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helipirate

Inspire OSD heading indicator

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Not sure if this info is elsewhere...

I am using the Inspire OSD. I am really pleased with this unit! The features are great and after yesterdays field testing of the RSSI functioning, I am totally stoked..

Now.. I am using the 5Hz micro GPS, and after going up to 1000 ft yesterday, (a requirement of our AP work) I found that it was a little hard to find the home field! All those roof tops look exactly the same! I got back ok, but immediately realised the value of a bearing and distance to home indicator.

Luckily the inspire has a waypoint bearing/distance indicator! Only problem is I dont want to use the garmin geko and I only want to have the distance and bearing to home, not other waypoints.

Is there any way of using a micro GPS or utilising a small circuit somewhere to enable the waypoint bearing/distance indicator to show the way home?

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Luckily the inspire has a waypoint bearing/distance indicator! Only problem is I dont want to use the garmin geko and I only want to have the distance and bearing to home, not other waypoints.

Technically speaking, "home" seeking would be a single waypoint application.

Is there any way of using a micro GPS or utilising a small circuit somewhere to enable the waypoint bearing/distance indicator to show the way home?

Inspire does not have a waypoint engine in it, so it needs that stuff to be handled externally. The Hexpert System people (the makers of the Zlog altimeter) were working on a low cost general purpose waypoint sequencer that used a micro-GPS module. It probably would have been compatible with Inspire (their little circuit was emulating a Garmin). Unfortunately the project stalled last year and I don't think they will finish it. So, the only supported solution at this time is to install a Garmin GPS.

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Technically speaking, "home" seeking would be a single waypoint application.

Inspire does not have a waypoint engine in it, so it needs that stuff to be handled externally. The Hexpert System people (the makers of the Zlog altimeter) were working on a low cost general purpose waypoint sequencer that used a micro-GPS module. It probably would have been compatible with Inspire (their little circuit was emulating a Garmin). Unfortunately the project stalled last year and I don't think they will finish it. So, the only supported solution at this time is to install a Garmin GPS.

Yeah I saw that project and suddenly it stopped.

So if the inspire does not have a waypoint engine, what input data does it use to display the distance/heading data on the screen.?

(In other words what do I need to feed it to make this waypoint display feature work?).

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The $GPRMB sentence is used. It supplies all the information that Inspire needs to display distance and direction to the waypoint. All the Great Circle computations that are involved are done externally by the Garmin GPS.

The nice thing about using the Garmin handheld is that you can edit the waypoint routing tables using its on-screen menu system (no PC needed). That is very handy if you want to make a change to the route at the field. However, in your case, you seem to only be interested in one waypoint (home), so this is not a plus in your application.

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I only just found out that the inspire is your creation! First.. Congrats! A great device.. Ah.. i must admit that I usually don't forum much, since my business is all about software I don't spend much time on the computer after work ! Does a mechanic go home and play with his car?? Answer: Not after being one for 20 years!

After reading the other project forum, my guess is that I need is a device that sits between the GPS module and the OSD.

Requirements:

1. A push to record the single waypoint (home position) switch from the current position.

2. The device passes through the $GPGGA and $GPRMC data without modification to the OSD.

3. The device calculates the bearing/distance data. Calculated from the current location and recorded waypoint.

So I would need to get the device to do the bearing/distance calculation and to modify the $GPRMB sentence to include the distance and bearing info and pass that.

Is this correct?

This is interesting. Might be worth investigating. It would be more simple than the other project's waypoint engine but still not easy!. It will not need to worry about waypoint arrival/departuure etc etc. My use is to get me back close enough to home to recognize where I am visually.

Second, I know you contributed to the other forum's project with comments etc. so if I started a project, pertaining only to the Inspire, could I count on your support for any info on the OSD I might need to get it going? I have the resources available to make something like this happen. Since we are planning to use 5 or so OSD in our fleet of AP machines it is worth our while to do it. The terrain here is very short on noticeable features for navigation!

Appreciate any help you could provide!

Edited by helipirate

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Sure, I'll help out where I can. I also recommend that you borrow a Garmin so that you can use it as a gold standard reference for your emulated $GPRMB sentence.

Also, you might want to look at the GPS market to see if someone has introduced a smaller handheld that has waypoint features and RS-232 (USB won't work with Inspire). Using one of these would solve the problem without soldering/compiling a thing. :)

I also responded to your PM.

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i hacked a geko 201 out of the case and added aj st connector to the back to power it off the inspire osd and now it barely weighs anything and i can fit it almsot anywhere. i use it for exsactly what you want, a home heading only for now. what i do is a make a route on the geko by marking the point of where i launch my plane as a route point and then i walk like 20 feet and mark another route point and i tell the geko to follow this route . when i take off and i pass the route points, no matter where i go the arrow is always pointing home since i only did a simple two point route that is right of where i launched.

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