Gary

What sort of= strength are u receiving the Alpha signals

This might gi= ve u an idea how strong amateur signals are likely to be by comparison

There is not= much information available from UK stations about their receiving capabi= lity

de mal/g3kev<= /span>

----- Original Message -----

<= b>From: Gary - G4WGT

To: rsgb_lf_group@bla= cksheep.org

Sent: Saturday, June 05, 2010 2:20= PM

Subject: Re: VLF: Two-Way QSO on= Dreamer's Band

Marcus, Walter, LF,

Well done for your VLF 8.97 Hz 2 - way communication.

Keep up the good work.

Monitoring most of the time here but nothing seen as yet, one day I= may see something.

73

Gary - G4WGT - North West England - IO83QO

On 4 June 2010 21:59, Markus Vester <<= a href=3D"mailto:markusvester@aol.com">markusvester@aol.com>= wrote:

Dear LF,

=

this morning,= June 4th between 6 and 8 UT, Walter (DJ2LF) and myself (DF6NM) were= able to successfully conduct a two-way contact (aka "QSO") on 8.97= kHz. The distance between us is 20.2 km, well outside the reactive= near field zone (lamda / 2pi =3D 5.3 km).

=

Both of us we= re using our small backyard Marconi antennas at home, for transmit an= d receive. Walter's antenna has 260 pF at an estimated effective heig= ht of about 5 m. He achieved about 370 mA current, resulting in a rad= iated power of about 5 uW (EMRP). I also got 5 uW from 270 mA into 24= 0 pF at about 7 m. I resonated the antenna using the same little "yog= hurt coil" described a while ago, having 1.3 henry from 9 x 480 turns= of 0.2 mm magnet wire, and a room-temperature DC resistance of 820 = ohms. Walter used a scaled up version of this coil, about 25 cm diameter= and 60 cm long, consisting of seven polypropylene household buckets= inserted into one another. Each bucket has 460 turns of 0.4 mm wire= on it, about 320 ohms total DC resistance. Each of us applied approx= imately 100 W of "RF" power from a car-HiFi amplifier.

=

Reception was= done by soundcard, without preamplification. We set Spectrum Lab to= 0.95 mHz FFT bandwidth, with noise blanking on, and samplerate track= ing based on the German 23.4 kHz MSK signal. We chose to transmit 30= minute dashes, separated by 15 minute quiet intervals to allow for= FFT processing delay.

=

We employed= a special "micro-QSO" format, which was designed to exchange the min= imum single-bit report and confirmation in only three turnovers, each= containing a single dash. Station identification was by frequency al= one, with preassigned pairs (8969.92 / 8970.02 Hz for DJ2LF, 8970.0= / 8970.1 Hz for DF6NM). Generally the lower frequency was assigned= to a negative response (ie. "not confirmed"), whereas the upper one = is positive ("received ok").

=

DF6NM started= by transmitting a carrier on his lower frequency, from 4:00 to 4:30= UT. This was indeed seen by DJ2LF, who replied on his upper frequenc= y from 4:45 to 5:15, reporting positive reception. Then DF6NM confirm= ed reception on the upper frequency from 5:30 to 6:00. The whole proc= edure took two hours.

=

Attached are= screenshots from both sides. Unfortunately the QRN level this mornin= g was much worse than we had hoped for, with active thunderstorms in= South Italy, Poland and Belorussia. To my surprise, our dashes= still made it through and were unambiguously visible, with an= estimated SNR of 6 to 8 dB. Walter's signal can actually still= be seen between my own dashes on my VLF grabber http://www.mydarc.= de/df6nm/vlf/vlfgrabber.htm .

=

As far as we= know, this was probably the first two-way amateur QSO on VLF, using= truely radiated fields. Another dream came true...

=

Best regards,=
Markus (DF6NM)