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[aprssig] Help setting up Kenwood D700A

Stephen H. Smith wa8lmf2 at aol.com
Mon Sep 12 10:04:56 UTC 2005


dave at emv.co.uk wrote:

>The D7 and presumably the D700, also have a TNC setting that defines
>what "NMEA sentence" the radio recognises as data to use when seen from
>the GPS.  I don't have a rig here with me now, but if that is set to the
>Kenwood default ($PNTS) and the GPS does not send that sentence, it will
>never work.  I know you can change it with a command over the PC-radio
>serial link, as Ui-View does just that, but I don't know at the moment
>if you can change it from the rig's front panel menu system.  (You don't
>seem to be able to on the D7, having just downloaded a manual!)
> 
>GPSTEXT $GPRMC  Is what Ui-View sends to change it to $GPRMC. (As listed
>in it's CMD files for the D7 and D700)
>
>  
>
The $PNTS string is not output by any GPS device.    It is prepended to 
the actual GPS string by the Kenwood firmware as it echoes data received 
from the dedicated GPS port out the main serial port to the computer.   
It is this distinctive prefix that programs like APRSpoint  and UIview 
use to separate the GPS data from the TNC receive data.  

The Kenwood firmware is capable of capturing and forwarding only ONE GPS 
data word.   The one word it will forward is determined by the GPSTEXT 
command. 



==== The gory details of the GPS data formats below are from a previous 
post I made on this issue ====
========== PASTE ===========

The most commonly used GPS Data Sentences, and the data they contain, 
are [ Full details on the structure of these strings is at the bottom of 
this post ] :

===  GPRMC   (Time, Lat, Long, Speed, MagVar) 

===  GPGLL   ( Lat, Long, Time)

===  GPGGA   (Time, Lat, Long, GPS Valid, Number of Sats Used, HDOP, 
Altitude) 

===  GPGSV   (Satellite Status)

===  GPZDA   (Time, Date)

===  GPVTG   (Compass, Ground Course Velocity)

Assuming your GPS device actually outputs GPRMC, GPGLL and GPGGA strings 
(in some GPS units each sentence has to be turned on or off in a setup 
menu) the results will be:

1)  When the US version D7A(G) or any D700 is used in standalone 'APRS" 
mode, the compressed Mic-E transmission format will contain altitude IF 
the GPS outputs the GPGGA string.    The Euro versions of the THD7 don't 
encode altitude, even if altitude IS present in the GPS data stream.  
Note that you can shorten the Mic-E burst (useful for posit-after-voice 
operation) by turning off the GGA string in the GPS device so the 
comment field doesn't get filled with altitude data.
 
2)  When the D7/D700 are used in "PACKET" mode with an external program, 
the radio internal firmware can echo ONE selected string of your choice 
received at the GPS input out the main serial port connected to the 
PC.    The command GPSTEXT sent to the D7/D700 internal TNC determines 
which one (and only one) GPS string is captured and forwarded to the PC 
each second. ( Use a basic terminal program like Hyperterminal set to 
9600baud 8-N-1 connected to the radio's main serial port to send this 
command, and to view the results.)

( You can see and/or alter this command in the "THD7.CMD" or  "D700.CMD" 
  TNC initialization file for the THD7 or D700 in UI-View. )

If you initialize with "GPSTEXT $GPGGA" the APRS program on the PC (i.e. 
UI-View) will be able to "see" (and therefore transmit) LAT, LONG, TIME 
and ALTITUDE but not speed and heading.

If you initialize with "GPSTEXT $GPRMC" the APRS program on the PC will 
be able to see LAT, LONG, TIME and SPEED. but not altitude.

If you initialize with "GPSTEXT $GPGLL" the APRS program on the PC will 
be able to see LAT, LONG, and TIME but nothing else.

3)  If you connect the GPS device directly to the PC through a second 
serial port (i.e. not using the Kenwood pass-through feature), the APRS 
software now has access to ALL the sentences the GPS is outputting.   
If  your PC-based APRS software knows how to parse and extract data from 
multiple GPS sentences and then format this data into APRS format,  you 
can potentially  transmit  LAT, LONG, SPEED, and ALTITUDE at the same time.

======================================================


Details on the GPS Data Sentences:

Note 1: Lat and long are always expressed as Degrees, Minutes and 
decimal fractions of minutes, --NOT-- as Degrees, Minutes and Seconds.  
There is no delimiter between the degrees and minutes but there IS a 
decimal between the whole and fractional part of minutes.  Resulting 
data  is formatted as DDMM.mmm   -- not DDMMSS

Note 2: Lat and long are not signed; a separate field indicates N/S or 
E/W. 

Note 3:  NMEA 3.0 format has added additional decimal places to the 
lat/long values for higher resolution.  Software that parses by counting 
character positions from the beginning of the string (i.e. BASIC MID$ 
functions instead of correctly using the comma delimiters) may not work 
correctly with NMEA 3.0 format.

 GPGLL   ( Lat - Long - Time)

$GPGLL,  LLLL.lll, N, LLLLL.lll, W, HHMMSS.ss, *CS

Fields:
1 - Latitude
2 - North/South
3 - Longitude
4 - East/West
5 - UTC (HoursMinsSecs.secs)
6 - Checksum

-------------------------------------------------------------------------------

GPRMC   (Time Lat Long, Speed, MagVar)  Always one per second

$GPRMC, HHMMSS.ss, A, LLLL.lll, N,LLLLL.lll, W, KK.k, HHH.h, DDMMYY
-------------------------------------------------------------------------------

GPGGA   (Time - Lat -Long - GPS Valid - Number of Sats Used, HDOP, 
Altitude)  Always one per second

$GPGGA, HHMMSS, ss, llll.lll, N, LLLLL.LLL, W, 1, NN, 1.7, AA.a, M, 
-A.a, , , *CS

Fields
1 - UTC (HoursMinsSecs.secs)
2 - Latitude in DD MM.mm format
3 - North/South
4 - Longitude in DDD MM.mm format
5 - East/West
6 - GPS Fix  Valid=1, Invalid=0
7 - Number of Sats in Use
8 - HDOP (One is Best, 10 is Worst)
9 - Altitude
10 - Units M=Meters, F=Feet
11 - Geoidal Sep
12 - Geoidal Units M=Meters, F=Feet
13 - Time Since Last DGPS Update Data (Not Used)
14 - Diff Corr Station ID#  (Not Used)
15 - Checksum

------------------------------------------------------------------------------- 


GPGSV   (Satellite Status)

$GPGSV, N, N, NN, 01, Ele1, Azi1, SN1, 02, Ele2, Azi2, SN2, 03, Ele3, 
Azi3, SN3, 04, Ele4, Azi4, SN4, *CS

Fields:
1 - Number of GPGSV Messages
2 - GPGSV Message Number
3 - Number of Sats in View (i.e. determines number of GPGSV messages)

4 - 1st Sat Num
5 - 1st Sat Elevation In Degs (Rounded to integer)
6 - 1st Sat Azimuth in Degs (Rounded to integer)
7 - 1st Sat SNR 00-99 dB, blank when not tracking sat

8 - 2nd Sat Number
9 - 2nd Sat Elevation In Degs (Rounded to integer)
10 - 2nd Sat Azimuth in Degs (Rounded to integer)
11 - 2nd Sat SNR 00-99 dB, blank when not tracking sat

12 - 3rd Sat Number
13 - 3rd Sat Elevation In Degs (Rounded to integer)
14 - 3rd Sat Azimuth in Degs (Rounded to integer)
15 - 3rd Sat SNR 00-99 dB, blank when not tracking sat

16 - 4th Sat Number
17 - 4th Sat Elevation In Degs (Rounded to integer)
18 - 4th Sat Azimuth in Degs (Rounded to integer)
19 - 4th Sat SNR 00-99 dB, blank when not tracking sat
20 - Checksum



-------------------------------------------------------------------------------

GPZDA   (Time Date)

$GPZDA, HHMMSS, DD, MM, YY, *CS
1 - UTC Hours, Mins, Secs
2 - Day
3 - Month
4 - Year
5 - Checksum

-------------------------------------------------------------------------------

GPVTG   (Compass, Ground Course Velocity)

$GPVTG,  DDD.dd, T, DDD.dd, M, NNN.n, M, NNN.n, K, *CS
1 - Heading (True)
2 - TRUE "T"
3 - Heading (Magnetic)
4 - Magnetic "M"
5 - Speed Knots or Mph
6 - Units  ("N" or "M")
7 - Speed KM/h
8 - Units ("K")
9 - Checksum




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

"APRS 101"  Explanation of APRS Path Selection & Digipeating
  http://webs.lanset.com/wa8lmf/DigiPaths

Updated 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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