[email protected] wrote:
Hi transatlantic gang,
Band full? No, I believe there is plenty of space, it's just that we may have
to move a little closer: QRSS or DFCW watched with 10 mHz resolution could
leasurely be spaced at 100 mHz intervals. As the level differences between
different Eu sigs seen in America will hardly exceed 15 dB, spectral widening
during the keying is not a problem. Propagational doppler spread should also
be less than 10mHz (though there has been one unexplained observation of wide
doppler on a ZL-P29 LF path, not sure whether this was real).
So it all becomes only a question of frequency accuracy and stability. Some
stations (e.g. BMU, FTC, YXM and hopefully myself) are within 10mHz of stated
freq (10^-7), which requires a calibrated OCXO or a very good TCXO. All
others I have seen lately apparently use standard <1ppm crystal oscillators
and have drifted less than 50mHz, which still is good enough. Only those rigs
generating LF by mixing two independent HF xtals are probably not stable
enough for real narrowband work.
7fsk must be regarded as a special case. In my opinion, much narrower tone
spacings (20 to 50 mHz) should be preferred, and could even improve
legibility because the sequence can be connected visually much easier.
Though I don't particularly favor the thought of "frequency ownership" (still
the anarchist in me, at age 43?), I agree that allocations will make life
easier, and the receiving side can associate T-grade traces to their owners.
I do not favour frequency ownership either and random frequency selection for
the
mode within a subband is to be preferred. Let the monitoring station identify
the
information being sent like call etc
and not be dependent on frequency identification. With my recent first
transatlantic qso I picked an unoccupied frequency and transmitted and was
identified by a number of stations in both the USA and Canada and in Europe. The
identification was on callsign and other info that I sent and not frequency
dependent. With a frequency dependent system, then anything seen on that
frequency would be attributed to a particular person, especially under marginal
conditions, and this could lead to misinformation.
de Mal/G3KEV
So some 30 stations could work in a 60s-Argo slot in parallel. (Btw I do
prefer the "90s slow" setting with equal frequency resolution.Temporal
resolution is anyhow limited by FFT bandwidth, the slower display simply
saves screen space.) And if that were not enough, we might eventually have to
ask Alberto for a higher window.
73 es have a nice sunny sunday
de Markus, DF6NM
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