Ublox Dead Reckoning GPS - Page 2

Naamanf · 01-10-2006, 01:11 AM

I don't know about the UBLOX but SIRF III receivers track at about -159DB. Some of the chips coming out track at -184 and below. Thats over 100 times less signal strength required to track.

MobiTekLink · 01-12-2006, 09:13 PM

Quote: Originally Posted by Naamanf

I would wait till the new more sensitive GPS receivers become available.

I doubt sensitivity would do much in some/almost all cases, the problem in situations like NYC with the tall buildings is that the GPS signals bounce all over the buildings and the receiver has no idea where it's at!
This makes for iG or any GPS software to start going in circles like crazy and all the routing is useless.
Therefore the need for an overiding system that would tell the receiver that it is still going in a straight or whatever direction is fundamental.
Also what good is a receiver under a tunnel? For me, I've used about 5 or 6 different receivers and for most purposes they work fine, until they get to Manhattan, when they do they all go nutz! For Colorado, I think you'll be fine with any receiver.

Edit: By the way, I have a SIRFIII and I have the same issue as with the BU-353, spinning around in NYC!! And not great noticeable change in reception.

Chris31 · 01-12-2006, 11:13 PM

There was an article somewhere about this, a SIRF3 against an old GPS with DR.

It was something like this...although the SIRF3 is showing 6 sats with 3D fix, it still doesnt really know where it is. The GPS with DR show 0 sat but can still navigate reliably.

Ill post the link if I find the article again.

Scouse Monkey · 01-13-2006, 04:17 AM

Quote: Originally Posted by Chris31

There was an article somewhere about this, a SIRF3 against an old GPS with DR.

It was something like this...although the SIRF3 is showing 6 sats with 3D fix, it still doesnt really know where it is. The GPS with DR show 0 sat but can still navigate reliably.

Ill post the link if I find the article again.

OMG! i nearly fell off my chair! You actually have something good to say about this project!

I vote DR over more sensitive persoanlly but i would like a more accurate inertial system but that would cost quite a bit

Inertial is much more accurate than GPS will ever be. DR as used in these modules is a trade-off though for cost and simplicity . some day solid state accelerometers and gyros will be cheap enough to do it right though - probably in a year or 2.

MobiTekLink · 01-13-2006, 03:57 PM

Quote: Originally Posted by Scouse Monkey

OMG! i nearly fell off my chair! You actually have something good to say about this project!

I vote DR over more sensitive persoanlly but i would like a more accurate inertial system but that would cost quite a bit

Inertial is much more accurate than GPS will ever be. DR as used in these modules is a trade-off though for cost and simplicity . some day solid state accelerometers and gyros will be cheap enough to do it right though - probably in a year or 2.

Well, if price wouldnt be an issues I have a list of things that I would rather have, including my better half! Im sure sh'ed agree LOL....
Life is full of compromises,,, I'm just hoping that we can buy a nice receiver w/ DR built into it for less than $200 bucks sometime this year....
Tha'ts the only thing that OEM navigation has over our system and itz a big one!!

jcdillin · 01-13-2006, 04:55 PM

The only complaint I have on our systems over OEM navigation systems is the jerky movement, if we could get the gps software people to actually support a refresh rate of higher than 1hz we would be in business.

MobiTekLink · 01-13-2006, 06:38 PM

Quote: Originally Posted by jcdillin

The only complaint I have on our systems over OEM navigation systems is the jerky movement, if we could get the gps software people to actually support a refresh rate of higher than 1hz we would be in business.

HEHE,,, I was think ing about that yesterday when I was on my friends' S500, the movement is more natural than iGuidance....

cherrybomb · 01-13-2006, 06:50 PM

I thought that most GPS software just acted upon the NMEA sentances as they arrived from the device?

Or is it a message/response mechanism?

Something like;

Software: GPS Give me NMEA Sentance
GPS: Here you go <NMEA Sentance Here>

As opposed to;

GPS: Software, I have a NMEA Sentance for you
Software: Thanks, I'll take that

My impression was always that the jerkyness was because there was only so much NMEA data available to work with, and it updated at a certain rate.

For instance, the specs on my Holux GM-210 say that it only provides updates every 1 second.

kbyrd · 01-13-2006, 08:20 PM

Quote: Originally Posted by cherrybomb

I thought that most GPS software just acted upon the NMEA sentances as they arrived from the device?

Or is it a message/response mechanism?

No, GPS mice dump data to the serial port. It's my understanding that lots of NMEA only devices dump at 1Hz, so lots of GPS software reads at about 1Hz. With Sirf chipsets, you get a much higher data rate, software just hasn't caught up.

Chris31 · 01-13-2006, 09:43 PM

Tomtom 5 (PDA) have a built in smoothing function that fill in those missing gap while the GPS receiver is updating. It predicts the car position between those 1 sec intervals.

The results is...a very smoth 3D animations.

Why the big company with all the resources cant do the same for a machine thats far more powerful than a little PDAs...no idea here.

Chris31 · 01-13-2006, 09:47 PM

Quote: Originally Posted by Scouse Monkey

OMG! i nearly fell off my chair! You actually have something good to say about this project!

We all wished you did

DeltaFX · 01-14-2006, 03:11 AM

Garmin sells a serial (or USB, can't remember) GPS working @ 5 Hz.
US market only,

kbyrd · 01-14-2006, 09:03 AM

Quote: Originally Posted by DeltaFX

Garmin sells a serial (or USB, can't remember) GPS working @ 5 Hz.
US market only,

Ok, but you would still be using software that update at 1Hz.

jcdillin · 01-14-2006, 09:11 AM

Quote: Originally Posted by DeltaFX

Garmin sells a serial (or USB, can't remember) GPS working @ 5 Hz.
US market only,

I can get a 8hz module right now, but it would do me no good as all software packages still read 1hz

cherrybomb · 01-14-2006, 11:29 AM

Do we know the update speed of the uBlox module?

It's looking like I'm going to have to write a plugin for one or more front ends for MapPoint, since that's the package I have.

Since I'll be using uBlox, and probably my own software, I could account for the right update speed.

Hmmn.. Just looked at the site, out of curiosity, and it claims an update of 1hz..

It claims that the DR stuff updates at 40hz though? Interesting.

specs