Question
What could be wrong if you cannot decode an RTTY or other FSK signal even though it is apparently tuned in properly?
Answer Options
- A) The mark and space frequencies may be reversed
- B) You may have selected the wrong baud rate
- C) You may be listening on the wrong sideband
- D) All these choices are correct
Correct Answer: D
Explanation
Successfully decoding an FSK (Frequency Shift Keying) digital signal, such as RTTY, requires matching several parameters precisely with the transmitting station. Even if the signal is visible on a waterfall display, failure to decode can be caused by: the wrong sideband selection (USB vs. LSB), the mark and space frequencies being reversed (known as ‘inverting’ the signal), or selecting the wrong baud rate (symbol speed).
In addition, incorrect audio tone settings or a slight frequency misalignment can also contribute to decoding failure. Since all of the listed options represent a potential mismatch in parameters between the transmitter and the receiver’s decoding software, any of them could be the cause of the problem.
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