FW: RE: W3SZ's files (W3SZ Oct 15 2002)

[Leif Åsbrink <leif.asbrink@xxxxxxxxxxxxxxxxxxxx]

-----Original Message-----
From: owner-linrad@xxxxxxxxxxxxxxxxxxxxx
[mailto:owner-linrad@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of W3SZ
Sent: Tuesday, October 15, 2002 5:46 AM
To: linrad@xxxxxxxxxxxxxxxxxxxxx
Subject: RE: [linrad] W3SZ's files


Hi, Josh!

> My first question is can the SSB audio be decoded.  When I 
> was trying to find a frequency that sounded good I was never 
> able to find one.  It may have been my frequency choice or 
> the filter was set wrong.

Yes it can be decoded.  Leif posted the best description of how to
adjust things, so I won't repeat.  I have just 2 comments.  First is
that the SSB audio with Linrad sounds superb.  IT is better than any
commercial receiver I've used, as long as you stay away from digital
clipping.  Watch your levels by typing "A" if you are having problems,
and make sure the gain in the baseband window is not set too high.  I
love listening to the guys on 160 meter SSB with Linrad.  They sound
like Hi Fi AM Broadcast stations (and they know it).

Second, as Leif said, click on the signal so that it is centered in your
filter window.  I use 2100-2300 Hz.  Then adjust the BFO to get proper
pitch.  If you can't understand it at all, go to the other sideband.  If
it just sounds funny, you need to adjust the pitch carefully.

> 
> The Second questions is setting the fft1 avgn and other 
> options to his values made a really big difference in finding 
> any of the VLF data.

This is true.  I thought of this after I posted.  When you bring up an S
file, Linrad makes multiple parameter files for it.  One of them,
####par_wg has the parameters like you are interested in in it.  Maybe
in the future I should put these on the webpage as well.  If anyone is
having trouble with particular files, I could email you the parameter
files.  Or if someone emails me a list of all of the files in question,
I will go thru my directories and find the parameter files and put them
on the web and publish a list of URL's for the parameter files.

> 
> Is there a good way to pass the parameter file around with 
> the audio files so we can see what they were seeing.  If 
> Roger had not posted the picture and given me some ideas on 
> the settings I don't think I would have found anything.  
> (Proof again a picture is worth a 1000 words).

I don't know if there is an easier way or not.  
> 
> I also had problems trying to play the audio files at first 
> because of the soundcard sampling rate.  I needed to the the 
> card READONLY to read the files, but it still had sound 
> output.  Is this expected?

With two cards here and 96000 Hz width I always run the Delta44 card on
READONLY.  The soundblaster does the output.  If I made these files with
96000 Hz (I forget if I did), then I don't think you could play them
with 44100 soundblaster card.

> I think having these files really helps show off the power of 
> linrad and hope with sending more ancillary data or parameter 
> files will help people learn how to really use the software.

Let me know what else you want.  I will make files of any band 300 KHz
to 144 mHz, any mode, and at any sampling rate 44100 to 96000 Hz, either
I/Q or conventional output, an dof any size/ length.  144 MHz will be
uninteresting with just 2 beacons until I get time to get back on EME.
Besides, Leif's 2 meter files are unbeatable.  My favorite (from the
album "SM5BSZ's Best Hits") is frh1135.  Pure listening pleasure, with
no commercial (or transmitter) interruptions. 

I made a one hour 44100 HZ sampling rate, conventional file on Sunday.
IT was 340 MB without compression.  You can figure from that the size
for files of different lengths and sampling rates, or for I/Q mixer.
 
> 
> Now if I could just figure out what hardware to build.  There 
> are a lot of ideas running around, but none of them seem to 
> have been created and described from start to finnish.
> 
> Roger has a simple design on his page, but it does not have I 
> and Q outputs.  Is this a problem?

It just means that with 96000 Hz sampling you get about 45000 Hz instead
of 90000 Hz bandwidth.

  I'm also not sure if I 
> completly understand the LOs and XTAL Filter.  Leif has lots 
> of ideas but he has a lot of cautions with all of them.  So I 
> don't know if any of those are really ready for me.  

Here is what I do here.  IT is very simple once you start playing with
it (or else I could not do it ;)  ).

154.7 MHz LO - 144 MHz signal = 10.7 MHz 1st IF

10.72 MHz 2nd LO - 10.7 MHz 1st IF signal = 20 KHz baseband signal.

Use a 10.7 MHz center frequency 40 KHz filter and you have 40 KHz
bandwidth, which is perfect if you use 96000 Hz sampling and Non I/Q
mixer like I do here when not using the time machine.

  

The ESS 
> Time Machine seems to be a starting point, but to get to 
> higher frequences people are rapidly making huge changes.

This is an excelent way to describe it.  IT is a good starting point.

> 
> How have people gotten started building homebrew stuff when 
> they don't know how everything (or anything) works.

I knew nothing about any of this and had built no RF hardware from
scratch before building this.  Leif's webpages and other websites were a
big help.  I learned a lot from DUBUS and QEX and some of the RSGB and
ARRL books on construction, UHF/Microwave techinques, etc.  And Leif was
a MAJOR help!  SO were the residents of Moon-Net and the Stanford VHF
reflector.  I'd recommend signing up for them, too.  And asking
questions.

I'd also recommend putting in your email address when you post to a list
like this asking questions.  Many of us won't answer to the list all the
time, because we 

1) don't want to look foolish if we are wrong
2) already feel like we post too many notes to the list
3) don't want to duplicate somebody elses post if it has most of what we
want to say

But if you put your email address in the email (with  spam protector if
needed) we WILL answer privately.  

> 
> I'm good with computers and software, but just starting to 
> try to get a handle on radio hardware projects and there is a 
> lot to learn.  I need a mentor in the Seattle area.

I had no expertise in ANY area ( and probably still don't).  But I was
able to get things to work with the above resources and persistence.
And now I find that I enjoy the building and tinkering more than
operating.  And I enjoy listening more than transmitting. 

Have a great week, Josh, and feel free to send questions about this
stuff direct to my email address below if you aren't comfortable posting
all of them to the list.  That goes for anyone else, too. 


73,

Roger Rehr
W3SZ   FN20ah
2 Merrymount Road
Reading, PA  19609-1718
http://www.qsl.net/w3sz



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