Digital Modes

 

PSK

From PSK31 in Wikipedia:

PSK31 or "Phase Shift Keying, 31 Baud" is a digital radio modulation mode, used primarily in the amateur radio field to conduct real-time informal text chat between amateur radio operators.  PSK31 was developed by English amateur radio operator Peter Martinez (G3PLX) and introduced to the wider amateur radio community in December 1998.[1] Martinez initially called his creation "varicode", because it uses variable length encodings (Huffman codes) to represent characters.

I have enjoyed PSK31 and some of it's variants.  It is probably the most popular digital mode on the HF bands.  It's very narrow bandwidth allows many qso's to take place in a very small window.  One problem that I currently have with it is due to the limitations of my TS-570.  The 570 uses Audio DSP as opposed to IF DSP.  I can use my DSP settings to home in on a small area and block the audio of nearby stations but unfortunately those signals are still in the IF bandpass.  This means that although they may not be very strong on the waterfall due to the blocking action of the audio DSP, the radio's AGC still detects them and attenuates all the signals.  IF DSP would be much better for the digital sound card modes that use ssb tones.

Feld Hell

I LOVE this mode! 

What is Hellschreiber?
Hellschreiber, or Hell, is a method of sending and receiving text using facsimile technology.  It is unique in that the characters are not decoded, but "painted" or printed on a screen.  There are several modes of Hellschreiber, the most popular being a single-tone version call Feld-Hell, an on-off keyed system with 122.5 dots/second, or about a 35 WPM text rate.  FH has a narrow bandwidth of about 75 Hz.  Feld-Hell also has the advantage of having a low duty cycle meaning your transmitter will run much cooler with this mode.
 
Hellschreiber was patented in 1929, and is still in use today using the original format. Hellschreiber was the first successful direct printing text transmission system, and was very popular at a time when teleprinters were complex and expensive (the Hell receiving machanism had only two moving parts). At first the Hellschreiber was mostly used for land-line press services, which continued well into the 1980s. A military version was used by the German Condor Legion during the Spanish Civil War (1933). During WWII, Hellschreiber was widely used for field portable military communications, for which it proved to be very suitable because the equipment was simple and robust. Today we use the term "Feld-Hell", or "Field Hell" for this system, to help differentiate it from the slightly different land-line press systems.
 
I am a member of the Feld Hell Club.  My FHC# is 1841.   Check their website for more information on this really cool mode.

OLIVIA - the Magic Digital mode

I really like this digital mode!  This mode shines in bad conditions or weak signal work.  Learn all about OLIVIA mode here.