Maybe a duhhh question but I found no apparent answer nowhere. Having a pc with, for instance, Breakaway installed, how is the ouput connected to the MPX input (BNC) of an exciter? From the soundcard, I suppose. What output of the soundcard? Stereo out (2 channels L/R)--->Mpx in? How?
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Processing Software - MPX Out
- Thread starter SFM-Ptgal
- Start date
You can use either the left or right output,both have MPX.if your card is 1/4 phone output you;ll need a cable with 1/4 phone on one end and a BNC on the other.Unless you;re using a Marian Trace card,you will need to check the tilt .I find a parallel BNC (T) adapter works fine for that.
Maybe I'm misunderstanding the question, but wouldn't you need a stereo generator between the sound card (L and R) and the exciter (MPX)? You can mix the L and R to mono and feed it in the MPX input but you would need to pre-emphasize it first unless the exciter has a baseband audio input.
If you have a soundcard that is capable of 192kHz, such as the Marian Trace, the MPX is generated IN the software and D/A converted at the card to standard composite out. Either the L or R channel carries the complete composite signal. 192/2 (nyquist) gives you 96kHz worth of audio. More than enough for the composite baseband. Preemphasis also happens in the software, prior to the MPX encoding (as it does in all processors).
I know it sounds crazy but as others have stated, the right sound card can output a composite MPX signal. Don't be too quick to rule out a Marian Trace Alpha sound card. They come from Europe so they'd be cheaper there than here in the USA. The beauty of feeding your FM exciter with a computer (using the Trace Alpha) and having 100% modulation with virtually no overshoot is quite a joy to behold when using Breakaway Broadcast Processor.
I don't know why it's so shocking that a sound card can generate MPX out! The composite video out on my old VCR passed 6MHz of bandwidth with no problem. The D/A converter on a DVD player (if you really want to use composite video for some nutty reason) can also do that as well. 192kHz is really nothing, outside of the recording world.
Huh?
I don't see anything in the specs that would indicate this card can generate a composite stereo signal...
That is, a signal with 75 u sec ( or 50 usec, which is still used in some places in Europe) pre-emphasis audio with a 19 KHZ pilot & 38 suppressed carrier sideband with the L -TR information.
E.G. something that can introduced into a standard analog exciter & produce a stereo signal that an FM radio can decode.
You can, of course, feed a mono signal into the composite input of an exciter if it has the correct pre-emphasis & produce a perfectly acceptable mono FM signal.
I don't see anything in the specs that would indicate this card can generate a composite stereo signal...
That is, a signal with 75 u sec ( or 50 usec, which is still used in some places in Europe) pre-emphasis audio with a 19 KHZ pilot & 38 suppressed carrier sideband with the L -TR information.
E.G. something that can introduced into a standard analog exciter & produce a stereo signal that an FM radio can decode.
You can, of course, feed a mono signal into the composite input of an exciter if it has the correct pre-emphasis & produce a perfectly acceptable mono FM signal.
TomT said:The card doesn't generate the signal..the Breakaway Broadcast program does! but it needs 192khz.
Huh?
I don't see anything in the specs that would indicate this card can generate a composite stereo signal...
That is, a signal with 75 u sec ( or 50 usec, which is still used in some places in Europe) pre-emphasis audio with a 19 KHZ pilot & 38 suppressed carrier sideband with the L -TR information.
E.G. something that can introduced into a standard analog exciter & produce a stereo signal that an FM radio can decode.
You can, of course, feed a mono signal into the composite input of an exciter if it has the correct pre-emphasis & produce a perfectly acceptable mono FM signal.
TomT said:Huh?
I don't see anything in the specs that would indicate this card can generate a composite stereo signal...
That is, a signal with 75 u sec ( or 50 usec, which is still used in some places in Europe) pre-emphasis audio with a 19 KHZ pilot & 38 suppressed carrier sideband with the L -TR information.
E.G. something that can introduced into a standard analog exciter & produce a stereo signal that an FM radio can decode.
You can, of course, feed a mono signal into the composite input of an exciter if it has the correct pre-emphasis & produce a perfectly acceptable mono FM signal.
Any waveform, including composite audio, can be reproduced by a sound card with a high enough sample rate. In the case of composite audio, the highest frequency is 53kHz, so the sample rate has to be at least 2x 53kHz in order to reproduce a composite output. Since most sound cards are sampled and 48kHz, 96kHz or 192kHz, the only commonly found card capable of reproducing composite is a sound card with a 192kHz sample rate. Producing the composite waveform (including pre-emphasis, 15kHz filtering, 19kHz pilot, and 38kHz sidebands) is just done in the software and the resulting wide-band waveform is sent to the sound card's output. This is not all that different than the way digital stereo generators have worked since the 1980s, except it's done in software rather than hardware. Theoretically, any sound card with a 192kHz sample rate can be used as a composite audio source, including the $25 variety. In practice, some cards are better than others, and will produce less distortion, fewer overshoots, etc. Also, for solid peak limiting performance, the amplifiers need to be dc coupled. If you have a 192kHz sound card, there are several sources for stereo encoder software online, including some free ones, that you can use to create composite audio suitable for driving an exciter's composite input.
Well... if by 'some places' you mean all of Europe, Asia and Australia you are right ;DTomT said:( or 50 usec, which is still used in some places in Europe)
Oops... meant all of Europe, Australia and some of Asiarichard.vanderveen said:Well... if by 'some places' you mean all of Europe, Asia and Australia you are right ;D
Bojcha said:I wonder why you ask that question on first place when you don't want to buy capable soundcard (?)
First thing you can 'read' in both mentioned software(s) is that for FM is needed 192kHz soundcard.
1st, this was a simple tech question. 2nd, I knew from the start that a 192khz is mandatory for the broadcast purposes. "How do" was the question.
I wont even answer to your "wonder"...
SFM-Ptgal said:1st, this was a simple tech question.... "How do" was the question.
The answer depends on the type of cnnector & output of your soundcard, but mainly, composite audio comes out of your line-out connector and is fed directly to the composite input of the exciter.
So is anybody using the M-Audio Audiophile 192 card with Breakaway Broadcast? I can find these cards on eBay for about $75 and I'm thinking about ordering one and trying the Breakaway software demo.
Also, since composite is unbalanced, you connect the high to the center pin, shield to shield, and low to where?
Also, since composite is unbalanced, you connect the high to the center pin, shield to shield, and low to where?
Lazy J said:So is anybody using the M-Audio Audiophile 192 card with Breakaway Broadcast? I can find these cards on eBay for about $75 and I'm thinking about ordering one and trying the Breakaway software demo.
Also, since composite is unbalanced, you connect the high to the center pin, shield to shield, and low to where?
Low floats. Don't connect it.
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