gps handheld vs. antenna for notebook
 

On Feb 10, 3:19 am, "Shaun Van Poecke"
wrote:
cross posted to rec.boats.electronics

Hi all,
Im looking at getting a cheap(ish) setup for my boat, i have a couple of
laptops with navigation software and charts, so what im looking at is a
couple of GPS units to hook up to them. Ive seen GPS receivers with serial
or USB connections that plug straight into a laptop, but these things cost
as much as or more than a basic hand held GPS. are they any better?

What im probably thinking is one basic handheld unit (maybe garmin GPS 72)
and one receiving antenna to plug straight in to the laptop. any ideas on
this setup?

Thanks,
Shaun

There is nothing complicated about this, in spite of what some others
have said. We use both a Garmin eTrex Legend and a Garmin GPSMap76 in
conjunction with Maptech charts on CD and the Cap'n. Maptech charts
Can be set for Garmin output, the Cap'n requires NMEA. Both handheld
units can be set for either Garmin output or NMEA. Both GPS units
come with a serial interface, so a serial to USB adaptor is necessary
(Best Buy or similar place). Our laptop is kept below decks and the
handheld GPS sits on the cabin top. The system works well regardless
of which GPS or which nav program we use. The advantage to the
maptech program is that you can get a lite version of Maptech's
Offshore Navigator Pro when you buy a Maptech chartbook. This is a
lot cheaper than buying the whole program and you get paper charts as
well. The Cap'n nav program has been bought out by Maptech and I'm
not sure if it is still available although Maptech is providing tech
support for it.

gps handheld vs. antenna for notebook
 

After looking at the GPS "mouse" devices, I decided I may as well get
an inexpensive handheld. The Geko 201 works great. It's just a little
larger than the "mouse" devices, works just as good, and is more useful.
I picked up the Geko for about $70 and a USB cable for another $20
on eBay. Besides providing NMEA input, the cable provides power
to the Geko via USB.


"Matt O'Toole" wrote in message
g...
On Sat, 10 Feb 2007 09:19:15 +0000, Shaun Van Poecke wrote:

cross posted to rec.boats.electronics

Hi all,
Im looking at getting a cheap(ish) setup for my boat, i have a couple of
laptops with navigation software and charts, so what im looking at is a
couple of GPS units to hook up to them. Ive seen GPS receivers with
serial or USB connections that plug straight into a laptop, but these
things cost as much as or more than a basic hand held GPS. are they any
better?

What im probably thinking is one basic handheld unit (maybe garmin GPS
72) and one receiving antenna to plug straight in to the laptop. any
ideas on this setup?

Get a handheld GPS with NMEA output. That way you'll have a backup if
your computer dies. You can use the GPS by itself, with a normal
chart.

Make sure you get a GPS that runs from a 12V socket. The last thing you
want is to have to worry about batteries.

Matt O.

gps handheld vs. antenna for notebook
 

In article ,
says...
Mark Borgerson wrote in
.net:

"For civilian L1-band applications, the GPS system is actually a simple
spread-spectrum communication system.4 Figure 2 shows the signal
generation block for civilian applications. First, the 50-b/s navigation
message is repeated 20 times to produce a 1000-b/s bit stream, then the
repeated signal is spread by a unique Coarse/Acquisition (C/A) code with
a length of 1023 chips (the rate at which the pseudorandom noise code is
applied). The result is a baseband signal of 1.023 Mchips/s. As a result
of this spread-spectrum approach, the total processing gain (G) of the
GPS system can resolve a signal well below the thermal noise level."



-159dbm....wow. Too bad the spread spectrum on the damned CDMA/GSM
cellular systems don't work that well. -105dbm and my cellphone goes dead.

I think that the GPS has an advantage in that it only needs a few
hundred bits per second throughput. At that bandwidth there is a lot
more redundancy for the signal processing. A cell phone with 200
Hz bandwidth would result in less than optimal audio clarity! ;-)

(Remember that GPS works by measuring time (or phase) differences on
multiple signals. The actual digital bits are used to update ephemeris
information and transmit the time signals. Not quite audio bandwidth
there.)


Mark Borgerson