[aprssig] Car radio APRS display?

Stephen H. Smith wa8lmf2 at aol.com
Sun May 17 23:17:29 CDT 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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