DF1UD EN
Decoder
Homemade > RTTY Decoder
NF-RTTY filter converter
In 1987, based in part according to documents from DJ6HP (H.-J. Pietsch).
For the short-wave operation at RTTY (Amateurfunkfernschreiben) used almost consistently narrow filter converter. The two Switching tone for MARK and SPACE are prepared to selectively, thereby providing maximum signal to noise ratio can be achieved. While Nf-Selektivkreise initially built with LC-filters, but provide the data used in this circuit, active filter significant benefits.
The following converter with active NF-selective filter is known under the name DJ6HP 001.
The '001 'is the most widely used in Europe converters, which were used for the first time in a RTTY-circuit active filter in this form. The development has proved especially by the simple construction and the unproblematic adjustment for use on the shortwave bands.
The circuit has been designed in view of the disorder range short-wave operation at maximum signal to noise ratio, which can be error-free texts take notes that in the LF range of the receiver are 12 dB below the noise.
The complete converter with all relevant documents etc was in the book 'Amateur RTTY Funkfernschreibtechnik' by H.-J. described Pietsch (DJ6HP) as RPB electronic-paperbacks in Franzis-Verlag München (second revised edition) 1979, ISBN 3-7723-0252-1.
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- All in discrete TTL technology on prototyping boards. Wired with copper wire was. The power supply was built up as an external self-built power supply (+ / -12 V and +5 V).
- Brought very good results with the PC before I switched to the commercial converters MFJ-1278 DSP.
- The high-frequency radiation resistance was excellent. No problems at high power levels, eg 500 watts on 20 meters.
As an accessory or an XY display in the absence of an oscilloscope.
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