realize they are doing a logging function, and cost money to leave on all the time. Just an "alert" mechanism can be much more robust and dependable.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VEBill]

And it meets the original requirement: "Essentially i need to be warned when the temperature spikes above/below a certain range."

All that's 'required' is an alarm signal. Perhaps carrying a minimal ID.

Radio range is still a variable. Budget is another.

 

[Comcokid]

If these assets are animals, you might try to contact Pet Safe, also know as RadioSys, located in Knoxville TN. In addition to making the wireless fence type devices for dogs (shock collars), they make cellular tracking collars for larger dogs and horses. These already might have temperature monitoring incorporated. I have seen police dogs wearing such devices.

However, with any company that sells to a large consumer market, penetrating the company facade in order to talk to the right person for a different application may take some doing a a lot of phone work.

 

[LaurenceSachs]

Thank you for the advice!

What about a device that works similarly to the race timing chips that are battery operated. The transponder sits on the bike/runner, and is activated by a trigger signal when it enters a range (just before the timing mat) and then when it crosses the mat, the Rf receivers pick up the activated signal.

So in my application maybe the base station can send out an activation signal every say 1 minute and then receive the recorded data via wireless/rf?

What do you think?

Thanks

 

[LaurenceSachs]

IRstuff (Aerospace)
22 Jul 09 10:13
That should be the least of your problems. There are tons of RF solutionsm like:

http://www.digi.com/technology/wireless/products.jsp

You can search for "radio modem" and get lots of hits.

Wow, I really like these products, it seems that I can build the entire system using one brand.

 

[DRWeig]

Laurence,

Just one more thought -- if you don't need to design something special, remote temperature alarms with adjustable setpoints and all the features you need are out there and available already. Contact the companies in your area who provide physical security systems (access control, intrusion dectection, CCTV, and such). They'll likely have a package that you can hook to any simple bimetal thermostat.

Good on ya,

Goober Dave

 

[LaurenceSachs]

Nice one Mate Dave,

I shall try that!!

Does anyone know of any books/websites I can get hold of that would help me understand the basics of putting a wireless system together as above?

I assume you're from Aus?

Regards
Laurence

 

[DRWeig]

Not Aussie, but close enough (Tennessee)!

Can't say I've seen any good books...

Best of luck to you,

Goober Dave

 

[biff44]

"Wireless Sensor and Actuator Networks: Technologies, Analysis and Design" Verdone, et al, is readable but good.

http://www.MaguffinMicrowave.com

Maguffin Microwave wireless design consulting