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covert
6th June 2006, 04:32 PM
Does anyone use one of these new 32 channel GPS's ? I have been seeing them popping up and eBay and I would like to know if anyone has had some impressive results with it.

They use a Fujitsu RFMD chipset that I have not been able to find any good information on them.

I have a 16 chan one and I am not so happy with the accuracy in high foliage area's or urban canyons.

hangover
6th June 2006, 04:57 PM
Do you use an external antenna with your gps ? if not then it may be a cheaper alternative to replacing the one you already have.

covert
6th June 2006, 05:18 PM
My GPS also takes forever to lock on while moving and a external antenna is not going to fix that.

If I sell my old GPS and get a new one I will be out of pocket about $40. An external antenna is going to cost me around $25.

I have tested my old GPS along side my mates SirfIII 20 channel and it is far superior to mine in lock on time and tracking.

festy
6th June 2006, 06:09 PM
How often do you have all 12/16 channels locked anyway? Having 32 channels is great,but if you can only see 6 sats, the extra channels won't help at all

covert
6th June 2006, 07:07 PM
How often do you have all 12/16 channels locked anyway? All 32 channels are used for scanning on startup. Cold Lockon is only 30 seconds.


Having 32 channels is great,but if you can only see 6 sats, the extra channels won't help at allYou can see upto 12 at the one time. I will see upto 10 on my 16 chan SirfII.

Extra channels are used for scanning for new sats only when needed.

Jackaroo
6th June 2006, 07:23 PM
As festy says

What good is a 32 channel receiver if you can only ever see 6 satellites, 12 satellites at the most.

32 channels sounds good, but will give no better performance that a 12 channel receiver with the same chipset

Jackarro :D

covert
6th June 2006, 07:33 PM
Look past the channel number and the fact you can only see 12 sat's max at one time.

Higher sensitivity, faster start up, faster (re)acquisition all equate to better performance.


Back to the topic. Anyone used one of these things ?

festy
6th June 2006, 07:50 PM
Sensitivity is (slightly) lower than SiRFIII (-157dbm/-159dbm respectively) and re-aquasition would not be any faster (their advantage seems to be cold start, not hot) so they don't seem too revolutionary, but would no-doubt out-perform my garmin geko in questionable reception areas, as would a SiRFIII chipset.

And no, I haven't used one.

arthurking83
6th June 2006, 08:47 PM
I suppose I have to put my 2bob's worth in.... :rolleyes:

With my (limited) understanding of the way the SatNav constellations work (GPS and Galilleo), I was under the impression that Galilleo is going to be backward compatible with GPS, which means when Galilleo becomes fully operational by 2008(??..not 100% when), that it will mean that there should be about 24 satellites in view, most of the time.

So I suppose having the ability to track 20 satellites may be an advantage in 2 or 3 years time, and if you are in the market for a GPSr, then get something that is going to be more modern in the years to come.

I agree with the 'better sensitivity v's number of channels' argument though!

the 32 channels 'feature' is purely a marketing gimmick though, as the average joe user, that may be unaware of how GPS works....is going to immediately think "hey I can receive more sats"!
(ps. I've seen this phenomenon first hand, when my brother was looking for a GPS/PDA thingy!)

:)

Nicko
6th August 2006, 10:31 AM
By the time the galileo system is up and running with a full constellation your current GPS will most likely be dead. Thus, for now anything more than 16 channels is superfluous. However, the 20 Channel SiRF is suitable for the odd Euro sat that is up and running before the full constellation is in comission. In saying that, manufacturers like SiRF are aware of end user gullability and may take that into consideration. What they do spend most time doing is ensuring the GPS savvy are provided with quality GPS with excellent sensitvity and sufficient channels to do the job today and over the next few years, because they know a 32 channel may come in handy for the GPS savvy in 2008...... R&D spending on sensitivity rather than adding channels is clearly money well spent, considering that the largest recreational GPS manufacturer in the world (Garmin) is now implementing SiRF engines is an indicator of the company doing the right thing or even the smart thing.

arthurking83
6th August 2006, 04:58 PM
One thing I found amusing in one of the advertising material "Schpeeels" it said words to the effect of....


" 32channel reciever...blah, blah...but only 8 channels are used in the final position calculation.....etc..and more blah, blah...!"

(ps. that's not the exact quote, just my summary of it! :D)


just wondering how the 32 channels makes this feature worth the effort then?
Would it amke sense to conserve battery power and only have 8 channels?

I'll find the ad or link, and post it :)

PED04
9th September 2006, 08:51 AM
Don't forget that potentially 1-2 channels will be used for WAAS information (not that we can use it in Australia).

Nicko
1st February 2007, 10:31 PM
I have noticed in other forums that the MediaTek 32 Channel is very stable, has same sensitivity of -159db to that of SiRF but tends to track better than SiRF III. Plus, MediaTek engines are cheaper which in my mind makes it worth while anyways, so much so I have ordered some into the country to play with. :grinning-

festy
2nd February 2007, 03:00 AM
What's their power consumption like? I understand that the main advantage of the SiRFStarIII CS is it's extremely powerful collation engine - but the price you pay for that is higher power consumption than the competing chipsets.

Nicko
2nd February 2007, 10:07 AM
Well put it this way, the F-Tech solar BT GPS consists of two engines, one is SiRF III and the other is MTK 32 channel and the MTK lasts twice as long as the SiRF III. 45mA as opposed to 75mA says it all.