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[wxsig] Newbie question

William Beals will at beals5.com
Fri Mar 2 05:29:12 UTC 2007


The modulation requirements in terms of signal purity and frequency accuracy
are pretty stringent.  For the T238+ and a lot of the other APRS
projects--including PIC ones, the MX614 chip is a nice solution to implement
the modulation/demodulation.  I have a long term science project where I'd
like to implement it digitally with an FPGA, but nothing more than thinking
about it so far.

The T238s value is really taking the raw data (counts for wind speed, A/D
values for temperature) from the 1-wire sensors and converting them to
human-readable units and formatting them for APRS.  The T238+ added the
modem functions, saving a TNC.  If you get a commercial weather station that
puts out data already in serial format and human-readable form such as one
of the Peet units, then you could get a kit such as the TinyTrack, PicE, or
several others that accept serial data and send it out APRS.  Since you are
PIC expert, I suspect modifying its code for your purposes may not be too
bad.  I'm not sure on cost of the two solutions relative to eachother.  I
think the T238+ might be better.

Lots of options! :)


-----Original Message-----
From: wxsig-bounces at lists.tapr.org [mailto:wxsig-bounces at lists.tapr.org] On
Behalf Of Jim Gurley
Sent: Thursday, March 01, 2007 10:14 PM
To: TAPR Weather Station SIG Mailing List
Subject: RE: [wxsig] Newbie question

Thanks!  Good pickup! The buoy is one of your typical channel markers.
Probably 10 feet above the water, must weigh a few tons.  It's short term
stable, but might twist a little - maybe I need to add a flux gate compass.
I think they've gotten pretty inexpensive, but I'm not sure.

If I'm using an FRS radio (or the HTX202), can't I do the modem work with
the PIC controller and skip the T238+ ?

At 08:39 PM 3/1/2007, you wrote:
>To see if it makes sense, the T238+ information is at 
>http://www.beals5.com/wx.  All you should need is the AAG sensor, the 
>T238+, and a radio as mentioned below.  The T238 takes the raw pulses 
>and A/D values from the sensors, converts it to human-understandable 
>units, and does the modem function.  I do have some extra provisioning 
>in the T238 specifically for solar controllers, namely a control line 
>to turn the radio off except for the actual transmission of the weather 
>data.  It is based on a 6808 instead of a PIC, but all the source code 
>is posted as well if you want/care to make mods.
>Out of curiosity, is the bouy always pointed in the same direction somehow?
>If not, wind direction is going to be really squirly!
>-----Original Message-----
>From: wxsig-bounces at lists.tapr.org 
>[mailto:wxsig-bounces at lists.tapr.org] On Behalf Of wn0x at earthlink.net
>Sent: Thursday, March 01, 2007 8:37 PM
>To: Jim Gurley; TAPR Weather Station SIG Mailing List
>Subject: RE: [wxsig] Newbie question
>I think you will need a radio in both cases.  The old Realistic HTX202 
>are cheap, run off of twelve volts and have standard connectors for 
>power and audio.  The nice thing about handy talkies in general is that 
>they are designed to run on 12 volts or less, work with compromise 
>antenna systems and are relatively inexpensive.
>The T238+ will obviate the need to perform any additional processing on 
>the data from the weather station.  It performs the data collection, 
>averaging and modem functions and will report in standard APRS format.
>There is a modification to turn on the radio a few seconds before you 
>need to transmit, which would save battery power.
>You could also remove the backlighting on the LCD to save additional 
>power, but I think the T238 will even run without the display.
>A down side is that the basic weather station from AAG is wind speed, 
>wind direction and temperature only, they are only $88 bucks though.  I 
>am not sure how they would hold up in a salty wet environment.  Other 
>sensors are available as needed.
>You might consider a small solar controller like the MicroM+ 
>http://www.theheathkitshop.com/microm.html to charge your batteries. 
>This unit draws very little power and will not discharge your batteries 
>I am working on a similar project for land-based remote weather and 
>really like the T238 as an option.
>To be fair, there are also PIC based projects like the OpenTracker that 
>will perform a similar function to the T238+ and also supports Peet 
>weather stations.  I believe the Byonics WxTrack is a pic based unit 
>that supports Radio Shack WX200, the Oregon Scientific WM-918, and the 
>Peet Brothers Ultimeter 100, Ultimeter 800, Ultimeter 2000, and Ultimeter
>This may be an option for you as well.
>-----Original Message-----
> >From: Jim Gurley <jimg at cavenet.com>
> >Sent: Mar 1, 2007 5:38 PM
> >To: wn0x at earthlink.net, TAPR Weather Station SIG Mailing List 
> ><wxsig at lists.tapr.org>
> >Subject: RE: [wxsig] Newbie question
> >
> >My impression is the T238+ is just the modem.  I then need to add 
> >radio,
> >If I wasn't sure this package is going to be swept off the buoy 
> >during the odd gale...
> >
> >
> >At 02:29 PM 3/1/2007, you wrote:
> >>Any reason you wouldn't consider a 1-wire setup with T238+?
> >>
> >>Sounds like it has almost everything you need and be much simpler 
> >>and cheaper to implement.
> >>
> >>Rich
> >>
> >>-----Original Message-----
> >> >From: "Daron J. Wilson" <daron at wilson.org>
> >> >Sent: Mar 1, 2007 2:55 PM
> >> >To: 'TAPR Weather Station SIG Mailing List' <wxsig at lists.tapr.org>
> >> >Subject: RE: [wxsig] Newbie question
> >> >
> >> >> Our local sailing club would really like to know the wind 
> >> >> speed/direction at a spot offshore.  NOAA doesn't have the 
> >> >> budget to install a real weather buoy, so  it's up to me (us).  
> >> >> We think the USCG will allow us to place an instrument package 
> >> >> on a navigation buoy in the area of interest, although 
> >> >> installing it will
>be a good trick!
> >> >>
> >> >> Needs:
> >> >> 1) Wind speed/direction required
> >> >> 2) Able to communicate with base station about 1.8 miles away 
> >> >> (good line of sight).
> >> >> 3) Solar panel operated. (Night time observations not important, 
> >> >> so maybe no or very small battery?).
> >> >> 4) Marine environment (non freezing, but salt water and frequent 
> >> >> gale
> >> >> conditions)
> >> >> 5) Low cost, since the USCG has a hard time just keeping the 
> >> >> buoy in place, and it will probably be lost more than once.
> >> >>
> >> >> The Dallas Wind sensor seems like a reasonable input device, 
> >> >> although sufficient accuracy might be possible with a wand with 
> >> >> strain gauges.  I'm a competent PIC programmer, so that wouldn't 
> >> >> be too challenging.  The 1.8 miles is the gotcha for me.  There 
> >> >> are no available locations for repeaters, so I'm thinking it 
> >> >> will have to be either a packet radio or possibly a cobbled-up 
> >> >> FRS type personal walkie talkie.
> >> >>
> >> >> Any suggestions?
> >> >
> >> >I think a fiberglass watertight enclosure (Hoffman or similar) 
> >> >would be where I would start.  Inside there I'd try to fit a low 
> >> >power VHF radio, Kantronics KPC3+ TNC and possibly a Peet Bros 
> >> >Ultimeter 100
>weather station.
> >> >Our APRS weather stations
> >> >http://www.ocrg.org/telemetry_feed/ocrgwx.html use commercial 
> >> >mobile radios for more power, the KPC3+ which has been modified 
> >> >for our telemetry needs, our custom made telemetry adapter which 
> >> >gets a digital input and a couple analog inputs, and a device we 
> >> >make called the WeatherDOG which takes the Peet data stream and 
> >> >'massages' it with a PIC before sending it to the TNC.  This is 
> >> >done primarily to make the weather data standards compliant so it 
> >> >will show up on the Kenwood APRS radio displays (mobile and 
> >> >portable), but secondly we have an option in the WeatherDOG that 
> >> >allows the data to be 'human readable' and spits out the weather 
> >> >data in a UI
>packet with it in clear test format so you could easily parse it or 
>just read it on a computer screen.
> >> >
> >> >Many ways to do this of course, power will certainly be your 
> >> >challenge.  I'd use some photo sensor to shut the thing off at 
> >> >night if you want to conserver battery, using a couple of gel 
> >> >cells and a small solar panel for maintenance.  If all you really 
> >> >want is wind speed and direction, I guess you could take the 
> >> >output of the anemometer and feed it into the PIC, write a bunch 
> >> >of code, and get what
>you want.
> >> >
> >> >Another off the shelf option (more power required) would be the 
> >> >CAT200 repeater controller with the computer interface, connects 
> >> >directly to the Peet weather station and a two way radio, simple 
> >> >DTMF query to the radio and the synthesized voice could read back 
> >> >the
>wind speed and direction for you.
> >> >
> >> >Sounds fun, good luck on the installation!
> >> >
> >> >73
> >> >
> >> >N7HQR
> >> >
> >> >
> >> >_______________________________________________
> >> >wxsig mailing list
> >> >wxsig at lists.tapr.org
> >> >https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
> >>
> >>
> >>_______________________________________________
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> >>wxsig at lists.tapr.org
> >>https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
> >
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