[Fwd: LF: Transatlantic]

Andre' Kesteloot akestelo@bellatlantic.net
Fri, 28 Jan 2000 09:28:29 -0500

Klaus von der Heide wrote:

> Hello LF-Friends,
> the negative result of the recent transatlantic experiment only says
> that the usual ham methods for LF contacts are not adequate for a
> transatlantic distance. A weak signal never excludes information
> transmission, it only reduces the information bit rate. Why not try,
> as a first step, to get one single bit over the ocean?
> The communication theory says that BPSK is optimum, and a
> bandwidth considerably larger than the information bit rate is better
> than a small one.
> I therefore, propose the following experiment:
> 1. Both, transmitter and receiver, must be synchronized to an
>     atomic clock, i.e. all oscillators that determine the carrier
>     or the symbol rate. Especially the sampling frequency of
>     a DSP (not the processor clock) must be synchronized.
>     A soundcard normally cannot.
> 2. The symbol rate is exactly  1 bit/s.  Starting every minute,
>     a constant random pattern of 60 bits is sent out.
>     Appropriate matched filters must be used at both ends.
> 3. At the receiving end, a DSP adds the 60 new  values to
>     60 accumulators.
> 4. The contents of the accumulators is correlated with the
>     known random bit pattern. After many hours or days
>     (or years?) the correlation must become significant.
> 5. It is important to suppress the non-Gaussian noise as
>     good as possible before the data are accumulated.
> As I mentioned some weeks ago, phased array antennas
> at both ends would increase the signal by many dBs.
> There isn't any dought that hams can cross information
> over the atlantic. The minimum information of a ham QSO
> is 50 bits in either direction. The open questions only is:
> Is the possible information bit rate  1 bit per day  or is it
> 1 bit per 5 minutes  or in other words: can a QSO run
> within 10 hours or can it definitely not.
> 73 de Klaus, DJ5HG