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| uMPX encoder level control https://forums.stereotool.com/viewtopic.php?f=6&t=33317 |
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| Author: | brettk [ Thu Sep 15, 2022 4:20 am ] |
| Post subject: | uMPX encoder level control |
Hi We are testing ST processing and its inbuilt uMPX encoder for a possible solution We are not using FM Sound cards Just processing and FM uMPX encoder I cant see where we can set the uMPX encoder level. I can see that if using a sound card to generate analog composite that there is an composite level control. Even If I enable this sound card option , The uMPX level is unaffected The “Normal” output level also has no affect on the uMPX encoding level Because of this there appears no headroom in the uMPX encoder. it never goes above 100% mod even with all the limiters and clippers disabled One other thing I noted is when selecting "De-Emphasized version of FM out" for the "Normal Out" that the composite Clipper is not in this path. This kind of makes sense but it does not represent the same sound that you get when actually demodulating the uMPX composite Thoughts? |
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| Author: | M-N [ Thu Sep 15, 2022 8:26 am ] |
| Post subject: | Re: uMPX encoder level control |
Brett what are you using the 𝛍MPX plugged into and what you are driving on the end of the FM out please as it would help in understanding ? With most of the settings there is a pull down menu to change there location in the DPS stack. |
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| Author: | Mathijsco [ Thu Sep 15, 2022 9:05 am ] |
| Post subject: | Re: uMPX encoder level control |
There is no encoding level because it was designed to operate on 100% peak level at all times. It doesn't need headroom because a precisely clipped MPX signal does not have any peaks above 0dB. In the decoder there is an output level control so you can adjust the level of the signal flowing out of the soundcard. |
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| Author: | brettk [ Fri Sep 16, 2022 3:42 am ] |
| Post subject: | Re: uMPX encoder level control |
Hi Mathijsco Well there still needs to be headroom in the uMPX Transport Because. 1) if you choose NOT to run composite clipping 2) from my understanding ,the composite strictness setting , Lower values leave more small spikes in the output signal (from manual) 3) if the uMPX does hit 0db its a brittle digital clip without any harmonics filtering. Hi M-N I am using the Stereo Tool uMPX encoder -> Ip -> uMPX decoder (Tieline) -> composite into Harris - NEC FM Exciter -> Received on Deva FM monitor (radio explorer II) DPS stack doesn't appear to have ability to choose the uMPX encoder after any level control Thanks |
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| Author: | hvz [ Tue Apr 04, 2023 11:27 am ] |
| Post subject: | Re: uMPX encoder level control |
MicroMPX expects a compliant MPX signal, so without any overshoots. It needs to know where 0 dB is, and it cannot encode values higher than that - if it did, that would also cause overshoots on the transmitter side. When using it from inside Stereo Tool with the Composite Clipper *and* Hard Limit enabled (which is the case for all the built-in presets), it's impossible to get values above 0 dB. MicroMPX cannot encode values above 0 dB; if you use a stand alone encoder the encoder will show a warning if too high input values are present. |
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