Re: Assisted GPS UBlox7

[Gary E. Miller]

Yo Mike!

On Fri, 17 Nov 2023 18:07:59 +0000
Mike via <gpsd-users@nongnu.org> wrote:

> > Here is a NEO-M8N for #13, it does GLONASS and GPS, and works much
> > better than the M7N:
> > 
> > https://www.ebay.com/itm/183780263635  
> 
> The device I had at the moment is a IPx6, USB receiver with magnetic
> back, which is ideal for my use case.  It's connected to a Rapsberry
> Pi and mounted on a metal plate, out in the elements.  A rudimentary
> Google suggests that there are similar versions of the NEO-M8N,
> although it looks from Greg's email that the magic phrase is
> "160-channel receiver".

The 7 is GPS only.  It is specced at 29 s cold start, but in practice
usually longer.  A few models do GLONASS and GPS with 56 channels.
Needs to be outside to wrk.

The 8 is over 10 years old, but has GLONASS, Galileo, BeiDou and GPS, with 
26 seconds TTFF, using 72 channels.  Not bad.  Needs to be nar a window
to work well.

Then there is the 9 series and the 10 series.  As the models go
highr, they work better indoors.

If you are only outdoors, the 8 is fine, and will be a big step up
from the 7.

> > It not.  Getting it in the proprietary form that your u-blox needs
> > is hard.  Its all about $$$$.  
> 
> That would be that "market forces" thing.  Yes, I'm familar with that
> :-)
> 
> Incidently, are you able to recommend a service for aquiring the
> Almanac / Ephemeris?  One that doesn't require "market forces"?

Sure, gpsd.  As I said previously.  Just google it.

> I was reading the UBlox manual here:
> 
> https://content.u-blox.com/sites/default/files/products/documents/u-blox7-V14_ReceiverDescriptionProtocolSpec_%28GPS.G7-SW-12001%29_Public.pdf
> 
> Which on page 36 does talk about sending the necessary data to the GPS
> receiever and the linked pages do appear to explain the protocol.

Yeah, the protocol, but not the packet contents.  And that is a lot of
work that only has value if you GPS has been off for 4 months.

If you can do it, have at it, we'll take your code.

> I haven't doug into it in too much detail, as it's right on the edge
> of my knowlege, although my initial impression is that anyoen with
> more coding/comp sci/maths knowedge and a source of the data to hand
> could get this working on more sane timescales than myself.

Many have tried, and failed, feel free to try your hand.

> I also found the following code on GitHub:
> 
> https://github.com/gokuhs/ublox-agps
> 
> I see this uses a free trial and I haven't checked the format of the
> data that is provided.

Yes, free trial.  If faSt turn on from a cold start have $$ value you to
you, then just pay for it.  For what data costs, you could just upgrade
to a receiver that does not need it.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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