Based on target market, equipment popularity, and realistic implementation possibilities, here is what I would suggest for a GPS/CDI/HSI implementation and display:
Two RS-232 inputs, supporting the following formats: NMEA 0183 (Handheld GPS Units), Garmin AVIATION (Most Garmin Panel Mount Units), Garmin MAPCOM (GNS 480), and SL 30 Serial Out (Garmin SL 30 NAV/COM). This would allow for a NAV SOURCE selection of GPS1/GPS2, NAV1/NAV2, or GPS/NAV, depending upon what equipment is installed.
Two RS-232 outputs, which, via softkeys on the Dynon display, would allow selection of the desired radials on the Garmin units which offer NAV capabilities.
I would envision two separate display screens, one overlaid on the "main" attitude and heading screen, and a second HSI screen, available as either a full-screen display or as part of a split-screen display. The information displayed on each screen would vary depending upon the selected nav source. Here are the display combinations I would suggest:
Overlaid on the "main" attitude and heading screen, you would see Standard CDI "dots" across the bottom of the screen, above the "ball", and standard CDI glideslope "dots" along the left side of the screen, just to the right of the AOA indicator.
- GPS nav source: Assuming a loaded flight plan or direct-to, a triangle or small vertical bar would indicate horizontal deviation. Elsewhere on the screen, in magenta letters, the word "GPS" (with a "1" or "2" in dual GPS installations) indicating the nav source, the ID of the current "TO" waypoint, bearing and distance to the waypoint, and groundspeed would be displayed. Crosstrack and/or wind information might also be displayed somewhere on the screen. If there was no flight plan or direct to, there would be no CDI deviation indicator, the words "NO WAYPOINT" would appear below the nav source indication, and only the nav source and groundspeed would be displayed.
- NAV radio nav source: If the selected VOR/ILS was in range, a triangle or small vertical bar indicating horizontal deviation would be displayed, and if the glideslope was active, a triangle or small horizontal bar indicating vertical deviation would be displayed. Elsewhere on the screen, in green letters, the word "NAV" (with a "1" or "2" in dual NAV installations) indicating the nav source, the selected frequency or decoded VOR/ILS identifier (if available), and selected radial would be displayed. If the VOR/ILS was not in range, there would be no horizontal deviation indicator, and the word "FLAGGED" would appear in the area where the nav source, frequency, and radial info are displayed.
On the HSI screen, you would see the standard HSI compass rose, along with the standard pointer containing the horizontal and vertical CDI "dots" in the standard "cross" configuration.
- GPS nav source: The pointer would be colored magenta. Assuming a loaded flight plan or direct-to, the compass rose would be rotated to indicate the bearing to the currently selected waypoint, and the horizontal deviation indicator would be displayed. Elsewhere on the screen, in magenta letters, the word "GPS" (with a "1" or "2" in dual GPS installations) indicating the nav source, the ID of the current "TO" waypoint, bearing and distance to the waypoint, and groundspeed would be displayed. Crosstrack and/or wind information might also be displayed somewhere on the screen. If there was no flight plan or direct to, the compass rose would be "parked" in a standard direction, there would be no indicator on the CDI dots, the words "NO WAYPOINT" would appear below the nav source indication, and only the nav source and groundspeed would be displayed.
- NAV radio nav source: Assuming the selected VOR/ILS was in range, he pointer would be colored green. The compass rose would be rotated to indicate the currently selected radial, the horizontal deviation indicator would be displayed, and if the glideslope was active, the vertical deviation indicator would be displayed. Elsewhere on the screen, in green letters, the word "NAV" (with a "1" or "2" in dual NAV installations) indicating the nav source, the selected frequency or decoded VOR/ILS identifier (if available), and selected radial would be displayed. If the VOR/ILS was not in range, there would be no horizontal deviation indicator, and the word "FLAGGED" would appear in the area where the nav source, frequency, and radial info are displayed.
For Gamin units with both GPS and NAV capabilities, annunciation of the status of the CDI Selection should be provided below the "nav source" indicator with the pointer and lettering in magenta when the CDI "GPS mode" is active, and in green when the CDI "NAV mode" is active.
In installations where the #2 nav source is a NAV or GPS/NAV unit, a second bearing pointer and associated information colored blue might be provided.
Hopefully, this will be useful to Dynon, and provide a starting point for discussion among the other posters here...
