The Capn Voyager, How accurate?
 

I was playing with my GPS yesterday (rainy day) and had it wired to my
laptop, running Capn 6.1.

I noticed that the GPS was displaying the Long. and Lat. to three (3)
decimal places while The Capn, was displaying it to 3 decimal places, the
least significate digit was always zero. There didn't appear to be any
'rounding' either.

However, The Capn cursor coordinates were always shown to a three decimal
place precision.

I should think, that if the program is going to display the vessel position
to only two decimal places of accuracy, they shouldn't display that third
digit as a zero. In engineering drawings, that third digit would indicate
that all accuracy should be assumed to the third decimal place.

I suspect that since the decimal digit is simply dropped, there is no such
degree of accuracy.

My "lesson learned", if I need high accuracy, I will look at the GPS
display, and ignore the Capn.

BTW. In this observation, I'm using a standard GPS without any external
enhancements.

My observation and opinions, FWIW.

Steve
s/v Good Intentions

The Capn Voyager, How accurate?
 

Just another thought.

Is the NMEA sentence capable of sending the Long. and Lat. to three decimal
places of accuracy??


Steve
s/v Good Intentions

The Capn Voyager, How accurate?
 

"Steve" wrote in
:

Just another thought.

Is the NMEA sentence capable of sending the Long. and Lat. to three
decimal places of accuracy??

That's probably the problem. Look at how many digits your GPS is
outputting. My Capt'n display shows 3 digits.

-- Geoff

The Capn Voyager, How accurate?
 

"Steve" wrote in message
...
Just another thought.

Is the NMEA sentence capable of sending the Long. and Lat. to three
decimal
places of accuracy??

Yes. According to the standard document, the Lat and Long. fields are
fixed/variable, meaning that there is at least degrees and minutes left of
the decimal point and a variable number of digits for the decimal fraction
of minutes. So this can be any precision the GPS manufacturer likes to
output, as long as it fits within the maximum sentence length :-)
My GPS OEM-module outputs 4 decimal digits.

Meindert

The Capn Voyager, How accurate?
 

On Wed, 10 Sep 2003 11:47:06 -0700, "Steve" wrote:

Just another thought.

Is the NMEA sentence capable of sending the Long. and Lat. to three decimal
places of accuracy??


Absolutely! The M602 displays either the Garmin or Raymarine to 3
decimal places via the NMEA network from our multiplexer.....



Larry W4CSC

3600 planes with transponders are burning 8-10 million
gallons of kerosene per hour over the USA. R-12 car air
conditioners are responsible for the ozone hole, right?

The Capn Voyager, How accurate?
 

Thanks for putting my concern in proper prospective.

However, yesterday was another rainy day and I played around a little more.

The GPS I was using for my intial observation, was a Apelco GPS-15 handheld
but mounted in it's mount adaptor for connection to the power and NMEA cable
to the laptop serial port.

As I stated earlier, The Cap'n drops the third decimal digit. When I switch
to my dedicated GPS module connected via the USB port, The Cap'n displays
the position to the full third decimal place.

I also tried these two different units with the program Net Stumbler.. Net
Stumbler displays the position in degrees (no minutes) and 6 decimal places
(of a degree) of accuracy.

The surprising (and confusing) thing is, this program displayed the full 3
decimal places (of a minute) from the Apelco GPS-15..

So I now know the Apelco is sending the the data but for some reason The
Cap'n is ingnoring the third digit via the serial port while reading it from
the USB port.

(not a very scientific conclusion but the bests I can do. FWIW)

Steve
s/v Good Intentions