12 Channel Parallel?

[thequinox]

I am looking at some bluetooth GPS receivers and I really don't know anything about GPS. Anyways I was looking around and I noticed that many people said your want a "12 Channel Parallel" capable receiver. The two I am looking at don't say the word parallel. One says "12 Channel “All-in-View” tracking (WAAS/EGNOS)" and the other says "8 Channels all in view tracking". Are any of these parallel? Do I even need parallel? I plan on using this in my car with my laptop. I want it for screwing around and maybe some wardriving. I live in a small town in Alberta. I'm giving you all this information because I have no clue what you guys need. I appologise for any confusion my lack of knowledge may have caused you. Anyways, here are the links to the GPS units I was looking at:
- http://tinyurl.com/a4r52
- http://tinyurl.com/ajdjj

Thank you for any help you can provide.

[lbendlin]

To determine your position horizontally you need to get signals from three satellites (this is called a 2D fix). If you want altitude too you need at least four sats (3D fix). anything on top of four channels is only adding buffer - in case of poor reception, satellite misalignment etc.

The SBAS sats (WAAS for you) need another channel for the differential fixes.

12 channels is pretty much standard - it's also the practical limit of how many sats you can see at any given time unless you are in space. 8 channels is a bit on the cheap side, but sufficient for Alberta - no skyscrapers there as far as I remember. (And no, Calgary doesn't count)

The more advanced receivers have 16 or even 20 channels to utilize bounced and multipath signals.

Eventually it's up to you - I personally would go for a newer chipset like the SiRF III - this one comes with 20 channels

Regarding the "parallel" blabla - they all work on pretty much the same principle, and most of them aren't even truly parallel - the initial sat locking still occurs serially, one after the other. (Again, SiRF III is truly parallel)
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Lutz

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