Re: [gpsd-dev] [RFC] Add support for Airmar PB200 Weather station

[Jim Thompson]

To be clear, if you're into boats, you only need one of the Airmar units and a 
boat speed sensor (GPS alone can't do it.)

They're very cool.  Hats off to Chris for this work.

Jim

On Apr 21, 2012, at 10:23 AM, Eric S. Raymond wrote:

> address@hidden <address@hidden>:
>> The Airmar PB200 [1] is a weather station to be installed on boats.
>> It has built-in GPS, accelerometer, compass, gyro, anemometer, pressure and 
>> temperature sensor. It has 2 outputs, one for NMEA0183 and one for
>> NMEA2000 (I've seen the recent addition for NMEA2000, I'm interesting
>> to make some tests and hacking around). 
>> 
>> It provides quite a lot of information and use the following NMEA sentences:
>> - Usual GPS ones
>> - TIROT, HCHDG and HCHDT for heading related data
>> - WIMWD, WIMWV, WIVWR and WIVWT for wind related data
>> - WIMDA for other meteorological data
>> - WIXDR for detailed transducer measurements/calculations
>> 
>> This is a WIP, I thought it might be worse to start the review early.
>> Things I didn't look at yet:
>> - Update other tools (xgps, gpspipe, ....)
>> - Update the testsuite(s)
>> - Update documentation
>> 
>> I naively added a wind data structure, but the WIMDA would require to
>> add yet another one (and in my case the WIXDR will bring even more
>> meteo data than the WIMDA). So maybe these two should be merged
>> together. Though, I didn't do it because there are several ways to
>> express the wind, both for the wind direction and for the wind speed
>> can be viewed from different referential frames: the moving boat, the
>> moving water or the fixed ground, and why not one of these days the
>> moving air mass (for flying things obviously).
>> 
>> It is likely that I will come one day with yet another structure:
>> engine. I would like to install my openwrt/gpsd based system on a
>> boat, and it has two engines that speak NMEA200 only (I let you
>> imagine how high I jumped off my chair when I saw the new NMEA200 code
>> coming in... ;))
> 
> I've merged the first two patches, and these patches in general look
> good - thorough, clean, and workmanlike.  I encourage you to continue.
> But as you note, there are some missing pieces.  Adding a device log
> to the regression-test suite is a requirement.  And yes, you do need
> to update the documentation.
> 
> There's a larger piece missing.  You've written JSON dumping for the
> daemon, but you also need to write the JSON parsing for the client
> side. That has to be in places before trying to modify cgps and xgps 
> to display the new data will make any sense.
> 
> I've just written a Hacking Guide section on how to add a sentence
> to the supported set.  It's a serious amount of work, and my hat is
> off to you for having deduced and done so many of the right things on
> your own.
> -- 
>               <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>
>