Wednesday, September 5, 2012

Visual MS

This article was created in 1997 and I have published it here again just for historical purposes. This was the starting point of a road that finished at the fantastic WSJT software.

Visual MS

    In summer of 1996, Pedro EB4GIA and me, EA4EOZ were at the MS expedition to IM89, EA1EW/4, and that was our starting point in MS. We observed the method for working MS and later, we were trying to start our activity in MS.

    First EB4GIA made some contacts on SSB, but it was obviously that the best results, are obtained in CW, and that was the problem, EB4GIA is a NO CODE license, and I am very bad at CW. What to do? To learn CW, or to try another method for receiving CW??

    The first experiment was made with Multimode TNCs, but TNCs don't work faster than 500 lpm. Later, we try to use the DTR from DF7KF and the multimode TNC, but the tone from the DTR is not good for the TNC. The TNC was substituted by some CW receiving programs, but nothing worked fine.

    One day, I was measuring the bandwidth of the SSB filter in my old FT-290R with the program Cool Edit 96, from David Johnston, at Syntrillium Software. and I noticed that the program can display the sound in Waveform, or in Spectral View, and I spent some time looking at a small carrier that I had recorded some minutes ago. There was a clearly visible line in the screen of CoolEdit... Later, I put my TRX on a packet frequency and I made some records from some packet signals at 1200 bauds. When finished, I looked at the screen and saw a strong line in the window of CoolEdit. I pressed some times the button ZOOM, and... I was looking at the bits of the transmission!!, ones at 1200 Hz and the others at 2200 Hz. I thought "Maybe, this is useful for MS".

    And it was. When I recorded a real transmission of CW-MS at 1200 lpm, the letters were perfectly visible on the screen. What is the advantage of this method?? Persons who don't know morse code can SEE the letters, and can work MS-CW:

Can you SEE the call in this 1500 lpm transmission? Yes, it's SM3MXR.


    First, you must to have configured your soundcard for working with Windows, then install the program, it is a very simple task.

    Once the program is installed, run it by double-clicking on its icon and choose two of the possibilities that the program brings to you. I always choose Save, external clipboard functionality and sample converting and Filter and noise reduction. Be sure to choose the first one, because if you get a nice burst, you will not be able to save it to disk, unless you become a registered user of Cool.

    Press OK. The window of Cool will appear on the screen. For use Cool in MS, we must to configure some options. First, go to the menu Options>Settings and select Spectral.

    Set the options like this:

  • Windowing Function: I have found that Blackmann-Harris is the best for MS.
  • Logarithmic Energy Plot>Range: +/- 50 dB. You must to try with different values, trying to find the best view of bursts and pings, because it depends of the kind of receiver used. Also try to use Linear Energy Plot with values around 0.1%. Sometimes it brings much better results!!.
  • Resolutions: Use 16 bands if you use a slow computer (386 or 486 sx/dx) or use 32 if you use a 486 DX2, DX4 and faster.

    Press OK. In the menu View, select Spectral View. In the meter at the bottom of the window, click it with the secondary button of the mouse and select Show on play and record, 30 dB range, and Dynamic peaks, maybe, it's possible that you must to select Adjust for DC too.

    Take an audio cable to connect the audio from the receiver to your soundcard, put the receiver in a free frequency and set up the volume for a comfortable listening. In the menu Options, select Monitor VU Level. In this moment the bar indicates to you the level of audio at the input of the soundcard. Adjust the Record Gain of your soundcard for a reading between -15 db and -12 dB on the meter at the bottom of the screen. This is an experimental value that we had found, maybe with your specific equipment, you need other value.

    Press STOP for stopping the meter and press Record. In this moment you must to indicate the characteristics of the new record:

  • Sample rate: Use 6000 for MS speeds up to 2500 lpm and 11025 for speeds faster than 2500 lpm
  • Channels: Use always MONO.
  • Resolution: 8 bits. I have not found any advantages of using 16 bits, and 8 bits save a lots of memory!!!.

    Press OK, the program will start to record the audio from the receiver. If you have the good luck of record a burst, when you stop the record (usually in the tx period) you will see something like this:

    The left arrow indicates a ping ( a bit difficult to see if you are not familiarized ) and the second arrow indicates a burst. You can see the background noise like a continuous black/dark-blue and the bursts in red/yellow. Select with the mouse the ping or the burst and press Zoom. If it's necessary, repeat the action until you be able to see the letters. Something like this:

    This is a bit of the burst zoomed . Can you SEE this?? Yes, EB4GIAG3IMV27. And , what about a ping?? :

    This is a faint ping, where you can see the end of a "4", the string "GIAG" and the beginning of the "3", duration was of 0.25 seconds, ( from 1:20.35 to 1:20.60 ). Once you are familiarized with the program is very easy and FAST to find pings and bursts , read it, and if you like it, save them to the hard disk.


    Pedro and myself are using this method since April of 1997, and we are continuously investigating in the facilities of Cool to obtain the best performance for receiving MS-CW. Pedro is using this method in ALL of his MS-skeds and the results are very interesting. Other hams that have seen our method in action, say that it's faster than the tape recorder... We only can say that is the only one to allow "NO-CW" stations work MS in high speed MS.

    Here you have some suggestions if you try to work with this method:

  • Familiarize with Cool as soon as possible.
  • Try to catch bursts and pings at random, (144.100) and practice with them.
  • If possible, turn off the AGC.
  • Use the clarifier/RIT for getting an audio frequency that will be easily visible in the cool window.
  • Download from Internet .WAV files with records of MS and practice with them.
  • Use your monitor at maximum resolution, then, resize the Cool's window to minimum height and maximum width
  • Use the time counter of Cool like the turns counter of a tape recorder.
  • Read the help file of Cool.

    When you are using Cool in a real sked, open two instances of the program, and record the audio with the first one. If you hear a burst, stop the first instance and quickly record with the second one the rest of the period. In this way, you can look for the pings and bursts in the first instance of Cool WHILE you are recording in the second. For open a second instance, use the menu File > New Instance.

    If you have any comment, suggestion or want to ask about the method, you can contact us.

73 & MNI bursts from Pedro and Miguel Angel.
Miguel A. Vallejo, EA4EOZ

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