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#1
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You are 100% correct... Lack of interest is, in my opinion, the largest
single factor. The speed is also a big deal, as you say... 1200 bps vs. a 2-4 Mbps cable connection seems to be a slam dunk. But, keep in mind that we are talking about is an easy to build and use device that, with a 15+ year old design, was known to 80 Mbps over a fairly short path. That sort of makes mucking about with 802.11 junk sort of a wasted effort. The mistake was made about 15 years ago when the drive was to effectively duplicate the Internet on the ham bands. Simply put, there are not, never have been, and likely never will be enough hams in the world to do that. Besides, why try to duplicate a defective system? For the life of me, I can see no reason why Frank's device could not be re-designed today to well over 512 Mbps, perhaps very close to gigabit speeds. If you make the jump to the new copper solutions for 10 Gbps, we may even be able to get close to that... Imagine a large metropolitan area, like maybe Dallas/Fort Worth, ringed by an 8 Gbps nodes with spokes at 8 Gbps "dropping" into and through the city. A series of 1 Gbps nodes come off of the spokes to feed into the neighborhood. In the neighborhoods, picture a bridge node that users can connect to at, say, 100 Mbps. Lastly, picture these "City Wheels" being connected to other city wheels at 10 Gbps. Are you drooling yet? ![]() Take Care & 73 -- From The Desk Of Marty Albert, KC6UFM "n3soz" wrote in message oups.com... I've been a ham for almost eleven years. The year I got started (1994) was the same year the Web became open to commercial traffic, and I guess the decline of packet began around that time. I keep an APRS snipped for space's sake |
#2
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Marty Albert wrote:
For the life of me, I can see no reason why Frank's device could not be re-designed today to well over 512 Mbps, perhaps very close to gigabit speeds. If you make the jump to the new copper solutions for 10 Gbps, we may even be able to get close to that... What was the on-the-air bandwidth of Frank's 80Mbps signal? Dana K6JQ |
#3
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![]() As I recall, at 23 cm and 80 Mbps we had an effective bandwidth of around 100 KHz on the "final" design... That design incorporated TDM, limited SS, and WDM of the signals. Obviously, with multiple forms of simultaneous multiplexing, the bandwidth would through the roof, most likely to around 100-150 MHz. Today, we could use TDM, WDM, SDM, high-end SS, and a few other tricks and, assuming a target data-rate of 100 Mbps, get the on air bandwidth down to around 50-75 KHz, maybe even a little less. With a similar set up except for a target data-rate of 10 Gbps, my back-of-the-envelope calculations are coming up with an on air bandwidth on the order of 30-50 MHz. There may be as much as a 10-15% decrease in bandwidth by using a well designed DSP. Essentially we would need to look carefully at the Ethernet 10+ Gbps over copper and copy those concepts... I have my upper division and grad students looking at ways to do just that.I am hoping in the next month or so, I can reach an agreement with EE department and the RF engineering department to bring in some of their students to help out with those aspects... My students have already found one thing... BASIC Stamps and PIC processors will only work up to about 115 Mbps. Beyond that, they are just too slow. Take Care & 73 -- From The Desk Of Marty Albert, KC6UFM "Dana H. Myers" wrote in message ... What was the on-the-air bandwidth of Frank's 80Mbps signal? Dana K6JQ |
#4
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Marty Albert wrote:
As I recall, at 23 cm and 80 Mbps we had an effective bandwidth of around 100 KHz on the "final" design... That design incorporated TDM, limited SS, and WDM of the signals. What exactly does this all mean? Passing 80,000,000 bits/sec in 100,000Hz of bandwidth sounds pretty fantastic - to the extent that makes me question the validity of the measurements. Today, we could use TDM, WDM, SDM, high-end SS, and a few other tricks and, assuming a target data-rate of 100 Mbps, get the on air bandwidth down to around 50-75 KHz, maybe even a little less. Whoa. Hold on. Help me understand what units and methods of measurement you're using. Right now, you're off by several decimal places in even the most generous way. Dana K6JQ |
#5
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"Dana H. Myers" wrote in message
... Marty Albert wrote: As I recall, at 23 cm and 80 Mbps we had an effective bandwidth of around 100 KHz on the "final" design... That design incorporated TDM, limited SS, and WDM of the signals. What exactly does this all mean? Passing 80,000,000 bits/sec in 100,000Hz of bandwidth sounds pretty fantastic - to the extent that makes me question the validity of the measurements. This in 100 Hz of bandwidth we can obtain 80 Kbps. Shannon twirling in his grave. Today, we could use TDM, WDM, SDM, high-end SS, and a few other tricks and, assuming a target data-rate of 100 Mbps, get the on air bandwidth down to around 50-75 KHz, maybe even a little less. Whoa. Hold on. Help me understand what units and methods of measurement you're using. Right now, you're off by several decimal places in even the most generous way. Lost a decimal point for sure. BTW ... why does everyone always mention 1200 baud? Doesn't everyone use at least 9600 for local links, and PACTOR II / III on HF? Think I have a 1200 baud TNC around here ... yeah there it is over in that cabinet. Big black box, says TAPR TNC-1 on it. -- ... Hank http://home.earthlink.net/~horedson http://home.earthlink.net/~w0rli |
#6
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TDM = Time Domain Multiplexing
WDM = Wide Dimensional Multiplexing SDM = Statistical Domain Multiplexing. TDM and, to a limited degree, WDM have been around and used for several decades in high performance networking. SDM is relatively new, about 5 years. There are far more ways to multiplex intelligence on a medium than PSK and FSK, although both are used in high performance systems. You are 100% correct... I may very well a few decimal places off... The mathematical models show that 100 Mbps should be possible in as little as 10 KHz. Take Care & 73 -- From The Desk Of Marty Albert, KC6UFM "Dana H. Myers" wrote in message ... Marty Albert wrote: As I recall, at 23 cm and 80 Mbps we had an effective bandwidth of around 100 KHz on the "final" design... That design incorporated TDM, limited SS, and WDM of the signals. What exactly does this all mean? Passing 80,000,000 bits/sec in 100,000Hz of bandwidth sounds pretty fantastic - to the extent that makes me question the validity of the measurements. Today, we could use TDM, WDM, SDM, high-end SS, and a few other tricks and, assuming a target data-rate of 100 Mbps, get the on air bandwidth down to around 50-75 KHz, maybe even a little less. Whoa. Hold on. Help me understand what units and methods of measurement you're using. Right now, you're off by several decimal places in even the most generous way. Dana K6JQ |
#7
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"Marty Albert" writes:
You are 100% correct... I may very well a few decimal places off... The mathematical models show that 100 Mbps should be possible in as little as 10 KHz. Yes, you are a few decimal places off, but in the wrong direction ;-). |
#8
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"Marty Albert" wrote in message
... TDM = Time Domain Multiplexing WDM = Wide Dimensional Multiplexing SDM = Statistical Domain Multiplexing. TDM and, to a limited degree, WDM have been around and used for several decades in high performance networking. SDM is relatively new, about 5 years. There are far more ways to multiplex intelligence on a medium than PSK and FSK, although both are used in high performance systems. You are 100% correct... I may very well a few decimal places off... The mathematical models show that 100 Mbps should be possible in as little as 10 KHz. The model is wrong. Post it and I'll be glad to explain why. -- ... Hank http://home.earthlink.net/~horedson http://home.earthlink.net/~w0rli |
#9
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I will see if the University that I am using to develop the model will allow
that at this point... It is actually their intellectual property. I doubt, however that you will find any major errors in the algorithms.... There have been many professors, PhDs, and grad students looking at it to find those errors as well as engineers from Motorola, Maxim, and TI. Take Care & 73 -- From The Desk Of Marty Albert, KC6UFM "Hank Oredson" wrote in message ink.net... The model is wrong. Post it and I'll be glad to explain why. |
#10
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Marty Albert wrote:
TDM = Time Domain Multiplexing WDM = Wide Dimensional Multiplexing SDM = Statistical Domain Multiplexing. TDM and, to a limited degree, WDM have been around and used for several decades in high performance networking. SDM is relatively new, about 5 years. There are far more ways to multiplex intelligence on a medium than PSK and FSK, although both are used in high performance systems. You are 100% correct... I may very well a few decimal places off... The mathematical models show that 100 Mbps should be possible in as little as 10 KHz. The last time someone made such fantastic claims, they weren't correctly measuring bandwidth. Perhaps you'd like to share independently-verifiable references to your "mathematical models"? Dana |
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