Message-ID: <005701bf6981$37448bc0$2301a8c0@maly.gmc.net>
From: "Petr Maly" <p.maly@gmc.net>
To: rsgb_lf_group@blacksheep.org
References: <E12E8kh-0004Ru-00@mail1.isys.net>
Subject: LF: Re: Transatlantic
Date: Fri, 28 Jan 2000 12:17:00 +0100
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Sender: <majordom@post.thorcom.com>

Interesting anyway, but is this still amateur radio transmission or rather 
scientific experiment? Or, at least, I really don't have atomic time base
in the ham-shack. 

73, Petr, OK1FIG


----- Original Message ----- 
From: Klaus von der Heide <v.d.heide@on-line.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: Friday, January 28, 2000 11:28 AM
Subject: LF: Transatlantic


> 
> 
> 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
> 
> 
>