| Stereo Tool https://forums.stereotool.com/ |
|
| Spark (DRM sideband support) https://forums.stereotool.com/viewtopic.php?f=4&t=4387 |
Page 1 of 2 |
| Author: | jwjstudios [ Tue Nov 20, 2012 7:04 pm ] |
| Post subject: | Spark (DRM sideband support) |
I currently use Stereo Tool for stereo FM which sounds fantastic and works well, however I'd like to add a little digital radio into the mix as well. For testing I use Spark which generates clean, reliable DRM30-DRM+ signals, even with my FM transmitter. Problem is I would like to use the FM signal, and have DRM on the side much like HD Radio. There is more than enough space in the 200khz spread to make this happen. Issue is there is no real way to insert it into the signal. All the sideband options are SCA 67 and 92 and those are nowhere near practical when working with DRM. Is there a way to manually inject the DRM signal into Stereo Tool? |
|
| Author: | hvz [ Wed Nov 21, 2012 1:30 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
Looks like HD radio is running on very high frequencies, above 100 kHz? If so, it cannot be passed through any sound card that I know - the solution would indeed be to add it to the signal afterwards. That should be no problem - I just don't know if it needs to be synchronized with something else? |
|
| Author: | jwjstudios [ Fri Dec 28, 2012 1:03 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
Bumping. It appears the DRM+ signal is in the VHF band and works fine processed by itself and, based on what I can see is more than capable of sitting beside ST's FM signal. Issue is, the SCA options in Stereo Tool do not accommodate for this. Is there a way I can inject the signal starting at the 67khz point? Like this? (Horrible mockup) 
|
|
| Author: | hvz [ Fri Dec 28, 2012 1:48 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
No, because sound cards cannot handle high enough frequencies (max 96 kHz, but anything that gets really close to that is probably very bad in quality, so for practical purposes it's even less). So what you need is some external encoder (if it's called that) that gives you a side chain, and mix that with the sound card output. Which leaves my other question: Does the signal need to be synchronized with anything else, such as the 19 kHz pilot tone? That would make things more difficult. |
|
| Author: | jwjstudios [ Fri Dec 28, 2012 1:56 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
It has its own pilot as it is independent from the FM signal itself, a special radio, in my case an RTL-SDR is required to pick it up. When you say a sound card cannot handle high frequencies (over 96) that makes me wonder how a 192khz sample rate is achieved. I use sodira to monitor the stereo signal at a resolution of 192khz and it would appear there to be some unused space. |
|
| Author: | hvz [ Fri Dec 28, 2012 2:01 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
The sample RATE is 192 kHz, that means that the highest possible frequency you can generate with it is 96 kHz - half of the sample rate. (Nyquist). Short video (not completely correct but good enough to explain what happens): http://www.youtube.com/watch?v=Fy9dJgGCWZI |
|
| Author: | jwjstudios [ Fri Dec 28, 2012 2:09 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
Alright, I get that now.  So what about the SCA1/2 space? (from 57-96khz?) I'm sure a DRM30 signal will fit in that space. 39khz isn't much for anything but....
|
|
| Author: | hvz [ Fri Dec 28, 2012 2:22 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
Quote: Alright, I get that now.
Hm could be... Like I said, near 96 kHz it will get bad (as the video shows, although it's not THAT bad). So what about the SCA1/2 space? (from 57-96khz?) I'm sure a DRM30 signal will fit in that space. 39khz isn't much for anything but....Can you put this signal at any frequency you like? |
|
| Author: | jwjstudios [ Fri Dec 28, 2012 4:53 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
I should bul no. When I use Spark it doesn't allocate frequencies like ST or Breakway do, it shoves it at 0 and calls it done. I was able to fiddle with the OFDM modulation and shift it over about 4khz but it still sat over the stereo signal. |
|
| Author: | hvz [ Sun Dec 30, 2012 3:04 am ] |
| Post subject: | Re: Spark (DRM sideband support) |
No what I meant is: In Stereo Tool you can put an SCA channel at 67 kHz. But at which freqency (range) can this HD stuff be placed? In other words: If I just move the SCA frequency to - say - 75 kHz, would that work? |
|
| Page 1 of 2 | All times are UTC+02:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|