[Kahuna]

While playing with the APRS stuff, I have had the chance to hold in my little hand a complete 12 channel, WAAS, GPS the size of the small black puck antennaes. Its less than $60 from Byonics.

It requires 5v, gnd, and is outptting NMEA.

My question is, instead of the $400 external GPS from GRT, why not have this little bugger? I do notice that the pin outs for GRT do not have +5volts. No doubt that the system has it given that most off the shelf embedded GPS's require it. Is the NMEA data stream fields enough for the grt to be happy and do all it needs including all A/P controls?

This little puck can sit on your glarehield and do it all I believe.
What am I missing?

 

[Radomir]

Yes, NMEA is all you need. I thought there were other (Garmin?) models that would take 12V so no stepdowns were needed.

It used to be that you had to pay 400 anyways for the moving map software (and GPS was "included").. but no more.. now it's part of the system.. so it's bring-your-own-gps

 

[AllanC]

Seems to be a nice little unit, and I note on the web page that they also sell a compatible 12V to 5V adapter. Seems like you could wire this in quite easily into your electrical circuits....

__________________
Allan

 

[hevansrv7a]

There are some 5V sources on GRT

Maybe only on the engine monitor, but for sure there.

 

[Ironflight]

I used (and still have) a Garmin GPS18 "hockey puck" as the Number 2 GPS for my GRT's for a couple years. It came with a cigarette Lighter plug on the end, and I repackaged the power supply inside that to go behind my panel. The serial lines went right into the GRT, and the thing has worked perfectly - no issues. I'd say go for it!

(I have recently been Beta Testing the GRT WAAS module, so the Garmin 18 is "idling" on the glare shield - still powered, still connected, just disabled. I can re-enable it with a couple of settings in the GRT. I just feel better having FOUR GPS's on board - counting my 430 and 396.... )

Paul

 

[jwriteclub]

Only four!?!?!?!

Why, wheres the pentuple redundancy that we need on an exprimental airplane???

What happens if all four recievers quit!?!?!?



~ Christopher

 

[apatti]

I used (and still have) a Garmin GPS18 "hockey puck" as the Number 2 GPS for my GRT's for a couple years. It came with a cigarette Lighter plug on the end, and I repackaged the power supply inside that to go behind my panel. The serial lines went right into the GRT, and the thing has worked perfectly - no issues. I'd say go for it!

(I have recently been Beta Testing the GRT WAAS module, so the Garmin 18 is "idling" on the glare shield - still powered, still connected, just disabled. I can re-enable it with a couple of settings in the GRT. I just feel better having FOUR GPS's on board - counting my 430 and 396.... )

Paul

Paul,
I know this is from a while back. However, do you remember how you configured the GPS 18? I just got one today and can't seem to make it talk to my PC via COM1. I am pretty sure it is spitting out data because my PC seems to think it has found new hardware - a serial mouse. This is exactly what the Garmin manual said could happen. However, I can't seem to get the Garmin configuration program to "connect" to the puck.

Thanks,

 

[Ironflight]

Paul,
I know this is from a while back. However, do you remember how you configured the GPS 18? I just got one today and can't seem to make it talk to my PC via COM1. I am pretty sure it is spitting out data because my PC seems to think it has found new hardware - a serial mouse. This is exactly what the Garmin manual said could happen. However, I can't seem to get the Garmin configuration program to "connect" to the puck.

Thanks,

I never hooked it up to a PC, so I don't think I can help you much. I think that once you give it power, it just starts spitting out sentences on the RS-232, and the GRT recognized it once I set up the serial channel with the right bit rate and format (NMEA). I found a manual for the -18 on line, but that was four-five years ago or more - couldn't find the file on my computer just now.

You might try running a mapping program like Streets and Trips - it might very well see the GPS (I have done that before with other stand-alone GPS's)

Paul

 

[apatti]

It did finally start working for me. I am not really sure why, though. Like you said it just starts sending out the RS232 data in NMEA format. I downloaded a "data scope" for my PC from the web and eventually starting seeing the data being output by the puck. So, I hooked it up to my GRT serial 5 input and could see the byte count in the general config screen counting up. So, that was good. However, I wasn't get my position on the MAP page. Then, all of a sudden there I was, where I was. Then, I wasn't. It seems as though if you are sitting still for too long, the GPS stops sending position sentences. If I moved the puck around some, my location would eventually pop back up on the GRT.

So, is that consistent with what you see? Do you have to be moving in order for your position to show up on the MAP page? I know you have said you turn the GRT on via the aux battery while you do your walk around and stuff. That gives the GRT time to align. Do you get your location on the MAP page even before you begin your taxi?

Thanks,

 

[Ironflight]

So, is that consistent with what you see? Do you have to be moving in order for your position to show up on the MAP page? I know you have said you turn the GRT on via the aux battery while you do your walk around and stuff. That gives the GRT time to align. Do you get your location on the MAP page even before you begin your taxi?

Thanks,

Mine seemes to work like a normal GPS Tony - I never saw it dropping out like you describe. I'm wondering if you have the right bit rate set (my archives said I used 4800)....but know, what you see is not, in my opinion, normal.

Paul

 

[apatti]

Well, I took the GPS and the GRT for a ride on Saturday (note my last name ends in a vowel ). Unfortunately, it was only in the two dimensional world. However, I didn't have any trouble with the setup. Everything worked as expected. So, I am guessing my intermittent problem had something to do with the GPS being indoors and possibly loosing signal. I wish there was a way on the GRT to display how many satellites the GPS is "seeing". Anyway, it was exciting to see this work.

I am planning on building a little shelf on the firewall in the engine compartment on which to mount the GPS puck. I will also mount the 430 GPS antenna there. Does anyone have any experience with doing this? I am wondering if the hockey puck GPS might emit some RFI that would interfere with the 430 GPS antenna. I would hope Garmin sealed (RF-wise) the GPS-18 pretty well. Do I need some distance between the two?

Thanks,

 

[Ironflight]

There is a GPS status page in the setup menus Tony - I forget right now how to get to it, but it's there somewhere (about two layers down) - shows a sky map and everything! I suspect that you were losing lock due to blockage.

My 430 Antenna is on a shelf on the firewall, and my GPS-18 was on the glare shield, so they seemed happy with that distance of separation. I've had as many as three self-contained GPS "hockey-pucks" on my glare shield at one time without any problem, if that means anything...

Paul

 

[apatti]

Thanks, Paul. Sounds like the hockey pucks can peacefully reside near one another. That helps a lot.

 

[Kahuna]

You may find the technical specs for the Garmin gps 18 unit here or here.

Software for configuring the unit can be found here.
Best,

 

[DGlaeser]

Got one, works great

While playing with the APRS stuff, I have had the chance to hold in my little hand a complete 12 channel, WAAS, GPS the size of the small black puck antennaes. Its less than $60 from Byonics.

It requires 5v, gnd, and is outptting NMEA.

My question is, instead of the $400 external GPS from GRT, why not have this little bugger? I do notice that the pin outs for GRT do not have +5volts. No doubt that the system has it given that most off the shelf embedded GPS's require it. Is the NMEA data stream fields enough for the grt to be happy and do all it needs including all A/P controls?

This little puck can sit on your glarehield and do it all I believe.
What am I missing?

That's exactly what I have as GPS2 on my Sport. I took the power from the EIS (the 4.8V supply for the fuel gauges).
My reason for doing it is that my 300XL doesn't provide the time in it's data stream, so I have to remember to start out on GPS2 until the time display updates, then I can switch back to GPS1.

 

[ezpilot82ZE]

Did adding an external gps such as the GPS-18 or Byonics on the #3 port activate/enable the gps nav and moving map functions on the GRT Sport? (PFD/HSI split page, HSI page, ability to manipulate waypoints and flight plans from the GRT EFIS?)

Chris

 

[DGlaeser]

Yes...

Did adding an external gps such as the GPS-18 or Byonics on the #3 port activate/enable the gps nav and moving map functions on the GRT Sport? (PFD/HSI split page, HSI page, ability to manipulate waypoints and flight plans from the GRT EFIS?)
Chris

The external GPS is GPS2 and all the features you mention work when it is selected as the nav source. If I want to enter a flight plan, the internal Sport flight plan features are used.

 

[ezpilot82ZE]

Thanks Dennis now I have money burning a hole in my pocket!

Chris

 

[Fred.Stucklen]

How about using the TruTrack ADI NMEA output at 4800 baud? I already have that in my RV-7A, and would like to utilize it as a secondary GPS in case the GNS480 craps out. I know it's not WASS compliant, but some sort of GPS feed to the GRT is better than none.
How do I set this up on the GRT as a secondary device? Will it automatically switch over to this GPS (GPS2) if GPS1 craps out?

Fred Stucklen
RV-7A N924RV

 

[DGlaeser]

Easy enouh...

How about using the TruTrack ADI NMEA output at 4800 baud? I already have that in my RV-7A, and would like to utilize it as a secondary GPS in case the GNS480 craps out. I know it's not WASS compliant, but some sort of GPS feed to the GRT is better than none.
How do I set this up on the GRT as a secondary device? Will it automatically switch over to this GPS (GPS2) if GPS1 craps out?
Fred Stucklen
RV-7A N924RV

Connect the ADI Serial output to a free Serial In port on the GRT and then configure that port appropriately.
The GRT will not automatically switch GPS inputs. If the one you're using isn't sending valid data, you'll get a message on the GRT, but you'll have to switch inputs manually.
To set a route or destination when using the ADI's GPS you'll have to use the GRT internal Flight Plan features.

 

[Radomir]

It may be a newer thing, but it does automatically switch...

I just helped a friend with his setup.. he had to take out his Garmin 430 and send it for repairs.. His GRT Sport flagged it as GPS1 LOST (in red) and then right below it displayed GPS2 ... (in green)... Moving map reflected this automatic switch. This is all without changing the NAV source.

When we switched NAV source to GPS2, then the GPS1 Lost message disappeared (as it wasn't "relevant" to the selected source)... we were only left with the green GPS2 status line.

 

[CarlosF@grtavionics]

The GRT will not automatically switch GPS inputs. If the one you're using isn't sending valid data, you'll get a message on the GRT, but you'll have to switch inputs manually.

Radomir has it correct in the previous post. If a GPS is lost the EFIS will annunciate and automatically use the second GPS position data.

Regards,

Carlos Fernandez
Sales & Support
GRT Avionics

 

[DGlaeser]

Learn something every day!

Radomir has it correct in the previous post. If a GPS is lost the EFIS will annunciate and automatically use the second GPS position data.
Regards,
Carlos Fernandez
Sales & Support
GRT Avionics

Fantastic! Is that documented anywhere?
The reason I didn't think it switched is: I typically have my GPS2 (the hockey puck) as the active GPS when I start up (it sends the time signal). Usually when the Sport comes up, that GPS shows a red "GPS signal lost" for a few seconds - I guess the Sport typically wins the boot-up race. I've never seen it switch to GPS1 (300XL). Maybe the 300XL is still coming up as well - I've never paid attention!

 

[apatti]

Problems with GPS 18

All,
I recently started flying and find that my GPS18 is now very intermittent. I really don't think it is a wiring issue. But the next time I have someone over at my hangar I'll wiggle some wires while it is working and have the other person let me know if my GRT's give me an alarm.

I was wondering if the heat may be getting to it. I have the GPS 18 mounted in the engine compartment high up near the top of the cowling. I am sure it is getting warm in there. The specs in the manual say it can operate at 80 deg. C (176 deg F.). I guess it could certainly be that warm in there. But, honestly it happened today just after startup. So, that suggests a different cause.

The other thing is I also mounted the antenna for the 430W on the same ledge right behind the GPS18. They are only inches apart. I wouldn't think the 430W antenna is emitting anything that may be blocking the GPS18's reception. But I really don't know this.

Anyway, anyone else put the GPS18 in the engine compartment or near a 430W antenna?

Thanks,

 

[Ironflight]

I've never had a problem with my GPS18 on the glareshiled - but I know that doesn't help you! I would be a little worried about putting the GPS 18 too close to the 430W antenna because it might shadow the 430W (according to Garmin), and give you early drop-outs on the WAAS.

Paul

 

[apatti]

Thanks, Paul. I think I am going to have to move it. I flew again this morning and on takeoff, it failed again. I think it came back at some point and then dropped out again. So, I may try a temp mount on the glare shield and see what happens.

Tony