OTUSB not smart beaconing while walking
Looking for any ideas on how to get the OTUSB with internal GT-525 GPS receiver to generate reasonably consistent smart beaconing while walking -- as yet I've been largely unsuccessful. Using beaconing parameters (INTERVAL 60 and SMARTBCON 6 84 90 20 5) captured NMEA output shows the following:
While walking (~2-4mph), no beaconing whatsoever occurs during a variety of corner turns (range 45 to 180 deg). While clearly significant course change data is being generated (as per the $GPRMC sentences) that seemingly should trigger at least a few corner beacons, the only thing observed is a few beacons on straightaways.
In contrast, during a driving test at just slightly faster average speeds (~3-10mph) using the same parameters, smart beaconing DOES occur on all turns.
A bit baffled on what needs to happen to make the unit smart beacon while walking as opposed to driving. Appreciate any feedback.
- On Thu, Jun 5, 2014 at 2:03 PM, kirkmendenhall@... [tracker2]
> Looking for any ideas on how to get the OTUSB with internal GT-525 GPS receiverI've taken the liberty to edit your email, copying and pasting your
> to generate reasonably consistent smart beaconing while walking
sentences into a new paragraph.
> A bit baffled on what needs to happen to make the unit smart beacon while walking as opposed to driving.Do you see the answer? You need to walk faster!
> While walking (~2-4mph), no beaconing whatsoever occurs during a variety of corner turns
> In contrast, during a driving test at just slightly faster average speeds (~3-10mph) using
> the same parameters, smart beaconing DOES occur on all turns.
Here's what the SmartBeacon parameters map out to...
SMARTBCON <low speed> <high speed> <low rate> <angle> <time>
INTERVAL 60 and SMARTBCON 6 84 90 20 5
So, what this means that if you are moving at 4 MPH or slower, the
OTUSB will beacon every 90 seconds. As you increase your speed up to
60 MPH, the beacons will get slightly closer together, happening every
60 seconds at 60 MPH or faster. (The speed units are 32 cm/second when
you set them this way.) With these settings, the speed varied portion
of SmartBeaconing is almost disabled.
CornerPegging looks at the angle, which is modified by turn_slope, and
speed to determine when a critical course deviation has been achieved.
I can't find the source code for the OTUSB right now, but the way that
SmartBeaconing was defined, was to look at the speed, and if you are
below the slow speed threshold, beacon at the slow rate, and there's
nothing else to do. CornerPegging only gets implemented once you are
above the slow speed threshold. The basic premise being, if you are
stopped, why bother looking to see if you are turning around?
It really isn't baffling when you look at what the unit is being asked
to do. SmartBeaconing was developed at a time when all that was
available was time based beaconing. People would set their APRS rig up
in the car to beacon every 3 minutes. (This was deemed to be an
acceptable value at the time) These APRS trackers in the vehicles
would beacon every 3 minutes, day or night, whether zipping down the
interstate at 70 MPH, or sitting in the driveway for hours on end.
SmartBeaconing looked at the rate of speed the unit was travelling,
and as the speed slowed, the beacon rate spread out. Once the vehicle
was stopped, the unit spaced position reports out at the slow rate.
There are some people that seem to believe that SmartBeaconing was
designed produce more position reports as speed increases, whereas
it's exactly the opposite. SmartBeaconing was designed to DECREASE the
number of position reports as speed decreases. CornerPegging was added
in to be able to catch significant changes in course, and to report
those as they happened.
All of this was designed with motor vehicle traffic in mind. Trying to
use SmartBeaconing at extremely slow speeds is problematic because of
the accuracy of GPS position reporting. You can't get a very accurate
speed reading at slow speeds because of the inability of the GPS
receiver to resolve a highly accurate location. If you are standing
perfectly still, you will probably see minor variances in the location
reported. This makes it look like you are moving, even though you are
standing still. If that GPS "jitter" shows motion in the 2-3 MPH
range, and you are walking at 3 MPH, you could end up looking like you
are walking anywhere between 0 and 6 MPH, wiggling back and forth
across your actual track. In a vehicle moving significantly faster,
this minor variance is hardly noticable, but when walking, it is a
significant fraction of the desired information.
If you drop your slow speed down far enough to try and make
SmartBeaconing work at extremely low speeds, you'll find it providing
false reports a whole bunch due to the "jitter".
If you want to capture detailed tracking events while walking, rig up
a BeaconNow! button that can be triggered to send a position report
when the button is pressed.
- Hi James,Excellent info! My settings were based on the following from the OTUSB manual, with my specific [values] inserted:"When stopped or moving at a speed below the low speed setting [6kmh/4mph], the trackerwill transmit at a fixed rate [90 sec] determined by the lower rate setting. Above the specifiedhigh-speed threshold [84kmh/60mph], the higher rate setting [60 sec] is used. Between thesetwo extremes, the interval varies between the low and high rates depending on the speed.A turn angle [20 deg] can also be specified to cause the tracker to transmit when turning. Thefinal setting ensures that the tracker will never transmit more often than the specified interval[5 sec], regardless of speed and turn rate."Since the highlight about corner beaconing said nothing about a speed dependency, I assumed (always dangerous of course :-) that corner beacons would be triggered strictly on the basis of turn angle, regardless of speed. Key thing I was unaware of is your comment that "CornerPegging only gets implemented once you are ABOVE the slow speed threshold."Yes, I can confirm my slow speed NMEA data shows more "jitter" which I anticipated and assumed might cause some undesired beaconing and/or inaccurate position reports based on current GPS technology. In any case, I will definitely adjust my SB parameters per your advice, do some further testing and report back.Many thanks for the feedback.KirkK7KPM
- James, your advice was spot on. Since my typical speed is 3.5-4mph once I dropped SMARTBCON <low speed> to 4kmh (2.5mph) the tracker began beaconing consistently on turns while walking, thx!Now on to a few other challenges with this unit (feedback from anyone appreciated):1) Beacons are accepted by APRS network roughly 10% of the time when outside under clear sky conditions/unobstructed view to repeater. Interestingly, when indoors where there is more shielding, success ratio actually increases to around 50%, better but still not great. Have tried increasing TXDELAY to 500 msec and toggling SWDCD to no effect. Suspect tracker default TXLEVEL (255) may be too high. Since I don't currently have access to a deviation meter or another receiver any suggestions what approx TXLEVEL would provide better modulation with a Wouxun HT?2) USB connection drops frequently. Have tried multiple cables and it happens regardless of which USB port used on the PC running Win 8.1 (no driver install issues following instructions on the Wiki). Seems to happen more often when toggling away from Hyperterm to another app for a few minutes; then when returning, connection has been lost requiring physical USB cable disconnect-reconnect, sometimes several times.3) Slow GPS lock time. The GT-525 has advertised cold start lock time of 40 sec. Under unobstructed clear sky conditions my unit (mounted inside tracker) takes at least 80 sec, sometimes longer. Indoors, also has a tendency to lose sat lock much more easily than my cheapo TomTom GPS. This is the 2nd GT-525 in this tracker. Wondering if others have observed similar performance or if the internal mount may be a factor.Thanks all for any ideas!KirkK7KPM
- On Sun, Jun 8, 2014 at 3:25 PM, kmende@... [tracker2]
> 1) Beacons are accepted by APRS network roughly 10% of the time when outsidehttp://www.febo.com/packet/layer-one/transmit.html
> under clear sky conditions/unobstructed view to repeater. Interestingly,
> when indoors where there is more shielding, success ratio actually increases
> to around 50%, better but still not great. Have tried increasing TXDELAY to
> 500 msec and toggling SWDCD to no effect. Suspect tracker default TXLEVEL
> (255) may be too high. Since I don't currently have access to a deviation
> meter or another receiver any suggestions what approx TXLEVEL would provide
> better modulation with a Wouxun HT?
- Hi James, re (1) yes I was aware of that article, but as mentioned without access to a deviation meter or another radio for calibration I was hoping others might be able to share TXLEVELs that worked well with their HT's.Sorry, I guess items (2) and (3) were off-topic, should I re-post under new headings, or perhaps they are inappropriate for this forum?ThanksKirkK7KPM
- Kirk K7KPM wrote…
> without access to a deviation meter or another radio for calibration I was hoping others might be able to share TXLEVELs that worked well with their HT's.Using a deviation meter would be ideal, but you can get it pretty close by turning the level all of the way up and having the T2 send the tones while listening on another radio, and then turning the level down until it sounds quieter and then turning it down some more.
73 Keith VE7GDH
- On Sun, Jun 8, 2014 at 9:39 PM, kmende@... [tracker2]
> Hi James, re (1) yes I was aware of that article, but as mentioned without accessWell, you can try lowering the TX level and seeing if you get heard
> to a deviation meter or another radio for calibration I was hoping others might be
> able to share TXLEVELs that worked well with their HT's.
better. Work your way from high to low, record the max level that
works well, and the min level that works well. Split the difference,
and maybe a little lower.
Your unit is reporting that you are in Salt Lake City... aprs.fi shows
quite a few amateur radio operators running APRS in the area. Try
disconnecting your HT from the OpenTracker, and tune it to a local
repeater. Give a call out, and see if you can find another person with
a radio. You could meet up with them and have a listen to the
deviation of your HT when connected to the OT.
I'm always amazed at how isolated amateur radio operators can be in a
hobby that's all about communication.
> Sorry, I guess items (2) and (3) were off-topic, should I re-post underWhy would you assume they were off topic? Because I didn't respond
> new headings, or perhaps they are inappropriate for this forum?
with information about them? I don't know why your USB might be
dropping, and I don't have a GT-525 to know how it should respond.
Others may have answers.