Feld Hellschrieber

This is a semi popular type of mode , Feld Hell shines the most when other modes fail (due to lightning hash for example) Where the code was hidden from being decoded correctly , The Feld Hell mode might take a hit but, still can be recognized by the human eye what the letter actually is. This mode is also fairly low duty cycle as well which means the radio will not over heat. There is a club that promotes Hellschrieber activities with sprints (contests) and awards in achievements. called simply Feld Hell Club which I am a member of #341 http://sites.google.com/site/feldhellclub/

Created by : Rudolph Hell in 1929
Description :
Baud rate : 245 bauds but, in fact, it is a pseudo-122.5 bauds (one "pixel" is 8.163 ms long)
Reading direction : column by column, from down to up and from left to right,
Matrix : height: 7 pixels et width: 7 pixels...so a total of 49 pixels per character
Speed : 25 wpm
Modulation : On-Off keying of an audio tone
Reception mode : indifferent (USB or LSB) but in general USB
Character set : all ASCII printable characters except small letters, carriage return (+ line feed) and error correction character. The used font (FeldHell) is derived from the font of G3PLX (Peter Martinez),
Shape of pulse : raised cosine profile
Bandwidth : about 300 Hz,
Synchronization : no need, each column is displayed vertically 2 times (but transmitted once)
Pmean/Ppeak : 0.25
Lowest S/N : - 12 dB

Category:

Science & Technology

Tags:

• Feld Hell
• Feld Hellschrieber
• Digital Modes
• Ham Radio
• FAX