Incorrect location of hostpot reported to aprs.fi

[KO4DBS]

Using MMDVM hat on Pi zero w. D-star mode under MMDVMHost is the the only config enabled. ID-5100 reports the correct location when keying up on D-star but the hotspot consistently reports it's location (CALLSIGN-B) as being approx 20mi to the south east. All lat/long coord's are correct in the general config as well as under ircDDBGateway and MMDVMHost expert configs.

This problem has driven me crazy for several weeks! I will be extremely grateful to anyone who has any ideas or can give me some clues on where I might be going wrong here.

TIA
Adam

[AF6VN]

Just a wild-card... Where is your ISP node located?

Code: Select all

C:\Users\Wulfraed>tracert 8.8.8.8

Tracing route to dns.google [8.8.8.8]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  dsldevice.attlocal.net [192.168.1.254]
  2    23 ms    18 ms    18 ms  76-255-152-1.lightspeed.gdrpmi.sbcglobal.net [76.255.152.1]
  3    18 ms    18 ms    19 ms  71.152.176.29
  4    35 ms    29 ms    30 ms  ^C
C:\Users\Wulfraed>

"gdrpmi", in my case, is most likely Grand Rapids MI -- which is ~15 miles west of my actual location. I have seen a number of situations which take the ISP as the location. {Note that the first link above is a private LAN IP, so the closest IP in the route to me is the one on the second line}

If your ISP is located near the reported location, your radio location may not be getting passed on, and the ISP is being used.

Also, double check the datum used in your GPS/radio. While 20 miles is a rather large shift, using anything but WGS-84 (for example NAD-27) could potentially result in mapping differences.

[KO4DBS]

Thanks for responding!

Well, my first hop ISP IP/URL does not contain any info that might indicate it's location. As far as the radio datum, the ID-5100 gives and appears on aprs.fi at it's correct location. It is the pi-star hotspot itself that is appearing in the incorrect location even though I've entered identical coords that the ID-5100 uses. I got a pointer from another user on reddit to make sure the corrrect datum is being used as well, but I have yet to find a config where I would specify or see what datum used is configured in any part of the pi-star config. Is this even configurable?

[AF6VN]

Datum only applies in converting from GPS to coordinate frame, and then using those coordinates with a map. Lat/Long lines on maps shifted between NAD-27 and NAD-83 (though not as much as you report... feeding my position into https://www.ngs.noaa.gov/NCAT/ and converting NAD-83 to NAD-27 shows a 3.5meter change in latitude, and 1meter change in longitude*). I believe NAD-83 is similar to WGS-84 (not exact, but close enough for most consumer gear)

* heh, looking at https://gisgeography.com/geodetic-datum ... d83-wgs84/ shows that I live practically dead center of the 0-shift area. When I was in California, I was in an area with >90meters shift.