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Author Topic: 6945 KHz XFM Shortwave C-QUAM AM Stereo test  (Read 6636 times)

Offline Kilokat7

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6945 KHz XFM Shortwave C-QUAM AM Stereo test
« on: July 23, 2012, 0210 UTC »
Signed on just after 0200 UTC with test tones at various frequencies, then XFM ID with "C-QUAM AM stereo test transmission" followed by The Cars "Moving in Stereo".  S5 signal, static crashes making C-QUAM decode a little challenging but I'm locked onto the 25 hz pilot tones and currently listening in stereo via Perseus SDR + SoDiRa.  Will post a recording later tonight or tomorrow evening.  Thanks for this test XFM!



As promised, here's the complete reception as it sounded here:

http://www.youtube.com/watch?v=nSMUnpkKoSM

Spectrogram (6mb) showing the signal and test tones:

http://amdxer.com/spectrograms/XFM_Shortwave_Stereo_23JL12.JPG
« Last Edit: July 24, 2012, 0313 UTC by Kilokat7 »
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Offline jFarley

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #1 on: July 23, 2012, 0213 UTC »
This extra LED on my receiver keeps flashing on and off...

With the hardware decoder on a TS-140S, I have pilot about 50% of the time .  Thought there was separation during the Cars piece when you got above S9.  Kind of eerie listening and just getting a feel for this.  It's noisy tonight with choppy fades.

The Meduci decoder in the TS-140S seems to lose pilot easily in a fade.  I am in and out of lock with fading, and it is sometimes a pronounced difference, sometimes it is more subtle.  But it is stereo!

Reception here was around S8-S9, and that would have been enough to keep pilot lock here, I feel.  Problem was the very choppy fades down to S5.  I also noted some unlocking due to noise.

Congrats redhat!  small steps...

Complete Show Audio:    http://www.mediafire.com/?213cuh1fuh6cxcc

« Last Edit: July 23, 2012, 0319 UTC by jFarley »
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Offline Danoman

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #2 on: July 23, 2012, 0234 UTC »
Very good audio here in "normal" am mode.
S9 +10 peaks with brief fades to S7.

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Offline Zoidberg

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #3 on: July 23, 2012, 0235 UTC »
7/23/12, 6945, 0230z: Music just barely audible, not enough to ID anything so far.
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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #4 on: July 23, 2012, 0237 UTC »
Signal is fair on west coast...up to S5 but modulation level is very low, hard to make out the music

Offline Kilokat7

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #5 on: July 23, 2012, 0241 UTC »
The Meduci decoder in the TS-140S seems to lose pilot easily in a fade.  I am in and out of lock with fading, and it is sometimes a pronounced difference, sometimes it is more subtle.  But it is stereo!

The pilot started out fairly consistent here, but now at 0230 UTC, it's averaging about 35%-50% with the signal fades.  I'd love for this test to repeat this winter without the summer static and a little stronger signal.  Agreed - great first effort here and like jFarley said - congrats!
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Offline skeezix

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #6 on: July 23, 2012, 0247 UTC »
Caught the last 10 seconds of the broadcast with the ID.

Stereo on SW. Amazing!

Tons of static here but would've been otherwise a great signal. Wish I heard more than 10 seconds...
Minneapolis, MN

Offline redhat

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #7 on: July 23, 2012, 0424 UTC »
Thanks for all the posts guys, its pretty cool that other people besides just me are getting into this.  Under difficult summer conditions ISB may be more effective and listenable.  Listening to Farley's recording, it seemed to me that the noise blanking was acting on lightning crashes and fades.  It will be interesting to see how Kilokat7's recording turns out.

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Offline Sealord

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #8 on: July 23, 2012, 1046 UTC »
6945 AM SIO 323

Caught the beginning sign on of XFM Shortwave - had to crash, but very cool doing the C-Quam test tx Redhat!

02:14z 'Moving In Stereo' - Cars
02:16z "...this is XFM..."
02:17z unknown song with keyboards

AM Sync. Audio (02:14z-02:17z): http://archive.org/download/ShortwavePirateRadioCont/XfmShortwave6945Am0214z-0217z07-23-12.mp3

Thanks XFM! :)
« Last Edit: July 23, 2012, 1142 UTC by Sealord »
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Offline ChrisSmolinski

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #9 on: July 23, 2012, 1406 UTC »
Mostly S8 here. I guess I need to add stereo demod to my SDR I/Q recording file player software.

Thanks for the interesting test!
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Offline redhat

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #10 on: July 23, 2012, 2356 UTC »
Chris,

SoDira will directly play IF recording files if thats of any help.  They have a few demo files on their site you can download and try.

http://www.dsp4swls.de/sodira/sodiraeng.html

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lightkeeper

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #11 on: July 24, 2012, 0207 UTC »
Chris,

SoDira will directly play IF recording files if thats of any help.  They have a few demo files on their site you can download and try.

http://www.dsp4swls.de/sodira/sodiraeng.html

+-RH

Do you suppose that would work with a TenTec RX-320D? It has a 12 kHz IF output.

Offline redhat

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #12 on: July 24, 2012, 1200 UTC »
Supposedly yes, you feed the 12Khz IF into your soundcard input and set SoDira for line input.

Thanks for the youtube post Kilokat7.  I think we need either more power or better conditions.  The more I think about it, linear ISB may be the way to go after all.

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Offline jFarley

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #13 on: July 25, 2012, 0048 UTC »
Thanks for the video, kilokat7!  Very nice presentation.
Joe Farley, Near Chicago
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Offline ChrisLobde

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Re: 6945 KHz XFM Shortwave C-QUAM AM Stereo test
« Reply #14 on: July 27, 2012, 0200 UTC »
How about a Kahn AM Stereo test next??  Were there not three competing systems at one time?  :D
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