Would the latest stereo tools programme give out proper stereo sound and quality separation when using a 192 bit sound card on a PC using the 3.5mm jack output which would be plugged into a mono microwave link box?

I've tried messing around with Stereo tool and found it really adds a lot of noise to your carrier and when using my Tecsun radio the signal to noise ratio dropped dramatically.

For example:

The signal on Mono was 60dB with 56dB s/n.

In Stereo it was 60dB with 35dB s/n.

That's a lot of noise and affects the signal, personally I'd just buy a decent encoder with a 'brick wall filter'.

....I've never bothered with stereo though due to the fact you need about 12dB of your ERP power to be able to cover the same area clear without that nasty high pitched FM Stereo hiss.

As you can tell I'm not too clued up about FM Stereo for the above reasons and I just stick to Mono.
It's OK in cars but most domestic HiFi's really suffer when it comes to receiving FM stereo and it puts the listener's off!

Ah it all seems to be making perfect sense now! Was getting all of those problems that you've mentioned above but couldn't get my head round it. Stereo encoder with a strong / quality 'brick wall' filter it is then! Thank you for the advice teckniqs

No worries, I'm sure someone with a lot more knowledge will be able to answer more of your question a little later on...

yeah, you have to calibrate all the waves properly though. there's plenty of instructions on the website.

I've never had problems using the stereo & RDS encoder built into stereo tool. No problems with hiss or s/n ratio. Must have been really lucky. One good piece of advice is to use a good soundcard. The onboard soundcards sound crap and could be your problem.

Try something like RME Audio. You'll notice the difference right away.

I was using a Sony VAIO laptop with a built in 192KHz HD internal sound card. I wouldn't rule out that it had something to do with it, it was also going down a microwave link around 3 miles LOS to the TX site which probably didn't help with the s/n.

By disassembling lap top, i determined that it's not problem with DAC at all, it's output amplifiers and filters (capacitors) of low quality that affect s/n and separation issues with software based encoders.
Regarding stereo broadcasting and stereo hiss that appears on home tuners, it's by design. Car stereo actualy measures signal level and if it is not good enough for stereo decoding it automatically disables mpx decoder and leave just stereo indicator on. At home tuners, you are responsible to mount good fixed antenna and provide best possible signal, so tuner doesn't check on signal quality and leaves mpx decoder on. This way, you get stereo hiss if signal is bad, but usually have manual button to switch to mono...

Internal soundcards also have a habit of picking up noise from inside the PC... even decent ones.

Best way to get a clean signal out of a computer is to use an optical or coaxial cable to an external DAC of some sort. An old separates MD player with an optical in makes for a good quality and very cheap DAC these days, although it probably won't to 192kHz unfortunately... (Only ever used this set up on the audio side before)