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Report #110 04/01/15

This program is a means of decoding Random Digital File Transfer (RDFT) transmissions. The program was written by PY4ZBZ, a Brazilian Ham and it is available at

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.

In April the FCC will vote on a band sharing plan for 3550-3700 MHz for use by military, mobile service providers, and individuals. The demand for wireless spectrum has been increasing and there is pressure on the government to share or auction some frequencies. "Bandwidth-hungry services like streaming video and audio, plus wireless links for a growing array of connected devices, are expected to eventually place strains on the spectrum currently allocated to wireless data." Source: IDG News Service

As part of the upgrading of the Central Dispatch, the provision of interpreters for non-English speaking callers is to be improved. Not only will connection operating costs be less but the service will be faster. Source: Martinsburg Journal

"The need for the bill is growing, sponsors argue, because of the skyrocketing consumer demand for commercial mobile land unlicensed WiFi spectrum. "The bill would allow federal agencies to share in auction proceeds from spectrum they give up. Agencies could use the funds to pay for spectrum relocation costs or to offset congressional budget cuts." The article pointed out that U.S agencies control more than 480 MHz of spectrum between 225 MHz and 3700 MHz according to an FCC spectrum map.
Source: IDG News Service

I wonder why the callup is frequently not sent for this activity. They go right into the message text. How do the field stations know if the message is for them? During the month there were numerous instances on various schedules of this procedure. Normally there are three addressee groups sent but on 29 March I only heard two such groups on the 2100 UTC schedule on 7554 kHz. Then on 30 March the 1400 UTC schedule on 8096 had just one address group sent.

The operating mistakes continued. On 13 March the 1600 UTC schedule on 11435 had two transmissions at the same time. Then on the 1800 UTC schedule on 11635 kHz they did not resume sending after the half-way break. On 20 March the 2300 UTC schedule on 8135 kHz had both the YLSS with 5F groups mixed with the Cuban cut numbers in CW. On 23 March mixing of the Yl/SS with the CW signal took place again. Finally on 30 March, the transmitter was heard being tuned on 11435 kHz and that was followed by a brief Radio Havana transmission at 1554 UTC and then into HM01 at 1559 UTC.

13528 Beacon C Moscow 201354
13528 Beacon S Severomarsk 191426
16332 Beacon D Sevestopol 201352

14100 YV5B Caracas, Venezuela 191745
18110 VE8AT Eureka, Canada 191748
18110 YV5B Caracas, Venezuela 191751
21150 OA4B Lima, Peru 191754
21150 YV5B Caracas, Venezuela 191754
21150 4X6TU Tel Aviv, Israel 191756

12580   WLO call tape in CW. New Orleans, LA 191446
12798   FAX transmission. Probably USCGB NMG New Orleans, LA 191444
12842.7 CQ DE HLO Seoul, South Korea CW call tape QSX 12 MH K 191442
12934.6 CQ DE HLG Seoul, South Korea CW call tape 191437

End of Report

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