Holux GR-231

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

Just got one of these. TTN3 seems to connect fine using NEMA or SiRF Bluetooth protocols. Are there ANY pros/cons using one over the other?

W

DavidW · Posted: Fri Nov 19, 2004 5:32 pm Post subject:

There's really not much in it. SiRF may produce a slightly faster response, which is a double-edged sword, in that you'll notice a brief loss of lock in SiRF mode whereas in NMEA mode you won't see anything.

I tend to keep my GPS in SiRF mode because that way I can see what's happening with SBAS on (you don't see the GPS attempting to find an SBAS satellite in Winfast Navigator or similar in NMEA mode). However, that's a very minor concern, particularly as EGNOS now looks likely not to be in service until April 2005, and SBAS isn't needed for in-car navigation anyway.

The other problem with switching to SiRF mode is that some GPSes can be tricky to switch mode, and a lot of software only works in NMEA mode.

David

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

Thanks (an apologies for cross-posting in a way that's a no-no).

W

DavidW · Posted: Fri Nov 19, 2004 5:46 pm Post subject:

Don't worry about it - we feel that stopping multi-posting makes the forums easier to use, also it saves you getting two separate discussions on the same questions.

Maybe it would help if we posted a tutorial somewhere on posting links - as there's plenty of times that people would want to post links, but it's not the most obvious thing. This is something that never seems to get to the top of the "to do" list. There's always more work to be done, especially by the team members who are not only participating in the forums but also writing articles and reviews.

Most of the knowledgeable posters who read regularly do so by the "posts since my last visit" screen so they'll notice anything of interest irrespective of which forum is used.

David

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

DavidW · Posted: Sat Nov 20, 2004 6:09 pm Post subject:

The difference is only in the protocol. SiRF mode typically sends more data more frequently. In a typical NMEA configuration, information on the satellites being used is only usually sent every five seconds.

In either case, the GPS is doing all the work of positioning - it's not down to the application to decide what satellites are used (unless it chooses to get the raw PRN data and do all the work for itself, which is possible in SiRF mode and useful for survey type application on the cheap, but which TomTom GPS doesn't do).

David

	PocketGPS
	Web