NAVTEX Decoder v1.0 - Decoder / message logger for Windows
When the program is started, you'll see the display above. The light blue
trace is a spectrogram of the current soundcard input with a tuning cursor.
The red trace is the current decoded data stream. The other two panels are
the message output windows. Tune an SSB receiver to the NAVTEX frequencies
490kHz or 518kHz during your local NAVTEX transmitter's transmission times.
Feed the receiver's audio output into your soundcard either directly through
a cable connection to the line input socket or through the PC's microphone
and set the current Windows sound recording device appropriately. You can
make your own test datastreams by using the online generator
at -www.frisnit.com/navtex/encoder.html. If you have trouble using this
utility then you can download a ready made test stream test.wav.
If you are using the microphone as an input, test that the current recording
device is set correctly by whistling into the microphone. You should see a
single prominent peak on the display. If not, check your Windows sound
settings. Ensure the test signal is audible to the microphone. This may be
difficult if the microphone and speakers are fixed in the case of a laptop
computer. You may also experience difficulty with laptop computers when
playing back the generated streams because of the frequency response of
laptop speakers. Difficulty may also be experienced in noisy environments.
Best results will be obtained with a direct cable connection to the signal
source through the soundcard's line input socket.
When you play the data stream you should see two peaks appear in the
spectrum view like those shown below. These peaks correspond to the two
frequencies used to transmit the zeros and ones of the binary data stream.
Position the frequency cursor so the two yellow bars coincide with the two
peaks.
You should see some nice sharp square waves in the data output window.
After the regular beeping at the start of the data streams, you should see
text appearing in the raw data output window. If you don't get any text
output, try replaying the stream. The stream starts with some syncronising
beeps and the system may have trouble decoding if it misses them. You might
need to adjust the playback volume for optimum results. Quieter playback
usually results in better results as saturation of the soundcard input is
less likely to occur. Once you get the decoder working with the generated
data streams, download livesignals.mp3 to test the program using a real
NAVTEX transmission.
In addition to decoding NAVTEX streams, the program also logs individual
NAVTEX messages allowing the receiver and decoder to be set up and left
unattended to collect messages throughout the day. Messages that match the
NAVTEX message format are saved to disk in subdirectories of the main
program directory. They are saved as text files, so they can be used
separately from the main application if required. The default message on the
NAVTEX test message generator follows this format...
Download :
http://www.frisnit.com/navtex/navtex.exe
HomePage :
http://www.frisnit.com/navtex/
Registration :
Name : CRaCkeD bY JF3000
Serial : 841d0069592d21198eef0162a8825920
JF3000
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