This is getting, confusing, complex and interesting!

In the same line as the Omega hint, and in the same cole palmer
catalog, I saw a Digi-sense Digital Handheld thermistor thermometer,
which has range of -40 to +125 Degree C and claims accuracy of +- 0.2
Degree C. Also offers an optional probe. Now is there any fine print
here?

It appears to me till now, that the process of measuring "true"
temeperature is more complex than measuring temperature of the sensor
accurately?
I mean this friend person just wants to go outdoors (with the sun
shining and all) and go to a spot (a longitude/latitude that he
identified from his satellite thermal IR image) and take/sample the
temeperature there. and then he wishes to relate the satellite thermal
imagery with the on-ground samples that he thus takes, and come to some
conclusion about this urban heat phenomenon..and sometimes he cannot go
INTO dense vegetation, or a brick kiln, so he infers the temeprature at
THAT site by pointing the IR thermometer at it.

so what I mean is, Can he use this 30$ Digi-sense thermometer at the
site and just take a sample and note it and claim that AT THAT POINT ON
EARTH AT THAT TIME the temperature was X degree C +- 0.2 deg C? or it
just dosen't work like this?

But I shall, at least in my spare time and slowly, wish to interface
and calibrate the sensor, because he takes PDA computer, and it has a
RS 232 port, and I'd love it if he just pressed a button and the
temperature was directly logged with the time and the GPS position (yes
the GPS is fairly inaccurate!)

It also occurs to me that I need to better understand this
"temeprature" term!

Many thanks,
Suraj

P.S. As a bonus, I experimented with my digital camera and used my TV
remote to illumate a target, and gave a 5 second manual exposure and
the image came rather decently bright! this leads me to making a BIG IR
torch and do some "stealth" photography!




wrote:
In sci.electronics.design wrote:
It would be best if I can get cheap sensor(s) which I can interface
myself (to the PC), but worst comes I can buy one/seperate standalone
devices which preferable have some sort of computer connectivity and
some memory.

Look at Omega, http://www.omega.com . They have stuff in all kinds of
accuracies and price ranges; some of it is expensive, but it's handy if
you have a credit card and want it tomorrow. You might use their prices
to set an upper bound on how much you should spend trying to do it
yourself. Or, you might find that it's cheaper to buy than build. For
instance, for US$150 (HH12A + CAL-3-HH), you can fulfill 1) and 2) at
a basic level with NIST-traceable 0.1 C resolution (but read the spec
sheet).

Standard disclaimers apply; I don't get money from Omega.

Matt Roberds