I would like to use a GPS antenna that I could send NMEA data to both
my Glide Computer and my PDA running flight sortware.

Any thoughts on how something like that would be wired up?

I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
if that same unit would work, I would get another one, cut the plug
off and find the NMEA send wire, of course having the schematic would
help too.

Brad

Hi Brad,

I'm sorry, but I don't think that is possible.

It is possible to have a GPS send NMEA data to 2 soaring instruments or
PDAs. But each GPS engine needs its own antenna. I don't think a single
GPS antenna can be connected to 2 different GPS units - which is what I
think you are trying to do.

Good Soaring,

Paul Remde
Cumulus Soaring, Inc.

"Brad" > wrote in message
...
>I would like to use a GPS antenna that I could send NMEA data to both
> my Glide Computer and my PDA running flight sortware.
>
> Any thoughts on how something like that would be wired up?
>
> I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
> if that same unit would work, I would get another one, cut the plug
> off and find the NMEA send wire, of course having the schematic would
> help too.
>
> Brad

On Dec 31, 2:30*pm, "Paul Remde" > wrote:
> Hi Brad,
>
> I'm sorry, but I don't think that is possible.
>
> It is possible to have a GPS send NMEA data to 2 soaring instruments or
> PDAs. *But each GPS engine needs its own antenna. *I don't think a single
> GPS antenna can be connected to 2 different GPS units - which is what I
> think you are trying to do.
>
> Good Soaring,
>
> Paul Remde
> Cumulus Soaring, Inc.
>
> "Brad" > wrote in message
>
> ...
>
>
>
> >I would like to use a GPS antenna that I could send NMEA data to both
> > my Glide Computer and my PDA running flight sortware.
>
> > Any thoughts on how something like that would be wired up?
>
> > I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
> > if that same unit would work, I would get another one, cut the plug
> > off and find the NMEA send wire, of course having the schematic would
> > help too.
>
> > Brad- Hide quoted text -
>
> - Show quoted text -

Antenna feeds can be split to feed multiple GPS receivers, but it
often requires a splitter with a pre-amp*, and they're not cheap.
Additionally, signal strength from the splitter/pre-amp needs to be
tailored to the receiver. Not all GPS receivers are the same, and
overdriving the signal to a receiver can cause (at least) it not to
receive properly.
Antennas are cheap, it would be better to buy another one.
The NMEA sentences are the OUTPUT of the GPS receiver (though I don't
know if the 310 outputs them). The signal from the antenna is a very
low level psuedo-random-noise L band radio frequency signal.
* and all that I've worked with require an external power source.

Brad,

Like Paul mentioned, sharing a GPS engine between two device is a common "Poor Man's" navigation solution. For several years I have been driving both an EW Model D flight recorder and Compaq Aero 1550 with a Garmin 12xl.

Any FAI acceptable GPS unit can be substituted for the Garmin 12xl. The Goddard SPS-1 is a good power and device connection solution.
http://www.cumulus-soaring.com/goddard/sps-1.jpg

Wayne





"Paul Remde" > wrote in message ...
> Hi Brad,
>
> I'm sorry, but I don't think that is possible.
>
> It is possible to have a GPS send NMEA data to 2 soaring instruments or
> PDAs. But each GPS engine needs its own antenna. I don't think a single
> GPS antenna can be connected to 2 different GPS units - which is what I
> think you are trying to do.
>
> Good Soaring,
>
> Paul Remde
> Cumulus Soaring, Inc.
>
> "Brad" > wrote in message
> ...
>>I would like to use a GPS antenna that I could send NMEA data to both
>> my Glide Computer and my PDA running flight sortware.
>>
>> Any thoughts on how something like that would be wired up?
>>
>> I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
>> if that same unit would work, I would get another one, cut the plug
>> off and find the NMEA send wire, of course having the schematic would
>> help too.
>>
>> Brad
>

> "Paul Remde" > wrote:

>> I'm sorry, but I don't think that is possible.

Of course it is. E.g. http://www.vtec.ch/avionik.htm , scroll down to
"AntSplit".



Uncle Fuzzy wrote:

> Antennas are cheap, it would be better to buy another one.

Multiple GPS antennas can be a mess, because they mustn't be located
near each other.

On Dec 31, 4:04*pm, John Smith > wrote:
> > "Paul Remde" > wrote:
> >> I'm sorry, but I don't think that is possible.
>
> Of course it is. E.g.http://www.vtec.ch/avionik.htm, scroll down to
> "AntSplit".
>
> Uncle Fuzzy wrote:
> > Antennas are cheap, it would be better to buy another one.
>
> Multiple GPS antennas can be a mess, because they mustn't be located
> near each other.

News to me. I have several within a foot of each other on a
building. Been operating that way for 8 years now with no issues.
Two are mounted on the same ground plane, nearly touching.

In article > "Paul Remde" > writes:
>Hi Brad,
>
>I'm sorry, but I don't think that is possible.
>
>It is possible to have a GPS send NMEA data to 2 soaring instruments or
>PDAs. But each GPS engine needs its own antenna. I don't think a single
>GPS antenna can be connected to 2 different GPS units - which is what I
>think you are trying to do.
>
>Good Soaring,
>
>Paul Remde
>Cumulus Soaring, Inc.

Sure it can. You just need an L-band splitter with a DC block on one of
the outputs and DC pass through from the other. Then the antenna's active
amplifier can be powered by one of the receivers.

If you have receivers that both use passive antennas, it is also easy, but
you are at a bit more of a risk from signal level.

If one is active and one passive, you have a bit of engineering to do.

Alan

Uncle Fuzzy wrote:

> News to me. I have several within a foot of each other on a
> building. Been operating that way for 8 years now with no issues.
> Two are mounted on the same ground plane, nearly touching.

Lucky you. My experience is that one foot between the antennas is about
the minmal distance for reliable functionality.

On Dec 31, 2:24*pm, Brad > wrote:
> I would like to use a GPS antenna that I could send NMEA data to both
> my Glide Computer and my PDA running flight sortware.
>
> Any thoughts on how something like that would be wired up?
>
> I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
> if that same unit would work, I would get another one, cut the plug
> off and find the NMEA send wire, of course having the schematic would
> help too.
>
> Brad

Hmmmm...............let me clarify what I wrote earlier.

Situation: I have a iPAQ 3850 with no GPS, I also have an Ilec SB-8
with the Final Glide unit, this can accept NMEA data from a GPS.

What I want to do is buy one of those GPS "mouse" units, and send the
NMEA information to both of those units.

I mentioned the iPAQ 310 earlier just because I had an external
antenna and that it helped track more sattelites, and perhaps if I got
another Antenna, that I could use it.......or a mouse.

Thanks,
Brad

On Dec 31, 5:15*pm, Brad > wrote:
> On Dec 31, 2:24*pm, Brad > wrote:
>
> > I would like to use a GPS antenna that I could send NMEA data to both
> > my Glide Computer and my PDA running flight sortware.
>
> > Any thoughts on how something like that would be wired up?
>
> > I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
> > if that same unit would work, I would get another one, cut the plug
> > off and find the NMEA send wire, of course having the schematic would
> > help too.
>
> > Brad
>
> Hmmmm...............let me clarify what I wrote earlier.
>
> Situation: I have a iPAQ 3850 with no GPS, I also have an Ilec SB-8
> with the Final Glide unit, this can accept NMEA data from a GPS.
>
> What I want to do is buy one of those GPS "mouse" units, and send the
> NMEA information to both of those units.
>
> I mentioned the iPAQ 310 earlier just because I had an external
> antenna and that it helped track more sattelites, and perhaps if I got
> another Antenna, that I could use it.......or a mouse.
>
> Thanks,
> Brad

Brad

Several manufactures make an RS-232 mouse. More come with USB only and
maybe an adapter, obviously you want to find a real RS-232 one. You
also want one with a GPS receiver that supports WGS-84 ellipsoid, you
would think that is standard but there have been a few that have
problems here. That result in ~50-100' errors in places.

Most devices we use that listen to NMEA are incredibly dumb and don't
talk back to the GPS device, even for XON/XOFF flow control so you can
often just wire devices in parallel with both your PDA and flight
computer listening the the same RS-232 data pin. A buffering splitter
like Goddard make is usually _not_ needed in this case.

On the other hand you might find the redundancy of two completely
separate GPS antennas/receivers a nice idea. One option is to drive
the PDA with either a bluetooth GPS receiver or a CF card based
receiver and use a separate serial mouse GPS for the flight computer.
The advantage there is that both can be completely independent of the
ships main battery supply. I tend to prefer a CF car receiver plugged
into the PDA (maybe with an extended battery if available on the PDA)
then power the PDA m ountfrom the ships power, that way if you lose
main ships power the PDA and its on-board GPS may be capable of
running for many hours.

You don't mention badges or records. Obviously if that is an issue
then you might want to look at an IGC approved flight recorder (yes I
know about the new COTS GPS rule, a real IGC recorder is still the way
to go). In that case I recommend driving the PDA from the NMEA output
from the IGC recorder, that way you should become very aware things
are not working if there is a flight recorder GPS problem (plus you
should get to see the real pressure altitude the flight recorder is
reporting).

Does that help?

Darryl

On Thu, 31 Dec 2009 17:15:18 -0800 (PST), Brad >
wrote:

>On Dec 31, 2:24*pm, Brad > wrote:
>> I would like to use a GPS antenna that I could send NMEA data to both
>> my Glide Computer and my PDA running flight sortware.
>>
>> Any thoughts on how something like that would be wired up?
>>
>> I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
>> if that same unit would work, I would get another one, cut the plug
>> off and find the NMEA send wire, of course having the schematic would
>> help too.
>>
>> Brad
>
>Hmmmm...............let me clarify what I wrote earlier.
>
>Situation: I have a iPAQ 3850 with no GPS, I also have an Ilec SB-8
>with the Final Glide unit, this can accept NMEA data from a GPS.
>
>What I want to do is buy one of those GPS "mouse" units, and send the
>NMEA information to both of those units.
>
>I mentioned the iPAQ 310 earlier just because I had an external
>antenna and that it helped track more sattelites, and perhaps if I got
>another Antenna, that I could use it.......or a mouse.
>
>Thanks,
>Brad

For past 12 years I've been running a Volklogger feeding both a
Cambridge LNAV and a PDA running WinPilot.

I just feed the GPS Tx (Pin #3, signal line) and ground line
(Pin #5) onto a simple terminal strip. I hook both the IPAQ and LNAV
GPS inputs to these terminal points.

Works just fine, I've never seen any problems.

This appears to be simiilar to what you want to do with your GPS mouse
unit.

Bob

Hi Brad,

I sell a nice Garmin "Mouse" style GPS engine. It could supply data to your
PDA and SB-8. It's nice because it accepts 12V power input. You can see it
here:
http://www.cumulus-soaring.com/garmin.htm

Best Regards,

Paul Remde
Cumulus Soaring, Inc.

"Brad" > wrote in message
...
On Dec 31, 2:24 pm, Brad > wrote:
> I would like to use a GPS antenna that I could send NMEA data to both
> my Glide Computer and my PDA running flight sortware.
>
> Any thoughts on how something like that would be wired up?
>
> I have a Gilsson antenna with a brass plug that fits into my iPAQ 310,
> if that same unit would work, I would get another one, cut the plug
> off and find the NMEA send wire, of course having the schematic would
> help too.
>
> Brad

Hmmmm...............let me clarify what I wrote earlier.

Situation: I have a iPAQ 3850 with no GPS, I also have an Ilec SB-8
with the Final Glide unit, this can accept NMEA data from a GPS.

What I want to do is buy one of those GPS "mouse" units, and send the
NMEA information to both of those units.

I mentioned the iPAQ 310 earlier just because I had an external
antenna and that it helped track more sattelites, and perhaps if I got
another Antenna, that I could use it.......or a mouse.

Thanks,
Brad

On Dec 31 2009, 5:24*pm, Brad > wrote:
> I would like to use a GPS antenna that I could send NMEA data to both
> my Glide Computer and my PDA running flight sortware.
>
> Any thoughts on how something like that would be wired up?

There's a big difference between splitting a GPS Antenna wire, and
splitting the NEMA output of a GPS Receiver. I think different people
are approaching your question from each of those angles in different
posts in the thread.

You should note that two different GPS receivers on the same GPS
antenna may end up with different coordinates from each other,
depending on the receiver's chipset and firmware. If your goal is to
ensure that each nav system gets the exact same coordinates, then it's
the NEMA data that must be split, not the antenna connection.

If your objective is to get the same GPS fix in to each of your units,
I would recommend considering the K6-BT dingus sold at
http://www.cumulus-soaring.com/k6.htm

The K6-BT will make a wired serial connection from your NEMA-
outputting logger to your in-panel glide computer, and will also
transmit the exact same NEMA data wirelessly to a bluetooth-enabled
PDA. There are a few caveats, such as how you would have to declare
to the logger with the glide computer and not with the PDA, but those
are left as an exercise for the reader.

Cheers,

Rob
http://avia.tion.ca

On Jan 1, 9:48*pm, "Rob.Russell" > wrote:
> On Dec 31 2009, 5:24*pm, Brad > wrote:
>
> > I would like to use a GPS antenna that I could send NMEA data to both
> > my Glide Computer and my PDA running flight sortware.
>
> > Any thoughts on how something like that would be wired up?
>
> There's a big difference between splitting a GPS Antenna wire, and
> splitting the NEMA output of a GPS Receiver. I think different people
> are approaching your question from each of those angles in different
> posts in the thread.
>
> You should note that two different GPS receivers on the same GPS
> antenna may end up with different coordinates from each other,
> depending on the receiver's chipset and firmware. *If your goal is to
> ensure that each nav system gets the exact same coordinates, then it's
> the NEMA data that must be split, not the antenna connection.
>
> If your objective is to get the same GPS fix in to each of your units,
> I would recommend considering the K6-BT dingus sold athttp://www.cumulus-soaring.com/k6.htm
>
> The K6-BT will make a wired serial connection from your NEMA-
> outputting logger to your in-panel glide computer, and will also
> transmit the exact same NEMA data wirelessly to a bluetooth-enabled
> PDA. *There are a few caveats, such as how you would have to declare
> to the logger with the glide computer and not with the PDA, but those
> are left as an exercise for the reader.
>
> Cheers,
>
> Robhttp://avia.tion.ca

Brad already clarified he was talking about an antenna not a GPS
receiver and what he was after is a GPS source for his flight
computer.

A K6-BT would probably double Brad's entire PNA+software system cost.
With apparently no IGC flight recorder in his cockpit he will have no
issues making declarations to it.

As for the iPAQ 310 GPS signal, Brad can either simply use the built-
in GPS receiver on his iPAQ 310 (either with or without the external
antenna - FWIW my iPAQ 310 seemed to work pretty well in the cockpit
with just the internal antenna).

As for the flight computer it is likely much simpler to buy a
dedicated RS-232/serial GPS mouse and just feed the external computer
with that. That gives redundancy and no wiring hassles. Splitting
physical serial cables is possible as I mentioned earlier but that was
before I realized Brad had an iPAQ 310, and will need voltage shifters
etc. to use the RS-232 ports on the iPAQ 310 so maybe easier to just
avoid and stick with the internl iPAQ 310 GPS (with or without
external antenna). And a side benefit he gains redundant GPS devices.

All this of course presumes that XCSoar (and Brad) are happy with the
iPAQ 310 GPS engine and ellipsoid altitude difference handling in the
iPAQ 310. If you care about < 100' GPS altitude accuracy it might be
an issue. Maybe XCSoar ties to handle this OK, I don't know (I don't
use XCSoar). Since his current setup uses the iPAQ internal GPS I
presume this is not a problem.

Part of the reason for wanting something like a K6-Bt in installations
where there is an IGC approved flight recorder involved is to support
a PNA/PDA making declarations over bluetooth to the flight recorder. I
believe there are still combinations of PDA/PNA and flight recorders
where the K6-Bt won't do this. But for other it will. So worth looking
at the details before buying. This is a reason to avoid bluetooth in
some cases and hardwire the NMEA serial connections between the PDA/
PNA and flight recorder. After all why would somebody have XCSoar on a
PNA and want to live with not being able to make a declaration from
that to an IGC recorder. But again I don't think that interests Brad
at all.


Darryl

On Jan 2, 2:19*am, Darryl Ramm > wrote:
> Brad already clarified he was talking about an antenna not a GPS
> receiver and what he was after is a GPS source for his flight
> computer.

Um, no, reread his 31-Dec post...

On Jan 2, 7:57*am, Dave Nadler > wrote:
> On Jan 2, 2:19*am, Darryl Ramm > wrote:
>
> > Brad already clarified he was talking about an antenna not a GPS
> > receiver and what he was after is a GPS source for his flight
> > computer.
>
> Um, no, reread his 31-Dec post...

Oh doh. I read both posts and a private email and still kept parsing
the iPAQ 310 into the picture, had it right the first. With no iPAQ
310 involved. The easiest approach is to just hardwire an external
serial GPS mouse in parallel like I and others originally suggested.
Since you already likely need to wire the PDA cradle/mount for DC
power you might as well hardwire the GPS. Which I understand Brad now
has somebody helping him do.

Darryl

On Jan 2, 9:39*am, Darryl Ramm > wrote:
> On Jan 2, 7:57*am, Dave Nadler > wrote:
>
> > On Jan 2, 2:19*am, Darryl Ramm > wrote:
>
> > > Brad already clarified he was talking about an antenna not a GPS
> > > receiver and what he was after is a GPS source for his flight
> > > computer.
>
> > Um, no, reread his 31-Dec post...
>
> Oh doh. I read both posts and a private email and still kept parsing
> the iPAQ 310 into the picture, had it right the first. With no iPAQ
> 310 involved. The easiest approach is to just hardwire an external
> serial GPS mouse in parallel like I and others originally suggested.
> Since you already likely need to wire the PDA cradle/mount for DC
> power you might as well hardwire the GPS. Which I understand Brad now
> has somebody helping him do.
>
> Darryl

I'm the somebody. One point early in the thread was confusing; Brad
is NOT trying to connect two GPS receivers to one anntenna. Rather he
is wanting to get two client devices receiving data from one GPS
device's outout.

I have a circuit that I paid a friend to design that is similar to the
units available from Cumulus or Craggy. I am using one in my Grob 103
with two PDA units. It takes the 12V ship power and passes that
through to the ICG logger, and provides two 5V regulated sources for
the PDAs. The the serial serial signal is split using a Maxim chip
that provides true RS232 signal voltage level shifting on both
outputs. Both PDAs get full strength signals and via a toggle switch,
either can declare to the logger.

Since Brad isn't planning on using a logger, the RS232 splitter will
take the GPS NMEA stream and split it for the PDA and SB-8. No toggle
switch is needed as there will be no declaration process. The 12V
pass-through will drive the GPS unit. One 5V supply will drive the PDA
and the other will be used for a turn&bank indicator he is
installing.

I have circuit boards and parts for one additional unit (after Brad's)
and if there are interested parties you can contact me via email.

After this run of parts I will not be doing any more units, but if
there is interest I can release the design to interested parties,
including all the design documentation and circuit board files. If
there is interest, email me.

Mike Bamberg