BFO setting for JT65B EME

[Conrad PA5Y]

Hello.

I am successfully using Linrad with an RX converter and AFEDRI AFE822x
SDR in conjunction with MAP65 and IK7EZN's Trakbox whilst simultaneously
using a Virtual Audio Cable to send data to WSJT. My transverters and TX
radio are ref locked and with this system I am able to get perfect
agreement of any frequency offset between the radio and the Linrad. The
SDR is not locked but has excellent stability.

I set the BFO in a fairly arbitrary way in the base band graph for USB.
I think that it is around 1500Hz. I would like to know how to do this
properly to ensure that when I TX my sync tone ends up at 0Hz when
viewed in WSJT. Can I actually find the BFO frequency in a par file? Is
it possible to set the BFO frequency and whether it is upper or lower
sideband? This would be useful.

I have a good workaround that works perfectly well but I would prefer to
enter things numerically. I don't understand why there are 3 vertical
bars in baseband graph for the BFO. The frequency displayed in the Base
band graph shows the frequency and includes the BFO offset. Can it be
set up to work more like PowerSDRmrx or similar where the Base band
frequency takes into account the BFO offset.

I apologise if this is common knowledge but I have never come across a
document that explains this, I realise that one probably exists!

Regards

Conrad PA5Y

So far I have not really listened to the audio on any SSB signals.

[Leif Asbrink]

Hi Conrad,

> I set the BFO in a fairly arbitrary way in the base band graph for USB.
> I think that it is around 1500Hz. I would like to know how to do this
> properly to ensure that when I TX my sync tone ends up at 0Hz when
> viewed in WSJT. Can I actually find the BFO frequency in a par file?

All the parameters belonging to the baseband graph are in the files
par_xxx_bg and you can find 'BFO freq' there.

> Is it possible to set the BFO frequency and whether it is upper or lower
> sideband? This would be useful.

Yes, you can set the frequency. The sign will select upper or lower.

> I have a good workaround that works perfectly well but I would prefer to
> enter things numerically.

OK. (There are many other things that you might want to enter numerically
but you would bypass all sanity checks so it is a good idea to save
par*.* before you start editing.

> I don't understand why there are 3 vertical bars in baseband graph
> for the BFO.

Select a 15 Hz bandwidth for CW and select fairly steep skirts with
say 4 pixels for each Hz. The baseband might be 240 pixels wide
(60 Hz in total.) Two of the vertical bars would be on the same position
at the left or right spectrum end if you want the bfo 400 Hz from
the center.

> The frequency displayed in the Base
> band graph shows the frequency and includes the BFO offset. Can it be
> set up to work more like PowerSDRmrx or similar where the Base band
> frequency takes into account the BFO offset.

The displayed frequency is the frequency of the carrier. ALWAYS.
I can not see any reason to change that and I do not understand
what you mean by "the Base band frequency takes into account the
BFO offset."

In SSB mode the (suppressed) carrier is on the bfo frequencies and therefore
the bfo frequency is displayed. Note that a receiver could equally well
be built with a crystal filter directly on the antenna and with a bfo
on the suppressed carrier frequency right on HF. Mixing would be done
down to audio and the indicated frequency is the frequency of the bfo.
In all other modes the carrier is the passband center ant that is
independent of whether a bfo is used or not and of course independent
of the bfo frequency selected.

I can not see how one could motivate something else (except for JT65
where Joe has added an arbitrary offset as a convetion in his software.
That is something I find unfortunate, the actual frequency of the
sync tone is a property of the radio wave. What is indicated in wsjt is
something else.

You may use Linrad in cw or ssb mode together with wsjt. One or the other
should fit your needs (I think.)

73

Leif

[Conrad PA5Y]

Hello Leif, yes I had a play around and now I get it. Very good to know
about par_ssb_bg. Is there a list anywhere with a brief description of
all the parameters in each of the par files? That would be very useful.

Regards

Conrad PA5Y

[Leif Asbrink]

Hi Conrad,

There is no list describing parameters. (I do not
want to maintain such a thing.)

The main files are:
par_userint = global parameters
par_ssb = fixed parameters for ssb. Those that
you can change by pressing X, then P.
The order is the same as they appear on screen
and F1 will describe their action.
par_ssb_ag = AFC graph
par_ssb_bg = Baseband graph
par_ssb_cg = coherent graph
par_ssb_eg = EME window
par_ssb_fg = Rx frequency and gain control box
par_ssb_hg = high resolution graph
par_ssb_mg = S-meter graph
par_ssb_pg = polarization graph
par_ssb_tg = Tx frequency and power control box
par_ssb_wg = main spectrum and waterfall graph

These parameters exist in all modes in case you have selected
to use the corresponding window. In each window you can press
F1 to read about what each parameter is doing. Note that
some parameters may be hidden depending on how other parameters
have been set. If you disable AGC you will not see the boxes for
setting AGC times for example.

There may be many more parameter files. Essentially one for
each supported hardware plus files for the network and
the Tx. Speech processor, CW timing and radar.

Knowing what buttons you have in each window and with the
information you would get by pressing F1 you should be
able to understand which parameter in the associated file
corresponds to each button.

73

Leif

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[ON4KHG]

Dears,



There is a listing of parameters on my website with verbose explanation of them + my own parameter' sets within an Excel file (also verbose). It is not exhaustive since it is stuck to Linrad V3.37 but almost, not many more parameters have been added since then.

I have updated the list to V4.05 but I haven't put it online yet. I'll do it if there is interest.
My above mentioned files also speak about linking Linrad with MAP65-IQ, obsolete for some time now. When free time, I'll update for MAP65.

73,

Gaëtan, ON4KHG
http://on4khg.be