Other Radio Hobbies
Report #110 04/01/15
DIGTRX COMPUTER PROGRAM (Revised)
There are two versions of DIGTRX. One is a download DIGTRX 3.11 for the older type XP computer (this is what I am using) and the other is for a Windows 7 computer (DIGTRX 2.14D). It is suggested the program be loaded outside of the Windows shell in a separate directory on your hard drive. This will preclude possible conflicts with the Windows Operating System.
The signal has been designated by ENIGMA as HM01. This is composed of an audio group followed by RDFT. This occurs for each of the 6 audio groups. The decoding yields enciphered text. The AM mode is the normal method of operation but better results can be realized using the USB mode and zero beating the carrier. This results in a narrower bandwidth and less noise. Connect the receiver's headphone jack to the computers MIC IN (or AUDIO IN) jack. The audio level is lower this way and results in the DIGTRX program not being overloaded quite as often. A very low, clean level is all that is required for proper decoding.
Tune the HM01 test tones, which are broadcast directly before the RDFT data, to coincide with the 110 and 1520 Hz alignment marks. The program will indicate how much you are miss-tuned. Adjust the receiver's output so the DIGTRX program audio level bar is just peaking from dark to light green. Red is much too high. As each transmission is completed DIGTRX will automatically switch to decode mode and display and save the decoded file number. An option to add a Date-Time-stamp with the saved file number is available in the settings tool bar. Clicking on the file number will display the decoded text. A print option is also available on the DIGTRX tool bar. You can connect the receiver's headphone jack to a tape recorder's monitor jack and record the broadcast before decoding but you will not be able to adjust the test tones, which is extremely important.
It is possible to connect he receiver to the recorder and then to the computer. This allows you to tune the signal, record the transmission and decode the text in one operation. This works well if you want to go back and try again after the live broadcast. Remember, a little audio signal always works best. There are variations to the above decoding method but that described was found to be most practicable. Thanks to Joe Pierce for this revision.
To date several different decoded texts have been observed. We have designated these as follows: System A is Oriental appearing characters. System B is mixed computer keyboard characters. Three File extensions can not be decoded. These are .F12G, .F1C and .PIR The first four digits of a voice group are the same as the last four digits of the File number. The Cubans were possibly having technical problems on 26 March. Several monitors reported no signals. Ary Boender in the Netherlands reported he heard the 27 March 0730 UTC transmission and I heard the 27 March 1400 CW schedule and the 1600 HM01 so it looked like things were back to normal.
FCC SPECTRUM SHARING PLAN
MARTINSBURG WV CENTRAL DISPATCH
FEDERAL SPECTRUM INCENTIVE ACT
RUSSIAN MILITARY BEACONS
End of Report
©2015 Don Schimmel.