Code Samples

For learning the code you should always use the internal tone generator. This is a pure sine wave with an amplitude envelope that has been carefully tailored for maximum readability.

The code samples feature allows you to select some alternative code sounds to give you an idea of what CW transmissions might have sounded like in the past and to demonstrate faulty CW transmissions. The feature does not attempt to give completely authentic renditions of code and the speed displayed in the speed control box is an approximation based on the size of the selected external sample.

The feature works by playing dits or dahs from external audio files and stringing them together along with spaces to generate Morse code. You can select which files to use for the dits and dahs. An assortment of ready made files is provided but you can easily make your own. Instructions on how to make your own samples are provided below.

Use internal/external group. This is the master switch that controls whether code is internally generated or if the code is based on the selected samples.

Each browse button allows you to select samples of code. A dot and a dash sample are both required. NuMorse Pro will add character and word spaces. The files that come with NuMorse Pro have filenames ending with Dot... or Dash... and they all have filename prefix .wav to indicate that they are Microsoft PCM wave files. Normally you would select dot and dash files with the same name in front of the dot... Dash... Part.

Most of the included spark transmitter samples were derived from longer recordings at the website of David Ring, Jr. n1ea. David says that the audio was obtained using transmitter and receiver components that would have been in use at that time. A modern tape recorder was used to record these sounds. Please note that the output from NuMorse Pro will differ from the original transmissions in several ways:

1)	The code will be "neutral" and perfectly consistent. NuMorse cannot replicate the style or "fist" of the original hand-sent transmissions. The original operators often varied the code element timing and spacing from standard and the resulting code was often almost musical and wonderful to hear.

2)	The original transmissions from which these samples were taken used American Morse code which differs from the International Morse code used in amateur radio in several important respects. To those people familiar with American Morse code the output from NuMorse Professional will sound very odd.

Here is a list of the sample Dot files provided with a short comment on each. For each Dot file there is a corresponding DASH FILE.

SparkCW Dot.wav. A basic spark generated carrier. Early radio transmitters used a high voltage spark gap in air to excite a tuned circuit which was coupled to the antenna. The resulting signal was relatively broadband and noisy.

SparkTransformer Dot.wav. Some transmitters used a transformer to raise an AC supply to the high voltage required for the spark gap. This sample gives an idea of the rasping sound that a transformer based spark transmitter would produce due to the modulation of the spark by the AC waveform. This sample has strong components at multiples of 60 Hz.

SparkCoil1 Dot.wav. One way to generate the high voltage for the spark was to rapidly switch the current through an inductor, or coil. A vibrating actuator acted as the switch and this could be adjusted to give a reasonable quality tone as in this sample. It was helpful to have some sort of amplitude modulation on the carrier due to the relatively simple crystal detectors used as receivers. A pure carrier would result in no audio output from a crystal AM detector.

SparkCoil2 Dot.wav. This is another example of a coil type spark transmitter that is badly adjusted and sounds mushy. Both the vibrating actuator and the spark gap required frequent adjustment for a good tonal output.

RotarySpark1 Dot.wav. Another way to modulate the transmission was to use a rotary interrupter instead of a vibrating actuator. This sample simulates the sound of a rotary spark transmitter.

RotarySpark2 Dot.wav. This is another rotary spark transmitter. The rotor is spinning at a different speed. Receiver selectivity was limited and so several CW transmissions would often be present in the audio output. It was useful to have a distinctive sound from each station to allow operators to distinguish between them.

QuenchedGap Dot.wav. This type of spark transmitter used an arrangement of several spark gaps to obtain the modulation tone.

GKZ Dot.WAV. Samples derived from a transmission by radio station GKZ. I do not know what technology was used to generate this sound.

Chirp1 Dot.wav. This is a transmission that has chirp. This fault is usually caused by poor power supply regulation. During a dit or dah the transmitter draws extra current from the power supply and the voltage drops. The fall in voltage causes the oscillator frequency to shift. The cure is to improve the transmitter power supply regulation or improve the regulation to the transmitter oscillator circuitry or both. Mobile/portable equipment with failing batteries sometimes displays symptoms of chirp.

Chirp2 Dot.wav This is the same problem as in DotChirp1.wav. In this case the receiver is tuned to the other side of the CW signal.

Clicks Dot.wav. The click is caused by faulty shaping of the carrier envelope. This fault is mainly heard in older or home-brew equipment.

Ripple Dot.wav. The carrier is being amplitude modulated at 60 Hz line frequency. This is a symptom of a problem with the power supply smoothing circuitry. The smoothing capacitors in older power supply units are often the culprits.

Ripple2 Dot.wav. In this case the carrier is being frequency modulated at 60 Hz line frequency. Again, power supply smoothing is probably inadequate.

Sounder Dot.wav. Here is what code might have sounded like on a telegraph sounder. This uses a "Click-Clack" system to mark the start-end of each code element. In fact, International Morse Code would not have been used by telegraphers in the U.S.A. They would probably have used American Morse Code instead.

Marconi Dot.wav This sample was derived from an actual transmission from vintage Marconi ship based equipment.

The requirements for producing your own samples are simple, but must be adhered to. Any deviation from the requirements below will cause NuMorse Pro to reject the sample:

Audio files generated by NuMorse. See the SelectOutputDevice topic for details of this.

You will normally need third party audio editing software to get your samples into the above format so that they can be used by NuMorse. A good shareware audio editing program is Cool-Edit by Syntrillium Software.

David Ring, Jr. n1ea. http://www.qsl.net/n1ea David has a great web site with many resources for those interested in historical radio equipment and sounds. He gave much help and provided the files on which I based the spark transmitter and other historical samples. Some of the files on this site were originally produced by Mr. John Belrose.

John Belrose, VE2CV, wanted to record exactly what Canadian spark transmitter and pioneer Fessenden heard in his headset. A web page of his work is here:

Jim Farrior, w4fok Radio Amateurs and railroad and telegraphy enthusiasts are invited to download his program, "The Mill". http://www.net-magic.net/users/w4fok "The Mill" and supporting documents provide many features for those interested in CW, especially American Morse. The dialog feature of this program allows you to listen to various fists and CW sounds with the simulated stations having authentic conversations using the correct operating procedures.

"The Telegraph Office" at http://fohnix.metronet.com/~nmcewen/tel_off-page.html A Tribute to Morse Telegraphy and a Resource for Wire and Wireless Telegraph Key Collectors and Historians by Neal McEwen, K5RW

"The RMS Titanic Radio Page" http://www2.dynamite.com.au/rmstitanic/ Specializing in the radio aspects of the Titanic disaster

"The Antique Wireless Association" at http://www.antiquewireless.org/ Some of the samples were based on AWA original files.

"The Art and Skill of Radio-Telegraphy A Manual For Learning, Using, Mastering And Enjoying The International Morse Code As A Means Of Communication" by William G. Pierpont N0HFF This is a "Must Have" book for anyone serious about Morse Code. The online version can currently be obtained free from http://www.raes.ab.ca/book/

A French language version is available at http://radioamateur.f1rfn.online.fr/jcm_livre_nohff.htm Traduction et adaptation de l’Anglais par M. Colombani-Gailleur Maurice F6IIE – UFT 061