Re: Roberts Gemini 49

On 24/08/2009 17:35, DAB sounds worse than FM wrote:
"Peter Watson"<peter@xxxxxxxxxxx> wrote in message
news:7fepgdF2kpe4nU1@xxxxxxxxxxxxxxxxxx
On 24/08/2009 01:17, steve41@xxxxxxxxxxxxxx wrote:

<Snip text not relevant to the post I made>


Oh no, you don't get to snip the bit were you came out with complete
and utter nonsense! You still need to respond to this:

I freely admit that I don't know enough to know if this is true
*but*
common sense says it is not. Is it likely that the noise *in the
real
world* on the Mono FM component and the noise Stereo DSBSC component
has
the same spectrum, amplitude and variance?


Here's a diagram of the received FM multiplex spectrum:

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

So the spectrum of n1 is different to that of n2 (n1 has a bandwidth
from 0 to about 15 kHz, n2 covers a far wider bandwidth). "Amplitude"
isn't really relevant to random signals - you describe random signals
using their probability distribution, precisely because you can't
predict what the amplitude of the signal will be from one moment to
the next, you can only say things about the amplitude using
probabilities. And the variance equals the power of the noise signals
(because they're zero-mean), and the power of the noise signals is
proportional to their bandwidth (power = noise power density x
bandwidth), and as I've just mentioned above, the bandwidth that n1
and n2 cover is very different indeed, so the noise power and
therefore the variances of n1 and n2 are also very different indeed.

Make your mind up, previously you said "in this case, n1 and n2
are Gaussian random, zero-mean signals with the same variance
(variance = power)" - This I disagreed with and clearly you do now as well.

<Snip>

and reread the entire thread again.


I must have written almost half of the posts on this thread, so don't
try to tell me what *I* was discussing. I have re-read some of the
earlier posts from the 18th August onwards,

<Snip>

Interesting choice of date, try reading the 17th onwards...

A few examples of the posts that preceded the argument were as
follows:

http://groups.google.com/group/alt.radio.digital/msg/ae48572a0d172e4b?hl=en
http://groups.google.com/group/alt.radio.digital/msg/f686f19af5b2c297?hl=en

Note in the above post that Jamie Know-Nothing suggested taht the
amount of "audible hiss" was the same for both stereo and mono - an
utterly, butterly preposterous suggestion of gargantuan proportions.

Try re-reading what he wrote! He said nothing of the sort...

http://groups.google.com/group/alt.radio.digital/msg/569238c42a36df4c?hl=en
http://groups.google.com/group/alt.radio.digital/msg/f5b0241bbb949f5f?hl=en
http://groups.google.com/group/alt.radio.digital/msg/3d10540af7b4b9e3?hl=en

The argument basically stemmed from that last post. Up to that point I
had been discussing stereo FM and noise levels with different people.
Jamie may well have been rambling on about his preposterous suggestion
that an FM tuner would reconstruct the mono FM signal by adding the
Left and Right stereo FM signals together,

He didn't say that - He questioned your view that a MONO radio would have different noise performance if the FM tuner was operating in STEREO or MONO

<Snip>



In the context of the original discussion, the phase of the noise is
entirely relevant and cannot simply be dismissed for the reason I
gave
earlier.


"the phase of the noise". Good luck finding teh "phase angle" of a
random noise signal.


I don't have to find the phase angle of random noise. I was referring to the subtraction of the *same* randmon signal, therefore cancelling out its effect.

This is a 'real world' example and not just a piece of mathematical
theory...


<Snip>

.

Relevant Pages

  • Re: Unit pulse for White noise
    ... i can tell you that, from the point-of-view of audio, white noise sounds ... the answer is that the power spectrum of white noise does not (and can ... bandwidth) is an infinite energy and finite power signal. ... finite energy signals happen sorta once. ...
    (comp.dsp)
  • Re: Mobile signal boosters/amplifiers - are they effective on the road?
    ... how much power you are allowed to run. ... But, with the bands just jam packed with signals, and now ... directions (if you will quit laying the antenna out sideways and laying ... never goes away, it becomes so weak it is buried in the background noise, ...
    (alt.cellular.verizon)
  • Re: CDMA receiver sensitivity
    ... correlation will give another noise like signal.. ... where Bc is the bandwidth of the chip. ... than the noise power in the chip bandwidth(or the bandwidth after band ... UWB signals, each symbol is coded over multiple chips. ...
    (comp.dsp)
  • Re: Real-time sound cyphering algorithm
    ... >> We are talking about recording a sound with a microphone. ... >> Talking about power when the subject is volume is irrelevant. ... > random noise signal. ... If your talking about RF signals, which are measured in terms of power input ...
    (sci.crypt)
  • Re: What is the optimal estimator?
    ... Noise zero mean with variance of 90 is added to the DC value. ... Since it's 128 then the mean after sampling is apparently also 128. ... As with audio signals, you usually don't want to clip. ...
    (comp.dsp)