Re: Red Dot vs Dead Reckoning + More

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• ok, that invovled more math than my sleep deprived mind can handle at the moment, will try it again tomorrow when I ve had some sleep. regardless, I ve got my
Message 1 of 25 , Apr 1, 2011
ok, that invovled more math than my sleep deprived mind can handle at the moment, will try it again tomorrow when I've had some sleep.

regardless, I've got my red dot turned off as it doesn't give me anything useful for my purposes.

If I can get the new Dev version before I leave at 3pm I'll have the YL see what it does as we drive home.

KC2ANT

and James, thanks for your patience in trying to educate me. I'm playing catch up on some of this stuff.

--- In aprsisce@yahoogroups.com, "Lynn W Deffenbaugh (Mr)" <kj4erj@...> wrote:
>
> Very well explained James. I have isolated the problem, implemented the
> solution, and am about to release a new Dev version for those of you
> that can (safely) see your screen while mobile can test (and hopefully
> verify) my correction. I base the Dead Reckoning of ME on whether or
> not you have Configure / Beacon / CourseSpeed checked. If so, ME will
> dead reckon based on the (hopefully) same information a recipient of
> your last beaconed packet would be using. If you don't beacon
> CourseSpeed, then I don't DR ME since you KNOW where you are and where
> you're heading and you haven't told anyone else anyway.
>
> As for the difference/similarity of ME's DR vs the Red Dot.... If you
> measure the deviation between ME's actual position and the corresponding
> DR symbol, scale that according to the Configure / Genius / Forecast
> Error setting, you'll have a bearing (from actual to DR) and a
> percentage of error (distance / Forecast Error * 100%). Plot that
> value on the circle based on the compass points where touching the
> circle = 100% and you have the red dot, a Visualization of the range and
> direction of the error between a time-based extrapolation of your last
> beaconed position, speed, and course vs your actual current position, in
> other words, the red dot displays the magnitude and direction of the
> error between where an outside observer thinks you are based on the time
> since and values within your last beacon and where you know yourself to
> actually be.
>
> If the DR is on top of you (constant, straight line motion), the red dot
> will be on top of you and invisible. You won't see the DR symbol
> either, most likely.
>
> If you speed up (still in a straight line), the DR symbol will start
> falling behind, and the red dot will start drifting towards the circle,
> lagging directly behind your current direction of motion, but the DR and
> red dot will be at different rates because the red dot is a percentage
> of the allowed Forecast Error (when it touches the circle), and the DR
> will be where that outside observer would think you are. So, the DR
> moves according to map scale and the red dot moves according to the
> magnitude of the allowed Forecast Error.
>
> If you slow down (still in a straight line, we can do that here in
> Florida for long distances), the DR symbol will start pulling out in
> front of your direction of motion, and so will the red dot, again at
> different rates. If you take the distance between your actual position
> and the DR symbol, divide it by the configured Forecast Error, that's
> relatively how far the red dot will be between the center and edge of
> the circle, still in your direction of motion.
>
> I'll leave it as an exercise for the reader to figure out where the DR
> and red dots will go if you vary just the direction and maintain speed
> (should drift away from you at 90 degrees) or if you vary both speed and
> direction.
>
> For extra credit, you can play the "red dot game" (yes, this is
> absolutely worse than just glancing at the APRSISCE/32 screen while
> driving). Purposely vary your speed and/or direction to control where
> the red dot is on the circle. Hint: it's a lot easier if you have a
> very long stretch of very straight road and works fairly well at giving
> you something to do to stay alert, even if not truly looking where
> you're going). Hint #2: it's highly discouraged to attempt to control
> the red dot in any orientation other than directly ahead or behind your
> current heading unless you're driving on a salt flat or something.
>
> Now, to quit typing, do a few release notes entries, and get this
> development release out there for testing!
>
> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
>
> On 4/1/2011 1:52 PM, James Ewen wrote:
> > On Fri, Apr 1, 2011 at 10:35 AM, apenadragon<kc2ant@...> wrote:
> >
> >>> So, I just need to fix ME's DR to use the last beaconed speed/heading
> >>> rather than the current GPS speed/heading and all will be well.
> >> Do you?? personally I don't see the issue... the DR is a projection of where
> >> the station "should" be...
> > Actually Adam, it sounds like you're missing the issue.
> >
> > If you take the last reported speed and heading and project that from
> > the last reported location, as time progresses, the dead reckoned icon
> > will move to where the station "could" be.
> >
> > The problem with what we are seeing is that Lynn is using the CURRENT
> > speed and heading, and projecting a possible location using that
> > information from the last reported location.
> >
> > Lets suggest that a position was reported, with a speed of 60 mph, and
> > a heading of 90 degrees. After one minute, the dead
> > reckoned position should be 1 mile east of the reported location.
> >
> > The way it is implemented, if I stop driving east after 30 seconds,
> > the DR position would return back to the last reported location. If I
> > were to turn south and drive for 1 minute at 60 mph (without sending
> > an updated position report), there would be a DR object 1 mile south
> > of the originally reported position.
> >
> > Now, if this instantaneous line were to originate from the current
> > location, it would still be wrong. The line leaving my current
> > location would not be a dead reckoned position, but rather a projected
> > location for a future position report based on the current speed and
> > course, projected into the future the amount of time since the last
> > reported position.
> >
> > When Lynn gets it straightened out, you'll see something interesting
> > happening. As Lynn said, if you continue in a straight line at a
> > constant speed, you won't see the projected icon. If the road turns,
> > or you change speed, then you'll see the projected (DR) icon continue
> > along the last reported vector. Once the Genius settings determine
> > that you've strayed too far, a new position report will be sent, and
> > the DR icon will start moving away from the reported position again.
> >
> > James
> > VE6SRV
>
• ... As a diagnostic aid, yes. As a game to play on long drives, maybe. For non-interested parties, that s why you can turn it off. ... Nope, the scales are
Message 2 of 25 , Apr 1, 2011
On 4/1/2011 2:17 PM, apenadragon wrote:
> That may be, but the APRSIS32 does that on its own, does it really need to display that on your local map??

As a diagnostic aid, yes. As a game to play on long drives, maybe. For
non-interested parties, that's why you can turn it off.

> I guess that's the question, if you have your Red dot turned on, right now doesn't that show up in the same place as the DR for "Me" in its current configuration? (did go and read the Red Dot explanation on the wiki)

Nope, the scales are different. DR is in map scale miles. Red Dot is
in % of Genius / Forecast Error where the circle is 100%.

> if Lynn changes the DR of ME to the same as the DR for everyone else, ie last reported packet, I'm not sure what use that is to the originating station on a local map.

It shows the originating station where an outside observer would think
you are, relative to your desired maximum error in the red dot, and
actual forecasted position in the DR symbol.

> Genius is also set to beacon after a set time, or a set distance, or after changing direction so many degrees, all of those user configured. (if I'm understanding it correctly, which I may not be)

You are correct. The overriding current factor is what is displayed as
a percentage towards the beacon ("Transmit Pressure") in the APRS-IS OK
pane on the display as well as the bottom-most bar at the bottom of that
pane. Hit Transmit and you'll see that bar drop back to zero (left) and
start growing to the right and morphing from green to red based on the
displayed Transmit Pressure.

> So, my understanding at this moment is that the DR for ME is showing in the same place that the Red Dot would be, only with the DR Line and beacon icon.

Different scales as already mentioned, so they may be in the same
relative location as ME (I'm still not sure about that), but probably
different distances away.

> If the DR for ME is set to use the same information as the other stations, last reported packet, I'm not sure what purpose that would serve.

It shows you what other's would believe based on what you've told them.

> It's an interesting phenomenon... I'd like to see a way to turn off Red Dot (available) and DR for ME Only, and still leave DR for all other stations, regardless of if DR gets changed from its' current configuration or not.

To turn off DR for ME, you'll have to turn off Configure / Beacon /
CourseSpeed as I've coupled them together in the upcoming release.
Prior to that, if you have Screen / Dead Reckoning turned on, it'll DR
me. With the upcoming release, if you are beaconing CourseSpeed, then
you'll be seeing what you're leading others to believe. I think it will
be informative.

Of course, turning off Screen / Dead Reckoning turns it off for both ME
and others.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

> KC2ANT
>
>
>
> --- In aprsisce@yahoogroups.com, James Ewen<ve6srv@...> wrote:
>> On Fri, Apr 1, 2011 at 10:35 AM, apenadragon<kc2ant@...> wrote:
>>
>>>> So, I just need to fix ME's DR to use the last beaconed speed/heading
>>>> rather than the current GPS speed/heading and all will be well.
>>> Do you?? personally I don't see the issue... the DR is a projection of where
>>> the station "should" be...
>> Actually Adam, it sounds like you're missing the issue.
>>
>> If you take the last reported speed and heading and project that from
>> the last reported location, as time progresses, the dead reckoned icon
>> will move to where the station "could" be.
>>
>> The problem with what we are seeing is that Lynn is using the CURRENT
>> speed and heading, and projecting a possible location using that
>> information from the last reported location.
>>
>> Lets suggest that a position was reported, with a speed of 60 mph, and
>> reckoned position should be 1 mile east of the reported location.
>>
>> The way it is implemented, if I stop driving east after 30 seconds,
>> the DR position would return back to the last reported location. If I
>> were to turn south and drive for 1 minute at 60 mph (without sending
>> an updated position report), there would be a DR object 1 mile south
>> of the originally reported position.
>>
>> Now, if this instantaneous line were to originate from the current
>> location, it would still be wrong. The line leaving my current
>> location would not be a dead reckoned position, but rather a projected
>> location for a future position report based on the current speed and
>> course, projected into the future the amount of time since the last
>> reported position.
>>
>> When Lynn gets it straightened out, you'll see something interesting
>> happening. As Lynn said, if you continue in a straight line at a
>> constant speed, you won't see the projected icon. If the road turns,
>> or you change speed, then you'll see the projected (DR) icon continue
>> along the last reported vector. Once the Genius settings determine
>> that you've strayed too far, a new position report will be sent, and
>> the DR icon will start moving away from the reported position again.
>>
>> James
>> VE6SRV
>>
• I think I m starting to get it now, I m pretty sure the math its self would drive me batty at the moment, but I think I m getting the concept... I ll be
Message 3 of 25 , Apr 1, 2011
I think I'm starting to get it now, I'm pretty sure the math its self would drive me batty at the moment, but I think I'm getting the concept... I'll be interested to watch it on the way home (thinking about making the YL drive home) and see what the differeces are between the DR icon, and the Red Dot.

I like the DR feature, and I'm going to transmit course and speed normally, so I'll just deal with seeing the DR on my screen and say thanks for putting up with us unedumacated youngsters.

KC2ANT

--- In aprsisce@yahoogroups.com, "Lynn W Deffenbaugh (Mr)" <kj4erj@...> wrote:
>
> On 4/1/2011 2:17 PM, apenadragon wrote:
> > That may be, but the APRSIS32 does that on its own, does it really need to display that on your local map??
>
> As a diagnostic aid, yes. As a game to play on long drives, maybe. For
> non-interested parties, that's why you can turn it off.
>
> > I guess that's the question, if you have your Red dot turned on, right now doesn't that show up in the same place as the DR for "Me" in its current configuration? (did go and read the Red Dot explanation on the wiki)
>
> Nope, the scales are different. DR is in map scale miles. Red Dot is
> in % of Genius / Forecast Error where the circle is 100%.
>
> > if Lynn changes the DR of ME to the same as the DR for everyone else, ie last reported packet, I'm not sure what use that is to the originating station on a local map.
>
> It shows the originating station where an outside observer would think
> you are, relative to your desired maximum error in the red dot, and
> actual forecasted position in the DR symbol.
>
> > Genius is also set to beacon after a set time, or a set distance, or after changing direction so many degrees, all of those user configured. (if I'm understanding it correctly, which I may not be)
>
> You are correct. The overriding current factor is what is displayed as
> a percentage towards the beacon ("Transmit Pressure") in the APRS-IS OK
> pane on the display as well as the bottom-most bar at the bottom of that
> pane. Hit Transmit and you'll see that bar drop back to zero (left) and
> start growing to the right and morphing from green to red based on the
> displayed Transmit Pressure.
>
> > So, my understanding at this moment is that the DR for ME is showing in the same place that the Red Dot would be, only with the DR Line and beacon icon.
>
> Different scales as already mentioned, so they may be in the same
> relative location as ME (I'm still not sure about that), but probably
> different distances away.
>
> > If the DR for ME is set to use the same information as the other stations, last reported packet, I'm not sure what purpose that would serve.
>
> It shows you what other's would believe based on what you've told them.
>
> > It's an interesting phenomenon... I'd like to see a way to turn off Red Dot (available) and DR for ME Only, and still leave DR for all other stations, regardless of if DR gets changed from its' current configuration or not.
>
> To turn off DR for ME, you'll have to turn off Configure / Beacon /
> CourseSpeed as I've coupled them together in the upcoming release.
> Prior to that, if you have Screen / Dead Reckoning turned on, it'll DR
> me. With the upcoming release, if you are beaconing CourseSpeed, then
> you'll be seeing what you're leading others to believe. I think it will
> be informative.
>
> Of course, turning off Screen / Dead Reckoning turns it off for both ME
> and others.
>
> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
>
> > KC2ANT
> >
> >
> >
> > --- In aprsisce@yahoogroups.com, James Ewen<ve6srv@> wrote:
> >> On Fri, Apr 1, 2011 at 10:35 AM, apenadragon<kc2ant@> wrote:
> >>
> >>>> So, I just need to fix ME's DR to use the last beaconed speed/heading
> >>>> rather than the current GPS speed/heading and all will be well.
> >>> Do you?? personally I don't see the issue... the DR is a projection of where
> >>> the station "should" be...
> >> Actually Adam, it sounds like you're missing the issue.
> >>
> >> If you take the last reported speed and heading and project that from
> >> the last reported location, as time progresses, the dead reckoned icon
> >> will move to where the station "could" be.
> >>
> >> The problem with what we are seeing is that Lynn is using the CURRENT
> >> speed and heading, and projecting a possible location using that
> >> information from the last reported location.
> >>
> >> Lets suggest that a position was reported, with a speed of 60 mph, and
> >> a heading of 90 degrees. After one minute, the dead
> >> reckoned position should be 1 mile east of the reported location.
> >>
> >> The way it is implemented, if I stop driving east after 30 seconds,
> >> the DR position would return back to the last reported location. If I
> >> were to turn south and drive for 1 minute at 60 mph (without sending
> >> an updated position report), there would be a DR object 1 mile south
> >> of the originally reported position.
> >>
> >> Now, if this instantaneous line were to originate from the current
> >> location, it would still be wrong. The line leaving my current
> >> location would not be a dead reckoned position, but rather a projected
> >> location for a future position report based on the current speed and
> >> course, projected into the future the amount of time since the last
> >> reported position.
> >>
> >> When Lynn gets it straightened out, you'll see something interesting
> >> happening. As Lynn said, if you continue in a straight line at a
> >> constant speed, you won't see the projected icon. If the road turns,
> >> or you change speed, then you'll see the projected (DR) icon continue
> >> along the last reported vector. Once the Genius settings determine
> >> that you've strayed too far, a new position report will be sent, and
> >> the DR icon will start moving away from the reported position again.
> >>
> >> James
> >> VE6SRV
> >>
>
• % of Genius I hate it when the % of Genius is low. I either go home or grab more coffee!
Message 4 of 25 , Apr 1, 2011
"% of Genius"

I hate it when the % of Genius is low. I either go home or grab more coffee!
• ... And, since this IS Florida we re talking about, the vehicle slowing down in a straight line for a long distance would probably be a Mercury Marquis, in the
Message 5 of 25 , Apr 1, 2011
On 4/1/2011 2:21 PM, Lynn W Deffenbaugh (Mr) wrote:
>
> If you slow down (still in a straight line, we can do that here in
> Florida for long distances),

And, since this IS Florida we're talking about, the vehicle slowing down
in a straight line for a long distance would probably be a Mercury
Marquis, in the center lane, with the turn signal flashing, and totally
oblivious.

(Sent from a fellow Florida resident, who may indeed be in the center
lane himself... :) ).

Gary Sanders WB0BZR
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