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Re: [gpsd-users] Is gpsd supposed to be filtering NMEA sentences it does

From: Ed W
Subject: Re: [gpsd-users] Is gpsd supposed to be filtering NMEA sentences it doesn't understand?
Date: Wed, 04 Feb 2015 14:54:15 +0000
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On 04/02/2015 13:40, Eric S. Raymond wrote:
Ed W <address@hidden>:
I'm using GPSD 3.10.  I'm feeding it data from an airmar 200WX combined
wind/temp/pressure/everything sensor.  The raw serial port output includes
such sentences as:


However, these don't emerge from gpsd (using gpspipe -[rR])

- Is this deliberate?
The packet getter discards these packets because the prefix YX is not in the
list of known NMEA talker IDs:

I'm not sure where your referenced list comes from? The gpsd web page lists "$YX" as being the talker id for "transducer"

Assuming your list is from the source itself, would it be sensible to sync the source with the list of known talker ids on the web page?

2. GPSD's job is not to reveal NMEA quirks, it's to hide them.  Those sentences
are a case in point; obviously XDR ought to be translated to a JSON ATT report.

Actually, be careful. The XDR seems to be a general purpose way to provide transducer data and appears to be the direction NMEA are suggesting vendors should implement certain sensor readings. eg I note several older sentences deprecated and referred to using XDR messages

The XDR format is described on the gpsd web page (, but real examples seem to use multiple quadruplets to describe various sensor readings. The standard doesn't appear to enforce any special relationship or ordering on the quadruplets.

See the referenced PDFs below to see that various sensor data is returned by the 200WX, more than just attitude, eg temp (but that instrument has quite comprehensive attitude sentences - if you want a really full test then those docs would show good examples of all the sentences likely in the field)

The right question for you to be asking would be "Can we add YXXDR to the
set of accepted and parsed sentences?"  Possibly.  Full documentation, please.

Yes please. Actually, from what you answered already, it seems I should request "Can we please add $YX and optionally other missing talker ids from to the list of valid talker ids in gpsd"?

Further documentation to show this isn't theoretical is the docs for the PB100 on the airmar website:
Also for interest I found a document for the (unreleased?) 300WX here:
The later document is perhaps worth saving if you have an Airmar/Furuno instrument since it covers the extra data offered by the 150/200WX which I haven't found documented anywhere else?

At least extending the talker ids to cover the $YX seems reasonable. I will ask others to chime in on whether other talker ids are sensible to add also?

Thanks for your consideration

Ed W

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