When similar callsigns appear in the message, an experienced operator can often tell which call is correct and which one is corrupted. GRITTY not simply prints what was decoded, but performs some intelligent analysis of the decoded text. The bit error probabilities are also used in other, more interesting ways. The net result is very little garbage in the output.
This works better than the traditional squelch since it allows decoding of very weak signals but suppresses strong signals when interference makes accurate decoding impossible.
In GRITTY, the squelch function is based not on the signal amplitude but on the error probability. One obvious use of these extra data is to compute the error probability for each character in the text, and color-highlight the unreliable characters. In particular, the Bayesian decoder computes not only the 5-bit Baudot codes, but also the probability of error in each of the bits. In the Bayesian framework, all information is represented in the form of probabilities.
#Rtty decoding trial#
This results in a better decoding accuracy than other algorithms, created by the trial and error method, typically achieve. The decoding algorithm in GRITTY is based on the methods of Bayesian statistics. This is not a skimmer, it decodes a single signal in the 3-kHz audio coming from the transceiver via a soundcard, just like any other RTTY program. GRITTY is an RTTY decoding program based on the technology developed for the RTTY Skimmer Server project.
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