LF: LF band plan]
Sat, 30 Jan 1999 11:51:47 -0500
Frank Gentges wrote:
> I have been thinking about special modulation schemes that we can detect and
> decode at extremely low signal to noise ratios. My thinking is along the
> lines of a Multi-Frequency Shift Keying approach.
At least at the beginning, I would think that we will be stuck with the kind of
modulation schemes readily available/authorized in the U.K., i.e., slow
morse-code and possibly BPSK. After some success we may be able to convince some
of them to invest time and money into other, more esoteric modulation schemes.
> Any ideas to get some serious directivity/antenna gain?
Loops are better at nulling than maximizing, and are difficult to keep erected
for long periods of time (and by definition we will never know when the next good
day will take place). Realistically, maximum directivity can probably be
obtained by _phasing_ the output of several e-field probes, separated by some
wavelength, i.e., probes located at different QTHs, and somehow added in phase.
Note that long DX in LF is being achieved in Europe with regular antennas (except
for OH1TN who has I believe a fairly long wire). Of course not the extra
thousands of miles we are looking for... :-)