[aprssig] GPS/Puck or Other Wise
Stephen H. Smith
wa8lmf2 at aol.com
Sat Jul 9 17:14:34 EDT 2005
rgilson at adelphia.net wrote:
> Any one got any suggestions for a WASS GPS which interfaces with a D7
> or D700 and powers on with a signal from the Kenwood's. Please no
> Garmen Earthmate. A display is not necessary but power on from the
> Kenwood's is mandatory. Power supply can be 12, 6, 5 VDC or
> whatever. I'm sure something has replaced RS Digitravelier. Thanks.
> WA2WWK
> Ron
>
>------------------------------------------------------------------------
>
1) Earthmate is Delorme, not Garmin
2) The Kenwoods don't provide any kind of explicit power-on control
signals, especially the TH-D7 which has only a three-conductor bare
minimum serial hookup (TXD, RXD, common through a 3-cond 2.5mm stereo
minijack). What they can do is provide a constant voltage on the
outgoing data line from their dedicated GPS jacks indicating to an
external device that the radio is turned on. .
3) The Garmin ForeTrex wrist devices will respond to (indeed require)
the wakeup voltage on their incoming data lines before they start
talking. However this only turns off/on the RS232 interface in these
devices (one of the most power-hungry subsystems); the main GPS RX and
it's local LCD display remains live even when the RS232 is turned off.
A review of the ForeTrex is here on my website:
http://webs.lanset.com/wa8lmf/ForeTrex
4) Why worry about switching the GPS on and off at all? A device like
the Garmin GPS-18 powered by a decent switching mode regulator (not a
7805 linear device) only draws 50-60 mA at 12VDC which translates to
about 1 Amp-Hour a day. You can leave this device on for a week or
more without affecting the car battery significantly. The advantage is
that the GPS is always locked and has a currrent ephemeris and almanac
ready-to-go.
Stephen H. Smith wa8lmf (at) aol.com
Home Page: http://wa8lmf.com
New APRS Symbol Chart
http://webs.lanset.com/wa8lmf/miscinfo/APRS_Symbol_Chart.pdf
New/Updated "Rev G" APRS http://webs.lanset.com/wa8lmf/aprs
Symbols Set for UI-View,
UIpoint and APRSplus:
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