# [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
*