[Liverpool] USB GPS receivers

[Dan Lynch]

Hi,

I don't really have much use for GPS adaptors right now and certainly can't
offer you any advice, but I just thought I'd say I found this interesting to
read. It's funny how often the most expensive piece of equipment is not the
best. I found the same with USB sound cards. The chipset makes all the
difference.

Can't wait to see an update on the project once you have it adding GPS data
as well. Very cool!

See ya,

Dan



On Mon, Jun 13, 2011 at 11:25 PM, Sebastian Arcus <shop at open-t.co.uk> wrote:

> Hi all,
>
> I'm not sure if there is any interest in this, but during my work to add
> gps tracking to the cctv bus system, I had to test several usb gps adapters
> because of variation in behaviour by some of them. The main point of my
> research so far seem to be that the adapters based on the SirfStar III
> chipset (which covers a good majority of models available) are pretty low
> quality. They take a long time to get a fix - specially if they haven't been
> used in the last 24 hours and have to re-download data from the satellites.
> On cloudy days - some of them can take 30-40 minutes to obtain the first
> fix.
>
> I have enquired on the gpsd mailing list (which, by the way, I wouldn't
> call "friendly" to say the least). I haven't really obtained much
> information. They mostly seem to be involved with the "embedded" market -
> not entirely sure what they mean by that. I could assume they really work
> for various gps manufacturers - which would explain the really abrupt
> attitude and at times disguised hostility towards the Linux kernel and
> tools.
>
> To cut the story short - I am now the proud owner of 6 gps adapters. The
> bottom line (and useful conclusion) is that the BluNext BN-903S adapter,
> based on the Adopt SkyTraq Venus 6 chipset seems to be an excellent piece of
> hardware. You can just plug it in, and it gets a fix within at worst 2-4
> minutes, if you are in between buildings, on a cloudy day, and it hasn't
> been used for few days. Otherwise, it will get a fix in a matter of seconds.
>
> The funny thing is that this is the cheapest adapter of all I bought -
> £16.95 on Amazon.co.uk with free delivery. It has 65 channels (can listen
> to 65 satellites at the same time, although I doubt the current
> constellation has that many satellites anyway) - versus 20 channels for the
> SirfStar III chip. I'm not sure how much difference that makes in practice,
> but whatever the reason, it works brilliantly.
>
> On the other hand, the SirfStar III is always referred to in glowing terms
> on all websites I've seen adapters for sale. Go figure. Either their
> marketing machine is one great contraption, or I'm the unlucky owner of 3
> different adapters from different manufacturers with their chipset in them -
> all of them naff.
>
>
> In case somebody will find the above useful.
>
> If anybody else on the list is using usb, serial or bluetooth gps receivers
> with a computer, I'd be curious of their point of view. Performance of
> adapters in smartphones might be a little bit skewed, as lots of them also
> use AGPS over Internet, which makes the the quality of the actual chip more
> difficult to assess solely on its gps reception merits.
>
> Hope you are all keeping well,
>
>
> Sebatian
>
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