Re: [linrad] frontend LO frequency stability ( was : audio channels )

["Peter van Daalen" <vandaalen@xxxxxxxxx>]

Dank Rein,

For your quick and extensive response.
I'll look around furthermore for the Delta card.
I'll get it, that's for sure !

As to my second question ( and your advice to emigrate to other lists.......
:-) :-)

I guess my question is very Linrad related.
I am building a frontend for Linrad.
My question relates to THAT ( DC )  frontend.
So, no RF front end in general.
I doubt whether other fora can resolve my question, coz they don't know
Linrad.

I paste my question of May 21st :

****************************************************************************
*********************************
 I am building the Brooks Shera GPS disciplined frequency standard (better
than 1x 10^-11  for a 100 sec. dot ),
HP 10811 OCXO : phase noise : offset 1 Hz < -100dBc.. ....1 KHz <-160 dBc.

I started this frequency standard project for quite different reasons than
Linrad.
However, does it make sense to use this standard for LO ( 144 MHz ) in a DC
front end for Linrad ?
Or is this overkill  ( e.g. : doesn't the SBL-1 or TUF spoil alot as to
converter noise c.a. ? ).

I intend to experiment with EME QRSSS  and I have the idea that short term
stability ( for very small but stable FFT bin bandwidth  during the dot
length ) and oscillator noise cannot be good enough.
Right ? Or overdone ?
****************************************************************************
**********************************

OK,  apparently I didn't make myself clear ( enough ).
Let me put it this way :

Leif told me that QRSS is not done ( no, the other meaning...  :-) on EME.
But now I paste from his original mail to me, OK Leif ? ) :
( > is Leif and >> is Peter ) :

>Hi Peter and All,

>> Is  QRSS  used in EME ? ( just as the LF guys do ).
> >If not, why not ? ( It certainly will be obvious, but
>> not yet to me... :-) I understand that it can offer
> >( with 3 -10 sec/dot ) 12-20 dB S/N improvement over regular cw.

>> If so, does QRSS offer better S/N than Linrad, JT44 and other
>> modes and programs ?



>The QSB over the EME path does not allow 3 - 10 sec/dot. If you
>like to run QRSS via 144 MHz EME the speed has to be lower, 30 to 300
>sec/dot.

>The sensitivity is then extremely good. Have a look at
>http://antennspecialisten.se/~sm5bsz/kk7ka/kk7ka.htm

>Here you can see how the signal Stewart sent with his 12dBd
>single yagi using 25 W only was received on my 4x14 X-yagi array
>on a day when the degradation between optimum EME conditions was 3.6dB.

>Making EME contacts this way does not seem very attractive to me.
>The qso times would become very long but as far as I understand this
>will be the most sensitive mode possible. By use of several tones it is
>possible to improve the speed quite a bit at a relatively small loss
>of detect threshold.

snipped by Peter....

Since I intend to find out what happens with Linrad , using >60-100 sec/dot
( with D{ual}T{one}CW  using e.g. ON7YD's QRS Tx program " QRS " ) and very
narrow filtering and very long integrating ( FFT averaging ), my question
seems to be relevant for Linrad.

End of all, such QRSSSSS.... dots with very narrow filtering ( 0.1-0.01 Hz
or less ? ) demands for very stable LO, if the FFT bin bandwidth in Linrad
may not be spoiled by frequency drift ( walking from the one bin into the
neighbour bin which decreases the " readability " of Linrad's trace on the
screen and " smears "  that trace.

Thus, the crux of my question was : is a Linrad front end LO stability of
better  than  1x10^-11 ( which I can get easily ) necessary for my purpose ?
Actually, it does cost me some effort to finish this type of LO and if this
is not worth the effort  I'll renounce and use a ordinary TC(V)XO LO, being
however then no better than 1 x 10^-7 ( if at all ).

I do hope I made myself more clear now.
Maybe Leif ( too ) can comment somewhat, will you Leif ?

Leif apparently - click his above link - made EME tests with a 1 bit/minute
rate and a 0.2 Hz filterwidth.
And Leif also did emphasize that frequency stability in this test was the
limiting factor and  that with better frequency stability ( and that  is
where my question was about ! ) the treshold could be expected to be even
lower.

So, Rein, please consider my questionable question in above contexts, OK
:-)   ?

Any commnets welcome ( should I use  my GPS disciplined LO for Linrads RF
frontend yes or no ? ).

BTW, Linux is installed on the other computer.
But.. you won't believe. .. I got a problem.
See my separate mail.

Thanks.
73, Peter PE1ECM

 )
From: "Rein A. Smit" <rein0zn@xxxxxxxxxxxxx>
To: <linrad@xxxxxxxxxxxxxxxxxxxxxx>

>    Hi Peter,
>
>    Thanks for your future contribution. It is for the good for future
>    LINRAD users and to get more people on board.

>    I do not want to throw you of the track so the say, but
>    there are a few other reflectors that cover DSP etc.
snip.....
>    Good luck during the weekend,
>
>    73 Rein


> Peter van Daalen wrote:
> >
> > Dag Rein,
snip.....
> > Yes Rein, as soon as I'll have something working I will have my set up
list
> > into your Linrad archive.
> > However, as I stated before, it is only this weekend ( to be precise,
I'll
> > begin right after this mail has been sent....)  that I will start
installing
> > Linux.
> > So, I have some adventures ahead....( I am told ).
> >
> > BTW, on this Linrad list I asked a question about the possible sense of
a
> > GPS locked HP OCXO local oscillator for the DC converter front end ( I
am
> > building Brooks Shera's GPS locked frequency standard  ).
> > I asked about the possibilities of very small FFT bin bandwidth
filtering
> >  for possible QRSSS  ).
> > I am talking about 144 MHz......, yes I know, but I still want to try.
> > Unfortunately, nobody responded.
> > So, I'm not sure as yet on this aspect of my set up.
> > Maybe, someone still has any thought on this ?
> >
> > I will shortly return to the list to report on my installation
adventures of
> > Linux and Linrad.
> >
> > 73, Peter PE1ECM
>


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