REVIEW COMMENTS: SysOnChip CF Plus GPS

david76 · Occasional Visitor Joined: Mar 16, 2004 Posts: 3

Bought and received my Syson GPS CF Plus and TomTom Nav 2 this week. I'd read here about the lag but assumed the firmware would be fixed by now. Have tried both NMEA4800 and Sirf38400 (which both work) but there's a consistent 5+ sec lag in either mode under normal town driving speeds (30mph).

I have an 0312****** serial number and using TomTom Nav 2 (GPS v2.09 302/393 and TTN 2.24.2 (363)). I have no other Nav software to test with but from reading this thread I think I understand it's an Xtrac issue.

Is there a way to update our own firmware or disable Xtrac, if that's the issue?

David

Dave · Posted: Wed Mar 17, 2004 8:14 am Post subject:

There were early firmware revisions that did have bad lag, but lag per se isn't a firmware issue. It's how XTrac is designed. Rather than discarding the bad satellites, when you're in hard to reach signal places (which the GPS won't actually know that you are), it will rather than discard the bad signals, it will try and utilise them. If you have more bad signals than good, then yes you could see positional errors and latency.

It also depends on whether you have a UV coated windsceen, if you do then you'll notice a lot more latency and lag because you will never have a great amount of good sats on a UV coated windscreen.

No way to disable XTrac it's in the chip.

jeffx · Occasional Visitor Joined: May 15, 2004 Posts: 7

Will you be reviewing the Plus II card?
http://www.buygpsnow.com/item.aspx?itemid=303

Dave · Posted: Sat May 15, 2004 7:46 am Post subject:

We will, but I can't say when. Technically though there is not an XTrac V2 chip, there are only tweaks to the software that are incorporated within the chip and it's still designated XTrac.

Many companies are labelling this as XTrac V2 when SiRF themselves haven't labelled it as a major upgrade.

jeffx · Occasional Visitor Joined: May 15, 2004 Posts: 7

Got my SysOn CF GPS Plus II card and have to say I LOVE IT! There is no lag, location is right on and it is super sensitive. It's also so small, I have just been leaving it in my iPaq 2210 all the time.

To give an idea of how sensitive it is, I was able to lock on to 7 satellites in my car, in my masonry garage, with the garage door closed. Wow!

Both Semson's and and BuyGPSNow have really good iGuidance packages on sale now with this GPS, so check them out.

TheSquare · Occasional Visitor Joined: Apr 07, 2004 Posts: 12

I have been impressed with the sensitivity of the SysOnChip. It got a signal while I was walking in the Lakes (coming off Scafell Pike) when the eTrex Vista didn't!

latinware · Occasional Visitor Joined: Apr 23, 2004 Posts: 11

My SysOnChip GPS Plus works great, I'm using NEMA since it's more reliable, besides I have used many apps like Vito's Navigator II, SmartMap, GPS Dash and now Megalith GPS Tuner 3.5 which is a wonderful software. I used this soft with my own maps (I live in Colombia). So, remember for people that are having problem with this brand thatt some times the trouble is with the software and not the hardware. Thumbs Up

Ref: iPaq H5450 + SysOnChip + GPS Tuner 3.5
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latinware
H5450
SysOnChip GPS Plus
GPS Tuner

MarkHewitt · Posted: Wed Nov 17, 2004 1:25 pm Post subject:

I've been having a few problems with my unit, which I bought just a few weeks ago, it is the 512mb CF card version.

It was working fine for a couple of weeks but recently, in doing the exact same journeys I've been doing before it has been off by quite some margin. It has been placing me in streets about 5 miles away, my speed according to it seems to be erratic, I was doing 250mph at one point! It doesn't just seem to be searching for a signal, I drove for about 20 minutes one time and it consistenly placed me about 2 miles to the west of my true location.

I've found that when exhibiting this behaviour if I turn my Ipaq 2210 off for a few seconds, then back on and reenable the GPS it finally gets the accurate location, but it's often meant I'm about 15 minutes into my journey before I can get an accurate poisition.

Johnson · Occasional Visitor Joined: Dec 03, 2004 Posts: 18

Iif you got about 100m to 150m delay, it is time to switch the datum of your map, which is saved in your TomTom. I guess the map is using a local projection.

Johnson

DavidW · Posted: Thu Dec 09, 2004 11:16 am Post subject:

TomTom maps, like many maps designed for GPS usage, use WGS84, the "native" GPS datum.

Whilst recent SiRF firmware GPSes do have switchable datums, I've never come across one set to anything other than WGS84, particularly by default.

Lag problems with SiRF GPS hardware are usually either down to using XTrac version 1 firmware or SiRF binary mode at a low serial port speed like 4800 bps.

David

hanu · Occasional Visitor Joined: Mar 03, 2005 Posts: 2

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