Re: ✘NEO-M9N

[Gary E. Miller]

Yo Frank!

On Tue, 11 Feb 2020 21:19:23 -0500
Frank Nicholas <address@hidden> wrote:

> I purchased this module, with the same chip, in December - haven't
> had a chance to play with it yet:
> https://www.sparkfun.com/products/15712
> <https://www.sparkfun.com/products/15712>
> 
> It's more expensive and has some other options/connectors.  

I think the GNSS 7 is somewhat better:

Price:              $40          $65
Antenna Connector:  SMA          u.fl
Backup:             Super Cap    battery
Berg Pins:          Installed    Just holes
Size:               57x25 mm     40x33 mm
Mounting holes      No           Yes

> I didn't know what Gary's "L1 only" was referring to. I found this
> clear explanation:
> https://www.mapleprecision.com/2019/01/16/l1-l2-l5-satellite-signals/
> <https://www.mapleprecision.com/2019/01/16/l1-l2-l5-satellite-signals/>

A start, but more complicated than that. That only applies to GPS, but
the NEO-M9N can also recieve GLONASS (L1), Galileo (E1), IMEI (L1)
and BeiDou (B1).  Which are all kinda sorta, not quite, in the same
frequency range as GPS L1.

Here is a slightly more complete list if frequencies.  Look at
Figure 2:  https://gssc.esa.int/navipedia/index.php/GNSS_signal

One takeaway is that GPS antennas do not work well with modern
multi-GNSS receivers.

> Is the "L1 only" a limitation of the NEO-M9N chip?

Yes.  Until the u-blox 9 series, all consumer grade GNSS receivers were
L1 (and similar) only.  The ZED-F9x receive L1 and L2 and are much more
accurate then L1 only receivers.

The advantage of L1+L2 over plain L1 is that the reciever can use the
two frequencies to cancel out the effects of the ionosphere on accuracy.

For somewhat over $200 the ZED-F9x can approach similar accuracy to
survey receivers costing thousands.  But the NEO-M9N will not be in that
class.  I'll post plots after I get the NEO-M9N that I orderd.

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

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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