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

Shaun,

I don't think you'll need an extra antenna. I have a couple of Garmin 72's
(one for a backup) that plug directly into my Dell laptop. I did need a
serial-to-USB converter cord, but the built-in antenna on the GPS seems to
be adequate. The GPS sits in a cradle on the dashboard and seems to read
the satellite signals right through the pilothouse roof with no trouble. We
navigated 2,500 miles with this set up a couple of years ago--to Alaska and
back--and it's worked fine ever since. (We're running MapTech Marine
Navigator, btw.) And with a special order cable from Garmin, the GPS runs
off the boat's 12v system.

Let me know if I can be of further help.

Dick Behan
M/V Annie
LNVT 37



"Shaun Van Poecke" wrote in message
...
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

On Sat, 10 Feb 2007 09:19:15 GMT, "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?

The small USB attached GPS units are very convenient, and typically
they get their power from the USB port also.

Here are a couple of options:

http://www.deluoelectronics.com/cust...productid=110#

http://www.deluoelectronics.com/cust...ome.php?cat=27

http://shop.delorme.com/OA_HTML/DELi...?section=10091

"Shaun Van Poecke" wrote in
:

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?




http://www.pcmaritime.co.uk/leisure/...eshooting.html

The handheld GPS units are made for NMEA, which is an RS-422 clone using
data that switches between 0V and +5 (or 12, I forget which). A serial
port on your computer is RS-232 standard which switches between -12 and +
12, which is more reliable over long lines as the -12 doesn't get buried
in the noise like 0VDC does, making false data. However, MOST, not all,
serial ports will read RS-422 data fairly reliably.

NMEA is also slower than dirt at 4800 baud, but that's fast enough for
GPS data streams, which are also slower than dirt.

Is your laptop old enough to have a serial port? New ones don't have
them any more as everyone else has gone to USB, up to 2Mbps in ver 2.x.
It just works better and doesn't have those nasty "what speed is this
supposed to be set to by me" problems old serial ports had. USB is
automatic, right down into the operating system, plug n play. It takes
care of itself.

How cheap is cheap? Here's a 20 channel, WAAS-enabled GPS receiver
Froogle at Google lists for $36 that plugs right into the USB port and
folds for storage. Is that cheap enough? It uses the same chipset as
the $150 Garmins and the spec says it will track at -159dbm which is
below the noise level, so I believe impossible....

http://store.luluusa.com/nausbgpsrewi.html
I know someone who is using one of these stuck to the top of his SUV for
Streetmaps. 12 channels, WAAS accurate, same chipset as the rest, nicely
made, simple with a cable for $50, marked down from $199 since the
Chinese took over the market, which is depressed at the moment, flooded
with GPS. I see its only good up to 1000 knots, which might be a problem
for racers...(c;

Get the USB if you're using a laptop and quit screwing around with
handheld nonsense with tiny screens hard to see. You don't need to buy
another computer.

Larry
--
VIRUS ALERT! VISTA has been released!
NOONE will be spared!

Large Snip

How cheap is cheap? Here's a 20 channel, WAAS-enabled GPS receiver
Froogle at Google lists for $36 that plugs right into the USB port and
folds for storage. Is that cheap enough? It uses the same chipset as
the $150 Garmins and the spec says it will track at -159dbm which is
below the noise level, so I believe impossible....

http://store.luluusa.com/nausbgpsrewi.html
I know someone who is using one of these stuck to the top of his SUV for
Streetmaps. 12 channels, WAAS accurate, same chipset as the rest, nicely
made, simple with a cable for $50, marked down from $199 since the
Chinese took over the market, which is depressed at the moment, flooded
with GPS. I see its only good up to 1000 knots, which might be a problem
for racers...(c;

Get the USB if you're using a laptop and quit screwing around with
handheld nonsense with tiny screens hard to see. You don't need to buy
another computer.

Larry

Didn't see the 20 channel you reference but did find several 12 channel in
the same price range.
Looking at one, the tech info stated that this is a "receiver only" not a
gps.
I take that to mean that it receives gps information such as time and
location but doesn't do any of the navigational computation requiring memory
storage. By that I'm referring to waypoint storage, way made good, cross
track error, etc.
Is this a reasonable assumption or is there a different meaning to "receiver
only"?

BF

"BF" wrote in
:

Looking at one, the tech info stated that this is a "receiver only"
not a gps.
I take that to mean that it receives gps information such as time and
location but doesn't do any of the navigational computation requiring
memory storage. By that I'm referring to waypoint storage, way made
good, cross track error, etc.
Is this a reasonable assumption or is there a different meaning to
"receiver only"?

BF


He's gonna plug the GPS data, in NMEA format they all produce into a
COMPUTER and use NAV SOFTWARE to do all the mapping and computing, as it
should be. What he DOESN'T need is a rinky dinky handheld palm pilot GPS
display unit, what with all that laptop/nav software computing power with
REAL memory and REAL storage....(c;

The "receiver only"s is just that, the receiver that generates the
statements for the USB port input to his nav software. Works just great.



Larry
--
VIRUS ALERT! VISTA has been released!
NOONE will be spared!

"BF" wrote in news:a0f7c$45cde30a$d066b4a0$13409
@FUSE.NET:

http://store.luluusa.com/nausbgpsrewi.html

Supported NMEA 0183 command: GGA, GSA, GSV, RMC, GLL, VTG

The $50 unit outputs these NMEA 0183 statements to the USB port, which also
powers the receiver from the laptop.

If I didn't have a $12 Garmin GPSMAP 185, I might buy one, myself....(c;

Larry
--
VIRUS ALERT! VISTA has been released!
NOONE will be spared!

In article ,
says...
"Shaun Van Poecke" wrote in
:

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?




http://www.pcmaritime.co.uk/leisure/...eshooting.html

The handheld GPS units are made for NMEA, which is an RS-422 clone using
data that switches between 0V and +5 (or 12, I forget which). A serial
port on your computer is RS-232 standard which switches between -12 and +
12, which is more reliable over long lines as the -12 doesn't get buried
in the noise like 0VDC does, making false data. However, MOST, not all,
serial ports will read RS-422 data fairly reliably.

NMEA is also slower than dirt at 4800 baud, but that's fast enough for
GPS data streams, which are also slower than dirt.

Is your laptop old enough to have a serial port? New ones don't have
them any more as everyone else has gone to USB, up to 2Mbps in ver 2.x.
It just works better and doesn't have those nasty "what speed is this
supposed to be set to by me" problems old serial ports had. USB is
automatic, right down into the operating system, plug n play. It takes
care of itself.

How cheap is cheap? Here's a 20 channel, WAAS-enabled GPS receiver
Froogle at Google lists for $36 that plugs right into the USB port and
folds for storage. Is that cheap enough? It uses the same chipset as
the $150 Garmins and the spec says it will track at -159dbm which is
below the noise level, so I believe impossible....

Not at all. GPS receivers do receive signals that are below ambient
RF noise levels. They do this through the magic spread-spectrum
signal processing.


http://www.mwrf.com/Articles/Index.c...rticleID=14303

"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."




http://store.luluusa.com/nausbgpsrewi.html
I know someone who is using one of these stuck to the top of his SUV for
Streetmaps. 12 channels, WAAS accurate, same chipset as the rest, nicely
made, simple with a cable for $50, marked down from $199 since the
Chinese took over the market, which is depressed at the moment, flooded
with GPS. I see its only good up to 1000 knots, which might be a problem
for racers...(c;

Get the USB if you're using a laptop and quit screwing around with
handheld nonsense with tiny screens hard to see. You don't need to buy
another computer.

Before you do so, make sure that the 6-foot cable on the GPS unit will
allow you to position the antenna where it will get a clean signal. You
will probably want it to be as far as possible from other electronics
that might generate interfering signals. Strong signals can overload
the front end amplifier on the GPS antenna. You can usually prevent
this type of problem by keeping the antenna 3 or 4 feet from other
electronics.

If your're going to be using the system in the Continental US, make sure
that you get a receiver with WAAS capability. That will usually reduce
positionion errors from around 15m to about 3m.


Mark Borgerson

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.



Larry
--
VIRUS ALERT! VISTA has been released!
NOONE will be spared!

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