# Fine Tuning Location **URL:** \ **Category:** ADS-B Flight Tracking\ **Created:** [May 24, 2020, 8:56pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292 "2020-05-24T20:56:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![erparker](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/erparker/32/82117_2.png) [@erparker](https://discussions.flightaware.com/u/erparker)\ **Post date:** [May 24, 2020, 8:56pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/1 "2020-05-24T20:56:38Z")
I just setup my receive station (127849 - KJPN - Barcroft) using PiAware and the FlightAware ProStick. I’m using an outdoor high-gain antenna and everything is working great except that my location in PiAware is off by about 70’ (basically showing up as being on the neighbor’s house). The Lat/Long is correct in Site Configuration and is accurate on Google Earth but I can’t get a change in Site Configuration to be reflected in PiAware. I’ve tried making a change and rebooting (a suggestion I found from older thread) but it didn’t work. Does the ProStick have GPS (meaning, basically, that the Lat/Long and the map don’t overlay perfectly)? Does it even matter or am I a newbie being OCD? ---
**Author:** ![geckoVN](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/geckovn/32/136508_2.png) [@geckoVN](https://discussions.flightaware.com/u/geckoVN)\ **Post date:** [May 25, 2020, 12:25am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/2 "2020-05-25T00:25:08Z")
Short answer - it doesn’t matter (other than it’s visually irritating) MLAT relies on correct receiver location, but not that level of precision. An error of a few 100 meters will still work fine. ---
**Author:** ![erparker](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/erparker/32/82117_2.png) [@erparker](https://discussions.flightaware.com/u/erparker)\ **Post date:** [May 25, 2020, 2:07am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/3 "2020-05-25T02:07:10Z")
That’s what I suspected. Thanks. ---
**Author:** ![wiedehopf](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/wiedehopf/32/114045_2.png) [@wiedehopf](https://discussions.flightaware.com/u/wiedehopf)\ **Post date:** [May 25, 2020, 6:52am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/4 "2020-05-25T06:52:47Z")
> [@geckoVN](#): > > An error of a few 100 meters will still work fine. That’s just wrong. It might still somehow work like that, but you want to configure it precisely. Note that i’m not sure if it would even work with 100m of difference. The reported inaccuracy was 70 ft, that will probably still work but is still unnecessary error. > [@erparker](#): > > my location in PiAware is off by about 70’ Seems you have gpsd running and piaware configured to use it. I think once that has been done, you need one of the staff to change the setting back to a user set location. Your gpsd is inaccurate and that’s being reflected in the position you see. The prostick doesn’t have gps, must be something else you connected to the pi. ---
**Author:** ![obj](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/obj/32/118984_2.png) [@obj](https://discussions.flightaware.com/u/obj)\ **Post date:** [May 25, 2020, 7:12am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/5 "2020-05-25T07:12:14Z")
> [@wiedehopf](#): > > I think once that has been done, you need one of the staff to change the setting back to a user set location. There is now an option in the stats control panel that lets you choose between using the device-provided GPS location or providing a manual location: ![Screenshot from 2020-05-25 15-11-08](https://us1.discourse-cdn.com/flex019/uploads/flightaware/original/3X/a/6/a6797c5f95a90c9e48941f304e53a50e7fe1ad90.png) ---
**Author:** ![chrislfa](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/chrislfa/32/113808_2.png) [@chrislfa](https://discussions.flightaware.com/u/chrislfa)\ **Post date:** [May 25, 2020, 7:13pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/6 "2020-05-25T19:13:03Z")
If this is set to use a device-provided GPS is it then possible to take the site mobile, such that every update is correct for both position on map/distances, and MLAT? Or is this setting still only intended for use with a static site, regardless of how location is obtained, such as with a manually entered location? ---
**Author:** ![astrodeveloper](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/astrodeveloper/32/117096_2.png) [@astrodeveloper](https://discussions.flightaware.com/u/astrodeveloper)\ **Post date:** [May 25, 2020, 9:02pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/7 "2020-05-25T21:02:29Z")
Don’t ask how I know this, but depending on the quality of your GPS receiver, the position will wander all over the place, lat, lon, and altitude. When the new GPS location is far enough from the last used GPS location, Dump1090 will be restarted, causing you to miss some messages, MLAT will be messed up and need to resyncronize too. Lots of stuff happens, just look at the /var/log/piaware.log file. Better to use a fixed location where you actually are, than trust the GPS dongle messing with your system. Just thought you might want to know. ---
**Author:** ![SoNic67](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/sonic67/32/119872_2.png) [@SoNic67](https://discussions.flightaware.com/u/SoNic67)\ **Post date:** [May 25, 2020, 9:19pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/8 "2020-05-25T21:19:08Z")
On [your site webpage](https://flightaware.com/adsb/stats/user/erparker), in the right side, where that Site Configuration wheel is, at Precision on Coverage Map you have the option to show it “Exactly” if that’s what you want. Of you can obfuscate the location randomly for privacy by 1km or 10 km. ---
**Author:** ![chrislfa](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/chrislfa/32/113808_2.png) [@chrislfa](https://discussions.flightaware.com/u/chrislfa)\ **Post date:** [May 25, 2020, 10:12pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/9 "2020-05-25T22:12:42Z")
> [@astrodeveloper](#): > > Better to use a fixed location where you actually are, than trust the GPS dongle messing with your system Thanks, I was asking more from a “is a mobile site using this approach technically possible?” angle, but I agree; in practice I would stick to manually entered details and a site that’s not moving. Even for a site setting up in different locations (eg a hobbyist going to events with a PiAware-in-a-box) I would still use a separate GPS to enter details and work out the antenna height seperately. Even then I’d probably not bother – I’d just VPN back home and watch the details on my home setup! ---
**Author:** ![geckoVN](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/geckovn/32/136508_2.png) [@geckoVN](https://discussions.flightaware.com/u/geckoVN)\ **Post date:** [May 26, 2020, 1:45am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/10 "2020-05-26T01:45:04Z")
> [@wiedehopf](#): > > That’s just wrong. I don’t know what the threshold is, so few of my local traffic _aren’t_ equipped with ADS-B that a survey wouldn’t be very reliable. However I will follow up and see if I can pick the distance where my site is rejected. My observations are that a few hundred meters makes no difference. Edit: Just to qualify “no difference” - it will of course degrade precision, but will still provide useful data. ---
**Author:** ![obj](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/obj/32/118984_2.png) [@obj](https://discussions.flightaware.com/u/obj)\ **Post date:** [May 26, 2020, 2:03am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/11 "2020-05-26T02:03:48Z")
An error of ~100m is not _huge_. It’s roughly equivalent to a timing measurement error of about 0.3µs. That is similar in size to the unavoidable timing measurement errors we get from how the clock synchronization itself is done. So you’re doubling the measurement error, but it’s not 10x or anything. If you have many other nearby receivers, that error won’t have a huge impact. The mlat servers will just end up giving less weight to your data (they measure the clock stability per receiver and use that as an input to the solver; an error in the receiver position ends up looking like clock instability) But it’s certainly worth getting the location right if you can; no point in introducing extra position error. ---
**Author:** ![SweetPea11](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/sweetpea11/32/137137_2.png) [@SweetPea11](https://discussions.flightaware.com/u/SweetPea11)\ **Post date:** [May 26, 2020, 9:02am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/12 "2020-05-26T09:02:22Z")
> [@geckoVN](#): > > I will follow up and see if I can pick the distance where my site is rejected. I adjusted the location of one of my receivers and at 600m it still synced with about 60 other sites and displayed the location of some MLAT aircraft. At 1km piaware disabled MLAT and reported a timing or position error. It is now back to normal. YMMV S. ---
**Author:** ![geckoVN](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/geckovn/32/136508_2.png) [@geckoVN](https://discussions.flightaware.com/u/geckoVN)\ **Post date:** [May 26, 2020, 9:03am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/13 "2020-05-26T09:03:10Z")
> [@geckoVN](#): > > My observations are that a few hundred meters makes no difference. Had one site set to 1000m position error - no timing errors, and still got my ‘one MLAT plane’ for the day. > [@SweetPea11](#): > > I adjusted the location of one of my receivers Thanks for running the test. My ‘one MLAT plane’ for the day doesn’t provide a lot of scope for testing. ---
**Author:** ![MC130E](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/mc130e/32/137074_2.png) [@MC130E](https://discussions.flightaware.com/u/MC130E)\ **Post date:** [May 27, 2020, 9:48pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/14 "2020-05-27T21:48:27Z")
> [@erparker](#): > > I just setup my receive station (127849 - KJPN - Barcroft) using PiAware and the FlightAware ProStick. I’m using an outdoor high-gain antenna and everything is working great except that my location in PiAware is off by about 70’ (basically showing up as being on the neighbor’s house). The Lat/Long is correct in Site Configuration and is accurate on Google Earth but I can’t get a change in Site Configuration to be reflected in PiAware. I’ve tried making a change and rebooting (a suggestion I found from older thread) but it didn’t work. Hi, I ran in to this back in December 2019 and reported it to FA then. While a small change like your 70’ will be reflected in the site configuration display, it WILL NOT be updated in PiAware. The previous uncorrected coordinates will continue to be used and displayed in htop. PiAware ignores changes \< approximately 250 meters. The way to make them perfect is to make two changes. 1. First move the coordinates \> 250 meters away. I did this by increasing my lat by 0.01 degrees = 0.6 nautical miles. This change will restart everything with the new “bad” coordinates. 2. Then go back and put in the correct coordinates. Everything restarts and now both the control panel and PiAware are using the exact coordinates. -Dan ---
**Author:** ![MC130E](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/mc130e/32/137074_2.png) [@MC130E](https://discussions.flightaware.com/u/MC130E)\ **Post date:** [May 27, 2020, 10:01pm UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/15 "2020-05-27T22:01:45Z")
> [@obj](#): > > But it’s certainly worth getting the location right if you can; no point in introducing extra position error. FA staff, I reported this behavior back in December 2019 in the direct message traffic related to the post I created here. This link is for reference only for you to locate the direct message traffic. The position error problem is not discussed in the post linked. > [@Unique Identifier: xxxx Assigned to PlanePlotter sites for transition?](https://discussions.flightaware.com/t/unique-identifier-xxxx-assigned-to-planeplotter-sites-for-transition/58347): > > Hi all, I fully understand the changes FlightAware is making on 31 DEC 2019 regarding PlanePlotter data sent using the “secondary sharing” method direct from PlanePlotter. I understand why it is being done. This is not meant to be a us or them type of post. My question is: Is it possible for FA to assign a Unique Identifier: xxxx-xxxx-… to my fairly low number PlanePlotter receiver site internally on their servers so that I can migrate that to a Pi and maintain my fairly low number FA sit… When I identified the problem, eric1tran located code that shows home location position changes of approximately \< 250 meters are ignored. Here is the code he linked to: > ## Here was my suggestion at the time by direct message: Just my opinion, but while a 250 meter “error” in home location might not impact FA, it could impact other sites that are using the dump1090-fa receiver location for their mlat purposes. You guys might want to consider dropping the 250m to something smaller like 30m or so. Just a thought. * * * Thanks, -Dan ---
**Author:** ![erparker](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/erparker/32/82117_2.png) [@erparker](https://discussions.flightaware.com/u/erparker)\ **Post date:** [May 28, 2020, 1:47am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/16 "2020-05-28T01:47:15Z")
Thank you. Very helpful. I will probably not bother trying to correct it for the time being since I’m considering moving my station to a building that has much greater visibility. If I decide to keep it where it is then I’ll try and make the correction. ---
**Author:** ![obj](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/obj/32/118984_2.png) [@obj](https://discussions.flightaware.com/u/obj)\ **Post date:** [May 28, 2020, 3:52am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/17 "2020-05-28T03:52:25Z")
> [@MC130E](#): > > Just my opinion, but while a 250 meter “error” in home location might not impact FA, it could impact other sites that are using the dump1090-fa receiver location for their mlat purposes. You guys might want to consider dropping the 250m to something smaller like 30m or so. Just a thought. The configured location in dump1090 is irrelevant for mlat; what matters is the location that the mlat _server_ knows. I’m not aware of any mlat system that uses the parameters passed to dump1090 as a receiver location. FA uses position data sent directly upstream, which is updated every 5 mins or every ~250m, whichever comes first. Other systems typically have a manually configured location and don’t see any position changes at all. ---
**Author:** ![SweetPea11](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/sweetpea11/32/137137_2.png) [@SweetPea11](https://discussions.flightaware.com/u/SweetPea11)\ **Post date:** [May 28, 2020, 6:34am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/18 "2020-05-28T06:34:40Z")
> [@SweetPea11](#): > > At 1km piaware disabled MLAT and reported a timing or position error. Sorry to quote myself but when I was testing and got to the point where both piaware and the Flightaware stats page showed a timing/position error for MLAT (red boxes) two or three of my other receivers also reported the same error message. One of those receivers reporting that error is located about 1 km away and has MLAT turned off on the stats page. Just an interesting observation and all my sites are now have their location correctly set up but I am now curious to know if my erroneous locations cause other stations around me to have similar errors. S ---
**Author:** ![obj](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/obj/32/118984_2.png) [@obj](https://discussions.flightaware.com/u/obj)\ **Post date:** [May 28, 2020, 6:43am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/19 "2020-05-28T06:43:11Z")
> [@SweetPea11](#): > > two or three of my other receivers also reported the same error message. IIRC this is a display/query bug where the error gets displayed against the wrong site when you have multiple sites. At a low level, timing errors are symmetric in the sense that for a given pair of receivers which are failing to keep sync, the mlat server doesn’t know which of the two is the problem. But the mlat server then aggregates that data across all receiver pairs to decide which are the actually unstable ones and which are the innocent victims. If you’re in a well populated area, individual receivers with sync problems won’t affect other sites. ---
**Author:** ![SweetPea11](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/sweetpea11/32/137137_2.png) [@SweetPea11](https://discussions.flightaware.com/u/SweetPea11)\ **Post date:** [May 28, 2020, 6:48am UTC](https://discussions.flightaware.com/t/fine-tuning-location/65292/20 "2020-05-28T06:48:00Z")
> [@obj](#): > > IIRC this is a display/query bug where the error gets displayed against the wrong site when you have multiple sites. Thanks. That means that the MLAT server is smart enough to ignore an erroneous location and it is not an error in the system but just an error in reporting the position error. Surprisingly, it flags a receiver with MLAT turned off under those circumstances. S. [Next page](https://discussions.flightaware.com/t/fine-tuning-location/65292.md?page=2)