No or incomplete tracks

[John Gillett]

Running v1.6.6.2 against iOS 10.3.3.

Tracks are either incomplete (they don't show everywhere I've been in a given trip) or sometimes don't show at all. Tracks on the app map are usually different than shown on aprs.fi. Also when there are tracks they do not follow the roads - it's just an as-the-crow-flies straight line. On the app the blue dot GPS indicator does follow me around properly but the vehicle icon usually does not know where I am.

Attached are 3 files...

settings.jpg - the app settings page - yes, I turn the beacon on when I'm in the truck

last-track.jpg - one of the doesn't follow the road tracks

missing-track.jpg - the aqua track is what the app gave me, the red track I added to show where I actually went

The previous app - 32-bit, I think - worked perfectly on this same iPhone.

Thoughts appreciated.

[Heikki Hannikainen]

Hi,

On Sat, 19 Aug 2017, John Gillett wrote:

> Running v1.6.6.2 against iOS 10.3.3.
> Tracks are either incomplete (they don't show everywhere I've been in a given trip) or sometimes
> don't show at all.

One thing to check first: In iOS Privacy / location settings, have you
allowed aprs.fi to access your location Always? i.e. not "when using the
app"?

> Tracks on the app map are usually different than shown on aprs.fi.

Could you describe this behavior in more detail: which tracks exactly?
Yours? Someone else's? The app loads the tracks from the same database as
the web site, there shouldn't generally be any difference in what is
shown as it's the very same data being used.

> Also when there are tracks they do not follow the roads - it's just an
> as-the-crow-flies straight line. On the app the blue dot GPS indicator
> does follow me around properly but the vehicle icon usually does not
> know where I am.

APRS tracks in general are not designed to follow roads exactly. A
position is transmitted every now and then, and some attempt is made to
transmit one when there is a tight turn, which sometimes leads to the
track mostly following, roads, but the APRS system does not know where the
roads are.

> missing-track.jpg - the aqua track is what the app gave me, the red track I added to show where
> I actually went
>
> The previous app - 32-bit, I think - worked perfectly on this same iPhone.

aprs.fi has been shipped as both 32 and 64 bit for a very long time, there
have been no recent changes in this.

- Hessu

[John Gillett]

On Sunday, August 27, 2017 at 12:39:50 PM UTC-7, Heikki Hannikainen wrote:

One thing to check first: In iOS Privacy / location settings, have you
allowed aprs.fi to access your location Always? i.e. not "when using the
app"?

Initially I had it set on Always allow. However that proved to be extremely hard on the battery so I switched it back to When using. Could you please explain why the app needs to know where I am even when it's not running?

 

Could you describe this behavior in more detail: which tracks exactly?
Yours? Someone else's? The app loads the tracks from the same database as
the web site, there shouldn't generally be any difference in what is
shown as it's the very same data being used.

Sorry - my tracks. They don't follow where I go exactly and almost always are not a complete picture of where I've been on any given trip. This is on both the app map and the website.

 

APRS tracks in general are not designed to follow roads exactly. A
position is transmitted every now and then, and some attempt is made to
transmit one when there is a tight turn, which sometimes leads to the
track mostly following, roads, but the APRS system does not know where the
roads are.

Then I misunderstand the Minimum transmit interval setting. I 'assumed' that to mean a transmission every 15 seconds (as I have it set). Apparently not?

 

aprs.fi has been shipped as both 32 and 64 bit for a very long time, there
have been no recent changes in this.

I was just trying to explain the previous app I had been using (until the app store banned it and many others). I don't remember the version number. It was the free version. That one always knew exactly where I was and also followed all the roads I travelled exactly Very nice. I was looking for the same performance with this version.

Thank you for your time and explanations.

John

[Heikki Hannikainen]

On Mon, 28 Aug 2017, John Gillett wrote:

> On Sunday, August 27, 2017 at 12:39:50 PM UTC-7, Heikki Hannikainen wrote:
>
> One thing to check first: In iOS Privacy / location settings, have you
> allowed aprs.fi to access your location Always? i.e. not "when using the
> app"?
>
> Initially I had it set on Always allow. However that proved to be
> extremely hard on the battery so I switched it back to When using. Could
> you please explain why the app needs to know where I am even when it's
> not running?

This setting is quite often misunderstood. The "when using the app"
selection only lets the app get your location when the app is in the
*foreground* (visible on the screen), and a very short while after it goes
out of view. This mode does not let aprs.fi beacon on the background, even
though you might think that you're, sort of, using it, since you've
enabled beaconing and you expect beaconing to happen. Beaconing will only
work as long as aprs.fi is displayed on the screen and the screen is not
locked or powered down.

The "Always" setting allows aprs.fi to get positions after it goes out of
view, the display is locked and blank. This setting allows aprs.fi to
continue beaconing. This will surely drain the battery quite a lot due to
the GPS being powered on all the time.

Even with the "Always" setting, the app will *not* request the OS for
positions when Beaconing is not enabled and the app is not being actively
used, since that would drain the battery way too fast. And the app does
not at that time need the positions anyway. If beaconing is not enabled,
the app will close the location API immediately when it goes out of view,
to conserve power. You'll notice that the GPS arrow in the top right
corner switches, with a small (~10 seconds) delay, from solid color
("location used now") to an outline ("location used recently"). Unless, of
course, iOS or some other app also uses the location around that time.

> APRS tracks in general are not designed to follow roads exactly. A
> position is transmitted every now and then, and some attempt is made to
> transmit one when there is a tight turn, which sometimes leads to the
> track mostly following, roads, but the APRS system does not know where the
> roads are.
>
> Then I misunderstand the Minimum transmit interval setting. I 'assumed'
> that to mean a transmission every 15 seconds (as I have it set).
> Apparently not?

Below the setting it reads, with a smaller font: "Positions will not be
sent more often than this."

In other words: the slider can be used to set a minimum time interval
between transmissions: it will never ever send a packet more often than 15
seconds (or whatever you choose). This can be used to reduce battery use
and maybe improve privacy a bit, if you don't wish to send positions that
often.

It does not make the app send a packet exactly every 15 seconds. There is
an algorithm which works a bit like Smart Beaconing: it sends less often
when you're not moving, and more often when you're moving fast, and tries
to detect tight turns and send a position at those.

- Hessu

[John Gillett]

Thank you for the additional explanations.

I changed the access location item to Always and took a short trip. It included local streets, freeway, and a stop of about 30 minutes. Total trip time 60 minutes. Good thing is both the app map and the website recorded exactly what I did, leaving nothing out, and also closely followed the streets. Not so good thing is this short trip killed 27% of the battery time. At least it's working.

Thank you.

John

[John Gillett]

Forgot to add the maps.