Black Cat Systems
Follow our tweets!

Home
Purchase
News
Mac OS X Software
Mac OS 9 Software
Windows Software
Ham Radio iPhone/iPad
Linux Software
Documentation
Support/FAQ
Update Policy
Lost Reg Code?

Radiation Detectors
USB Icom CI-V Interface
MIL-STD-188 Interface

General Interest Programs

  Atomic Mac/PC
  Audiocorder
  Audio Toolbox
  Black Cat Timer
  Diet Sleuth
  iUnit
  Graffikon
  Graph Paper Maker
  Health Tracker
  Knitting Wizard
  Label Wizard
  Prog Audio Gen
  Sound Byte
  Synth 76477

Amateur Radio Programs
  Audiocorder
  Black Cat CW Keyer
  Cocoa 1090
  Cocoa RTL Server
  DGPS Decoding
  DX Toolbox
  Elmer
  eQSL Factory
  MatchMaker
  MININEC Pro
  Morse Mania
  MultiMode
  mySdrPlayback
  RF Toolbox
  SelCall
  Sonde

iPhone/iPad Apps
  ALE
  Atoms To Go
  dB Calc
  Clik Trak
  DGPS Decoder
  Drill Calc
  DX Toolbox
  Elmer Extra
  Elmer General
  Elmer Tech
  Feld Hellschreiber
  Field Strength Calc
  Function Generator Pad
  GMDSS
  Godafoss
  HF Weather Fax
  iAttenuate
  iFunctionGenerator
  iGeiger
  iSoundex
  iSoundByte
  iSweep
  iUnit
  Morse Mania
  ACARS Pad
  Morse Pad
  NAVTEX Pad
  Packet Pad
  PSK31 Pad
  SSTV Pad
  Photon Calc
  Rad Map Tracker
  RF Link Calc
  SelCall Tone Gen
  Sound Byte
  Sound Byte Control
  Spectrum Pad
  SWBC Schedules
  Synth 76477
  Synth Motion
  Transmission Line Calc
  Weather Calc
  Wire Calc

iPhone/iPad Bundles
  RF Calculator Apps
  Ham Radio Decoder Apps
  Audio Utility Apps
  Shortwave Weather Apps
  Ham Radio Exam Study Apps
  Shortwave Decoder Apps

Android Apps
  ACARS
  Audio Function Generator
  
DGPS Decoder
  HF Weather Fax
  NAVTEX
  Rad Map Tracker
  SelCall Tone Gen
  Sound Byte Control
  SWBC Schedules
  Wire Calc

About Black Cat Systems
Geiger Counter
Site Map
Our software for Mac OSX
Privacy Policy
Press/Media
HFunderground
Apple /// Emulator

Macintosh Links
Shortwave Radio
Pirate Radio
Spy Numbers Stations
Science and Electronics
Ham Radio Software
Geiger Counters


   

Decode DGPS Transmissions With Your iPhone and iPad

Available in Android Market

This app can decode DGPS (Differential Global Positioning System) beacon transmissions. DGPS stations transmit the difference between positions indicated by GPS satellite systems and the known fixed position of the station. This allows higher accuracy. DGPS transmissions are 100 or 200 baud and are transmitted on frequencies from 285 kHz to 325 kHz. Hundreds of these stations are operated by the Coast Guard and other agencies, and they can be interesting DX targets.

The app uses the microphone to listen to audio from the radio, so be sure you gave it permission when you ran the app the first time. If you didn't, you can go to the Privacy Settings for your device, tap Microphone on the right side, then make sure access us turned on for this app. Likewise, you want to give it permission to use Location Services, so it can set your location, for use when computing the distance to received beacons.

To use this app, you need a radio that can tune the correct frequency range, either in SSB or CW mode. Most “shortwave radios” can do this. Ideally you use a cable to feed the audio from your radio into your device, but you can also place the radio speaker near your device's microphone, or even better yet, plug earphones into the radio, and place them next to the device's microphone. You may need to experiment to get the best quality audio pickup, without any outside noise or distortion.

To decode the transmission, tune your radio to a DGPS frequency. You can either tune directly to the frequency in CW mode, in which case you set the center frequency in this app to frequency of the tone produced by your radio in CW mode, usually close to 800 Hz, or use USB mode, tune 1 kHz low, and set the center frequency in this app to 1000 Hz. The center frequency is set by tapping Settings, and changing it there. There is a display of the audio spectrum, to help you with tuning, if necessary.

While there, also be sure to set your location so that the correct distance and bearing is calculated. You can directly enter your longitude and latitude (negative for west and south) or tap Set Location and it will be set based on where your device thinks you are located.

Select the baud rate, either 100 or 200 baud, tapping the button in the upper left part of your device's screen. Eventually, if you have tuned into a DGPS transmission that is strong enough, you will start seeing decode messages printed.

A typical decoded message looks like this:

[23:24:00 08/08/16]  806   12   13  289.0 kHz Driver, VA United States     36.9633 -76.5622   306.61 km   172.711 deg 

First the current UTC date and time are printed in brackets.
Then the station ID, 806 in this case, as well as the two reference IDs, 12 and 13 in this case.
That is followed by the assigned frequency, 289.0 kHz for this station. You can compare this value to what your radio is tuned to, they should match. If they don't, then ignore this message, as it was incorrectly received. With weak signals, it is common to receive incorrect messages, because static or other interference has corrupted some of the bits. Just ignore them.
The location of the station is then displayed, the city, state, and country, followed by the station location.
Then the distance and bearing to the station is displayed, providing you have correctly set your location in the app.

Settings will also let you change the size of the displayed text. You can also clear the received text here, or clear it by shaking your device.

Recording mode can be turned on in Settings, any text that is displayed will be written to a text file that you can later view, or transfer to your computer using File Sharing in iTunes. You can select which recording file to append additional text to, or create a new file.

Buy your copy of DGPS Decoder today, and start DXing these beacons.

Visit the DGPS Decoder FAQ page for full details on how to use the app.

Are you looking for a technology or radio related iPhone/iPad app but can't find one that does what you want? Have an idea for an app that you'd like to see? Contact us at info@blackcatsystems.com!


Email your comments and questions to support@blackcatsystems.com

Last modified August 9, 2016