LF: LF band plan]

Frank Gentges gentges@itd.nrl.navy.mil
Sat, 30 Jan 1999 03:13:26 +0000 (GMT)

Some food for thought.  

If all the LF DX we wish to copy conforms to this 
recommended practice then....

Every signal of interest is within a 200 Hz bandwidth.  Other messages 
lead me to think that this really is the case now over there now.

If we build a special purpose receiver that covers the DX portion of the
band plus some slop 100 Hz on each edge.  

If we digitize 400 Hz bw at 1 kilo sample rate at 16 bits the data rate 
is 16 kilobits per second.  

Then, We could broadcast a data signal carrying this bit stream and 
members could copy the DX band at home from an optimum site. 

We could transmit a data stream at 19.2 and multiplex in some other site 
data of interest.  Thanks to Andre' for suggesting the idea of a remote site.

Next, I think we need a lot more processing gain than we had at Nags Head. 
30 dB may be needed.  Narrower bandwidths and more signal integration.  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.  

Any ideas to get some serious directivity/antenna gain?  

See you at tacos tomorrow. 


On Sun, 24 Jan 1999, Andre' Kesteloot wrote:

> An interesting idea, IMHO
> Andre'
> ***************************
> Toni Baertschi wrote:
> > >From  HB9ASB, JN36pt
> > Since it is difficult to check the whole band for weak Slow CW with the
> > Spectrogram I would appreciate a sort of band plan. It's much easier to
> > observe -
> > let's say two bands of 100 Hz.
> > 73 de Toni
> ***************************
> Peter Bobek replied,
> I remember that we discussed the matter during the RSGB HF Convention
> at
> Old Windsor in October 1998... There was, however, no general
> recommendation so far.
> But letīs call it "REP" (= recommended practice) to have this window
> between 137.6 - 137.8 kHz. Most of us have already adopted this REP.
> Unfortunately the socalled "Luxembourg Effect" very often gives us
> some headache when the carrier on 138.830 kHz (DBF39) takes over
> modulation from other radio stations in the MF- (or maybe even LF-)
> range....
> 73, Peter / DJ8WL