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[aprssig] Kantronics MT1200G

K7FTP k7ftp at commtechreview.net
Tue Dec 11 12:06:14 UTC 2007


"1)     A "Vista laptop" is just about the worst possible choice for APRS 
applications.  Any such laptop most likely does not have any real 
physical serial COM ports that are essential to most APRS applications 
involving computers, GPS and TNCs."

We just got finished testing and reviewing the Toshiba Techra A9-S9013.
It includes a real 9-pin serial port and worked very well with all of the 
applications we tested it with except for the software to program Clifford
alarm systems.  It shipped with Vista, but Toshiba now ships them with 
XP Professional.  

If you happen to be looking for a really good laptop that can survive in a
mobile environment (we hauled it on and off road in a Jeep Wrangler using
a RAM Mount), you should look into them.  

A review has been posted here...

http://www.commtechreview.net/jeep/a9s9013.htm

We went ahead and bought two of the next model up when we sent the
review unit back.  Same basic unit, but slightly better video, bigger HDD,
FireWire port, and 802.11 n.  


2)     Any tracker derived from a TNC like a KPC3 will be a very dumb 
tracker tracker inefficiently transmitting raw NMEA strings over the 
air,  that are over 10 TEN TIMES longer than the compressed Mic-E format 
posits generated by a TinyTrak or a Kenwood D7/D700/D710 in it's native 
mode.   These longer strings are far more likely to NOT be received 
successfully since there is a far greater chance that the packet will be 
hit by mobile flutter, a pop of noise or get stepped on by other 
stations.   Further they needlessly occupy more air time on busy APRS 
channels than necessary.   


3)     Note the description of this device as a "Wireless Modem" rather 
than a "TNC".  This is the tip-off that this device is primarily for 
commercial land-mobile NON-HAM applications. The MT-1200 is primarily 
intended for commercial AVL (Automatic Vehicle Location) and telemetry 
using proprietary protocols.  It only makes a token concession to ham 
standard operation, primarily for classic "connected" packet rather than 
APRS operation.   

It only supports basic "dumb" digipeating without the duplicate packet 
suppression and WIDEn-N callsign substitution digipeating characteristic 
of modern APRS operation.  It would be capable of simple WIDE1-1 
first-hop home fill-in digipeating.  It would not be able to function as 
a  modern mountain-top WIDEn-N digi in standalone mode

The easiest way to make this thing behave as a fully-functional 
digipeater is to let a program like APRSplus or UIview running on a PC 
place the TNC into KISS mode, bypassing it's slightly non-standard 
firmware.  


4)    The GPS in this unit is a rather dated unit not using the modern 
high-sensitivity SiRF III chipset or equivalent. 

I've always though embedding the active RF circuitry of of a GPS 
receiver in some other device's box (like a transceiver or TNC) is a 
rather perverse concept since it then forces you to deal with the 
horrendous coax losses at 1.6GHz to get from the external antenna to the 
GPS.  Not to mention having to deal with fabricating coax cable 
assemblies with those nasty subminiature connectors like SMAs or SMCs 
that GPS receiver modules and patch antennas use.  

It makes much more sense to combine the patch antenna and GPS receiver 
electronics (like a Garmin GPS18 or the low-cost Deluo units) into a 
single unit and then run DC power up/serial data down to the other 
device, avoiding the coax loss and miniature RF connectors.    I.e.  a 
Garmin GPS-18 all-in-one plugged into a TinyTrak or Kenwood serial port.




--

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

NEW!   World Digipeater Map
  http://wa8lmf.net/APRSmaps

JavAPRS Filter Port 14580 Guide
  http://wa8lmf.net/aprs/JAVaprsFilters.htm

"APRS 101"  Explanation of APRS Path Selection & Digipeating
  http://wa8lmf.net/DigiPaths

Updated "Rev H" APRS            http://wa8lmf.net/aprs
Symbols Set for UI-View,
UIpoint and APRSplus:



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