Re: [Xastir] extract_multipoints: invalid value in (filtered) Center of MaxConcern }d0`N M K M RAL {6JmAI: 0, -177
Lots of WFOs put out a point in the center of their CWA as the area of
max concern with the equivalent of Nothing going on here. Nothing to
see. Move along which may still give us something to look at. If
_anyone_ spots anything please send it along and I'll try to look at it.
gerry
Richard Polivka, N6NKO wrote:
In checking the SPC forecasts for the next couple of days, testing
fodder may be few and far between. Even then, stuff can still slip
through. I can put BigBox to record all day and see what I pick up in
the nets.
73 from 807,
Richard, N6NKO
Gerry Creager wrote:
I watched it for a couple of more days after it last came up and it
started calming down. I'll try to carve some time out on Monday.
What I need to identify if this is something with the latest build of
AWIPS or WarnGen being fed into the system.
gerry
Tom Russo wrote:
On Sat, Oct 06, 2007 at 02:12:09PM -0700, we recorded a
bogon-computron collision of the [EMAIL PROTECTED] flavor,
containing:
Here is the offending line:
JSJSMWAPRS,qAS,WXSVR:;JSJM1948z*062145z1851.60NM05606.00WWCenter of
MaxConcern
}d0`N#65533;M#65533;K#65533;M#65533;R#65533;L#65533;{6JmAI
The commas near the end were appearing as '?' but in black
(unprintable character?).
Is this an issue with WXSVR or with whomever JSJ is?
This is happening all over the place. I see it dozens of times a
day. The
weather services are obviously using some new program that is generating
invalid characters in the multipoints. Gerry was going to look into
it, but
got busy.
The wxsvr.net pages documenting the protocol haven't changed, but
obviously
these weather sites are generating objects with multipoints that
don't conform
to the published protocols.
--
Gerry Creager -- [EMAIL PROTECTED]
Texas Mesonet -- AATLT, Texas AM University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
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Re: [Xastir] I did something stupid?
On Sat, 6 Oct 2007, ac7yy wrote: I shutdown xastir in error and now when I restart xastir it starts brings up a partial map I was running then stops . Perhaps your config file got corrupted. Try renaming one of the backup config files in the xastir/config/ directory to xastir.cnf and then restarting. You might want to keep a backup of those config files somewhere as they'll get renumbered and the oldest one deleted each time you shut down Xastir. If you don't care about what's currently in your config file you can just delete Xastir and restart. If you're having problems with one of your maps, start Xastir with the command-line flag that causes it to start without maps. -- Curt, WE7U: www.eskimo.com/~archer/ XASTIR: www.xastir.org Lotto: A tax on people who are bad at math. -- unknown Windows: Microsoft's tax on computer illiterates. -- WE7U The world DOES revolve around me: I picked the coordinate system! ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
[Xastir] Question about APRS GPS position precision
Hi, all.. I have been told that the limiting factor in position precision is the APRS system transmission standard-- that transmissions are limited to 1/1000th of a degree or approximately +/- 60 feet. Is this true? If so, why? If not, what is the limiting element in the final display of tracker position on Xastir? For those of you using Xastir for Search Rescue, do you run on the APRS frequency or a different (quiet) frequency? What are the arguments for each school of thought? We are going to be running some field tests in the near future with a variety of equipment setups does anyone have suggestions of things we should test? We have a list, but new ideas and comments would be appreciated from those that have already taken the stumblesgrin. Many thanx.. jt -- Jim Tolbert RiverRidge Consulting, LLC PO Box 536 Webster, WI 54893 715-866-4398 home office 715-349-8993 fax [EMAIL PROTECTED] ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Question about APRS GPS position precision
Jim, Most GPS units are good to 4 decimals. Any higher precision requires post-processing or L1/L2 reception (not avail in consumer equipment). When you factor in multipath and all the other variables, 4 decimals is quite good but it takes time and patience - think searching for a geocache in a forest. Plus, at four decimals, on a patch antenna minus ground plane, it is quite unstable. Plus, I have a feeling that when Bob B. designed APRS, he was not looking at this being used for what we are doing. Until the data output is smoother and better accuracy, five decimals in - broadcast 4 - rewrite the standard, this may be the best for now. 73 from 807, Richard, N6NKO Jim Tolbert wrote: Hi, all.. I have been told that the limiting factor in position precision is the APRS system transmission standard-- that transmissions are limited to 1/1000th of a degree or approximately +/- 60 feet. Is this true? If so, why? If not, what is the limiting element in the final display of tracker position on Xastir? For those of you using Xastir for Search Rescue, do you run on the APRS frequency or a different (quiet) frequency? What are the arguments for each school of thought? We are going to be running some field tests in the near future with a variety of equipment setups does anyone have suggestions of things we should test? We have a list, but new ideas and comments would be appreciated from those that have already taken the stumblesgrin. Many thanx.. jt ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Question about APRS GPS position precision
On Sun, 7 Oct 2007, Jim Tolbert wrote: I have been told that the limiting factor in position precision is the APRS system transmission standard-- that transmissions are limited to 1/1000th of a degree or approximately +/- 60 feet. Is this true? If so, why? Mic-E format or standard APRS format, yes. In my neck of the woods it describes a box of about 60' by 40'. Xastir users can zoom way in on a station and (perhaps) see a white box. That describes the precision they are transmitting. Stations that are transmitting NMEA sentences directly that have 3 or 4 digits after the decimal will display a smaller box. So will stations that are transmitting Base-91 packets, which Xastir and OpenTrackers are capable of sending. For Base-91 it's something like a 2' by 3' box (in my area). Look at any D700/D710/D7A station to see the larger box. The box in Xastir shows where they _might_ be based on what they are transmitting, and the box is oriented in the correct direction for the truncated digits in each hemisphere. Bob Bruninga came up with yet another method of adding precision, called DAO. With this method you add some extra characters to the comment field that give you the extra precision _and_ specify the datum for the posit. Very few APRS clients have implemented DAO at this time. Bob likes it because it doesn't make the Kenwood radios obsolete I think. As I recall the Kenwoods can handle Base-91 just fine for posits, but have a problem with Base-91 Objects or maybe it was just Base-91 Items. If not, what is the limiting element in the final display of tracker position on Xastir? *) Accuracy of the GPS position of the tracker. *) Precision transmitted across the air. *) Accuracy of your base maps. *) Registration of your base maps. *) Datum of your maps vs. what you mapping software can do. *) Projection of your maps vs. what your mapping software can do. *) Accuracy of your mapping software in displaying those maps. For those of you using Xastir for Search Rescue, do you run on the APRS frequency or a different (quiet) frequency? What are the arguments for each school of thought? We are going to be running some field tests in the near future with a variety of equipment setups does anyone have suggestions of things we should test? We have a list, but new ideas and comments would be appreciated from those that have already taken the stumblesgrin. I have a lot to say on this subject but have said much of it before on the SAR_APRS list. Perhaps read up on it there and then discuss more about it there? -- Curt, WE7U: www.eskimo.com/~archer/ XASTIR: www.xastir.org Lotto: A tax on people who are bad at math. -- unknown Windows: Microsoft's tax on computer illiterates. -- WE7U The world DOES revolve around me: I picked the coordinate system! ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Openstreetmap?
On Sun, 2007-10-07 at 23:08 +0100, Dave H wrote: O.k thanks for that - I'm no geo-whatever expert - in fact most of the acronyms floated in here mean very little - i suspect to many this side of the Ocean. I am a geo-whatever expert. ;-) Most of acronyms used here are used in the Geographic Information Systems (GIS) and geo-informatics industries. It's a small, large industry in the sense that it is everywhere, yet few have heard of it. It seems to me your so lucky in the US that your public-tax-$ investments in geo-data collection - the data seems to be handed back freely back to you.. Certainly in the UK either we have no of our own or its damn-secret or we have to pay a second time. This is true that the US has been inherently blessed in the past with good quality data. This is changing at a fast (and IMO, alarming) rate. There really hasn't been truly freely available orbital data since LANDSAT-7 and the SRTM shuttle mission. Street and feature data extracted from Census data is really a byproduct of the Census, complete with varying amounts of error. This error can be easily demonstrated on this page a friend did on the subject: http://casoilresource.lawr.ucdavis.edu/drupal/node/433 I've suggested that at a minimum, OSM should include metadata specifying projection parameters, but it falls on deaf ears. It would be much better if users either uploaded data consistently (and rejected outliers) or the system reprojected upon upload. OSM may be a useful last resort for Xastir in areas where better data does not exist. Xastir in the UK is often poor looking simply due to lack of decent map sources and probably zero overlays. Either we don't have them or some buggers got copyright over things we paid for once already. We get desperate or use outlines for lack of much else. Aside from Census data, that is largely the case here in the States, too. I don't know how things of this nature function in the UK, but here we are able to request data from local municipalities. I've had no trouble getting needed data for projects that local governments have collected. Have you tried asking various levels of government for a Shapefile of roads? Try asking for street center-lines, first. They are generally high accuracy. Be specific of what you want so that you aren't creating work that they don't need to do...and they might respond to you favorably in the future. -- Brad Douglas rez touchofmadness comKB8UYR/6 Address: 37.493,-121.924 / WGS84National Map Corps #TNMC-3785 ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Question about APRS GPS position precision
Andrew Rich wrote: Yeah but in the real world, it still puts me off the road or runway. Andrew Rich VK4TEC [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] http://www.tech-software.net -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Gerry Creager Sent: Monday, 8 October 2007 6:54 AM To: Richard Polivka, N6NKO Cc: Jim Tolbert; XASTIR Subject: Re: [Xastir] Question about APRS GPS position precision Richard Polivka, N6NKO wrote: Jim, Most GPS units are good to 4 decimals. Any higher precision requires post-processing or L1/L2 reception (not avail in consumer equipment). When you factor in multipath and all the other variables, 4 decimals is quite good but it takes time and patience - think searching for a geocache in a forest. Plus, at four decimals, on a patch antenna minus ground plane, it is quite unstable. 9 cm more or less should be plenty good enough for most of our users. That's 4 decimal-place precision. That said, an L1 signal (L5 won't be available for some time still) position assuming really good geometry and a stable antenna platform is likely to be good only to ~6m horizontal and ~13.7m vertical... at best. Plus, I have a feeling that when Bob B. designed APRS, he was not looking at this being used for what we are doing. Until the data output is smoother and better accuracy, five decimals in - broadcast 4 - rewrite the standard, this may be the best for now. The limitations in precision are in rank order, the spec and the spec. For accuracy the limitations are: User equipment antenna configuration Ionosphere Troposphere Multipath GPS Signal Specification for L1 When I resolve cm accuracy, or better, I do it using dual-frequency (L1/L2) receivers, multiple stable baseline processing on ground-plane or choke-ring antennas, at a fixed and measured height about the ground, and post-process the data to include a least-squares adjustment of the position. The process is as much statistical as matrix-mathematical in accomplishment. gerry Well, worst case is I am still within shouting distance. Not bad by any means. Steve/WM5Z ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Openstreetmap?
That was pretty much my take on it, after looking yesterday and before I scurried off to kids' activities. gerry Brad Douglas wrote: On Fri, 2007-10-05 at 21:53 +0100, Dave H wrote: I've had a quick look at the archive but haven't seen any reference to OpenStreetMap - I wonder if this could be incorporated into Xastir? - sorry if its a dumb question but it seems something that would benefit both Xastir and that project ..esp if Google maps isn't playing ball. IMO, OSM is a useless kludge. There are no specs for coordinate systems, datum, etc. That means each data collector uploads data in the system they deem useful to them, which makes accuracy, by any stretch of the imagination, impossible. Just because something has coordinates doesn't mean it's useful. What's the point of using a GPS when nobody uses it consistently? I can get more reliable results using satellite imagery and a zero-crossing filter. -- Gerry Creager -- [EMAIL PROTECTED] Texas Mesonet -- AATLT, Texas AM University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Question about APRS GPS position precision
Which tells us nothing. You don't tell me the origins of your map sources, the datum, the satellite constellation, antenna occlusions, etc. All these affect how good your accuracy is for GPS positioning. Or, was this simply flame-bait? gerry Andrew Rich wrote: Yeah but in the real world, it still puts me off the road or runway. Andrew Rich VK4TEC [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] http://www.tech-software.net -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Gerry Creager Sent: Monday, 8 October 2007 6:54 AM To: Richard Polivka, N6NKO Cc: Jim Tolbert; XASTIR Subject: Re: [Xastir] Question about APRS GPS position precision Richard Polivka, N6NKO wrote: Jim, Most GPS units are good to 4 decimals. Any higher precision requires post-processing or L1/L2 reception (not avail in consumer equipment). When you factor in multipath and all the other variables, 4 decimals is quite good but it takes time and patience - think searching for a geocache in a forest. Plus, at four decimals, on a patch antenna minus ground plane, it is quite unstable. 9 cm more or less should be plenty good enough for most of our users. That's 4 decimal-place precision. That said, an L1 signal (L5 won't be available for some time still) position assuming really good geometry and a stable antenna platform is likely to be good only to ~6m horizontal and ~13.7m vertical... at best. Plus, I have a feeling that when Bob B. designed APRS, he was not looking at this being used for what we are doing. Until the data output is smoother and better accuracy, five decimals in - broadcast 4 - rewrite the standard, this may be the best for now. The limitations in precision are in rank order, the spec and the spec. For accuracy the limitations are: User equipment antenna configuration Ionosphere Troposphere Multipath GPS Signal Specification for L1 When I resolve cm accuracy, or better, I do it using dual-frequency (L1/L2) receivers, multiple stable baseline processing on ground-plane or choke-ring antennas, at a fixed and measured height about the ground, and post-process the data to include a least-squares adjustment of the position. The process is as much statistical as matrix-mathematical in accomplishment. gerry Jim Tolbert wrote: Hi, all.. I have been told that the limiting factor in position precision is the APRS system transmission standard-- that transmissions are limited to 1/1000th of a degree or approximately +/- 60 feet. Is this true? If so, why? If not, what is the limiting element in the final display of tracker position on Xastir? For those of you using Xastir for Search Rescue, do you run on the APRS frequency or a different (quiet) frequency? What are the arguments for each school of thought? We are going to be running some field tests in the near future with a variety of equipment setups does anyone have suggestions of things we should test? We have a list, but new ideas and comments would be appreciated from those that have already taken the stumblesgrin. Many thanx.. jt ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir -- Gerry Creager -- [EMAIL PROTECTED] Texas Mesonet -- AATLT, Texas AM University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir -- Gerry Creager -- [EMAIL PROTECTED] Texas Mesonet -- AATLT, Texas AM University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Openstreetmap?
A couple of points... Brad Douglas wrote: On Sun, 2007-10-07 at 23:08 +0100, Dave H wrote: O.k thanks for that - I'm no geo-whatever expert - in fact most of the acronyms floated in here mean very little - i suspect to many this side of the Ocean. I am a geo-whatever expert. ;-) Most of acronyms used here are used in the Geographic Information Systems (GIS) and geo-informatics industries. It's a small, large industry in the sense that it is everywhere, yet few have heard of it. Glad to have you. I do a little in the industry, too, with the technical committee of the Open Geospatial Consortium. I'm currently active on the Defense-Intelligence working group and Sensor Web Enablement. I'm also working with the somewhat fractious Coordinate Transformations ad hoc group, which I think will achieve a working group status in December. It seems to me your so lucky in the US that your public-tax-$ investments in geo-data collection - the data seems to be handed back freely back to you.. Certainly in the UK either we have no of our own or its damn-secret or we have to pay a second time. This is true that the US has been inherently blessed in the past with good quality data. This is changing at a fast (and IMO, alarming) rate. There really hasn't been truly freely available orbital data since LANDSAT-7 and the SRTM shuttle mission. Depends on your sources. Data here in Texas are good, free, and readily available. Street and feature data extracted from Census data is really a byproduct of the Census, complete with varying amounts of error. This error can be easily demonstrated on this page a friend did on the subject: http://casoilresource.lawr.ucdavis.edu/drupal/node/433 Nice site. Had not seen that before, but it's interesting. Unfortunately, Census, who uses the old DRG/STDS mapping info from USGS, also munges the data for their purposes. I really wish they'd not made their data widely available and so discoverable since they don't maintain good (or adequate or even minimal real) metadata. Unfortunately, a simple affine isn't always satisfactory, nor is the affine transform matrix consistent for more than a small area (with small being somewhat relative). Wish it was true but to correct all of Tiger, you'd not only have to do all the county offerings, but actually would end up subsetting some and doing unique transformations to get them all right. I've suggested that at a minimum, OSM should include metadata specifying projection parameters, but it falls on deaf ears. It would be much better if users either uploaded data consistently (and rejected outliers) or the system reprojected upon upload. I'd be able to come up with a minimum metadata list, but I fear I'd hit the same response as you already have. At a minimum I'd love to know what datum is being used and then transform to a common datum, ITRF2000 or WGS84 (2005). OSM may be a useful last resort for Xastir in areas where better data does not exist. Unless you're thinking you'd get better data in Europe with OSM than you can find now, OSM looks too sparse to be of a lot of use, anyway. Xastir in the UK is often poor looking simply due to lack of decent map sources and probably zero overlays. Either we don't have them or some buggers got copyright over things we paid for once already. We get desperate or use outlines for lack of much else. Aside from Census data, that is largely the case here in the States, too. Ordinance Survey tell me (and I asked specifically about this at the summer OGC meeting) they are working on a policy statement and fee structure to provide data of this sort to certain users at solely cost recovery. Should happen this calendar year. And radio amateurs are now added to the list. I confirmed this 2 weeks ago at the Fall OGC meeting. I don't know how things of this nature function in the UK, but here we are able to request data from local municipalities. I've had no trouble getting needed data for projects that local governments have collected. Have you tried asking various levels of government for a Shapefile of roads? Try asking for street center-lines, first. They are generally high accuracy. Be specific of what you want so that you aren't creating work that they don't need to do...and they might respond to you favorably in the future. Lots of municipalities here and over on the other side of the pond have a fee-recovery system. Sometimes I can get their data by asking, sometimes by paying, and sometimes I have to use other means, like going to their state or the Feds. I expect you'd see the same thing in UK. gerry -- Gerry Creager -- [EMAIL PROTECTED] Texas Mesonet -- AATLT, Texas AM University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 ___ Xastir mailing list Xastir@xastir.org
