On Fri, 07 Jan 2005 13:41:29 -0600, Cecil Moore
wrote:

|Roy Lewallen wrote:
| There's no sharing when there's only one user, channel, or LED
| involved, so no multiplexing. Except, I guess, for digital types who can
| share an LED between a 1 and a 0.
|
|A two-wire serial ASCII RS232 line is time-multiplexed between
|marks and spaces, i.e. you can't have a mark and a space occurring
|at the same time. :-)

Baloney. By this definition, OOK Morse is a "time-multiplexed"
system, eh?

Why not just Google this: define: multiplexing

Then try this: define: time multiplexed. And the answer is, "Huh?"

What you mean is that the LEDs are pulsed at some rate and/or duty
cycle. I wouldn't call this, "multiplexing."

|
| Just out of curiosity, what does your revered IEEE Dictionary have to
| say about it?

Took the words right out of my mouth, Roy. I almost asked that in the
previous post.

Wes Stewart wrote:
On Fri, 07 Jan 2005 13:41:29 -0600, Cecil Moore
wrote:

|Roy Lewallen wrote:
| There's no sharing when there's only one user, channel, or LED
| involved, so no multiplexing. Except, I guess, for digital types who can
| share an LED between a 1 and a 0.
|
|A two-wire serial ASCII RS232 line is time-multiplexed between
|marks and spaces, i.e. you can't have a mark and a space occurring
|at the same time. :-)

Baloney. By this definition, OOK Morse is a "time-multiplexed"
system, eh?

Why not just Google this: define: multiplexing

Then try this: define: time multiplexed. And the answer is, "Huh?"

What you mean is that the LEDs are pulsed at some rate and/or duty
cycle. I wouldn't call this, "multiplexing."

|
| Just out of curiosity, what does your revered IEEE Dictionary have to
| say about it?

Took the words right out of my mouth, Roy. I almost asked that in the
previous post.

Time Domain Multiplexing is where two or more signals share one data
pipe. Under TDM each signal is allocated one domain. Each domain is sent
in sequence. At the other end each domain is isolated and combined with
other domains elements from the same source. i.e. a, b, c fragmented and
sent as a1, b1 , c1, a2, b2, c2, a3, b3, c3 received and defragmented as
a, b, c. Commonly used to sent telephone conversations and internet
packets over copper wires and radio.

Dave WD9BDZ

Wes Stewart wrote:

Cecil Moore wrote:
|A two-wire serial ASCII RS232 line is time-multiplexed between
|marks and spaces, i.e. you can't have a mark and a space occurring
|at the same time. :-)

Baloney.

Didn't you ever use an 8 to 1 *MULTIPLEXER* chip to change
parallel BAUDOT to serial BAUDOT? The parallel BAUDOT bits
are time-multiplexed into a serial bit stream by the
three clock bits. The first parallel bit is hard-wired to
yield a start pulse and the last two parallel bits are hard-
wired to yield a stop pulse. The center five parallel BAUDOT
bits are time-multiplexed from parallel to serial by five
states of the clock.
--
73, Cecil http://www.qsl.net/w5dxp


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On Fri, 07 Jan 2005 23:29:16 -0600, Cecil Moore
wrote:

|Wes Stewart wrote:
|
| Cecil Moore wrote:
| |A two-wire serial ASCII RS232 line is time-multiplexed between
| |marks and spaces, i.e. you can't have a mark and a space occurring
| |at the same time. :-)
|
| Baloney.
|
|Didn't you ever use an 8 to 1 *MULTIPLEXER* chip to change
|parallel BAUDOT to serial BAUDOT?

Actually, no. I have however, worked on monopulse RADAR missile
seekers where the requirement for three phase and gain matched
receiver channels (sum, delta elevation, delta azimuth) was reduced to
two by time-sharing one delta channel. You can call this multiplexing
if you want (TDMA?), but as an r-f guy, I have a different take. At
any point in time the only data in the delta channel was *either*
elevation *or* azimuth, not both elevation *and* azimuth. (* maybe a
digital system after all? :-)

|The parallel BAUDOT bits
|are time-multiplexed into a serial bit stream by the
|three clock bits. The first parallel bit is hard-wired to
|yield a start pulse and the last two parallel bits are hard-
|wired to yield a stop pulse. The center five parallel BAUDOT
|bits are time-multiplexed from parallel to serial by five
|states of the clock.

Fine, but how does this support your statement above to which I
responded?

I think I'm catching on tho...in ham terms, a digital multiplexer is
like a two-meter repeater; only one guy can talk at a time. I'm more
familiar with analog multiplexers, a 20-meter DX pile-up for instance,
where everybody talks at once. [g].

Wes Stewart wrote:
Fine, but how does this support your statement above to which I
responded?

The 8-bit ASCII could be generated using a digital multiplexer.
If one had a 10-bit digital multiplexer chip, one could use an
ASCII byte stream into it to generate serial ASCII. That's eight
separate input bit data streams being time-multiplexed into one
output data stream and that comes under the definition of multiplexing.

One problem here is the age of my vocabulary. When I learned and
worked on this stuff, there were digital multiplexers and decoders,
i.e. the word "encoder" was not in common use yet. Reference:
"Fundamentals of Logic Design", 2nd edition, Charles H. Roth, Jr.,
copyright 1979, pages 184-190. "Multiplexers" and "decoders" are
described in detail but absolutely no mention of "encoders" anywhere
in the book. Back then, "encoders" were included in the definition
of "multiplexers".
--
73, Cecil http://www.qsl.net/w5dxp


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This is really funny! On the 5th, someone posted a question about how a dish tracks a satellite, and I told them to go
look up monopulse techniques for the answer and got roundly slapped around the head and shoulders for offering a non
answer. Now, here the three channel monopulse technique appears in a discussion of AUTOMOBILE TAIL LIGHTS for gosh
sakes.

Go figure.

--
Crazy George
Remove N O and S P A M imbedded in return address
"Wes Stewart" wrote in message ...

snip

Actually, no. I have however, worked on monopulse RADAR missile
seekers where the requirement for three phase and gain matched
receiver channels (sum, delta elevation, delta azimuth) was reduced to
two by time-sharing one delta channel. You can call this multiplexing
if you want (TDMA?), but as an r-f guy, I have a different take. At
any point in time the only data in the delta channel was *either*
elevation *or* azimuth, not both elevation *and* azimuth. (* maybe a
digital system after all? :-)


snip more

On Sat, 8 Jan 2005 20:42:05 -0600, "Crazy George"
wrote:
Now, here the three channel monopulse technique appears in a discussion of AUTOMOBILE TAIL LIGHTS for gosh sakes.

Hi George,

A sucker post is how we got there.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
"Crazy George"
wrote:
Now, here the three channel monopulse technique appears in a discussion of AUTOMOBILE TAIL LIGHTS for gosh sakes.

A sucker post is how we got there.

I asked two simple questions out of curiosity: Has anyone
else ever noticed those taillights? & What would be the
advantage to that design? I finally got an answer to the
second question. Nobody else has reported seeing them but
they definitely exist. I suspect you still don't know what
I am talking about.
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil Moore wrote:

Richard Clark wrote:

"Crazy George"
wrote:

Now, here the three channel monopulse technique appears in a
discussion of AUTOMOBILE TAIL LIGHTS for gosh sakes.


A sucker post is how we got there.


I asked two simple questions out of curiosity: Has anyone
else ever noticed those taillights? & What would be the
advantage to that design? I finally got an answer to the
second question. Nobody else has reported seeing them but
they definitely exist. I suspect you still don't know what
I am talking about.
Yes I have seen these taillights. According to a news article about them
there is a significant difference in how fast the new lights work
compared to the older conventional lamps. One time I was following a
truck that had diode lights on its trailer and conventional lamps on the
tractor. There was a very noticeable difference in the two tail lights.
The diode lamps were full on while the conventional lamps were still
thinking about glowing. Supposedly this converts to about 17 feet
difference at 55-65 miles per hour on the highway.

Dave N

David G. Nagel wrote:
Yes I have seen these taillights. According to a news article about them
there is a significant difference in how fast the new lights work
compared to the older conventional lamps. One time I was following a
truck that had diode lights on its trailer and conventional lamps on the
tractor. There was a very noticeable difference in the two tail lights.
The diode lamps were full on while the conventional lamps were still
thinking about glowing. Supposedly this converts to about 17 feet
difference at 55-65 miles per hour on the highway.

Hi David, I'm not talking about conventional LED taillights. I'm
talking about LED taillights that are pulsed and maybe pulse-width
modulated between the taillight function and the brakelight function.
This seems to be something new on maybe one manufacturer's 2005
models. They may have a 1/3 duty cycle for taillights and a 2/3
duty cycle for brakelights, or something akin to that. It's a
mystery to me that I am trying to solve.

Some lights on towers and some roadside warning lights are pulsed on
and off at a ballpark rate of 100 Hz. If you sweep your eyes from
side to side, these pulsed lights appear as a dotted line in your
vision. That's the kind of taillights I am talking about. If you
sweep your eyes from side to side, the trail they leave on your
retina looks something like this:

____ ____ ____ ____ ____ ____ ____ ____

--
73, Cecil http://www.qsl.net/w5dxp


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