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lef
PostPosted: Tue Jun 21, 2011 1:32 am 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
BACK-EDIT FROM PAGE7.

This is the step-by-step guide to calibrate your FM transmitter.
Thanks eldoradofm!
Quote:
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.

Anyone had experience on running ST in full broadcast mode (incl. stere and RDS) using M-Audio 192 PCI?
What OS did have installed? WinXP or Win7?
I'm suspicious that M-Audio's latest 64bit drivers for Win7 is causing some weired stuff with stereo-seperation and phase-shifting. Maybe I'm wrong on that. :roll:


Last edited by lef on Thu Sep 22, 2011 3:29 am, edited 1 time in total.

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lef
 Post subject: FM calibration. How to?!
PostPosted: Tue Jun 21, 2011 1:46 am 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Can somebody write a step-by-step and in detail walkthrough on how to complete the FM calibration? I know that there are some info on the FM calibration section in ST, but is there anyone willing to spend some time over here?!
(The simple way, without an MPX decoder)
Thanks! 8-)
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Bojcha
PostPosted: Tue Jun 21, 2011 1:49 am 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4163
I don't have expirience for speciffic soundcard, but i can tell you what other users talking....

Use WindowsXP pro for dedicated PC, and check "TILT" ! Other users even do some hardware modification on that soundcard to correct tilt... and again fine softer tweak is needed. You can do that from ST in "FM Transmitter Callibration"
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lef
PostPosted: Tue Jun 21, 2011 1:56 am 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Do you suspect that Win7 is the cause of the problem? Or are you saying in terms of "stability"?
Dunno, maybe I'll reformat and install XP. Btw, I'm getting a phase shift checked by pira75 around -60 deg! I've played along with the angle on the stereo page on ST, but nothing happened.. 64bit drivers? Win7? Incorrect FM calibration?
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Bojcha
PostPosted: Tue Jun 21, 2011 3:03 am 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4163
Quote:
Do you suspect that Win7 is the cause of the problem? Or are you saying in terms of "stability"?
Because more stable drivers for XP, and XP is much lighter and just better for that use.
Quote:
I'm getting a phase shift checked by pira75 around -60 deg! I've played along with the angle on the stereo page on ST, but nothing happened..
That can be corrected in ST by adjusting 57kHz slider, because that what you measured with pira Analyzer has nothing with overall 'tilt' but Phase Difference between Pilot and RDS tone only! (You can check that by turning OFF RDS - tell us what are you going to measure)
Anyway that phase difference should be 0, if not, Hans need to correct this. or your transmitter is not good. I can't test because i don't have Pira Analyzer.
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hvz
PostPosted: Tue Jun 21, 2011 12:58 pm 
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Joined: Mon Mar 17, 2008 1:40 am
Posts: 11211
Lef, you wrote elsewhere that the signal is clipped tight between +/-75 kHz. If that's the case, the signal should already be perfect.

You also wrote (to me) that you're getting a 60 degree tilt in the stereo signal - can you tell me how you determined that? Because if the signal is that bad, I would also expect big spikes, not a signal that's tight between +/- 75 kHz.

What happens if - inside the calibration window - you select 'only right channel' audio? How bad is the separation then? (Note: I think this functionality was broken in version 6.10, you might want to download the latest BETA from the news section - Stereo Tool 6.10 thread (last page).
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lef
PostPosted: Tue Jun 21, 2011 2:19 pm 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Okay, I'll install latest BETA and run on Win XP. I'll troubleshoot a little bit using the Pira75 analyzer and will get back here with the update.

The 75khz modulation is indeed really ok, giving a few spikes of modulation at 80-82KHz which is legaly acceptable, as far as I know.
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Bojcha
PostPosted: Tue Jun 21, 2011 4:28 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4163
To be clear here about pira analyzer and phase shift !

That's measurement of Phase Difference between Pilot and RDS signal !(which should be 0 in StereoTool case), as i wrote you here .. viewtopic.php?f=2&t=3736

And you can read that here
Quote:
- Pilot-to-RDS phase difference
http://pira.cz/fm_broadcast_analyzer/p175-brochure.pdf
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lef
PostPosted: Wed Jun 22, 2011 1:37 am 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Yes I know. I will make more tests and write back.
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lef
PostPosted: Wed Jun 22, 2011 6:41 pm 

Joined: Fri May 13, 2011 11:21 pm
Posts: 52
Update!
I've turned off RDS and I still measure a RDS signal of around 3-4 KHz. I suppose I should tune the slider of 57KHz in FM calibration, right? I don't have direct MPX tools to check, so I should only move the 57KHz slider at the third step?
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