Apologies for general/off topicness, but does anybody have any
comments/opionion about these guys:
http://www.xgtechnology.com/technology.asp
Useful innovation or snake oil?
TIA
–Chuck
Interesting however have a read of the following old Register article:
and
http://www.ka9q.net/xmax_schwartz.html
So, this appears to have been doing the rounds since mid 2005 but
apparently nothing concrete to show 2 years later.
Difficult to find any articles more recent than 2005 on this
‘technology’.
Anyone else find anything more concrete or recent regarding this?
Richard
Charles S. wrote:
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I think the most comprehensive page I’ve found is < http://
Vislink Technologies - Wikipedia >. Links to patents and reviews (e.g.
Phil Karn’s). - MLD
Michael-
I think the most comprehensive page I’ve found is < http://
Vislink Technologies - Wikipedia >. Links to patents and reviews (e.g.
Phil Karn’s). - MLD
Phil Karn is a Qualcomm employee – maybe not the most impartial source.
Here is
something recent, starting with an actual face-to-face meeting with xG
management:
-Jeff
Phil Karn has done a more recent analysis at
http://www.ka9q.net/xmax.html . This matches with my personal analysis
that it smells a bit like a reptile cage. They have been doing some more
press releases through Mobile Radio Technology Mag, claiming they are
close to a rollout.
Their claimed understanding of the spectral requirements of “single
Cycle Modulation” don’t match my understanding of the inverse
requirement between time resolution and bandwidth (The faster you yank
signals around, the more bandwidth you need).
Dave
On Wed, 2007-08-15 at 22:54 -0500, Jeff B. wrote:
Michael-
I think the most comprehensive page I’ve found is < http://
Vislink Technologies - Wikipedia >. Links to patents and reviews (e.g.
Phil Karn’s). - MLDPhil Karn is a Qualcomm employee – maybe not the most impartial source. Here is
something recent, starting with an actual face-to-face meeting with xG management:
Thanks guys - will check those out.
–Chuck
Charles S. wrote:
something recent, starting with an actual face-to-face meeting with xG management:
Thanks guys - will check those out.
–Chuck
I couldn’t find Jeffs response in my “discuss-gnuradio” archive, so I’m
responding here.
I’ve known Phil personally for many years (yikes, a couple of decades
now!). I’d be utterly
shocked to find him simply “spouting the company line”.
I’ve read his analysis, and talked to him in person about some of this
stuff, and I find the approach
of going back to first principles to be compelling. There seems to
be a fair amount of “perpetual motion machines”
happening in modulation schemes, and Phil has usually “taken them on”
with grace and scientific rigour.
I’d be keen to see the analysis that Jeff pointed out, but as I said, I
don’t appear to have that e-mail in the
discuss-gnuradio archive I have here…
Marcus-
be a fair amount of “perpetual motion machines”
happening in modulation schemes, and Phil has usually “taken them on”
with grace and scientific rigour.I’d be keen to see the analysis that Jeff pointed out, but as I said, I
don’t appear to have that e-mail in the
discuss-gnuradio archive I have here…
Here is a fairly recent (29 Jun 07) Phil Karn page on xG’s xMax
technology:
-Jeff
Jordan-
Phil Karn is a Qualcomm employee – maybe not the most impartial
source.Hey, Jeff: welcome to the Internet. I see this must be your first day
It seems like Phil has worked carefully and thoroughly to show areas of
weakness –
or unexplained gaps – in xG’s approach and technical data. And he’s
qualified to do
so.
My comment would be that putting a “Snake Oil” image at the top of the
web page is
not a good way to immediately convey a sense of impartiality.
-Jeff
Jeff B. writes:
Phil Karn is a Qualcomm employee – maybe not the most impartial
source.
Hey, Jeff: welcome to the Internet. I see this must be your first day
/jordan
Jeff B. schrieb:
It seems like Phil has worked carefully and thoroughly to show areas of weakness –
or unexplained gaps – in xG’s approach and technical data. And he’s qualified to do
so.My comment would be that putting a “Snake Oil” image at the top of the web page is
not a good way to immediately convey a sense of impartiality.-Jeff
I looked at the various posts on this topic and all I can say is…
given that I was in Florida a few months ago, working with a ‘very low
bit rate’ link set up over about 15 miles, using a 25 W transmitter in
the ISM band (hey it was their FCC problem not mine…), and
getting quite a bit of interference none the less… I would have loved
to have some snake oil to grease the skids… as long as
the customer signed off…
As it was, with a few replacements of cables, turning off other ‘local’
transmitters operating in the same band, etc… all was well…
At 35 or 50 mW of power over 18 miles, in the 902-928 ISM band, and at 3
Mbits/s, I’m wondering where they were in Florida…
On the topic of Phil Karn… my ‘contact’ with that name was using the
ancient AX-25/Packet Radio networking stacks of yore
to do incredibly low speed networking (as a note my system in Florida
was replacing a KA9Q based implementation…). So
perhaps while now Karn may have surcome to the corporate coolaid… at
least at some point he was involved in the
early phases of what we now call ‘open software’… like GNURadio…
The last time I had anything to do with Packet Radio was
when I ported it to an OS/9 setup for a small company called ITT… I
thought that would be my entry in to the big time… ha… well
anyway…
John C…
John C. wrote:
anyway…
Phil’s worked in the telecom industry for a long time, first for
Bellcore and then for Qualcomm. But at the same time, he’s done a
tremendous amount of engineering in the public interest, not only with
his KA9Q TCP/IP implementation but with spread spectrum, signal coding,
and all sorts of other cool stuff.
He was also an activist against the US’ absurd export controls on
encryption, and has worked to defeat bad patents using prior art.
And, in his spare time, he takes down people who don’t believe in what
those Nyquist and Shannon fellas had to say.
John