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Garmin GLO Bluetooth GLONASS receiver
Marvin Hlavac
A Garmin bug that works in your favor! : - )

Boyd, thanks for sharing your first experiences with your GLO.
Boyd
My pleasure Marvin. Feel free to ask any questions. There is a real lack of info on this device out on the net. Using it today, I am really pleased - It makes Mobile PC a pleasure to use. It connects instantly - before the Mobile PC warning screen even appears. Map is much more responsive in track up mode.

Running a new battery test on the Slate right now under the same conditions as my previous test with the USB GPS. Will see if I get better battery life using bluetooth vs USB. Almost 3 hours into the test now with 44% battery remaining so I think the Slate is going to run longer with the GLO than it did with the USB Microsoft/Navation stick.
Marvin Hlavac
Boyd, does the GLO come with a utility software that would allow users to change the default 10Hz to a different refresh rate, for example 1Hz, to enable compatibility with software, such as Microsoft Streets & Trips, which doesn't handle higher refresh rates well?
Ken in Regina
Boyd is definitely not getting 10Hz refresh from the GLO if it's working through a virtual port at 4800bps. Way back when we were testing various refresh rates with programs that are capable of supporting the higher connection speeds, Terry and I did some back of the envelope calculations to determine what COM port speed was needed to support the various refresh rates. It seems to me that you won't get more than 1HZ, or 2Hz at most, through a 4800bps connection.

I don't recall the numbers now. They are somewhere on the site but I don't even recall what section they were in. But I'm pretty sure that you needed to be up around 19.2kbps or 38.4kbps to get 5Hz through.

...ken...
tcassidy
Maybe that was why Boyd got a communications error in Ozi moving map mode. From our previous experience, i'll bet S&T would find the GPS but wouldn't work, complaining of faulty data.

Terry
Ken in Regina
I think you're right, Terry.

Here's a link to one of the messages discussing the refresh rate versus COM speed question:

http://www.laptopgpsworld.com/3933-i-blue-gm-2-usb-gps-receiver-p3#post33736

4800bps only gets you 1Hz refresh rate. At 1Hz it's already using 95% of the available bandwidth to transmit all the data once per second.

You need to go to 38.4kbps just to get 5Hz. It's using 65% of the available bandwidth at 5Hz refresh rate so you would not be able to get 6Hz without a faster port speed.

...ken...
tcassidy
Since 95% of 4800 bps is used for a 1 Hz refresh rate, I would assume you need about 4560 bps per Hz. Since I know GMPC can handle 57600 bps, it makes sense that it can deal with a 10 Hz update rate which would be around 45600 bps.

I guess the question is does it make any difference at speeds under 100 mph. The accuracy could be due to the availability of more satellites in many situations because of GLONASS or just a factor of the chipset used.

Terry
Boyd
Quote:
Originally Posted by Marvin Hlavac
Boyd, does the GLO come with a utility software that would allow users to change the default 10Hz to a different refresh rate
Nope, it's a black box with a pushbutton. No software to control it. In a way, that's the beauty of it - nothing to configure.
Boyd
Quote:
Originally Posted by tcassidy
Maybe that was why Boyd got a communications error in Ozi moving map mode.
I think so Terry. Ozi reported communication at 4800 baud, GMPC doesn't tell you what the settings are. But it didn't seem to work at all in Ozi even though the config said it was recognized. I also tried manually changing the speed to the max (115k?) and the config didn't complain. But it still gave me a communications error.

But really, this was the result of about 2 minutes of messing around with no attempt to troubleshoot. I will look into this in more depth soon, maybe try some other software on the slate.
tcassidy
I am not familiar with Ozi Explorer. Are you saying you changed something internally in that software to 115.2k and it still didn't work?

I'm definitely going to get a GLO next month to test against some other GPS devices I have. Sounds like a great device and lots of software to try the 10 Hz with even if I'm not a pilot!! I'm also pretty sure that GPS Gate could deal with the refresh rate and allow it to work with other programs.

Terry
Boyd
Quote:
Originally Posted by tcassidy
I guess the question is does it make any difference at speeds under 100 mph. The accuracy could be due to the availability of more satellites in many situations because of GLONASS or just a factor of the chipset used.
Clearly it isn't "needed" for anything with Mobile PC. But I like the way the moving map looks in track up mode, much more fluid and responsive than what I saw with the Microsoft USB stick. Sort of like the difference between newer generations of the Nuvi like the 3xx0 series and old models like the 7x0 series. But I suspect the Nuvi only receives one position update per second, and is just extrapolating your position and refreshing at a higher frame rate using the graphics hardware.

Look at the tracklogs I posted. The Montana is running full speed and recording one point per second. GMPC is using some formula of speed vs distance to determine when to record track points (like the automatic setting on the handheld), and that results in less than 1 point per second. So there's no advantage to the higher data rate for track recording. That's a shame, because that might be an advantage. I want to find some other software to record the full data stream, just out of curiosity.

Another thing that interests me would be software that supports waypoint averaging. You would get 10x the number of samples with the GLO.

And look at the way Garmin lists the GLO accuracy. Very simple and straightforward with no range of values or disclaimers:

https://buy.garmin.com/shop/shop.do?pID=109827#specsTab

Accuracy: 3 meters

They no longer even publish accuracy specs for any of the handhelds, either on the product page or manual (unless I'm missing something). Older devices like the 60csx have specs in the manual - see page 91 here for example:

http://static.garmincdn.com/pumac/GPSMAP60CSx_OwnersManual.pdf

Accuracy
GPS: <10 meters (33 feet) 95% typical
DGPS: 3-5 meters (10-16 feet) 95% typical
Boyd
Quote:
Originally Posted by tcassidy
I'm also pretty sure that GPS Gate could deal with the refresh rate and allow it to work with other programs.
That's also what I was thinking. But I prefer to keep it simple and not use GPSGate unless it's needed. The mighty atom processor in the Slate doesn't have a lot of CPU cycles to spare.

Ozi has several configuration screens where you can manually set parameters. That doesn't mean your choices will necessarily work of course. It worked fine with the Microsoft GPS so I never really dug very deep.
Boyd
Just had another play and got OziExplorer to work with no problem. Been a long time since I used that program (I'm actually more familiar with the barebones OziExplorer CE which runs on Windows CE devices).

Anyway, the user interface is pretty confusing. My problem was really basic... you have to choose the "Start NMEA communication with GPS" command from the menu before anything works. That's why there was a data error... it wasn't reading any data.

When it automatically scans the ports for a GPS, it counts up starting with 4800 baud and stops if it finds anything. So the software never even tries the higher speeds. But you can manually enter any value you like on another tab of the config window. I set it to 9600 and then 115,200 and everything continued working fine.

I'm just here in the house, so I can't tell if it made a difference. I think there are pretty extensive tracklog config settings, so I will check this out tomorrow and see if it will record at 10hz. Also will see if it does waypoint averaging.

It's a pretty feature-rich program, but not always so "intuitive".
Marvin Hlavac
Quote:
I'm also pretty sure that GPS Gate could deal with the refresh rate and allow it to work with other programs.
I'm not so sure about that. I think GPS Gate helps if navigation software cannot deal with the output baud rate of a USB GPS receiver (not needed for BlueTooth connected units), but GPS Gate I think does nothing for refresh rate software/hardware incompatibility.
Boyd
I just fired up GPSGate for a quick test. It scanned and did not find a Bluetooth GPS but did find the GLO on COM6, just like Ozi. So I started nRoute and it immediately recognized the virtual Garmin device on COM1. It is working here on my desk and showing my position correctly, with accuracy ranging between 9 to 11 feet on the Satellites data tab. But it only shows reception from 7 satellites, so I'm not sure if that's correct. Quitting from nRoute and GPSGate, I started up Mobile PC again and it shows 12 satellites.

Anyway, it is definitely working with nRoute. I don't know if GPSGate was adjusting the refresh rate or if nRoute is able to deal with that itself. Will try to give this a road test later. If I record a track it might give some clues about what is really happening.

Mobile PC, OziExplorer and nRoute were the only programs I really used on this tablet before, and they all work with the GLO, so that is pretty cool.
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