I am pleased to report a successful "Coherent BPSK" QSO between DF6NM
and IZ7SLZ on LF using EbNaut program of Paul Nicholson.
QSO took place in the night between Friday 2015-09-18 and Saturday
I think it was the first time that anyone tried this on 137 kHz !
Frequencies used were 137510.00 Hz (DF6NM) and 137502.12 (IZ7SLZ).
We exchange messages of 16 characters in coherent BPSK with UT
synchronous symbols, using a symbol period of 1 second and 8K19A scheme
Software used were the Windows' versions of EbNaut-TX and EbNaut-RX (tnx
to P. Nicholson: your software is working without problems!).
Also Spectrum Lab (tnx Wolf !) was used to export FFT data, in a similar
way of the Markus' OPDS setup.
Other programs, written by Markus, were used: one to convert FFT
exported data for the EbNaut entry and another to search for the best
frequency and time offsets.
There was not much phase drift during the qso and in other test
transmissions, since we reach a good frequency stability at both ends
thanks to Rubidium Reference Oscillator (Markus side) and a good quality
OCXO from my side.
You can see reported symbol / carrier EbN0 and also the messages
exchanged, in the attached screen-shots taken at both ends.
We hope now to joint other stations that want to challenge the timing
and frequency accuracy, to have a QSO in LF close to the Shannon limit.
Markus DF6NM, will report soon all particulars and his comments of the
experiment. Thanks in advance Markus!
73, Domenico (iz7slz)
EbNaut LF QSO 19-09-2015.rar
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