Bangle 2 GPS - time for first fix, quite variable #5525
Replies: 1 comment
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Posted at 2021-10-28 by @allObjects I suspect the antenna and its gain is different, antenna is differently placed, and the casing is definitively different: metal. This has all a great impact on how much signal is received. And of course, sensitivity of the GPS receiver matters too... In addition to that, a house side may shield greatly the number of 'visible' satellites... GPS receivers can use (ever changing) signal reflections but try to eliminate them for actual calculations. Posted at 2021-10-28 by @gfwilliams IMO the Bangle.js 2 GPS isn't as good at getting fixes. I guess maybe it gets more confused if it can't see satellites it thinks it should be able to. It does support AGPS though and that'll help a lot with a fix (as might setting the time on it), however the AGPS data is in a different format to UBlox, so that's something else that'll need implementing. Posted at 2021-11-11 by blogmywiki I've not been able to get a GPS fix at all on my Bangle.js 2 yet - left by a window for 15 minutes, taken on a ~40 min walk - nothing. Posted at 2021-11-11 by @gfwilliams Yes, it can take an extremely long time for the very first fix. I believe giving the GPS chip the current time would help a lot, but that isn't implemented right now. Once you do get a fix, subsequent fixes should be much faster though. Posted at 2021-11-19 by Todd I've still been unable to get a fix. Posted at 2021-11-20 by Andrewmk I used GPS on my Bangle.js 2 today for the first time. First fix happened sometime during a 20 minute bike ride (travelling at about 10mph) but I'm afraid I don't know how long it took. Subsequent fixes today have been very quick - something like 30 seconds. Posted at 2021-11-21 by johan_m_o I did some testing today and the accuracy seems pretty good. Gonna compare to a Garmin bike computer later. The first fix took about 5-10 minutes. Posted at 2021-11-21 by andrewg_oz If the GPS is starting from fresh, it needs to download the almanac and ephemeris data. This takes a minimum 12.5 minutes, assuming no errors. If there are errors, then depending on what data is missing it could be another 12.5 minutes before that data is re-sent. It's quite likely the first fix will take two goes, or 25 minutes. It's down to a bit of luck, really. Posted at 2021-11-21 by HughB
@gfwilliams what would be needed to do this? Posted at 2021-11-22 by @gfwilliams It's just a matter of sending the right data down Serial, much like is done to configure the GPS on the Bangle.js 1 The receiver is the AT6558 - There should be a datasheet somewhere detailing the commands, but the closest I have found so far is this one in Chinese (https://m5stack.oss-cn-shenzhen.aliyuncs.com/resource/docs/datasheet/unit/Multimode_satellite_navigation_receiver_cn.pdf) It's possible that given some digging I could also find something in the original SMA firmware too. Posted at 2021-11-23 by user136447 My GPS loaded after about 15-20 minutes while I was driving (I have a 1.5 hour commute one way). Once loaded it worked fine (did the GPS time setting too). Posted at 2021-11-24 by HughB @gfwilliams does the GPS not remember the time after it has the first fix? I got a fix yesterday and switching the gps on from GPS touch just now I can see it has the time set. Other times I have seen this set to 00:00:00 maybe because I let the bangle battery run out. Posted at 2021-11-24 by Tx
AT6558 has 56 channels. Posted at 2021-11-25 by andrewg_oz Sadly, Navstar satellites are synchronised, so the number of channels are irrelevant for downloading ephemeris and almanac data. Posted at 2021-11-25 by Tx
Yes and no. The data is the same, but the TTFB of the data can be massivly reduced. Multi channel is used as a method for shortening the time to 30 s to 3 min. The mathematicians at the chip designers do the rest of the improvement. Posted at 2021-11-25 by @gfwilliams The GPS should remember the time after first fix, but maybe there's some issue where the very first NMEA sentence doesn't have it set? Posted at 2021-11-26 by @wminarik The GNSS receiver on my Bangle.js 2 was able to get a fix fairly quickly. However it only finds 5-8 satellites at a time (I've occasionally had up to 10, briefly). Looking at the output NMEA sentences: It's found 10 GPS satellites ($GPGSV) but only 6 are used for the fix ($GNGSA; sats 01,07,08,17,21,30). It doesn't look like it's even trying to find GLONASS satellites; there's a line for Beidou ($BDGSV) but no satellites are listed. Galileo satellites are also missing. uBlox receivers allow the choice of frequencies; the inexpensive ones allow the choice of two (e.g. GPS and GLONASS or GPS and Beidou). There must be a way to turn on at least the GLONASS frequency. The last line worries me a bit: From the datasheet Gordon linked in, the choices are: This implies that part of our problem is that the antenna is not connected, or that there is no antenna (open circuit). If anyone has done a teardown of the production units, this could be verified. Posted at 2021-11-26 by @fanoush
Yes, there is so send Posted at 2021-12-01 by @gfwilliams @fanoush did you have a reference for those commands (or perhaps other useful ones?). Sorry, I think you may have sent me one before and I lost it. Just did a quick google and found this which is pretty interesting - specifically about decreasing time to fix: geary/AnyTone-D868UV#61 - they even have a translated manual at https://docs.google.com/document/d/e/2PACX-1vQaEH6gbVeQds5AOQ7c2dJoNef1o6vCL4SeDRDB9YNtRzI1MKUYzDqS9clEdwL_RdI9TpjErreM-wiM/pub edit: It even mentions getting fix time down from 17s to 1.5s - although I wonder how much of that is that it already downloaded all the data it needs. Posted at 2021-12-01 by @fanoush Attached is the Chinese datasheet automatically translated to English with most formatting there, but sometimes it is good to check the original it was generated from http://www.icofchina.com/d/file/xiazai/2017-05-02/ea0cdd3d81eeebcc657b5dbca80925ee.pdf interesting conversation, I think they mostly turn off Beidou to make it faster? I also downloaded stuff from http://www.icofchina.com/xiazai/# and build the agps demo source and it did download some binary agps data that is supposed to be pushed to the device but did not try that yet. At least in B5 firmware there is code that uses second GPS uart atached to different pins at 230400 speed so maybe that is the way to upload it (or maybe that is to update GPS firmware) Attachments: Posted at 2021-12-01 by @fanoush BTW if anyone from EU is interested I can send few of these B5 fitness trackers with this GPS for $15 a piece plus shipping ($5-$10). There is local distributor of https://eshop.evolveo.com/evolveo-fitband-b5-gps--fitness-band-with-a-heart-rate-monitor--also-suitable-for-swimmers/ here who is dumping them on local auction site periodically, got few of them and they look new and working perfectly, most of them still with sticker on display and old updatable firmware so never used/paired with phone. As bangle 2 they have SWD on usb connector (same manufacturer) so no problem repurposing them (e.g. as BLE GPS running Espruino). Just checked the site and they are selling 5 pieces again. Posted at 2021-12-02 by @gfwilliams Great - thanks! Yes, if we can load AGPS data that's got to help massively! Interesting about the second UART - I don't remember seeing the Q3 firmware do that but I guess we'll just have to give it a try and see. But yes, it sounds like they just turn off Beidou. Possibly with that off the extra receivers are all used for GPS so it can get a lock quicker? Posted at 2022-06-03 by TTBangler Just thought I'd mention that my Bangle 1 seems to acquire a GPS lock much more quickly and reliably than my Bangle 2 as well. In particular, my Bangle 2 usually takes somewhere between 15-30 minutes to get a lock, outside with an unobstructed view of the sky (while I'm walking my dog). Because of the discussion about BeiDou reception possibly having been turned off, I thought I'd mention that today--for the first time since I started experimenting with GPS about a week ago--the GPS Info app (BTW, many thanks to its author--it's very neat!) indicated it detected a BeiDou signal: Attachments: Posted at 2022-06-04 by Serj I also noticed that BJS1 catches GPS faster and holds more stable than BJS2. I use AGPS on both devices. On BJS1, I used AGPS only a few times a month, and satellites were found very quickly on the street. Posted at 2022-06-07 by @gfwilliams Yes, Bangle.js 1 does have better GPS reception (however it seems using AGPS and setting it to just use GPS you can improve Bangle.js 2). Unfortunately I think it's just a side-effect of the maybe not so good GPS chip (AT6558 vs Ublox) and the much more constrained size for the aerial. Posted at 2022-06-15 by TTBangler Thanks for the tips! Indeed, after installing the AGPS app, my Bangle2 now usually acquires a GPS lock in about 10-20 seconds. It seems that the AGPS data is lost after shutting down the watch, however. Posted at 2022-06-16 by @gfwilliams
It shouldn't be... It'll be lost when the watch runs out of power, but not due to powering the watch off via the menu Posted at 2022-06-16 by TTBangler Interesting--perhaps the AGPS data "expired" while my watch was turned off then? I noticed that the AGPS app for Bangle.js 1 gives the user the option to select how much data to download but that option isn't provided for Bangle.js 2. I think it had been a couple of days since I last uploaded AGPS data so perhaps only a couple days' worth of data is uploaded to Bangle.js 2. Posted at 2022-06-17 by @gfwilliams
Yes... On Bangle.js 2 we only get enough data to last for ~48 hours I think, so that's probably it Posted at 2022-06-22 by Hank Can't you "just" implement frequent AGPS data uploading (like once a day) to Gadgetbridge as an option? Posted at 2022-06-22 by @halemmerich Github user pidajo is developing an app for pulling the AGPS data directly from the bangle over the Gadgetbridge http functionality: espruino/BangleApps#1974 Posted at 2022-06-28 by @gfwilliams I think that app is merged now too.
I could, if I had any time at all :) Others are welcome to contribute code though! In an ideal world, we'd have a way to have JS running on the phone push data to the Bangle, but I think in the absence of that, the app mentioned above is really the way to go. Posted at 2022-06-29 by myownself I am having an issue with GPS. I didn't use it much when the Bangle first arrived. I tested it and got a (slow) lock outside, but because I couldn't run for months after having covid that was about it. I recently started running again and I had a couple of weeks getting a really fast lock as long as I uploaded agps immediately before going, but the last few times I have uploaded the data but still no lock before giving up. This morning I fired gpsinfo up to see what was happening and it showed GP/BD/GL 10 2 0, but no lock. I only selected GPS onthe AGPS config and its the first time it I have noticed more than 1 for BD, but guess that is a red herring. Any thoughts? Posted at 2022-06-30 by @gfwilliams That's an odd one - not sure... But the fact it's reporting 10 satellites for GPS implies that you should have a good lock. I think as long as you have 4 or more, GPS usually starts giving you location information. So maybe it's actually a software issue? Posted at 2022-06-30 by myownself Did anything change around GPS in the latest firmware? Before I saw how many satellites it was seeing I thought maybe the AGPS data was off somehow. Now I am wondering whether it is "seeing" satellites that aren't there. All wild speculation. Posted at 2022-06-30 by @gfwilliams
Not that I'm aware of, no... I guess you could try using some code like Posted at 2022-10-03 by myownself I missed your last message Gordon, I will try that next time. In case anyone else has the same issue: I've had it happen a few times and running the battery down to completely power the watch off is what solves it for a while. I can't see a pattern about when it happens. Posted at 2022-10-04 by myxor
I see something similar on my B2: I can only get a GNSS fix after rebooting the watch. Posted at 2022-12-19 by user151682 Hi everyone! Experiencing the same issue here. Posted at 2022-12-19 by @gfwilliams How do you upload AGPS data? Was it with https://banglejs.com/apps/?id=assistedgps or something else ? And how long before using the Bangle did you update the data? There have been issues with the other app/widget there not always being able to update, so that could be an issue. Posted at 2022-12-19 by user151682 @gfwilliams I upload exactly using the "assistedgps" app. My procedure is as follows:
Despite that it takes a lot to get the first fix (I selected to upload all constellations). Posted at 2022-12-19 by @gfwilliams
Is this for Bangle.js 2? If so you may be having the opposite effect to what you intend. For instance by enabling just GPS you're actually freeing up more computation in the GPS receiver so you can get a fix more quickly.
You need to get it from the internet - but if you check out the AGPS app, it can do that via Gadgetbridge Posted at 2022-12-20 by user151682 @gfwilliams yes it's for Bangle.js 2. I'm trying every day with different configurations and this morning I've tried uploading GPS data only and I still got 17-19 mins for the first fix.
Posted at 2023-01-06 by @gfwilliams Hi, How are you waiting for the fix to occur? Do you leave the Bangle somewhere outside where it can see GPS satellites, or are you inside, in a city, or wearing it while walking around? It can be pretty hard to get a satellite fix when it's being moved around a lot because the satellites it is searching for come and go.
There may be a way to delete the AGPS data but I don't know it. I'd maybe run the battery down until the device turns off which will 100% reset the GPS, then you could just partially charge it to do some tests, then discharge it (there is an option in Settings->Utils to quickly discharge). In terms of improving time to lock, it may be possible to upload the estimated GPS location and time. I would love to do this and there are some threads about it, but the GPS chip is pretty badly documented so it's hard to know exactly what data needs to be sent. |
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Posted at 2021-10-27 by HughB
Just wondering what others have experienced with the Bangle 2 GPS.
I live in a terraced street and Bangle 1 can usually get a fix fairly quickly when out in the street.
With Bangle 2 I have not been sucessful getting a fix in the street - especially if I move about.
If I leave it on top of the wheely bin in the back yard I can get a fix
And it gets a fix within 50 seconds if I put it next to the window in our attic bedroom.
The receiver seems more susceptable to buildings etc.
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