 
okiezz
@198.133.x.x | and? Does that mean wireless all over the place or wut  | |
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 | Pictor Guy
join:2004-06-21
Sammamish, WA | Re: and? Sorry but this sounds a little like snake oil to me. | |
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FightingBlue
@direcpc.com | All well and good, but What kind of requirements would there be for this tech? What kind of antenna would you require to get a signal? Half the point of wireless internet is the efforts to make it mobile, and that can't happen if you have a 2-foot antenna to carry around. | |
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Healbot
Premium
join:2003-07-16
Vancouver, WA | Re: All well and good, but maybe a way for internet for people who dont have dsl or cable, I know how they feel I use to live in the middle of nowhere forced with direcway | |
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DaDogs
Semper Vigilantis
Premium
join:2004-02-28
Deltaville, VA
| said by FightingBlue:
What kind of requirements would there be for this tech? What kind of antenna would you require to get a signal? Half the point of wireless internet is the efforts to make it mobile, and that can't happen if you have a 2-foot antenna to carry around.
You have never seen the antenna on a Walkman have you? There will be no 2' antenna.
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| | Pictor Guy
join:2004-06-21
Sammamish, WA
| Re: All well and good, but said by DaDogs  :You have never seen the antenna on a Walkman have you? There will be no 2' antenna.
Actually yes. And, many 'walkmans' used the head phones as part of the antenna. Anyway... the site claims that they will be using UHF and VHF for this. If that's the case the antenna would be around 6" (give or take) for UHF. Larger for VHF. Higher frequencies need smaller antennas to be equally efficient. Next time you see a car with an XM or Sirius radio antenna and a standard FM/AM antenna compare the size of the two. But there is also missleading information on the site... "Because the propagation characteristics of low frequencies allow them to pass through dense obstacles, deployment of xMax in the VHF and UHF bands completely eliminates the line of sight issues that are problematic with higher frequency broadband technologies. "UHF is VERY line of sight. While it will penetrate some buildings better than something in the 2.4GHz ISM band it's still line of sight. And to a lesser extent VHF is also line of sight. Just ask a boater how far over the horizon they can xmit on their VHF radio. Now if xMax is going to use HF signals then it wouldn't have to be line of sight but now you're talking HUGE antennas.  | |
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DaDogs
Semper Vigilantis
Premium
join:2004-02-28
Deltaville, VA
1 edit | Re: All well and good, but said by Pictor Guy :Actually yes. And, many 'walkmans' used the head phones as part of the antenna. Then you realize that was an FM antenna for ~100 MHz, that would be VHF actually LVHF... Ever see a bar antenna for AM broadcast band? Doesn't have to be very efficient given the wave lengths involved in transmitting GROUNDWAVE for a couple of hundred miles, does it?
said by Pictor Guy :Anyway... the site claims that they will be using UHF and VHF for this. Yes it does. It also suggests they can do it anywhere in the spectrum.
said by Pictor Guy : If that's the case the antenna would be around 6" (give or take) for UHF. Larger for VHF. Higher frequencies need smaller antennas to be equally efficient. Really, interesting So if I made a quaterwave marconi for 10 meters (LVHF) it would be roughly 2.5 meters tall? And if I made the same kind of antenna for 3 GHz (UUHF) it would be roughly 2.5 CM tall? Cool.
said by Pictor Guy : Next time you see a car with an XM or Sirius radio antenna and a standard FM/AM antenna compare the size of the two. I'll do that.
said by Pictor Guy : But there is also missleading information on the site... "Because the propagation characteristics of low frequencies allow them to pass through dense obstacles, deployment of xMax in the VHF and UHF bands completely eliminates the line of sight issues that are problematic with higher frequency broadband technologies. "UHF is VERY line of sight. While it will penetrate some buildings better than something in the 2.4GHz ISM band it's still line of sight. And to a lesser extent VHF is also line of sight. Like 100 MHz VHF? Like Channel 2 TV, VHF? That kind of LOS? Yep, you are right these frequencies VHF and UHF are considered LOS and they are more readily absorbed by trees and there are more reflectors in the environment at these frequencies. What you are failing to understand is the fact that ANY electromagnetic emission exists and radiates forever. It may exhibit path losses to the point that it is below the ambient temperature of the universe but it is still there, still expanding outward. It is merely undetectable below the noise floor. Now the noise floor is an interesting phenomena, you see what "seems" to be a hard line isn't a hard line at all. At any given point in the spectrum any instantaneous reading of signal strength will vary significantly from any other time separated reading of signal strength at that frequency. This means that given sufficient receive sensitivity one can detect data below the , admittedly arbitrary, "noise floor", if one but knows when, where, and what signal level, to look for... but you obviously knew that.
said by Pictor Guy : Just ask a boater how far over the horizon they can xmit on their VHF radio. Now if xMax is going to use HF signals then it wouldn't have to be line of sight but now you're talking HUGE antennas. I have a better idea. Since we are getting "technical" here. Have a look at this web site »home.cogeco.ca/~dxinfo/tropo.html , then you tell me if I can reach the Bahamas from Charlestown, SC on 144 MHz today? All marine operators on Marine VHF can reach WELL beyond the horizon because of a layer of super saturated air which is always present near the surface of the ocean. Ducting at VHF is always present on the ocean.
Regarding HF antennas ... See my comments regarding portable antennas for AM band ...
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| | | | | Pictor Guy
join:2004-06-21
Sammamish, WA
1 edit | Re: All well and good, but said by BosstonesOwn :Out of curiosity exactly how far can a vhf wave travel ? I just bought a new boat and it has a vhf radio with the gps beacon signal tied in. I am sort of curious of exactly how far that sucker can broadcast. Ok back on topic after the answer Based on my experience and what most people will tell you at the USPS or USCG it's about 15 miles ship to ship but can be as much as 50 miles if both antennas are high enough. See... »www.yachtcom.co.uk/comms/
But alot of it has to do with the height of the antenna and sea conditions (rolling the ship/antenna).
\\\\edit
Here's more from the USCG...
»www.navcen.uscg.gov/marcomms/boater.htm
"Your VHF radio is intended mainly for short range communications, generally 5-10 miles, and at least 20 miles to a USCG station. To communicate at longer ranges, you will normally need a satellite telephone or an MF/HF marine radiotelephone. Marine radiotelephone equipment normally operates between 2 - 26 MHz using single sideband emissions. MF/HF marine radiotelephones can also be used to receive high seas weather broadcasts, and by using a computer and a special interface provided by some coast stations, can provide Internet email." | |
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DaDogs
Semper Vigilantis
Premium
join:2004-02-28
Deltaville, VA
| said by BosstonesOwn :Out of curiosity exactly how far can a vhf wave travel ? I just bought a new boat and it has a vhf radio with the gps beacon signal tied in. I am sort of curious of exactly how far that sucker can broadcast. Ok back on topic after the answer The reason they tell you the numbers they tell you is because planning must be absolute. If you want to calculate your range with VHF just figure the using this link:
»www.qsl.net/w4sat/horizon.htm
This as I said is because safety is an issue. The truth is your range will nearly always be greater than that returned by that calculator over water because ducting is very common over water. It is nearly always present.
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| | | | | | BosstonesOwn
join:2002-12-15
Everett, MA
clubs:
 ·Comcast
·Comcast Formerly ..
| Re: All well and good, but said by DaDogs :said by BosstonesOwn :Out of curiosity exactly how far can a vhf wave travel ? I just bought a new boat and it has a vhf radio with the gps beacon signal tied in. I am sort of curious of exactly how far that sucker can broadcast. Ok back on topic after the answer The reason they tell you the numbers they tell you is because planning must be absolute. If you want to calculate your range with VHF just figure the using this link: » www.qsl.net/w4sat/horizon.htmThis as I said is because safety is an issue. The truth is your range will nearly always be greater than that returned by that calculator over water because ducting is very common over water. It is nearly always present. Neat they told us 7 miles max. From the high of the antenna to the water is 15 feet on #1 and 12 on #2 , really interesting I have never dealt with vhf before. I usually carry a sat phone from work. But it looks like im in the market for a nice vhf antenna that may be telescopic
You learn something new every day.
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"It's always funny until someone gets hurt......and then it's absolutely friggin' hysterical!" | |
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DaDogs
Semper Vigilantis
Premium
join:2004-02-28
Deltaville, VA
1 edit | This Will Work This is a very interesting technology. It is time it came out of the closet and became something more than a military asset.
This approach solves a whole slew of problems. We can control whatever amount of bandwidth we want with the control channel simply by making the control channel wider. What if we allocated 6 MHz for the control channel instead of 6 KHz and placed the control channel at the lower end of the information channel? That would enable gigabit wireless on already allocated bandwidth. Still the central frequency of the information channel would have to be somewhere in UHF for a base band system, but the bandwidth that could be transmitted! WOOF!.
I can appreciate a system that operates in the 100 MHz region and which can deliver a 100 MBit channel for a range of 10 miles from a height of 50 feet with 36 dB EIRP. I can see where Verizon and the Bells as well as the cable companies would be interested in purchasing the patents on something like that, just so they could kill it.
Unlike WiMax, this is a break thru which represents an order of magnitude increase in range and thruput. If the FCC allows it, and the big players don't buy it out pronto, it won't be long before rural communities revel in excellent wide area fixed wireless broadband coverage.
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justncredible
@rr.com
| Re: This Will Work Your right, this is a awesome break thru. Might as well forget fiber this will be faster over existing lines such as BPL, or even the novel gas line. I have wondered if each wave can carry a wave. Like if you have a 3mhz wave and broke it into 10 sections for a wave to ride on it, giving each wave 10x the data without affecting the original wave. As a wave on the ocean that has tiny waves riding along would not affect the large carrier wave. Since they are so small as to not effect change in the original properties. Would this work with fiber? How many pumped diodes can travel on one line? Very interesting, oh how we need another Tesla. | |
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L337
Premium
join:2005-03-10
Chicago, IL | How's The Security ? Don't matter if it's more powerful or not cause if the security sucks than it just sucks lol | |
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DaDogs
Semper Vigilantis
Premium
join:2004-02-28
Deltaville, VA
| Re: How's The Security ? said by L337 :Don't matter if it's more powerful or not cause if the security sucks than it just sucks lol The problems with commodity WiFi WRT security have been solved, unfortunately the problems with *USERS* WRT security have not and never will be solved. A properly secured WiFi link is MORE secure than your DSL or cable connection.
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Matt
Gone playing Dragon Age Origins
Premium
join:2003-07-20
Jamestown, NC
 ·North State Commun..
| Re: How's The Security ? said by DaDogs :said by L337 :Don't matter if it's more powerful or not cause if the security sucks than it just sucks lol The problems with commodity WiFi WRT security have been solved, unfortunately the problems with *USERS* WRT security have not and never will be solved. A properly secured WiFi link is MORE secure than your DSL or cable connection. Don't feed the trolls. | |
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DreamWraith
Premium
join:2004-04-07
Mount Vernon, WA
·Comcast
| Re: How's The Security ? hehehe.
on a lighter note, i don't think they are really at the stage of worrying about security protocols yet, but when they are, you can bet that there will be something comparable, if not better than WPA2. Who knows, just because it uses a different frequeny range than 802.11 does not mean it won't eventually be able to use compatible protocols. Who knows, maybe it will end up being 802.11 compatible... is that possible? nothing would surprise me... | |
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RayW
Premium
join:2001-09-01
Layton, UT
clubs:
·XMission
| I wonder about the power claim Without going into a lot of differential equations (that I have not used in 20 years), it boils down to the fact that you can put out 1 watt at one frequency, or you can spread that watt out over several megahertz and have nanowatts at any given frequency, but you still need a watt to do that spreading (probably more due to losses in the circuitry). Any good spectrum analyzer and a knowledge of transmitters will show you that. And if the signal gets too far into the natural noise of the universe and man made muck, good luck at getting it out. I wonder how they figure that they can do this on one little battery for a long period of time?
Then consider that unless it is beamed at you, you have at least an inverse square power reduction in the signal taking it even further down by the time it travels the many feet to your antenna.
And on top of that, a lawyer as the mouth piece? And one that apparently has had shady dealings in the state of Utah back around 1985.
I could be wrong and they may have found a loop hole in the physics I learned 20+ years ago and use today, but I don't think I will put my money into buying their stock. I have seen too many technical scams over the years that sounded good until the principles head for South America or Switzerland with the bankroll.
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I am not lost, I find myself every time. | |
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TheNut
join:2004-12-19
Thornhill, ON
·Rogers Hi-Speed
| RE: xMax From reading xG’s website it seems like a great advancement in wireless technology. Extreme range and speeds to boot, great. I’m all for community wireless networks and this technology can definitely get large groups of people connected. Alas, only time will tell of its success or failure.
I just hope with all these companies inventing their own scheme they don’t ruin the whole wireless experience by turning this into a turf war. Last thing I want is to be on the lookout for an “all-in-one” wireless card at 3x the price just to connect to different APs. | |
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| bminish
join:2005-07-10
Ireland
| Re: RE: xMax Unfortunately it's 100% Snake Oil. The laws of physics and Shannon's theorem have not magically changed, nor are they likely to.
What is going on here is that they are playing with the FCC rules.
The rules define bandwidth as the bit containing 99% of the transmission power so if you generate a strong carrier that leaves you with 1% of the remaining power to do spread spectrum with.
If the carrier is Strong enough then you will be able to cover distance with the spread spectrum bit. However if the Spread Spectrum bit is strong enough to cover distances then it is also strong enough to interfere with other licensed users of the same section of radio spectrum.
It's all rather reminiscent of the VMSK Delusion
»cache.qualcomm.com/vmsk/
here is a PDF to a paper that discuses in mathematical terms why these 'new' narrow band modulation schemes do not work as claimed
»www.lkn.fe.uni-lj.si/lknpub/Clan···VMSK.pdf
.Brendan | |
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mamoon
@fdn.com | VMSK and XMax Sorry to burst your bubble but look again. VMSK is now called G1D transmission by the FCC. XMax appears to be VMSK pointing to the wideband data within the bit windows. | |
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| bminish
join:2005-07-10
Ireland
| Re: VMSK and XMax G1D is an ITU modulation mode classification, not a special new category for VMSK and it's relatives
G1D -phase modulation data transmission, without using a modulating subcarrier.
from »www.ac6v.com/modcodes.htm
VMSK, XMax and all the related modes that lay claim to beating Shannon's theorem are snake oil.
.Brendan | |
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