View previous topic :: View next topic |
Author |
Message |
gune Regular Visitor
Joined: Mar 15, 2005 Posts: 174 Location: Colchester, UK
|
Posted: Sun May 28, 2006 4:15 pm Post subject: does gps data transfer baud rate matter ? |
|
|
hi:
does gps data transfer rate matter with regards to speed of location updating etc? |
|
Back to top |
|
|
mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
|
Posted: Sun May 28, 2006 5:34 pm Post subject: |
|
|
Not really, the NMEA protocol sends very small data packets through to the PDA/ phone etc. Even at 4800 Baud it works quite well, at the higher speeds the port is left for longer with nothing to do.
The largest overhead that can delay the screen refresh is the actual redraw of the image, also enabling POI's can seriously slow the PDA down. VGA equipped devices suffer as the processor has four times the amount of work to do when compared to the more usual QVGA screens.
If you look at the NMEA sentences transmitted over a single second burst you will find its not too much in terms of data bits, you need a program to display the raw NMEA data, then look for the transmitted sentences, the text strings start with a $ symbol, then contain the Lat, long, time, date, speed, heading etc. I use my own program for doing this but it will only work with the Widcomm Bluetooth stack, any device using Microsoft (WM2005) will not work. - Mike |
|
Back to top |
|
|
gune Regular Visitor
Joined: Mar 15, 2005 Posts: 174 Location: Colchester, UK
|
Posted: Sun May 28, 2006 7:48 pm Post subject: |
|
|
hi mike:
Quote: | The largest overhead that can delay the screen refresh is the actual redraw of the image, also enabling POI's can seriously slow the PDA down. VGA equipped devices suffer as the processor has four times the amount of work to do when compared to the more usual QVGA screens.
|
so does it mean the x51 would be slower or of same speed in redrawing the map when compared with standard one like acer n35? ( even though taking in to the account of higher pocessor speed and higher rom and ram?) |
|
Back to top |
|
|
mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
|
Posted: Sun May 28, 2006 7:54 pm Post subject: |
|
|
It can do, it will depend how well designed the hardware is and how much spare memory the program has avail for it to use, the bigest problem in slowing the hardware down is normally down to the POI's being enabled, rather than set to "warn when near" - I wouldn't worry too much about the screen refresh rate, you only notice the slow down when comparing units next to each other, and as they are different devices/ processors etc it is an unfair comparison. The basic fact of the screen containing four times as many pixels does give the processor more work to do though - Mike |
|
Back to top |
|
|
neil01 Frequent Visitor
Joined: May 06, 2005 Posts: 902 Location: Leeds
|
Posted: Sun May 28, 2006 8:08 pm Post subject: |
|
|
It is also worth noting, that on some equipment it is not possible to increase the baud rate - it simply will not work. The default value also being the maximum value. |
|
Back to top |
|
|
philpugh Lifetime Member
Joined: Dec 28, 2005 Posts: 2003 Location: Antrobus, Cheshire
|
Posted: Thu Jun 08, 2006 5:44 pm Post subject: |
|
|
gune wrote: |
so does it mean the x51 would be slower or of same speed in redrawing the map when compared with standard one like acer n35? ( even though taking in to the account of higher pocessor speed and higher rom and ram?) |
The speed of redraw will be impacted more by speed of the memory than the processing overhead from the serial port. In fact it could be argued that faster data rates increase processing overheads - it depends on exact implementation. What with all the other overheads going on in WM5 I wouldn't worry about it. An AXIM is more than capable of running TT5 or topo-mapping at speeds likely to be encountered on (or slightly above) :D the earth.
NMEA mandates 4800 baud as it is a marine standard for inter-operability between ship-bourne navigation aids (eg GPS, Chart Plotters, Depth Measuring etc).
SiRF (the protocol) addresses the additional capabilities of modern GPS units and, naturally, can work at higher bit rates.
Phil |
|
Back to top |
|
|
|
Posted: Today Post subject: Pocket GPS Advertising |
|
|
We see you’re using an ad-blocker. We’re fine with that and won’t stop you visiting the site.
Have you considered making a donation towards website running costs?. Or you could disable your ad-blocker for this site. We think you’ll find our adverts are not overbearing!
|
|
Back to top |
|
|
|