information about EbNaut on LF
You can get more details at the HP of Paul: EbNaut
I started getting interested in EbNaut in 2017.
But the hardware requirements are already hi-end:
For coherent BPSK you need an extremely frequency stable TX and RX,
GPSDO or Rubidium frequency standards are mandatory. Max. frequency
drift < 3 mHz
A sound card synchronised by a 1ppm signal
A TX that can be phase modulated.
The possibility of switching the phase of its transmitted signal,
controlled between 0° and 180°.
EbNaut is a very experimental coherent BPSK transmission, it requires
synchronised frequency and time, these parameters must be available to
the receiving station explicitly for decoding.
This is therefore not a random mode of operation.
For decoding you need a fast computer, otherwise the decoding of a call
can take up to 45 minutes ;o)
When looking for a suitable transmitter, I only had to look to the
side, there stands my old HP 3326A dual generator, connected to a 10
MHz Rubidium frequency standard, which fulfilled all requirements for
The generator can be phase-modulated for this purpose there is a
control input on the back. The phase position is adjustable in
steps and is generated by a control voltage.
All I had to do was to convert the signals from the EbNaut transmitter
(software) into a control voltage that controls the generator, and that
was "Quick and Dirty" ;o)
Via the first COM interface the generator is supplied with a
high-precision control voltage generated on the board, EbNaut TX
switches this voltage to the generator via relays.
Unfortunately, EbNaut-TX has no PTT, i.e. the transmitter also operates
with keydown power during breaks.
For this purpose I have attached the Koaxrelais. This is switched via
the second COM port, by means of an external timer, and separates the
control transmitter and the PA, the signal from the control transmitter
is routed to a dummy load.
My OPDS decoder generates the reception data automatically every half
hour. As soon as I have the time and frequency of the transmitting
station I can decode from this data.
This is my signal at Markus, DF6NM
and the result