[aprssig] Car radio APRS display?

Stephen H. Smith wa8lmf2 at aol.com
Mon May 18 00:17:29 EDT 2015

On 5/17/2015 11:05 PM, Greg D via aprssig wrote:
> Hi folks,
> I recently acquired a new (to me) car, which has a Audio / Nav / etc. display
> unit in the dash.  The port for the backup camera is unused (no camera
> installed), so I was thinking it would make an interesting place to push an
> APRS map.  Baseband video is all that's required.  According to the manual, the
> reverse gear interlock can be disabled, so I should be able to select it when
> in motion.
> I was thinking the original Raspbery Pi might make for a good computer to drive
> it, as it is small, runs a full Linux graphical OS, has a built-in video out,
> and runs on minimal power.  But, what software to run, and how to control it
> without a QWERTY keyboard and/or mouse? There is no room on the dash or nearby
> to host a laptop or tablet or such, and none of the existing software I know of
> is car-friendly (thinking driver distractions).
> What I really need is something that just comes up with a map and moving
> icons.  Maybe a button or two for zoom in/out, one for a list of stations /
> messages heard, something simple for sending predefined messages back.  I'd use
> one of the small receive-capable "Tracker" sorts of units to provide the raw
> data (RF + TNC).  I don't think any of the existing "Ham HUD" sorts of units
> have internal maps and video out, but that would be even ideal.

1)    The backup camera inputs are normally classic ANALOG 640x480 composite 
NTSC (the former US broadcast standard now used by virtually nothing except 
CCTV cameras).   I.e. resolution equivalent to old-time analog TVs or early PC 
CGA video output, and not remotely high enough for today's GUI computer interfaces.

2)    The video-out on an unadorned Raspberry Pi is HDMI DIGITAL compatible 
with the majority of today's flat-panel monitors and digital TVs. The 
resolution is typically either 1344x720 or 1920x1080. I.e. equivalent to 
today's digital HDTVs.

3)    The one use I have toyed with for the analog composite input of these 
dashboard displays (even my Garmin Nuvi 855 has one) is as a live monitor for 
my mobile "SSTV LiveCAM" setup.   Here I feed an NTSC composite camera signal 
into the composite input of the Kenwood VC-H1 handheld SSTV device's scan 
converter where one NTSC fastscan frame is grabbed and down-converted to a 
Single SSTV image.  It would be nice to have a live "viewfinder" display for 
this setup.

Currently I use a Canon Powershot A520 point&shoot digicam.  This camera has an 
NTSC composite analog output intended for playback picture display on analog 
TVs of the day (15 years ago) that had the yellow RCA composite-in video jack. 
   The Powershot's own camera-back display functions as a view-finder but it's 
small (1.8"). I would really like to use a decent zoom-tilt-swivel CCTV camera 
that runs on 12VDC, and use the dashboard display as it's viewfinder.



Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

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