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[aprssig] FindU Telemetry page - Help needed

Mark Cheavens mcheavens at usa.net
Fri Oct 10 20:52:05 UTC 2008


Steve,
Thank you very much for the refresher course in Algebra!

For those interested,
Here is the solution: (In the form of the needed link!)
http://www1.findu.com/cgi-bin/tele1.cgi?call=PURG&last=96&param=1&b=3.52944&c=-443.02&label=Purg_Repeater_Cabinet_Temp&units=Temperature_F&autorange=1

Now to ship it North for the "rest of the crew" to go and install it! 
(I a stuck WORKING in Houston!)

Mark
KC5EVE
At 03:02 PM 10/10/2008, you wrote:
>Let me guess, you learned using the new math... if it doesn't involve
>apples or trains heading in opposite directions, you are lost ;-)
>
>First, this is also a linear system, which means that the a is zero.
>For a given change in the telemetered value, the measured parameter
>changed the same amount, whether the parameter change is from 99 to
>100 or 1 to 2.
>
>Given it is linear, the formula is bx + c
>
>You are right, the problem is easier without converting to F, so let's
>do it in C first.
>
>The way you wrote it is (with an extra set of parens added for clarity)
>
>((tele + 4.7) * 1.9608 ) - 273.15
>
>it is just algebra to put this in the form bx + c
>
>distribute the multiplication
>
>((tele x 1.9608) + (4.7 * 1.9608 )) - 273.15
>
>4.7 * 1.9608 is 9.215, add this to the other constant -273.15
>
>that makes the centigrade formula 1.9608 x + (-263.9)
>
>b = 1.9608 c = -263.9
>
>solving for x = 148 gives 26.3 degrees C, a reasonable room temp
>
>so you want F?
>
>F = (C * (9/5) ) + 32
>
>We know C is 1.9608x - 263.9 and 9/5 is 1.8
>
>F = ((1.9608x - 263.9) * 1.8) + 32
>
>Just like above, you distribute the 1.8, and add the two constants to
>get the b and c. This is left as an exercise for the reader. ;-)
>
>Steve K4HG
>
>On Oct 10, 2008, at 3:25 PM, Mark Cheavens wrote:
>
> > I am trying to work with the telemetry page on FindU. I have a
> > telemetry value that requires the attached math to make it display
> > the way I want. I haven't figured out how to make the math work to
> > get it to display correctly. Any help would be appreciated.
> >
> > Sample URL:
> > 
> http://www1.findu.com/cgi-bin/tele1.cgi?call=PURG&last=96&param=1&b=1.0&label=Purg_Repeater_Cabinet_Temp&units=Temperature&autorange=1
> >
> > I am reading telemetry parameter 1.
> >
> > I need to take the value (Currently sitting on my bench in an air
> > conditioned room!) with a value of 148
> >
> > I would LIKE to have the value in Degrees F (I know that C would be
> > easier).....
> >
> > So here is the formula:
> >
> > ((Telemetry + Correction Factor) X 1.9608 Sensor Multiplier - 273.15)
> > * 5 / 9 - 32 = F
> >
> > For this install the correction factor is 4.7.
> > 1.9608 is the sensor multiplier (Constant)
> > The rest if just the basic math...
> >
> > OR ((148-4.7)*1.9608-273.15)*9/5+32=TempF
> >
> > I don't understand how the a= b= and c= can get me there!
> > http://www.findu.com/cgi.html#tele1
> >
> > Any help would be appreciated!
> >
> > (I have figured out the easy linear ones in the past - Like this same
> > one for voltage -
> > 
> http://www1.findu.com/cgi-bin/tele1.cgi?call=PURG&last=96&param=2&b=.072254&label=Purg_Batt_Voltage&units=volts&autorange=1
> >
> > (FYI - This is the output of an OpenTracker+ being used in an outdoor
> > solar only radio site (Emergency Clinic) to record interior
> > temperature for the batteries and battery voltage. - I do have it on
> > the status line, but I don't like the resolution, and would like to
> > plot it like I have done for the voltage) http://map.findu.com/purg
> >
> >
> > Mark
> > KC5EVE
> >
> >
> >
> > _______________________________________________
> > aprssig mailing list
> > aprssig at lists.tapr.org
> > https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> >
>
>
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