Author Topic: CWOP Location for Meteobridge Now More Precise & All about CWOP Fake LORAN  (Read 1188 times)

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Offline galfert

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UPDATE: CWOP claims to use LORAN I but recently discovered that it isn't really LORAN. So every time you read LORAN in this post just change it to say Fake LORAN
But be sure to jump down to read about CWOP Fake LORAN even if this first topic doesn't interest you. https://www.wxforum.net/index.php?topic=35144.msg359840#msg359840

I discovered a bug in the way the Meteobridge converts Decimal Degrees to the format that CWOP requires (LORAN) [UPDATE: Fake LORAN, or just call its real name DM.m]. I've reported the bug to Boris and he let me examine that part of the code and I found the error and submitted a fix.  He has confirmed. Next update should fix this.

So if you own a Meteobridge and you report to CWOP your location will soon get more precise. You won't need to do anything except reboot your Meteobridge and let it load the latest version (it isn't out yet UPDATE: now available). The fix will change the LORAN [UPDATE: DM.m] location to slightly different numbers for some of you. You don't need to report anything to CWOP. Your Gladstonefamily location will not change. Only your FindU (APRS) location will change if you were affected.

You will automatically notice this fix in a few places like this:
- Your Raw data APRS packets will reflect new coordinates
- Your FindU.com Position map
- https://aprs.fi  map

This fix does not affect everyone because of the way the rounding was being done before. If you happened to luck out before and your decimal degree seconds needed to be rounded down then there was no error in location. But if you fell into the category where the decimal degrees seconds needed to be rounded up it was erroneously rounding down decimal degree seconds. This could have affected Latitude and Longitude. For example if you lived in the Northern hemisphere on West side of the Earth (like in the US or Canada) then you may have noticed your location to be a bit too far South and and/or too far East.

The LORAN coordinate system that CWOP uses is not as precise as Decimal Degrees. It also isn't as precise as Degree, Minutes, Seconds if decimal seconds are not used. The LORAN coordinate system is basically a hybrid reformatted Degrees, Minutes, Seconds with the seconds rounded off and converted to decimal. [UPDATE: Prior sentences were derived from having been misled that CWOP was claiming to use LORAN and it wasn't] Because of the format that is used by APRS it is normal to see a discrepancy in the location of around 60 feet UPDATE: they are only using 2 decimal places, if they add more digits the precision increases. But if you had a Meteobridge the discrepancy with the rounding error bug was more like 150 Feet. This was enough to put your station in your neighbors yard or across the street. So this fix should resolve some aggravation for some people.

CWOP uses this coordinate system because it uses the APRS protocol that has been in place long before it was used on the Internet and it was used by ham radio operators. So CWOP has to adhere to how the APRS protocol works. UPDATE: And there is nothing wrong or bad about it. It could be a bit more precise by adding a third decimal place is all.

If you upload to CWOP with some other software you may want to check that your LORAN UPDATE: "Fake LORAN" location posted on Gladstonefamily.net matches your Raw APRS Data packets. That is of course if the location registered with Gladstonefamily.net matches what you have configured in your software. If you notice a problem there is a chance that your software also has the same bug in their conversion formula.
« Last Edit: October 01, 2018, 05:12:10 PM by galfert »
WS-2000 & WS-2902A | ObserverIP | WeatherBridge (Meteobridge) | Ecowitt GW1000
WU: KFLWINTE111  |  PWSweather: KFLWINTE111
CWOP: FW3708  |  AWEKAS: 14814
Windy: pws-f075acbe
Tele-Pole flag pole is here (not installed yet)

Offline Mattk

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Instead of making things backward compatible with systems like LORAN one would have thought CWOP would be better off updating their out dated 60's technology?   

Offline galfert

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UPDATE: CWOP doesn't use LORAN ...even though they claim it is LORAN. It is just Degrees Minutes with decimal minute digits to add precision (sort of like seconds)

CWOP didn't really have a choice. The objective was about making it be backward compatible with what APRS uses. [UPDATE: Then they erroneously called it LORAN]. CWOP realized at its inception that there was a system already in place that ham radio operators were using and that was tied into NOAA MADIS. All CWOP did is integrate into an existing system (APRS). If CWOP wanted to do their own separate thing it would have required new partnerships with NOAA MADIS. And it would have required the invention of a new protocol. That would have been a much much bigger thing to have conquered. And NOAA would probably not have given CWOP the time of day for that effort at its inception. [UPDATE: These last few sentences were in response to being misled by CWOP thinking they were using LORAN] Realize that at first CWOP didn't use separate upload servers than ham radio operators. They were sharing them (but they really belonged to the ham radio people). In a short time (a few years) CWOP grew more rapidly than anyone expected. The amount of bandwidth that CWOP stations were using became many times over compared to the ham radio operators. This upset the ham radio community and CWOP had to set up their own separate servers. Again at this point the focus was to stay on the existing APRS network. Today though CWOP is so large that they could have the weight to reach out to NOAA MADIS and invent or use a new protocol [UPDATE: No need for new protocol as they aren't using LORAN. If more precision is desired all that is required is to add another decimal digit to APRS protocol]. But there is some benefit to be tied into with APRS and ham radio operators. CWOP is a volunteer network with hardly any revenue. The resources to do anything about this are not there. Just look at the web servers that they are running with decade old web server software.

CWOP is running on old outdated server software:
https://www.wxforum.net/index.php?topic=35142.msg359412#msg359412

CWOP is very different from any other weather reporting network. CWOP is just a small part of many different systems run by different organizations. It grew (or rather came to be) from the expansion of existing systems.

« Last Edit: February 01, 2019, 07:20:06 PM by galfert »
WS-2000 & WS-2902A | ObserverIP | WeatherBridge (Meteobridge) | Ecowitt GW1000
WU: KFLWINTE111  |  PWSweather: KFLWINTE111
CWOP: FW3708  |  AWEKAS: 14814
Windy: pws-f075acbe
Tele-Pole flag pole is here (not installed yet)

Offline galfert

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The update for the Meteobridge is out. Reboot your Meteobridges people! Go to the http://aprs.fi map and watch your station jump. I've never seen a WX station move before...it showed it move on the map with a pink line just like all those other moving things you can track on the APRS network. I'm sure that pink line will disappear soon. UPDATE: The pink line was only there for a short while like maybe 30 minutes...not sure exactly.

Very happy that finally my APRS network location is finally showing more precise and not across the street.

 [ You are not allowed to view attachments ]
The APRS network temporarily added that pink line showing the move.
« Last Edit: October 01, 2018, 11:38:06 AM by galfert »
WS-2000 & WS-2902A | ObserverIP | WeatherBridge (Meteobridge) | Ecowitt GW1000
WU: KFLWINTE111  |  PWSweather: KFLWINTE111
CWOP: FW3708  |  AWEKAS: 14814
Windy: pws-f075acbe
Tele-Pole flag pole is here (not installed yet)

Offline Mattk

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Well since LORAN is still linked to out dated weather systems then I thought I would put up the best ever thing that happened to LORAN in these modern times :) Yes I know there are some still kicking and screaming about the demise of LORAN but now other countries have also toned back upgrade plans. But LORAN can claim one distinction especially in the case of the Port Clarence, Alaska tower, the largest man made structure ever to be brought down using explosives, all 400 ton of it which was 1357 feet high, well it used to be 1357 feet high   

 https://www.youtube.com/watch?v=Cu-DFU7Xwq8
 

Offline galfert

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Re: CWOP Location for Meteobridge Now More Precise & All about CWOP Fake LORAN
« Reply #5 on: September 30, 2018, 10:53:11 PM »
THE BIG REVEAL - CWOP IS NOT USING LORAN !!!

I've since learned that LORAN and its many versions is not really what CWOP uses. I'm not sure why they (CWOP and Gladstone) call it LORAN. It is just Degrees Minutes.decimal minutes (without radial seconds), so it is called just Degree Minutes decimal minutes (although with added precision because of the decimal). The partial minutes portion is just expressed in decimal notation.  The CWOP format is also referred to as DM.m in many converters. The interesting part is that the DM portion is in Degrees and Minutes as in the same as the beginning of DMS. But everything after the decimal is base 10, meaning 0 to 9 are hence the use of the "decimal" point.  Which means that CWOP or rather APRS could be more precise if they upgraded to accept three decimal places or more. That would increase the precision just like we increase the precision with regular Decimal notation by just adding more digits after the decimal point. This also means that Degrees, Minutes and Seconds notation can also have decimal seconds to increase precision. Or you can add deciseconds (1/10 of a second) or centiseconds (1/100 of a second) and increase the precision of D M S as it becomes DMS + something more which I don't know the proper notation for or if it even really exists as a standard, but it could.

Also interesting about APRS is that they put the Degrees and Minutes together without a space between them. So rather than write DD° MM' they just write DDMM and then add the decimal minutes (the portion that is less than one minute sort of like seconds but expressed in base 10) which turns the whole thing into DDMM.mm but it is really expressed to be DM.m with two places for each variable. (or sometimes DDDMM.mm if needed).

If that hurt your head here is a cheat sheet:

List of Latitude Longitude formats:
Decimal = D.d  (everything after the decimal is the minutes and the seconds combined)
Degrees Minutes Seconds = DMS (here the degrees, minutes, and seconds are separated)
Degrees Minutes (with Decimal Minutes - not common) = What CWOP incorrectly calls LORAN = DM.m (everything after the minutes is just seconds in decimal notation)

...and you can add precision to any of these by adding more digits after the decimal point to any of these (or by adding a decimal point if it isn't there and then adding digits.)
...and you can also create a new category after DMS to continue the non-decimal notation and call it something like Deci or Centi or Milli - seconds.

So we could invent:
DMST (I made the T up)...to be a new group T that could separate the deciseconds or centiseconds or milliseconds or nanoseconds...etc...depending on how many digits we dedicate to the new group.

Real LORAN is so different and requires lookup tables and is much more complicated. I think its complicated, so much that I couldn't find a good source to really understand it well...yet....maybe I need to spend more time with it...but why? I don't need it...and nothing I have uses it. And it has been abandoned by just about everyone. Sort of like half pennies...nobody uses them.

So yes LORAN and later LORAN-C is antiquated ...but it isn't what CWOP uses even though they call it LORAN. And between the different formats (excluding real LORAN) none is more precise than the others if you take it far enough with enough digits and there is no limit. The conversion between the formats I listed is easy. The conversion to/from real LORAN...well forget it...we don't need that.

« Last Edit: February 01, 2019, 07:31:05 PM by galfert »
WS-2000 & WS-2902A | ObserverIP | WeatherBridge (Meteobridge) | Ecowitt GW1000
WU: KFLWINTE111  |  PWSweather: KFLWINTE111
CWOP: FW3708  |  AWEKAS: 14814
Windy: pws-f075acbe
Tele-Pole flag pole is here (not installed yet)

Offline Mattk

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Conversion from real Loran has no real mathematical solution but does produce an unreliable solution and can be improved knowing local area offsets. Loran (absolute) accuracy is extremely poor considering what Global Navigation Satellite Systems (GNSS) can provide today. Loran repeatability was reasonably good and the only real way to convert from Loran positions to more recognizable latitude/Longitude is to locate the point using a Loran then recording the position using GNSS/GPS but now there is no Loran then it's time to move on. Why CWOP call the position they use Loran has probably something to do with not understanding the format they are using.

Just to clarify some of the above comments regard typical latitude/Longitude formats commonly used and the wording that should be applied.

dDD MM.mmm would be the most commonly used format in the world today especially with aviation and maritime and which is in line with defacto standards based on NMEA (as used to interface navigation equipment). The reference here is Degrees Minutes & Decimal minutes (seconds should have no mention at all). Typical # decimal minutes is 3 providing an precision of less than 2.8 metres (~ 9 feet) and which can be typically achieved with GNSS/GPS. dDD MM.mmm is also directly usable with navigation charts based on the general value of 1 minute being 1 NM. Just don't confuse Accuracy & Precision, quite different things.

dDD MM SS.sss is more used for land based activities such as high precision surveying. Degrees, Minutes, Seconds and decimal seconds and typically a minimum of 4-5 decimal seconds provides and absolute accuracy of a few millimetres Deci, milli seconds don't come into position at all, those are more to do with time.

dDD.dddddd is simply degrees and decimal degrees and used quite a lot in weather type reports

For computer type applications, data transfer etc then most of the formats follow HP notation dDD.dddddd, dDDmm.mmm & dDDMMSS.sss etc

For non computer display then one must always use the symbols °, ' & " so as to eliminate and confusion with the intended format and if the hemisphere could be confused then also use the N, S, E & W designators or + & -

Mind you Latitude & Longitude is nothing more than a world wide coordinate system that mere mortals can recognize and understand, behind this sits Cartesian ECXYZ which is where all the maths is handled and something that make absolutely no sense to mere mortals.   

And yes accuracy/precision has nothing to do with the format, it's more about the application the position is be used for. But this isn't the end of it as any Latitude/Longitude position is rather useless without a datum as the same physical position on earth can have very different Latitude/Longitude coordinates in different datum, same in reverse the same latitude/Longitude coordinates can be a totally different location depending on the datum. Incorrect datum can make a far bigger impact on physical location than using the wrong format, lots of variables and factors with this one.

The good thing about LORAN is it went ..... Poof and the towers all fell down :)             

Offline galfert

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Mattk,
Thank you for the added commentary and clarifications.

Now can anyone get through to Steve Demise or Philip Gladstone and fix this Fake LORAN business? I haven't been successful in reaching out to them lately....no response.

It is really confusing to new people joining CWOP to see LORAN mentioned. I know it was for me. It took me down the LORAN rabbit hole and I didn't get it at first, as I wasn't really looking at the numbers at first. I was just looking for LORAN Internet converters ....that don't really exist. And now I know why they don't exist. But I initially got steered in the wrong direction, and I'm sure I'm not the only one.

Do you have any idea how much time I wasted trying to make sense of this:
https://www.navcen.uscg.gov/pdf/loran/handbook/APP-B.pdf

Then I was trying to convert using this LORAN tool and never getting any results:
https://www.nefsc.noaa.gov/loranconv/latlonarea.pl

All because CWOP's fake claim to use LORAN. Obviously it is a mistake and my use of the word fake may be a bit strong as I'm not trying to equate it to Fake News or something. I also can't believe I'm the one making sense of this now after so many years of CWOP existence. That is why I used the word Fake LORAN as it describes my flabbergasted shock.
« Last Edit: October 02, 2018, 07:09:03 AM by galfert »
WS-2000 & WS-2902A | ObserverIP | WeatherBridge (Meteobridge) | Ecowitt GW1000
WU: KFLWINTE111  |  PWSweather: KFLWINTE111
CWOP: FW3708  |  AWEKAS: 14814
Windy: pws-f075acbe
Tele-Pole flag pole is here (not installed yet)

 

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