Re: GPS Receiver .................
 

I like the idea of a logger. But I also like the idea of a 51 channel (The new Freedom 2000) receiver as opposed to the 16 channel.
The sensitivity looks about the same on both. Does the number of channels and the All -in-Sight on the Freedom make a difference in and under dense pine cover?

Thanks

Re: GPS Receiver .................
 

Another vote for GlobalTop MTK based bluetooth GPS receivers. Excellent performance - time to first fix is great, superior performance in the urban jungle. So glad I went that route.

Matthew

Re: GPS Receiver .................
 

5Hz - You can't go much distance, but you can change angles. This is where I noticed it most, going around a cloverleaf interchange. A 1Hz would update every 60 degrees, the 5hz about every 12. The speed measured is also updated faster or slower (one Globaltop product is a "heads up" display with speedometer, and you really want that going at 5hz).

I also have a datalogging application which makes use of the extra resolution.

But just for position, it is probably not worth it to go at 5hz, but then even .2Hz might be enough.

Re: GPS Receiver .................
 

A 51 channel receiver won't help much. There aren't that many satellites in orbit, much less that many in view at any one time. That's just marketing hype. You're lucky to see even 15 at a time.

Re: GPS Receiver .................
 

Hey I have the Navicore personal Nav kit I got it from amazon for 224. Ive been using it and it is great. Maemo Mapper is nothing compared to the navicore kit. navicore has much more features plus you dont need to download maps it comes with a 2gb mem card with preinstalled maps. BUT for some odd reason I cant use it (including Wayfinder) when I upgraded to os 2008. so I went back to os 2007.

Re: GPS Receiver .................
 

Sorry, I don't know and I bought the WBT-201 last autumn, so didn't have much dense cover yet. Still, I do orienteering runs and the reception also under conifers was pretty good. My naive (i.e. don't have much comparisons) impression is that the sensitivity is very good.

Tilman

Re: GPS Receiver .................
 

But that's not why it's got 51 channels.. or even 32, or 20. It's for a different reason: Shorter initial lock time. The GPS receiver starts by scanning for satellites, it doesn't know which ones are visible, on which frequencies, or where they are, or maybe even where it is itself (which all makes it difficult to take into account the doppler effect on the frequencies). So it starts out by looking on as many channels as it can, if it doesn't find any it maps its channels to another set of frequencies, and so on. Eventually it'll lock on to a satellite (or a set of satellites, depending), and start downloading initial ephemeris data, and precision ephemeris data.

From then on it goes on with better calculations until it finally knows everything and just listens to those 6-12 satellites it can usually see at the same time.

With a large enough number of channels it can simply look out for all possible satellites and frequencies at the same time, i.e. it'll need only one search cycle. Or fewer cycles, in the case of 20-channel receivers.

The net result is that the more channels, the shorter initial lock time. That's why there's been a transition from 12 channels to 20 channels to 32 channels to 51 channels. There's a big difference between a 12 channel receiver and a 51 channel receiver (I own both types).

Re: GPS Receiver .................
 

Yes, but 51 isn't likely much better than 20 or so. My cheap F-Tech locks on in about 10 seconds, often less. It's not worth paying more money for a couple of seconds quicker, if that. It's still marketing hype, IMO.

Re: GPS Receiver .................
 

51 _is_ better than 20.. it can do the search in one cycle most probably, where with 20 it'll usually take two or three at least. Anyway, when it locks in 10 seconds it is clearly good enough. But it depends a bit on location, and if it's a cold-start situation or not (where again more channels are good). However, 32 channels are probably more than good enough for most purposes - the sensitivity matters more. I paid in any case just $55 for my 51-channel Holux so I'm a happy camper. :D

Re: GPS Receiver .................
 

Thanks to this thread I have a iBlue- 737 on it's way. I don't quite know how to use the whole thing, but I'm sure it will be fun figuring it out.