The RST System
of Signal Reporting has been used for years (circa 1934) as a shorthand method
of reporting Readability, Signal Strength and for CW, Tone (i.e., quality of
the CW tone). For voice contacts only the R and S are used. The S component
is usually not the same as your S-Meter reading as most S-Meters aren't calibrated
to track the RST System. The RST is also reported on QSL Cards and must be filled
in correctly -- e.g., a 569 report for a Voice Contact is invalid. Note that
many DX operations and contest stations merely report 59(9) as a convenience
to avoid having to log each of the real reports. A questionable practice but
a fact of DXing/Contesting
used is the addition of a letter to the end of the 3 numbers.
These are: X = the signal is rock steady like a crystal controlled signal;
C = the signal is chirpy as the frequency varies slightly with keying;
and K = the signal has key clicks.
X is from the early days of radio when such steady signals were rare.
Today most all signals could be given an X but it is hardly ever used. It is helpful to report a chirpy or clicky signal by using the C or K, e.g. 579C or 579K.