wrote:
As a bit of trivia, Reed Solomon encoding was invented without a way to
decode it. That's what you get when you let mathematicians run wild.
For absolutely nothing of any value other than bragging rights, name
the guy who invented the decoding scheme for Reed Solomon. [Hopefully
this isn't wikied someplace. I did one class in grad school on error
detection and correction, and it was a pain in the ass if you get into
the theory. Implementation is quite simple.]

It makes sense. The encoding software had to be ready to put into a probe
before the launch date. Once it was up it could not be changed.

Decoding software was another matter. Since they had years, maybe even decades
to decode the data, and it did not have to be real time, they could continue
to work on it.

All they had to do is not loose the tapes. :-(

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 Fax ONLY: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

Radium wrote:
What would these errors sound like?

An error in a PCM system would manifest itself as a difference between
what you put in at the analogue input to the transmitter, and what you
got out of the analogue output of the receiver.

The magnitude and polarity of the difference would depend entirely on
whether the bit error was the MSB (polarity would be wrong), or one of
the LSBs (the amplitude would be wrong). It wouldn't "sound" like
anything in particular.

Well, my application was more to do with reception than transmission.

I'd like to know what I would hear on a 3MHz AM carrier whose receiver
[both the AM and the linear PCM part] is at its maximum bandwidth. The
3 Mhz AM receiver is attached to a linear-PCM receiver [once again,
both receivers have the maximum bandwidth possible for them]. The
linear-PCM receiver is attached to a DAC which converts the linear-PCM
signal to analog. This analog signal [which was PCM] is then sent to a
loudspeaker. Just to make things more interesting, the antennae and
receivers are so sensitive that they can pick signals as low as
.00000001 dB. Most likely, what would I hear?

Have a look he http://www.imdb.com/title/tt0375210/ :-)

Seriously though, I have no idea. Why don't you try it and post the
results here?

Cheers
Mike

Mike Gathergood (G4KFK) wrote:
Radium wrote:
What would these errors sound like?

An error in a PCM system would manifest itself as a difference between
what you put in at the analogue input to the transmitter, and what you
got out of the analogue output of the receiver.

The magnitude and polarity of the difference would depend entirely on
whether the bit error was the MSB (polarity would be wrong), or one of
the LSBs (the amplitude would be wrong). It wouldn't "sound" like
anything in particular.

What about the heterodyne tones present on analog AM radio? Would they
be audible on a linear-PCM receiver that receives PCM signals on an AM
station?

Well, my application was more to do with reception than transmission.

I'd like to know what I would hear on a 3MHz AM carrier whose receiver
[both the AM and the linear PCM part] is at its maximum bandwidth. The
3 Mhz AM receiver is attached to a linear-PCM receiver [once again,
both receivers have the maximum bandwidth possible for them]. The
linear-PCM receiver is attached to a DAC which converts the linear-PCM
signal to analog. This analog signal [which was PCM] is then sent to a
loudspeaker. Just to make things more interesting, the antennae and
receivers are so sensitive that they can pick signals as low as
.00000001 dB. Most likely, what would I hear?

Have a look he http://www.imdb.com/title/tt0375210/ :-)


Seriously though, I have no idea. Why don't you try it and post the
results here?

Easy for you to ask. I doubt any store has the device. And the
equipment required to amplify .00000000001 dB to an audible level would
take up the entire room.

So the best I could do -- at least for the moment -- is guess.

I am aware though that just because the PCM-receiver is digital does
not mean its completely immune to heterodynes, EMI, or RFI. If the
heterodyne, EMI or RFI has a waveform that sufficiently resembles a PCM
signal, it may very well be picked up by the PCM-receiver that is
connected to the AM receiver.

Physically, the digital reciever is still an electronic device and
hence it has some reception of EMI, RFI, and heterodynes. Its just not
affected as much as an analog receiver would be.

Cheers
Mike

I've seen that "white noise" movie. But thats more like Sci-Fi. Yet it
is one thing that gave me the interest to hear whatever is buried DEEP
in background noise.

On 9/12/06 3:57 PM, in article
, "Radium"
wrote:


Mike Gathergood (G4KFK) wrote:
Radium wrote:
What would these errors sound like?

An error in a PCM system would manifest itself as a difference between
what you put in at the analogue input to the transmitter, and what you
got out of the analogue output of the receiver.

The magnitude and polarity of the difference would depend entirely on
whether the bit error was the MSB (polarity would be wrong), or one of
the LSBs (the amplitude would be wrong). It wouldn't "sound" like
anything in particular.

What about the heterodyne tones present on analog AM radio? Would they
be audible on a linear-PCM receiver that receives PCM signals on an AM
station?

Well, my application was more to do with reception than transmission.

I'd like to know what I would hear on a 3MHz AM carrier whose receiver
[both the AM and the linear PCM part] is at its maximum bandwidth. The
3 Mhz AM receiver is attached to a linear-PCM receiver [once again,
both receivers have the maximum bandwidth possible for them]. The
linear-PCM receiver is attached to a DAC which converts the linear-PCM
signal to analog. This analog signal [which was PCM] is then sent to a
loudspeaker. Just to make things more interesting, the antennae and
receivers are so sensitive that they can pick signals as low as
.00000001 dB. Most likely, what would I hear?

Have a look he http://www.imdb.com/title/tt0375210/ :-)


Seriously though, I have no idea. Why don't you try it and post the
results here?

Easy for you to ask. I doubt any store has the device. And the
equipment required to amplify .00000000001 dB to an audible level would
take up the entire room.

There is no such thing as a .00000000001 dB signal

So the best I could do -- at least for the moment -- is guess.

I am aware though that just because the PCM-receiver is digital does
not mean its completely immune to heterodynes, EMI, or RFI. If the
heterodyne, EMI or RFI has a waveform that sufficiently resembles a PCM
signal, it may very well be picked up by the PCM-receiver that is
connected to the AM receiver.

Physically, the digital reciever is still an electronic device and
hence it has some reception of EMI, RFI, and heterodynes. Its just not
affected as much as an analog receiver would be.

In fringe areas, analog cell phones could be well understood despite the
poor signal-to-noise ratio. Digital cell phones in a fringe area just quit
working, or lose sync and you hear bits of other conversations.




Cheers
Mike

I've seen that "white noise" movie. But thats more like Sci-Fi. Yet it
is one thing that gave me the interest to hear whatever is buried DEEP
in background noise.

Don Bowey wrote:
On 9/12/06 3:57 PM, in article
, "Radium"
wrote:


Mike Gathergood (G4KFK) wrote:
Radium wrote:
What would these errors sound like?

An error in a PCM system would manifest itself as a difference between
what you put in at the analogue input to the transmitter, and what you
got out of the analogue output of the receiver.

The magnitude and polarity of the difference would depend entirely on
whether the bit error was the MSB (polarity would be wrong), or one of
the LSBs (the amplitude would be wrong). It wouldn't "sound" like
anything in particular.

What about the heterodyne tones present on analog AM radio? Would they
be audible on a linear-PCM receiver that receives PCM signals on an AM
station?

Well, my application was more to do with reception than transmission.

I'd like to know what I would hear on a 3MHz AM carrier whose receiver
[both the AM and the linear PCM part] is at its maximum bandwidth. The
3 Mhz AM receiver is attached to a linear-PCM receiver [once again,
both receivers have the maximum bandwidth possible for them]. The
linear-PCM receiver is attached to a DAC which converts the linear-PCM
signal to analog. This analog signal [which was PCM] is then sent to a
loudspeaker. Just to make things more interesting, the antennae and
receivers are so sensitive that they can pick signals as low as
.00000001 dB. Most likely, what would I hear?

Have a look he http://www.imdb.com/title/tt0375210/ :-)


Seriously though, I have no idea. Why don't you try it and post the
results here?

Easy for you to ask. I doubt any store has the device. And the
equipment required to amplify .00000000001 dB to an audible level would
take up the entire room.


There is no such thing as a .00000000001 dB signal

Whats stops a .00000000001 dB signal from existing?


So the best I could do -- at least for the moment -- is guess.

I am aware though that just because the PCM-receiver is digital does
not mean its completely immune to heterodynes, EMI, or RFI. If the
heterodyne, EMI or RFI has a waveform that sufficiently resembles a PCM
signal, it may very well be picked up by the PCM-receiver that is
connected to the AM receiver.

Physically, the digital reciever is still an electronic device and
hence it has some reception of EMI, RFI, and heterodynes. Its just not
affected as much as an analog receiver would be.


In fringe areas, analog cell phones could be well understood despite the
poor signal-to-noise ratio. Digital cell phones in a fringe area just quit
working, or lose sync and you hear bits of other conversations.






Cheers
Mike

I've seen that "white noise" movie. But thats more like Sci-Fi. Yet it
is one thing that gave me the interest to hear whatever is buried DEEP
in background noise.

"Don Bowey" wrote in message
...
There is no such thing as a .00000000001 dB signal

Sure there is. It's very close in amplitude to a 0.0dB signal. ;-)

Tim

--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

On 9/12/06 10:04 PM, in article , "Tim Williams"
wrote:

"Don Bowey" wrote in message
...
There is no such thing as a .00000000001 dB signal

Sure there is. It's very close in amplitude to a 0.0dB signal. ;-)

Tim

Yes Master.... I had a momentary lapse of acumen, but it is clear now. dBm
to the people. :-)

"Michael A. Terrell" wrote in message
...
dB without a reference is meaningless. How can you have a ratio
without a reference?

Easy. "dB" in general usually refers to acoustic power, where the reference
is some ungodly small power level (10^-12W/m^2 IIRC?).

I forget if there's a similar radio context used...

Tim

--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

The answer is this:

It would be far more suceptable to interference than the AM equivalent.

The far higher bandwidth gives you a far higher noise bandwidth than the
narrower AM equivalent.

So because of the large bandwidth, AM would beat it hands-down.


Sam

"Radium" wrote in message
oups.com...
This analog signal [which was PCM] is then sent to a
loudspeaker. Just to make things more interesting, the antennae and
receivers are so sensitive that they can pick signals as low as
.00000001 dB. Most likely, what would I hear?


I think you need to be a bit clearer in your thinking. I see several people
have commented on your use of dB and it seems Mike dealing with the digital
side so I'll not pick up on those. I'd like to comment on " the antennae
and receivers are so sensitive that they can pick signals as low as........"
and your other comment about wide bandwidth.

Firstly, a "sensitive antenna" isn't a good concept, better to think in
terms of gain.

However, more importantly, sensitivity isn't just about how "small" a signal
your receiver system can "pick up"- you can (in theory) just add more and
more gain. The issue is the ratio of the signal to the noise- that is the
noise your receiver introduces and that which is "picked up" by the antenna.
Winding up the gain doesn't help much with the latter- the noise in the
available bandwith is amplified as well. Often a good way to get a better
signal to noise ratio is to reduce the bandwidth so, before you get too hung
up on having a wide bandwidth, think about what you need to do the job.


I also notice someone mentioned Galois- there was a thread some time back in
uk.radio.amateur where I explained the maths behind these. I'd sure a search
of Google Groups will turn it up.

--
73
Brian
www.g8osn.org.uk