Lock it to 101% and remove
That would be first step.
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| SSBSC ( Single Sideband Suppressed Carrier ) FM broadcast https://forums.stereotool.com/viewtopic.php?t=4124 |
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| Author: | Bojcha [ Tue Mar 06, 2012 6:05 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Lock it to 101% and remove That would be first step.
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| Author: | Storm905 [ Wed Mar 07, 2012 6:41 am ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Quote: I have taken a quick peek at what I would need to do to create a composite clipper.
Interesting. How about a two stage approach to get the best part of it out the door and on air? When running maximum quality, we already have too much latency for off air monitoring. So *if* it is fairly easy to do the mpx clipper code and place if after the multiple core split code, I'd vote for that approach to start with - as long as if can be defeated for those that don't want the extra latency right now. A bit more latency (while best off minimised) I can live with in exchange for a good mpx clipper and SSB sooner! When time permits later on, you could then look at the more time consuming rewrite to reduce the latency. It would be useful though to be able to choose which core to run the mpx clipper on.Conclusions: - Converting the current L/R clipper to a composite clipper is very simple. Would probably take 1-2 days. All the protections that are built in would still work after the conversion (until yesterday I though that that wasn't possible, but I just figured out a very simple solution for this). There is another problem though. - The current code contains a lot of annoying stuff to split the processing over multiple cores, and to combine processed data. Rewriting this code is difficult, and will take much more time. An alternative would be to place the composite clipper *after* this code, but that would double the latency. . By the way, interesting discussion going on here re benefits of SSB: http://boards.radio-info.com/smf/index. ... c=207654.0 |
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| Author: | hvz [ Wed Mar 07, 2012 1:59 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
I'll check those video's this afternoon. Just wanted to mention that I've just started with cleaning up my code to make it easier - later - to change things. Since yesterday evening I have already removed over 200 kB of code! |
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| Author: | camclone [ Wed Mar 07, 2012 4:50 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Wow ! so , finnaly ..everything is possible using DSP codes! I can give 200 euros for mpx clipper and another 200 euros for SSBSC ! 400 euros for you when u are ready with those 2 projects! Hvz , YOU ARE A GENIUS ! OFF TOPIC ( don't believe the international media about the ..Greek Crisis things are not so bad in Greece ( OFF TOPIC ) |
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| Author: | Storm905 [ Sun Mar 18, 2012 1:07 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
I was curious about the possibility of extended audio frequency response using SSB. Traditionally, many tuners have a high end frequency limit of ~15kHz, while ST allows us to place the LPF @ 16 KHz while still providing solid protection to Pilot & RDS. Implementing SSB, if I understand the theory correctly, we should be able to raise the LPF to ~17 kHz+, while offering increased protection to RDS. I'm not sure how many average tuners could take advantage of this extended range, but I was curious in ST with the clipper design (and pending MPX clipper design) and new HF hole punch protect filters, in theory would there be any effect on <15 KHz, or any other negatives using a 17/17.5 kHz audio bandwidth with SSB? In particular here, I was thinking of the processors need to counter/fight the pre-emphasis curve, which is ~1.5 db higher at 17.5 kHz than it is at 15 kHz. AJ |
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| Author: | Bojcha [ Sun Mar 18, 2012 2:43 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Yes, you can raise LPF to even 18kHz with SSB.. Problem is not tuners. Tuners are usually are not limited in any way (lpf) if there is no some speciall filter. What you broadcast they will catch. Problem can be how noisy is tuner, how will it will make differencebetween edge 18kHz and 19khz pilot.. etc.. Also bigest problem for SSB is compatibility, wich is not 100% proved on field! Frank from Omnia claims that there is full compatibility but there are some tuners that just don't like SSB, small number of them but there is. Anyway, what i can see for now there is more gain from SSB then loss. video again http://www.youtube.com/watch?v=KlxeI2uqCOw |
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| Author: | Storm905 [ Mon Mar 19, 2012 12:16 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Quote: Yes, you can raise LPF to even 18kHz with SSB..
If it transpires that well under 1% of radios revert to mono with SSB, I can live with that in exchange for any notably improved multipath stereo performance that may benefit the many. In asking my question I was thinking in comparison to operating a 15 kHz bandwidth;Problem is not tuners. Tuners are usually are not limited in any way (lpf) if there is no some speciall filter. What you broadcast they will catch. Problem can be how noisy is tuner, how will it will make differencebetween edge 18kHz and 19khz pilot.. etc.. Also bigest problem for SSB is compatibility, wich is not 100% proved on field! Frank from Omnia claims that there is full compatibility but there are some tuners that just don't like SSB, small number of them but there is. Anyway, what i can see for now there is more gain from SSB then loss. video again http://www.youtube.com/watch?v=KlxeI2uqCOw - minor reductions in modulation loudness or minor increases in multipath when expanding from 15 - 17/18 kHz bandwidth. - any reduction in ST high frequency performance < 15 kHz, and/or increased likelihood to hole punch, given the pre-emphasis curve is nearly 2db higher at 18 kHz than 15 kHz. This question applies to the existing clippers and pending new SSB/multiplex clippers. While early days yet, according to posts on Radioinfo the ~50 US stations testing SSB have reported positive results. Lets hope it works out - it would be good for radio. Kind of strange its taken to 2012 to start getting SSB into the field on this scale. AJ |
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| Author: | hvz [ Mon Mar 19, 2012 6:28 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Bojcha: i think radios do filter the signal. Otherwise the FM pilot and RDS signal would be audible... |
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| Author: | Bojcha [ Wed Mar 21, 2012 6:55 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Yes ofcourse, i did not wrote well...i thought on something else.. |
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| Author: | ragnar.jensen [ Thu Mar 22, 2012 9:22 pm ] |
| Post subject: | Re: SSBSC ( Single Sideband Suppressed Carrier ) FM broadcas |
Quote: Bojcha: i think radios do filter the signal. Otherwise the FM pilot and RDS signal would be audible...
Not all of them do. This is what I get on the audio output of an ICOM PCR-100:
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