Active Topics
-
Is there a section to talk about Java ME? Apps, etc. (0)
to General by Kalatti - 3 days ago -
Extra softwares in Sailfish using CLI, repositories, etc (117)
to SailfishOS by nieldk - 4 days, 21 hrs ago -
Firefox with Leste (6)
to Maemo 7 / Leste by teroyk - 5 days, 17 hrs ago - more...
 |
|
2008-08-02
, 22:46
|
|
Posts: 880 |
Thanked: 264 times |
Joined on Feb 2007
@ Cambridge, UK
|
#12
|
agreed, basically surf-iii is the safest bet, but the nemerix and q-starz ones with 32 channels are also good.
make sure if you do buy one from an ebay listing, you check that the photo matches the model number and lookup the model on the manufacturer's site to check specifications. when I bought my bluetooth GPS from ebay, I noticed some sellers were exaggerating the specifications somewhat!
BTW, the whole N channels stuff is a bit misleading. GPS doesn't have channels, all satellites broadcast on the same frequency, they use spread-spectrum with different codes to differentiate each satellite.
make sure if you do buy one from an ebay listing, you check that the photo matches the model number and lookup the model on the manufacturer's site to check specifications. when I bought my bluetooth GPS from ebay, I noticed some sellers were exaggerating the specifications somewhat!
BTW, the whole N channels stuff is a bit misleading. GPS doesn't have channels, all satellites broadcast on the same frequency, they use spread-spectrum with different codes to differentiate each satellite.
|
|
2008-08-03
, 21:53
|
|
Posts: 348 |
Thanked: 61 times |
Joined on Dec 2007
|
#13
|
It isn't channels per se, it's the number of satellites the unit can communicate with simultaneously. There are only a few in view at any one time anyway, and having 30-some-odd channels when there are only a dozen in view is just marketing hype.
|
|
2008-08-04
, 09:13
|
|
Posts: 880 |
Thanked: 264 times |
Joined on Feb 2007
@ Cambridge, UK
|
#14
|
Originally Posted by sgosnell
well, if you want to get really picky...
It isn't channels per se, it's the number of satellites the unit can communicate with simultaneously. There are only a few in view at any one time anyway, and having 30-some-odd channels when there are only a dozen in view is just marketing hype.
the gps receiver does not communicate with the satellites, it passively receives the data stream from them (it's actually a very low bit rate - only 50 bits/s), they do not transmit! each "channel" is actually a correlator which synchronises and decodes the data stream from each satelllite (spread spectrum, remember).
the satellites are in low earth orbit moving pretty quickly, so satellites move into and out of view all the time.
so you need, say, 12 "channels" to receive the active satellites and a number of spare ones to watch for satellites coming into view. since there are only 24 satellites in total, you only need 24 channels. however, since the GPS signals could be time-shifted reflections additional channels allow locking onto the same sat multiple times with different time shifts.
here's more about it.
http://wapedia.mobi/en/Special:Searc...Go&searchtype=
|
|
2008-08-04
, 17:13
|
|
Posts: 2,102 |
Thanked: 1,309 times |
Joined on Sep 2006
|
#15
|
It's also useful to have lots of parallel channels/correlators when you're trying to do a cold fix as you don't know which satellites you're supposed to be looking for.
 |
|
2008-08-04
, 19:52
|
|
Posts: 2,869 |
Thanked: 1,784 times |
Joined on Feb 2007
@ Po' Bo'. PA
|
#16
|
Originally Posted by speculatrix
^Right on!
well, if you want to get really picky...
the gps receiver does not communicate with the satellites, it passively receives the data stream from them (it's actually a very low bit rate - only 50 bits/s), they do not transmit! each "channel" is actually a correlator which synchronises and decodes the data stream from each satelllite (spread spectrum, remember).
the satellites are in low earth orbit moving pretty quickly, so satellites move into and out of view all the time.
so you need, say, 12 "channels" to receive the active satellites and a number of spare ones to watch for satellites coming into view. since there are only 24 satellites in total, you only need 24 channels. however, since the GPS signals could be time-shifted reflections additional channels allow locking onto the same sat multiple times with different time shifts.
here's more about it.
http://wapedia.mobi/en/Special:Searc...Go&searchtype=
BTW, my reference to channels was not meant to indicate any technological advantage. Only that it is a metric that, in my experience, is reported in most marketing spec sheets and seemed to separate first (or second) generation devices from second (or third) generation ones.
The older devices like SiRFstar II report 12 channels and the newer devices like SiRFstar III, NemeriX, or MTK receivers report 20 to 32 channels.
Conceivably, having the ability to receive more, unique data streams could increase battery life by reducing search times during first fix or when one of its primary satellites are lost or is in and out view such as in canyons created by buildings in large cities.
I don't doubt that the channel metric is a marketing tool. SiRFstar themselves made it such when the released their newer chip-set in order to differentiate it from their older one. The other manufacturers who entered the market after, seized this metric and designed for more or just simply posted, higher channel numbers.
Whether or not a unit is even capable of receiving these streams and processing the information simultaneously is beyond my knowledge.
It's always good to cross check your search results for any negative reviews.
|
|
2008-08-04
, 20:07
|
|
Posts: 27 |
Thanked: 10 times |
Joined on Jan 2008
|
#17
|
I love my Holux M-241. It acquires in less than 3 seconds, and it stores tracks even when the Nokia isn't connected. This is nice when I want to just record a ride and I don't need the actual mapping abilities.
It was able to store my entire ride from Orlando, FL to Knoxville, TN for the Honda Hoot at a resolution of 50ft between points. It only needed 2 batteries for the trip too. (I think it takes a single AAA)
It was able to store my entire ride from Orlando, FL to Knoxville, TN for the Honda Hoot at a resolution of 50ft between points. It only needed 2 batteries for the trip too. (I think it takes a single AAA)
 |
|
2008-08-09
, 17:14
|
|
Posts: 716 |
Thanked: 236 times |
Joined on Dec 2007
|
#18
|
I use a wintec G-rays-1
http://www.buygpsnow.com/wintec-g-ra...mount-834.aspx
It can do WAAS/SBAS at 5Hz and is really configurable, and it can do non SBAS at 10Hz. It can also do 1Hz. Fast acquisition, sensitive, and flexible.
If you just "want a gps", just get the cheapest you can find. There's not that much different in normal usage. If you want to use it for something more specific, then you can look for improved accuracy of WAAS, faster cold/warm fix, longer battery, faster rates, logging, displays, etc.
http://www.buygpsnow.com/wintec-g-ra...mount-834.aspx
It can do WAAS/SBAS at 5Hz and is really configurable, and it can do non SBAS at 10Hz. It can also do 1Hz. Fast acquisition, sensitive, and flexible.
If you just "want a gps", just get the cheapest you can find. There's not that much different in normal usage. If you want to use it for something more specific, then you can look for improved accuracy of WAAS, faster cold/warm fix, longer battery, faster rates, logging, displays, etc.
 |
|
2008-08-11
, 14:47
|
|
Posts: 3,397 |
Thanked: 1,212 times |
Joined on Jul 2008
@ Netherlands
|
#19
|
Originally Posted by lma
Can I use this kit with a N810?
Get the N800 Navigation Kit. It comes with (and costs about the same as) the Nokia LD-3W which is a pretty good and compact GPS receiver (Sirf III, I think), and you also get some goodies like a car charger, tablet windshield mount and memory card as well as the Navicore licence which is transferable to the Wayfinder "Map" application in OS2008 (which is not a great piece of navigation software by any means, but at least you won't have to pay extra for it).
If you don't care about the mount you can probably find the 770 navigation kit even cheaper.
__________________
Goosfraba! All text written by allnameswereout is public domain unless stated otherwise. Thank you for sharing your output!
Goosfraba! All text written by allnameswereout is public domain unless stated otherwise. Thank you for sharing your output!
|
|
2008-08-11
, 14:58
|
|
Posts: 3,841 |
Thanked: 1,079 times |
Joined on Nov 2006
|
#20
|
Originally Posted by sgosnell
Hmm.. we went through that discussion before already!
It isn't channels per se, it's the number of satellites the unit can communicate with simultaneously. There are only a few in view at any one time anyway, and having 30-some-odd channels when there are only a dozen in view is just marketing hype.
The point with many channels is not to be able to lock on to more satellites at the same time. (As soon as you have about 12 channels that would be sufficient). In addition to what speculatrix said, the time-to-lock is vastly reduced with more channels - it can monitor more (as it doesn't know what's currently visible) at the same time, instead of trying this set, wait, then that set and so on. My own 12-channel receiver is useless compared to my 30-channel receiver when it comes to lock-on time.
__________________
N800/OS2007|N900/Maemo5
-- Metalayer-crawler delenda est.
-- Current state: Fed up with everything MeeGo.
N800/OS2007|N900/Maemo5
-- Metalayer-crawler delenda est.
-- Current state: Fed up with everything MeeGo.
Agreed. It seems that any of the second generation recievers work well.
I have both the Nokia branded LD-3W unit that came with the original navigation kit, and the Holux M-1000 that I use with another car. They both work equaly as well for the tasks at hand with no signifigant difference to justify a higher price.
Get the best deal on a unit that has 20 or more channels, then cross search you results for negative reviews.
Last edited by YoDude; 2008-08-02 at 22:38.