New Beta version for PocketPC's decoding APRS AX-25 data

and Plot stations with TomTom-Navigator & OziExplorerCE navigation software

 Version updated March 3th, 2005

Latest informations:

NEW: Latest information for dowloading "msvbppc.armv4.cab" can be found on my German language page: http://www.kh-gps.de/aprsdec.htm
Also possible: use Google and search with "download" &

NEW: There is a new software version  for use with OziExplorer (  or as stand alone text textcoder without using maps ):
It is offering a lot of new features and can be downloaded here: http://www.kh-gps.de/aprs9dec.zip.

After finding some bugs and adding some new features, improved version is available since March 3th, 2005.

In case your PDA is not using German version of "WINDOWS MOBILE 2003",
the function: "INTERN" has to be activated by pushing the belonging button.
The small square window right to button must change to GREEN color.
This setting will be stored when leaving the program.

The offer at APRSsoftware for use with pocket PC's is very limited. The well-known program "APRS/CE" permitted the sending and receive mode, but there are still problems regarding the availability of suitable map material. Thus it aroused my interest, when I heard some time ago of a SDK Tool of  the Netherlands program manufacturer TOMTOM. With its assistance the production of software should be possible, which would permit also a delivery of current item data to the wide-spread map program "TOMTOM NAVIGATOR" coming from the same company. The detail maps of Europe and also the USA used here, should be able to be centered according to the handed over navigation data. The idea consisted now of using this road-exact TOMTOM material also for the announcement of received APRS item data.  

Map display with using "Ozi Explorer CE"

Sometimes things are developing dynamically. Still during the occupation with "APRSDEC1" the idea developed, to knock off also other usual map programs on their serviceability for display of APRS position data. It turns out fast, that also the usefulness of the program "Ozi Explorer CE" should be possible.  Said, done,  TomTom version "APRSDEC1" was modified accordingly.  In the comparison to the version for the "TomTom-Navigator" result here some forwards -, in addition, disadvantages: An important advantage is that the program installation is substantially simpler. That is connected with the fact, that beside aprsdecoder software no additional files must be installed on the PPC. A further advantage is the ability for multi-object representation. Thus can be represented on the display up to 250 station marks with call signal inscription. That should be than sufficient with the small format more.

The delivery of the navigation data to the map program "OziCE" takes place automatically. Thus also the necessity for a separate delivery key is void. For the observation of the station happening, one can remain during the map display and has thereby a genuine Moving Map function.
When desired, the current map can be centered automatically also with arrival of new station data, according to the navigation information  contained in it.  The fact represents a certain disadvantage, that one must worry about the maps and their calibration. However one can seize particularly interesting subranges by integration according to detailed map material particularly comfortably.

Screenprints using "Ozi ExplorerCE"


Program functions of "APRS9DEC" ( Ozi Explorer CE-Version )

FIELD                                                                        FUNCTION

1    showing incoming raw data ( only for a very short moment )
2    radius of search range in kilometers ( only data coming from stations within this range will be handled over to OziCE ( E,SP )
3    latitude center of search position ( E,SP )
4    longitude center of search position  ( E,SP )
5    call within last decoded UI file ( could also be a file without any navigation data )
6    call used for selective decoding mode ( E,SP )
7    toggle-button "SEL-DECOD" for ON/OFF selective mode ( E,SP )
      ( in selective mode there only will be APRS data decoding in case calls in fields 5 and 6 are same  )
8     display of sender call

9    display of sender latitude
10   display of sender longitude    
11   display of speed and course ( if available ); in case international mode ( see 12 ) is used, speed values are in knots 
12   toggle button "INTERN" for ON/OFF international mode ( E,SP )
       ( must be "ON" in case PDA is using other than German country settings )      
13   display of distance ( in kilometers ) and bearing to received stations ( in relation to data taken from fields 3 and 4 )
14   display of additional message text's ( if available )
15   buttons "START" and "STOP" for short enabling or disabling data decoding ( E ) ;  also usable in case e.g. program hangs up
16   button "ERASE MAP POSIT" will erase all position markers on OziCE map ( E ).
17   toggle button "NO AUTO MAP" will activate/deactive PDA's automatic switch off function when using battery operation ( E,SP )
18   display of incoming stations "Maidenhead-Locator"
19   display of selected COM port ( default = COM1 )
20   button "RESET" will initiate TNC reset in case Kenwood TH-D7- oder TM-D700 is connected
21   toggle button "MAP CENTER"  is ON/OFF function for automatically centering OziCE maps according to incoming data ( E,SP )
22   COM port selection  if another than default port COM1 has to be used  ( E )
23   button for bringing program "OziExplorerCE" into foreground ( E )
24   button for showing version and copyright informations ( E )
25   toggle button "T" for ON/OFF test mode ( test mode is for checking the decoding function;
       is using lat/lon data according to contents of fields 3 and 4 ) ( E )

26   APRS symbol with only limited decodability by OziCE ( E ).

used abbreviations:  

"E"   = insertion possible  
"SP" = automatic storage when leaving the program
From here software "APRS9DEC " can be downloaded ( Ozi Explorer CE-Version )

Map display with using "TomTomNavigator"

APRSDEC1 will not be continued

"APRSDEC1" decodes APRS data, how they can be received on e.g. European frequency 144,800 MHz.  For doing this, serial entrance of the pocket PC's must be connected with the TNC data output of devices like Kenwood TH-D7 or TM-D700. In principle the program also should function with other types of TNC. Important it is however, that they possess a serial 9600bps-Data connection and are using ">" following the sender call and a colon before start of message informationen.
The program decodes all data provided in the
standard APRS and also in MIC-E format. Thus e.g. signals generated from wide spread software like "UI-VIEW" or "WIN APRS"  and also Kenwood devices or the "TinyTrak" could be processed.
Decoded data, like sender call, long & latitude degrees, as well as ( if available ) course and rate of motion appear on the display of pocket PC in large representation. In addition, also possibly existing message texts can be seen.
While in the standard mode, ALL arriving data with APRS Positionsdata contents are decoded, but there also is possibility of  processing ONLY data from a certain station. The selective call sign used for it can be entered by the user. With selection of this mode of operation, a decoding of arriving Messages takes place only  if station call and entered call signal are identical. The program generally signals a call-sign agreement by expenditure of an acoustic message.

By key depressing, program "
TOMTOM-Navigator" ( starting from version 1.5 ), installed on the same PDA, can be called. According to the long & latitude degree values supplied from the program "APRSDEC1" map centring takes place. Under the condition of the presence of the respective land maps, in this way a European- or USA-wide down to road level handing plot of APRS stations is possible.

Program functions ( TomTom-Navigator version )

The illustration above shows the window of the program "APRSDEC1". In the upper section for short time all received raw data are indicated. It serves mainly for  monitoring communication with the TNC. The last in each case recognized station call will be represented in the underlying left text field. Right beside it the call used for the selective identification. In the default condition here my call signal "DJ7OO" appears ", but it can be overwritten with any different one. During agreement of both calls represented in this line, a short audio signal sounds.
Over a checkmark at the right line margin it can be caused that a decoding takes place from item data
ONLY with agreement of both call signals.

To contents of the following lines much is not to be said. If no values for rate of motion ( SPD = speed ) and the direction of motion ( CRS = course ) are available or if only zero values are recognized here, then their announcement maybe will be suppressed. Over a hook at the right edge of the speed line, program can be switched to expenditure of the velocity values in KNOTS .
Below CRS field additional informations sent with message will be shown ( if existing ).

The program displays the received station data until onother one is decoded. If the frequeny is busy, the time you have for e.g. centering the map could be very short. For this, by using  key "STOP" you can interrupt further decoding at any time and continue with "START" in case you like to do so.

After pushing key "CENTER MAP", actual navigation data will be transfered to program "TOMTOM-Navigator". If  the program were not yet started, the well-known "egg timer" appears for short time. Map, if a fitting location data is present, then is centered according to the supplied navigation data. The map center is marked by a flashing mark. The map cutout first always appears in the stage with greatest possible detail representation, but can be changed however afterwards with the zoom shot slidegate valve at the right contour at will.

A return to the program "APRSDEC1" can take place via manipulation of the button in the right upper corner of the navigator window.

To the control functions at the lower contour:
Over key named "
R" the TNC of attached ( Kenwood -) equipment can be put back if necessary ( RESET instruction ).
An activation of the hook right beside it blocks the automatic shut-off of the PPC's when battery operated . Thus it is prevented that the PDA switches OFF independently, if the Touch screen were not affected for some time. Since the mechanism is causing however an effective protection against over-discharging of the internal equipment battery and the danger of a total overrun is reduced clearly thereby, it is advisable to use the blockage of this function only very carefully. In order to be able to react if necessary to indicated battery notifications of emergency, it is meaningful to keep the display of the PDA's thereby in the view.

Over the keys "SDK" and "TTN" can be queried the software-Versions of the used TOMTOM SDK and the TOMTOM-Navigator software if necessary. The results are indicated in the text field right beside the keys.

From Werner, OE9FWV comes the following tips:

The center points of maps can be stored very easily also as POI (POINT OF INTEREST). If with the pin for some seconds on the map center one presses, a menu opens, in which also one point is for the definition of  POI's. In this way one can produce oneself very easily a small data base with item data of the most important stations.

From here software "APRSDEC1 " can be downloaded ( TomTomNavigator-Version )

Information for program installation ( both versions )

Programs "APRSDEC1" and "APRS9DEC" are made with using "eVB" ( "Embedded Visual Basic" 2000er version ) and should run thereby under all WIN CE versions starting from 3.0.
In order to be able to operate it also with the current operating system "
Windows Mobile 2003", however still the associated new run time library "msvbppc.armv4.cab" must be downloaded by using URL:  


and transferred to PPC. In case by some reason above URL is not working, a couple of usable results also can be found by searching via GOOGLE.  Search words should be "msvbppc.armv4.cab" and "download".

Against it, for the Windows CE versions up to 2002, the "old" run time libraries transferred anyway with the remark program, can be used.

If for individual files a decision between versions with different production date has to be made, always the newer file should be selected.

APRSDEC1 for TomTomNavigator only:

For the linkage of the map software with the decoder program uniquely a TTN SETUP must be accomplished. The first beta tester Werner, OE9FWV describes the proceeding in such a way:
One must unpack the ZIP file first and e.g. place it in a temporary path. In this way one receives a listing "
TOMTOM Setup" and can start  "SETUP.EXE" in it. .
 In opening window the desired language is to be selected and the arrow to right to be pushed. In order to agree the license conditions, the box is to be clicked. It continues to go again with the arrow to the right.
After selection of  "
TOMTOM navigator SDK"  ( in the grey window ) is to be continued again with the arrow to the right.
Now ActiveSync is started and the question about the installation listing answered with "
Subsequently, the installation on the PPC should run off. After its completion the procedure is to be terminated by clicking the arrow to the right.
The necessary ZIP.Data can be downloaded here.

Connection between TNC and PocketPC by the example of
HP "Ipaq H2210" and Kenwood "TH-D7"

Unfortunately it is not longer natural that all offered pocket PC's are equipped with a serial interface, but for using my program this is necessary.  BEFORE the purchase of a new PDA's one should inform thus accordingly. In principle also an interconnection of pocket PC and TNC over e.g. IrDA or BLUETOOTH is conceivable, but currently no simple solutions seem to exist.
Since the programs "APRSDEC1" and "APRS9DEC" only processes data ARRIVING at the pocket PC, in principle a two-wire connection between both devices is enough. It is recommendable nevertheless ( e.g. to the use of  programs like  "APRS/CE" ), to wire also the reverse data direction of the PDA toward TNC.
For the connection of both devices a serial data cable fitting for the respective PDA type can be used. Appropriate cables mainly are for the connection of the pocket PC's with the COM Port of a PC's and are equipped with 9pole. Sub D socket. They are inexpensive available for most types of device. Data toward PDA must be available at Pin3 of the socket. Turned around, at Pin2 signals coming from the PDA are available. Pin5 is the common mass.
The further connection with the TNC can take place over a suitable 9pol. Sub D plug. Pin2 is to be connected with the data input ( middle ring ) and pin3 with the data output ( Tip ) of the 2.5mm-stereo-plug. The ground wire is to be put to the internal ring of the plug.
Who thinks itself it capable of  the detour over the Sub D patch cord, can itself  manufacture a DIRECT CABLE.. For this a device plug , like being  individually available for most pocket PC types, is necessary. With newer IPAQ's, e.g. the H2210 a 22pin version is used. Serial Data In will be over pin7, while outgoing data are available on  pin8. Common mass are the pins 10, 15 and 22.
The advantage of this solution consists still of the fact, that over the pins 1 to 4 external 5V-power supply of the PPC's can be realized in simple matter.
One finds information to the interface of the pocket PC's of HEWLETT PACKARD also here:
http://www.svenketel.de /0109000.htm

Simple Decoder for AX-25 APRS-Data

With a pocket PC, the software "APRSDEC1" or "APRS9DEC" and a Transceiver like the TH-D7 a miniature system for APRS decoding can be realized in a simple manner, but it is often interesting surely to be able; to use in place of the Kenwood equipment also different; if necessary more inexpensive available units ( e.g. different amateur radio devices, SRD transceivers or radio scanners); but still the problem of the APRS Data decoding remains solving.
As long as only EVALUATION from data must take place, the use a complete TNC's is not necessary thereby. Instead also a simple circuit can be used. The decoder developed in such a way gets along with relatively few construction units and uses software coming free available from  Mike Berg, N0QBH. It processes the AFSK-sound signals usually standing at the listener exit from receivers to the order and spends serial data with 9600bps. These signals must be supplied to the data input of the evaluating pocket PC's.
The negative tension necessary for RS.232-level is input from the data output line of the attached equipment. In most traps one can however also do without it and instead only with TTL output levels to work. Been void then the construction units D2, R13 and in place of C11 a cable link must be inserted.

Circuit APRS-DEC

Part List

FX614 or MX614 (CML)
PIC 16F627 ( programmed )
78L05 ( 5V Regulator )
LED1,LED2 e.g. red and green
BC557B or PNP Standard-Type C2
3.579 MHz
10uF 16V
10uF 16V
10uF 16V

PCB Board Layout

( the capacitor which must be wired between "U1" pin 9 and ground as well as the connection from
"U2" Pin 14 to +5V line [ e.g. emitter of Tr1 ] unfortunately have been forgotten with this version of layout )

Meanwhile the CML component modem chip FX614  ( USA: MX614 ) will not be manufactured any more. Thus its procurement might become ever more and more difficult. My supplier of many years for example, cannot supply it any longer. The selection of suitable IC's for FSK demodulation seems to become thus limited, but still available the EXAR "XR2211" is obvious. Compared with the CML type, here however the decoder center frequency is to be adjusted by assistance of a potentiometer. Nevertheless i am intending to use this chip, when designing a new version of decoder.

My contact email address:



Non-liability: For problems, which stand themselves from use of my program devoted or in
connection with information from my sides.
I do not take over any responsibility.

The first version of this page has been translated by JA1OGS ( ex VK4GO ) dated: 19-01-2004

remark from DJ7OO :
I have to thank Art, JA1OGS ( ex VK4GO ) very much for doing this hard job.  


Sorry, but remaining parts of bad English text are caused by me,
 when i had to make some corrections, hi.