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PostPosted: Fri Jul 22, 2022 10:42 am 

Joined: Fri Aug 07, 2020 7:24 pm
Posts: 65
Hello to the forum!

I use esi juli@ to output fm mpx with stereo tool with digital mpx as my transmitter can accept it.

i was wondering about tilt correction as i was setting up everything i saw that i had to set the rds level at around 6.75% in st in order for it to output 5% as i wanted it. same with pilot in order to get 9% i set it at 10%.

This got me into thinking that juli@ might need some tilt correction but even on digital mpx? i thought that there is no need to correct digital out on a juli@.

As i tested it i saw that under 100hz everything was a mess. from 100hz and up to 80000hz everything is pristine.

Is this supposed to happen or my card is faulty? Also is there any explanation of why i need to output much more rds level to get what i should get in the first place while the card is flat at the rds's frequencies?


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PostPosted: Fri Jul 22, 2022 8:41 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4151
It should be ideal. It also depends on transmiter and how it accepts MPX input. I would always measure with scope from air.
Is it Direct to channel transmitter?

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PostPosted: Sat Jul 23, 2022 8:31 am 

Joined: Fri Aug 07, 2020 7:24 pm
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Quote:
It should be ideal. It also depends on transmiter and how it accepts MPX input. I would always measure with scope from air.
Is it Direct to channel transmitter?
yes it is direct to channel. can this be an st bug? have you seen an audio card that outputs what it says ever? i measured it from air and what i saw was down from 100hz for example at 40hz instead of 75khz modulation there was 80-85. i used tilt correction and i got it to be flat but i was wondering how bad could juli@ be at its digital part.


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PostPosted: Sat Jul 23, 2022 10:13 am 

Joined: Fri Aug 07, 2020 7:24 pm
Posts: 65
So I tried installing st to a pc and have fm output to virtual audio cable and the input into mpx tool. What I saw was what i see in the real world example. If you set modulation at 75 everything is flat but on the rds’s frequencies there’s a tilt. How is that possible when there is no hardware audio interfaces involved? It can also be an mpx tool bug but I don’t know any other software that checks the modulation also via VAC. About the low frequencies I am pretty sure it’s juli@s fault but I am more worried about 35khz and up as it’s where I see the most tilt with vac but not on juli@.

Ps: everything is at 24/192 no audio resampling is happening.


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PostPosted: Sat Jul 23, 2022 4:41 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
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You def doing something wrong. I never tried digital output for mpx since i never had DDS transmitter, but it should work just fine. I know how analog output works on Juli@ and it's pretty good after small calibration.

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PostPosted: Sat Jul 23, 2022 7:16 pm 

Joined: Fri Aug 07, 2020 7:24 pm
Posts: 65
Quote:
You def doing something wrong. I never tried digital output for mpx since i never had DDS transmitter, but it should work just fine. I know how analog output works on Juli@ and it's pretty good after small calibration.
Hans might know something about it. If anyone else has a qlue any suggestion might help.

To be clear I see 85 modulation up to 80-90hz and from 100hz up to 80.000hz I see 75.


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