| Page 1 of 2 | 1 | 2 |
|
|
EM emissions from auto taillights.
Slightly off topic - I've seen a couple of new automobiles with
time-multiplexed LED taillights. What would be the advantage of such a design in an automobile? -- 73, Cecil, W5DXP |
"Cecil Moore" wrote in message ups.com... Slightly off topic - I've seen a couple of new automobiles with time-multiplexed LED taillights. What would be the advantage of such a design in an automobile? -- 73, Cecil, W5DXP longer mean time between failure? |
TimPerry wrote:
"Cecil Moore" wrote: Slightly off topic - I've seen a couple of new automobiles with time-multiplexed LED taillights. What would be the advantage of such a design in an automobile? longer mean time between failure? Does a time-multiplexed LED have a longer MTBF than a constant current LED? -- 73, Cecil, W5DXP |
"Cecil Moore" wrote in message ups.com... TimPerry wrote: "Cecil Moore" wrote: Slightly off topic - I've seen a couple of new automobiles with time-multiplexed LED taillights. What would be the advantage of such a design in an automobile? longer mean time between failure? Does a time-multiplexed LED have a longer MTBF than a constant current LED? -- 73, Cecil, W5DXP longer then an incadecent lamp at any rate |
Bill Turner wrote:
Multiplexed at what rate? Faster or slower than human eye perception? The rate is hard to estimate - maybe 60-200 Hz? You know how - if one sweeps one's eyes from side to side when looking at a time multiplexed light source, it looks like a dotted line? Well, on two occasions at night, I was shifting my eyes when I noticed the taillights on certain new models of automobiles are time multiplexed. I'm just wondering if anyone knows anything about them - like what is the advantage over constant current LEDs? Am I the only person in the world who notices such trivia? :-) -- 73, Cecil http://www.qsl.net/w5dxp |
On 6 Jan 2005 06:18:08 -0800, "Cecil Moore" wrote:
like what is the advantage over constant current LEDs? Am I the only person in the world who notices such trivia? It's been known for quite a long time: pulsed light looks brighter. Being imperceptible flicker has to do with the Stroud Moment. |
Richard Clark wrote:
"Cecil Moore" wrote: like what is the advantage over constant current LEDs? Am I the only person in the world who notices such trivia? It's been known for quite a long time: pulsed light looks brighter. I know that but am I the only person in the world who has noticed that it is now being used on automobiles. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Thu, 06 Jan 2005 11:03:10 -0600, Cecil Moore
wrote: It's been known for quite a long time: pulsed light looks brighter. I know that but am I the only person in the world who has noticed that it is now being used on automobiles. Just as I figured.... another sucker ball. |
On Thu, 06 Jan 2005 08:25:29 -0800, Bill Turner
wrote: What other reason could there be? Hi Bill, The usual reasons: Brighter; Lower Power; Longer Life; Lower Loss - as long as the added complexity is offset by the economic gain. If they were dual diodes connected parallel and reverse polarity driven by AC, then the advantage would be reduced cathodic reduction of contacts exposed to water (for years I noted how the poorly built US cars went through tail lights that burnt out due to corrosion). AC systems also extend lifetime to conventional filament lights. Now, by Brighter, this is not due to higher peak currents. LEDs don't really peak as well as other devices. Their overdrive capacity is somewhat limited. Rather, the Brighter is a physiological response. It is actually the same brightness, except we perceive it as brighter (although, if the period exceeds the Stroud Moment this may no longer hold). Light can be frustrating to compare to measurements, because impartial measurements will reveal little difference to what we perceive to be dramatic change. One of those tricks of the brain. 73's Richard Clark, KB7QHC |
Richard Clark wrote:
Cecil Moore wrote: I know that but am I the only person in the world who has noticed that it is now being used on automobiles? Just as I figured.... another sucker ball. Zero probability that you simply misunderstood my original question? Did you know it is now being used on automobiles? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Thu, 06 Jan 2005 12:49:36 -0600, Cecil Moore
wrote: Zero probability that you simply misunderstood my original question? More to the point, did you? Aside from its sucker spin, then why ask? Did you know it is now being used on automobiles? LEDs have been in general illumination for quite a few years - even for headlights. If they are new to you, you can't afford them. |
Richard Clark wrote:
LEDs have been in general illumination for quite a few years - even for headlights. I know that. The question was and is: WHEN DID THEY START TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS? I am asking for information and it's perfectly OK if you don't know. Constant current LEDs have been in use for years. But it's just over the last couple of months that I have noticed the pulse-width modulation on some automobile taillights. I suspect it's only one or two manufacturers so far. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
On Thu, 06 Jan 2005 13:30:37 -0600, Cecil Moore
wrote: WHEN DID THEY START TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS? Who is THEY? This still sounds like a sucker posting. Anyway, 5 years ago. Why don't you try rec.philosophy.automotive for this topic? |
Richard Clark wrote:
Cecil Moore wrote: WHEN DID THEY START TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS? Who is THEY? Shirley, you jest. Anyway, 5 years ago. Doubt it. I would have noticed long before now. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Bill Turner wrote: How interesting. I wonder if they are pulse width modulated to compensate for day/night? What other reason could there be? That might be it. It would be a convenient and efficient way of adjusting brightness. They also might be compensating for voltage and temperature by changing the pulse width. Roy Lewallen, W7EL |
On Thu, 06 Jan 2005 14:30:24 -0600, Cecil Moore wrote:
Richard Clark wrote: Cecil Moore wrote: WHEN DID THEY START TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS? Who is THEY? Shirley, you jest. Anyway, 5 years ago. Doubt it. I would have noticed long before now. Do you mean that the subliminal CW messages have had no effect on you? :-) Jonesy -- | Marvin L Jones | jonz | W3DHJ | linux | Gunnison, Colorado | @ | Jonesy | OS/2 __ | 7,703' -- 2,345m | config.com | DM68mn SK |
On 6 Jan 2005 22:37:03 GMT, Allodoxaphobia
wrote: Doubt it. I would have noticed long before now. Do you mean that the subliminal CW messages have had no effect on you? :-) Hi Jonesy, Like I figured, another sucker posting. Cadillac was doing this for its 2000 model: " The 2000 Cadillac DeVille was the first vehicle to go into production that utilizes HB LEDs for its rear combination lamps (RCLs) as well as for its CHMSL. Many of the benefits here are intangible-examples are the "jewel like" appearance of the RCL and the ability to provide the tail light function with a particular shape associated with the DeVille line. There are several tangible benefits that can be measured, however, including reduced electrical load, reduced mass, warranty savings, and mass production quality improvements. Although the Cadillac DeVille is the only production vehicle with a complete LED rear combination lamp assembly, several other recent car makes and models have incorporated LEDs into various signal functions. These are primarily limited production luxury cars, such as the Mercedes S-Class, BMW 5-Series, and Nissan Gloria." On the Lincoln Town Car: "light-emitting diode array on the rear of this vehicle in a research project at California Partners for Advanced Transit and Highways takes data from the wheels and brakes and sends a signal to following cars indicating the acceleration and velocity of the vehicle." which, of course, fulfills your anticipation of subliminal CW messages. ;-) As the old adage goes "if you have to ask, you can't afford it." rec.philosophy.automotive may provide more details - this is clearly beyond the pale of electromagnetic anything from anywhere. 73's Richard Clark, KB7QHC |
That might be it. It would be a convenient and efficient way of
adjusting brightness. They also might be compensating for voltage and temperature by changing the pulse width. Hi Roy, You can do all the above with a regular light bulb. I think the reason they use multiple LED's is to reduce the mean time between failures. If a regular bulb fails, you are dark. If half of the LED's fail you still have light. They generally have 20 plus LED's. in the stuff I have seen. Also, LED's tend to last than bulbs (I think) 73 Gary N4AST |
Richard Clark wrote:
Like I figured, another sucker posting. Cadillac was doing this for its 2000 model: " The 2000 Cadillac DeVille was the first vehicle to go into production that utilizes HB LEDs for its rear combination lamps (RCLs) as well as for its CHMSL. Many of the benefits here are intangible-examples are the "jewel like" appearance of the RCL and the ability to provide the tail light function with a particular shape associated with the DeVille line. There are several tangible benefits that can be measured, however, including reduced electrical load, reduced mass, warranty savings, and mass production quality improvements. Although the Cadillac DeVille is the only production vehicle with a complete LED rear combination lamp assembly, several other recent car makes and models have incorporated LEDs into various signal functions. These are primarily limited production luxury cars, such as the Mercedes S-Class, BMW 5-Series, and Nissan Gloria." Uhhhhhh Richard, like I figured, you have no clue. The subject is NOT LEDs used in automobiles. The subject is ***TIME-MULTIPLEXING*** of LEDs used in automobiles and there is absolutely no mention of time-multiplexing of the LEDs in your above posting, i.e. it is irrelevant to my question. On the Lincoln Town Car: "light-emitting diode array on the rear of this vehicle in a research project at California Partners for Advanced Transit and Highways takes data from the wheels and brakes and sends a signal to following cars indicating the acceleration and velocity of the vehicle." Again, absolutely no mention of any time-multiplexing of the LED currents so your posting is completely irrelevant to my original question which continues to be: WHEN DID AUTO MANUFACTURERS START MULTIPLEXING THEIR AUTOMOBILE TAILLIGHTS. I suspect it was on the 2005 models and certainly not five years ago as you mistakenly assert. I first saw a time-multiplexed LED taillight on my 2004 Thanksgiving trip to Memphis. I simply do not believe your assertion that time-multiplexed taillights have been around for five years. The onus of proof is upon you and your above posting is certainly NOT proof of time-multiplexed LED taillights. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
|
On 5 Jan 2005 17:07:51 -0800, "Cecil Moore" wrote:
|Slightly off topic - I've seen a couple of new automobiles with |time-multiplexed LED taillights. What would be the advantage of such a |design in an automobile? What the hell is "time-multiplexed"? |
Cecil Moore wrote: Wes Stewart wrote: On 5 Jan 2005 17:07:51 -0800, "Cecil Moore" wrote: |Slightly off topic - I've seen a couple of new automobiles with |time-multiplexed LED taillights. What would be the advantage of such a |design in an automobile? What the hell is "time-multiplexed"? In this case, on half the time and off half the time at about a 100 Hz rate. Maybe square-wave power? Maybe pulse-width modulation, different from night to day? I thought it was a simple question to which someone had a simple answer. "Time-multiplexed" means that they're turned on in sequence, without all being on at once. That would be as opposed to simply pulse modulated all at once. My guess is that they're pulse modulated to provide easy and efficient control of the brightness, and possibly compensation for voltage and/or temperature. If they're time-multiplexed as well, that would even out the total current drain rather than its being in the form of big current pulses. Are they really time-multiplexed, or are they all pulsed at once? Roy Lewallen, W7EL |
Wes Stewart wrote:
On 5 Jan 2005 17:07:51 -0800, "Cecil Moore" wrote: |Slightly off topic - I've seen a couple of new automobiles with |time-multiplexed LED taillights. What would be the advantage of such a |design in an automobile? What the hell is "time-multiplexed"? In this case, on half the time and off half the time at about a 100 Hz rate. Maybe square-wave power? Maybe pulse-width modulation, different from night to day? I thought it was a simple question to which someone had a simple answer. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Roy Lewallen wrote:
"Time-multiplexed" means that they're turned on in sequence, without all being on at once. That would be as opposed to simply pulse modulated all at once. The most trivial case of binary time multiplexing would be a single LED being turned on for a logic 'one' and off for a logic 'zero'. That "binary time multiplexing" concept is a carry over from 40 years as a digital engineer, 13 of them at Intel. Are they really time-multiplexed, or are they all pulsed at once? It appeared that they were all pulsed at once. Perhaps I should have used the word "pulsed" to avoid confusion in the RF analog (non-digital) world. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Roy Lewallen wrote: "Time-multiplexed" means that they're turned on in sequence, without all being on at once. That would be as opposed to simply pulse modulated all at once. The most trivial case of binary time multiplexing would be a single LED being turned on for a logic 'one' and off for a logic 'zero'. That "binary time multiplexing" concept is a carry over from 40 years as a digital engineer, 13 of them at Intel. Are they really time-multiplexed, or are they all pulsed at once? It appeared that they were all pulsed at once. Perhaps I should have used the word "pulsed" to avoid confusion in the RF analog (non-digital) world. Yeah, digicats have their own language. In analog parlance, multiplexing basically means sharing. As in telephony, where you share one line among many users by connecting each to the line for a short time in sequence (time division multiplexing or TDMA - time division multiple access), breaking the spectrum into pieces and giving each user his own channel (frequency domain multiplexing), or more complex methods such as spread spectrum code domain multiplexing, or CDMA (code division multiple access). 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. Just out of curiosity, what does your revered IEEE Dictionary have to say about it? Roy Lewallen, W7EL |
Cecil,
Here's the deal. I will assume the low intensity tail light and the high intensity brake light share the same LEDs. In a typical system there will be 10's to even 100's of LEDs. The required light output from the tail light function and brake light function is quite different. I have seen numbers from ranging from 7:1 up to 15:1. Let's say that the brake light requires 10X the output required from the tail light. Contrary to what was posted earlier in this thread, the light output from LEDs is roughly linear with forward drive current over several orders of magnitude. This is true up to nearly the point where the device explodes from overheating. So why not just change the DC current to get the varying output required? The problem is device matching. As you well know all semiconductor devices are subject to significant performance variation depending on exact process conditions, materials, phase of the moon, or whatever. LEDs are typically specified at one nominal current, with a nominal light output. When used at the nominal conditions a batch of LEDs can be selected to match light output performance so that no obvious visual artifacts appear. However, if these same matched LEDs are driven at significantly different conditions, the light output will have wider variation, perhaps detectable to the ordinary observer. Therefore the recommended method for reducing light intensity from a matched array of LEDs is to operate at nominal electrical conditions, but at a reduced duty cycle. I do not know the details of the vehicle you observed, but it is likely that the brake light function uses DC or a high duty cycle pulse, while the tail light uses a low duty cycle pulsed activation. There are other issues such as temperature variations and dealing with non-functioning LEDs, but that is enough for now. 73, Gene W4SZ Cecil Moore wrote: It appeared that they were all pulsed at once. Perhaps I should have used the word "pulsed" to avoid confusion in the RF analog (non-digital) world. |
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. :-) Just out of curiosity, what does your revered IEEE Dictionary have to say about it? I'm at the GED office presently. I'll check that when I get home. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Gene Fuller wrote:
I do not know the details of the vehicle you observed, but it is likely that the brake light function uses DC or a high duty cycle pulse, while the tail light uses a low duty cycle pulsed activation. Thanks very much, Gene, for that information. I only observed the pulsed taillight function and not the braking function so the above explanation didn't occur to me. Makes a lot of sense now. Thanks again. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Roy Lewallen wrote: Just out of curiosity, what does your revered IEEE Dictionary have to say about it? I'm at the GED office presently. I'll check that when I get home. Well, looks like I win. The IEEE Dictionary agrees with you and you have said in the past that the IEEE Dictionary is wrong. :-) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Well, looks like I win. The IEEE Dictionary agrees with you and you have said in the past that the IEEE Dictionary is wrong. :-) Ah, binary again. I disagree with all entries or I disagree with none, with no other possibilities. Spoken like a true digital engineer. Indeed, I often disagree with that book, and don't feel that it does a very good job of reflecting usage among working engineers. But apparently on this issue I do agree with it -- a possibility only in my analog world but seemingly not in your digital one. Roy Lewallen, W7EL |
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 ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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 ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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 ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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 ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
| All times are GMT +1. The time now is 11:17 PM. |
|
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com