Re: "Listeners don't want DAB"

"jamie powell" <jamie_p84@xxxxxxxxxx> wrote in message
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"DAB sounds worse than FM" <dab.is@xxxxxxxxxx> wrote in message
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"jamie powell" <jamie_p84@xxxxxxxxxx> wrote in message
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"DAB sounds worse than FM" <dab.is@xxxxxxxxxx> wrote in message
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You've acknowledged in your quack equation that L-R gets
subtracted
from
the right channel, and the correct minus symbol is there as it
should
be. But that last + should be a minus too.


No. It doesn't matter whether you add or subtract n2.

End of story.

It does in the context of the issue we were debating,


Actually, that reminds me, because THE MOST HILLARIOUS part of the
thread
was the realisation that you thought that an FM tuner would
reconstruct
the mono signal as follows:

http://groups.google.com/group/alt.radio.digital/msg/719a50b7afea2b0f?hl=en

"Stereo FM tuner set to FM mono mode:
Left = (L+R+n1)/2
Right = (L+R+n1)/2
Sum of Left and Right = L+R+n1"

OMG!!!!!!!!! The L+R signal is sitting at the output of the FM
demodulator ready and waiting to be sent to the Left and Right
channels.
But no, Jamie the Software Engineer has got a better idea. He
thinks
that it's a good idea to add the Left and Right channels together
to
get, er, an identical signal, apart from the fact that its
amplitude is
double what it was - even though the signal would be amplified by
both
the tuner and the system's amplifier anyway, therefore making
Jamie's
addition utterly redundant. That spoke volumes about your maths
skills
as well. That is, er, you should stick to software, son.

Considering we were actually debating ***what happens when the FM
tuner is
set to mono mode*** VS ***what happens when the FM tuner is set to
stereo
mode and its L and R outputs are subsequently summed into mono***, I
think
it was quite reasonable to actually talk about what happens during
these
two scenarios!! Cretin!


We were discussing the difference between stereo and mono FM, because
you claimed that I didn't know that the hiss disappears or why it
disappears when you press the mono button on an FM tuner.


That's why I also included this equation for the latter scenario:

"Stereo FM tuner set to FM stereo mode:
Left = ((L+R+n1) + (L-R+n2)) /2
Right = ((L+R+n1) - (L-R+n2)) /2
Sum of Left and Right = ( ((L+R+n1) + (L-R+n2)) /2 ) + ((L+R+n1) -
(L-R+n2)) /2 ) = L+R+n1 "


You wrote those equations when you were trying to change the subject
because I'd given a mathematical proof that showed categorically that
it doesn't matter whether you put a plus or a minus in front of n2.


I think you've finally cracked and gone insane. Perhaps it was Peter
Watson's thorougly correct post on the "Roberts Gemini 49" thread
(which
totally backed up what I've been saying to you all along, and
totally
wripped apart all the usual bull*** you've been posting over there)
that
finally burst your massive bubble of delusion and pushed you over
the
edge.


If you think Peter Watson's post is "thoroughly correct", then you
must have as bad an understanding of the FM stereo multiplex signals
as he does, because he thought that n1 and n2 were teh same in terms
of spectrum, amplitude and they had the same variance, when in reality
none of those things are true.

Basically, you and Peter Watson are very alike: neither of you
actually have a clue what you're going on about when it comes to
engineering matters.


which was the issue
of whether n2 gets cancelled out when the L and R outputs of an FM
stereo tuner (set to stereo mode) are summed into mono.
"n2" is the label you assigned to the noise present on the
demodulated
L-R
AM subcarrier which forms part of a Zenith FM stereo transmission.
Because
n2 gets added to the left channel, and subtracted from the right
channel, it ends up being 180degrees out of phase between the two
channels.


Here you go again. That's the same incorrect nonsense that I've
just
pointed out above. The FM multiplex signals are L+R+n1 and L-R+n2.
Er,
the L+R+n1 IS THE MONO SIGNAL, so n2 doens't come into it at all.

You just haven't got the faintest clue how any of this works, have
you?


Oh, the fucking irony of Jamie the idiotic numpty saying that, when
you actually didn't notice that in one of your set of equations you
were adding two identical signals together, and you basically thought
that FM tuners and radios would sum together the left and right
channel signals to get the mono signal when the mono signal is sitting
there ready and waiting to be used at the output of the FM
demodulation. In fact, you wouldn't even have a clue how FM is
demodulated, would you? Of course not, because you're a bloody
Software Engineering student!


You've completely misunderstood the incredibly simple principles
which I
and others have taken the time to spell out to you (with Sesame
Street
simplicity no less). It's all just gone completely over your head.


This coming from someone who sums two identical signals together to
produce an, er, identical signal with twice the amplitude! My brain
hurts.

I have known full well what argument you've been using since the start
of the weekend, or whenever this started, but it was simply an attempt
to desperately change the subject, because I was only discussing the
maths, because I know 100% that when you first claimed I'd made a
mistake you thought I'd simply got my algebra wrong, and I hadn't.


For this reason, when the two channels are summed into mono


They aren't summed into mono. The only time the stereo FM channels
are
summed to produce a mono signal is in the special case that Richard
mentioned where his amplifier had a button on it, which when
pressed
suppressed the hiss.

I bet your idiotic brain thinks it surpressed the hiss due to some
form of
low-pass filtering, or witchcraft, or something.


Oh, the irony again. The L+R signal is sitting there ready and waiting
to be used at the output of the FM demodulator:

http://upload.wikimedia.org/wikipedia/commons/c/cd/RDS_vs_DirectBand_FM-spectrum2.svg

You're the idiot who thinks that to get the mono FM signal, instead of
just using the L+R signal, they first combine the Left and Right
channels to make stereo, then they add those together to get the mono
back.

What utter fucking lunacy. Utter, idiotic nonsensical madness.


It surpressed the hiss because n2 cancelled itself out.


n2 never comes into it for mono.


This also happens
when a radio with a MONO speaker has a stereo-capable FM tuner which
is
set to stereo mode, such as the one you "reviewed" in some 3rd rate
hifi
publication, and misinformed your audience (of one person I bet)
about the
amount of hiss they'd hear, due to your general lack of basic
understanding.


I was absolutely correct to criticise a portable radio with one
speaker that is set to stereo FM mode by default. FM stereo requires a
higher SNR to achieve good receptin quality than mono FM, so it's
obviously ridiculous to set a portable radio up to be in stereo by
default. Only a fool would suggest otherwise. Oh, hold on...


(such as
happens in a mono radio,


Wrong. An FM portable radio will output the L+R+n1 signal sitting
there
ready and waiting to be used at the output of the FM demodulator.

Unless it's a stereo-capable FM tuner set to stereo mode, and the
summed
outputs of which then feed the mono speaker.


Why would they want to complicate thigns when there's no need to
complicate it?


when said radio includes only an internal mono
speaker, yet features an FM stereo tuner for use with stereo
headphones), n2 completely cancels itself out.
n2 - n2 = 0.


But my equations were SPECIFICALLY about the reconstruction of the
stereo
FM channels:

"The Left and Right stereo channels are reconstructed as follows:

Left = 0.5 * [(L + R + n1) + (L - R + n2)] = L + (n1 + n2)/2

Right =0.5 * [(L + R + n1) - (L - R + n2)] = R + (n1 + n2)/2"


There's an error in that "equation" - the final plus should be a
minus.


Wrong. I think we've been over this. It doesn't make any difference
whatsoever to the resultant signal whether you use a plus or a minus.


btw, you're a sad case. But I think you knew that already, deep down
inside.


Don't worry about me, Jimmy, my ego's the size of a small planet. You
worry about your incredibly poor maths skills, and your idiotic ideas
about how consumer electronics companies would go about designing FM
tuners.




--
Steve - www.savefm.org - stop the BBC bullies switching off FM

www.digitalradiotech.co.uk - digital radio news & info

"It is the sheer volume of online audio content available via
internet-connected devices which terrifies the UK radio industry. I
believe that broadband-delivered radio will explode in the years to
come, offering very local, unregulated content, as well as opening a
window to the radio stations of the world." - from the Myers Report


.

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