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PostPosted: Sat Jul 02, 2011 3:13 pm 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
I've already thinked that. My band pass filter is from 30Hz to 15900Hz.
Thanks for your message, though.


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PostPosted: Sat Jul 02, 2011 5:26 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 3312
Quote:
The problem appears again using the external stereocoder (it supports RDS) but only if I use ST as the processing software. If I use MBL or even Soundsolution, the phase is almost 0deg.
So I cannot rule out ST completely.
This is new .. and in same time impossible. FM and Normal outputs are very clean, ST just can't make problem like that (if all is adjusted as should), especially at normal output, which is (in that configuration) not responsible for FM output.

Can you, for test, Play music from same PC via VAC into ST standalone and not from Soundcard Input.. and see what will happen?


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PostPosted: Tue Sep 20, 2011 9:49 pm 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Update: I spent some time on the FM calibration window and I had my pira75 beside me. I've set to 0 the slider for the 57khz at the first step. Voila! Phase diff between stereo pilot and RDS signal is gone (at least pira75 shows nothing, not even +/- 1 or 2 deg)

After about 20+ days or so, sometimes there is a phase diff again, but it dissapears insantly IF I reset/cllear the soundcard's buffer. I'm not 100% sure that this trick works or if there is indeed a phase diff at the beggining, I'm just sharing my findings and my thoughts.

But for sure, setting the 57khz slider to 0 (at the first step) will fix the issue.

Quick resume' for those who are bored reading the previous posts: I'm trying to figure out why my M-Audio Audiophile 192 PCI is presenting a phase difference between 19 and 57khz. It might happen to some other sund cards, though.

8-)


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PostPosted: Tue Sep 20, 2011 9:55 pm 

Joined: Sun May 02, 2010 11:26 pm
Posts: 546
When the pira doesn't show a phase difference it can't see the rds anymore.
And when you set 57 kHz slider all the way to 0 in the first step you remove whole RDS so this is no fix.
So if you disable your RDS it does the same.


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PostPosted: Tue Sep 20, 2011 9:57 pm 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Hmm.. But I still see my RDS signal on the pira :shock:


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PostPosted: Tue Sep 20, 2011 10:01 pm 

Joined: Sun May 02, 2010 11:26 pm
Posts: 546
Ok i tried here with extreme settings. Big deviation and big RDS level.
It mostly removes the upper half of the RDS signal. You should clearly see this when you look at the MPX on the Pira with Double Timebase selected.
And the RDS runs like crap when i do it this way.


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PostPosted: Tue Sep 20, 2011 10:06 pm 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Strange.. my RDS is running fine, even in scrolling text. My RDS level is 3.3Khz
I'll check again tommorow cause it's really late for troubleshooting.

Anyway, If you could spent some minutes here, could you please reply with a step by step fm calib guide starting from total zero? Like: no music input, turn on fm processing on ST, apply a test tone via FM calib, listen to beep-something etc.

Thanks!


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PostPosted: Wed Sep 21, 2011 1:51 am 

Joined: Sun May 02, 2010 11:26 pm
Posts: 546
Load your FM preset in ST.
- Make sure HPF is at around 30 Hz.
- Make sure LPF is around 15 or 16 kHz.
- Make sure Post Amp is at x1.00
- Make sure Hard Limit is ON
- Make sure Keep composite MPX signal within limits is at Yes
- Pre-emphasis must be ON and 50us if you're not in US.
- Encode RDS ON
- Set Pilot level at 9.00%
- Set RDS volume level at 4.50%
- Play 320 Hz tone in FM transmitter calibration.
- Adjust output volume to be max at 75.0 kHz on the Pira.
- Adjust all other tones starting from 20 Hz to also be at max 75.0 kHz on the Pira. Some tones influence each other so repeat it a few times.
- Calibrate 19 kHz phase slider with a good tuner.
- You can now play music and if you have good transmitter / link then your max deviation will be 75 kHz for all music.
- The phase difference sliders can be adjusted with a good tuner so that you have little sound as possible on the right channel. Or you can look at l/r dB from pira to adjust for minimal signal on right channel.
- Now you can play some music trough stereo tool.
- Maybe you need to set output volume a little lower if there are still overshoots.
- Now you can adjust Pilot volume to around 6.8 kHz on the Pira or lower if you want.
- Now you can adjust RDS volume to around 3.4 kHz on the Pira or higher or lower if you want.
- Then adjust 57 kHz phase slider to get Phase difference to 0 on the Pira use little steps for it.

Good luck.

Or better option:
- Get a Marian Trace Alpha card.
- Get a good transmitter with DC straight input.
- Connect output Marian card directly to input of transmitter.
- Adjust output level for 75 kHz on the pira.
Done.


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PostPosted: Wed Sep 21, 2011 2:31 pm 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
:o :o :o :lol: :lol: :lol:
Overmodulated thanks! :D :D :D
I was not following that order, so maybe that's why I didn't get good results! I'm going to re-calibrate my station tonight, I hope that there will be a few listeners at 4am bothered by those "strange beeps" :lol:

@Hans:
This post should be sticky and the same text should be on the FM calibration window and on the help pages on this website!

UPDATE:
Ok, I've managed to calibrate my station thanks to eldoradofm. I must admit that I was not following the above procedure, so that's why I was geting overshoots really often and I had that strange phase diff between stereo pilot and rds signal.

This is how I've calibrated my transmitter. This is another proof that everybody using ST for FM purposes, MUST calibrate.
Image

And this is how is pira75 measuring all the above on Top40/Dance music (I'm using an MPX STL by the way).
Image

All the above were made totaly remotly. I'm using pira's excellent remotecom software. My pira75 is located in the studio and I'm doing all the work from home, wearing pyjamas :lol:

Although I'm really happy about all the above I've got some questions:
1) When I was ticking the boxes at the first step, at the tones of 23Khz till 53Khz, nothing happened when messing with the sliders. I was constantly geting 75khz modulation no matter what. So I left them on 1.00
2) At the last tone of the 57Khz, no matter what the slider's position was, I was getting 25Khz of modulation.
3) from time to time (like every 10mins) there is a phase diff of -20deg appearing instantly. Pira75 bug? Or my calibration needs fine tuning? Dunno :roll:

I'd like to thank once again eldoradofm for his step-by-step guide.:geek:
Remember: ALWAYS calibrate your ST for your specific transmitter. DO NOT SKIP ANY STEPS. And if you are on the broadcast business, get your self a pira broadcast analyzer. 8-)

btw, I'm using beta079


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