WiFi

And CAT-5 works even better ;-)

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |

Point to point laser!

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK

But strangely, with very high S/N ratios you can get sudden loss of transmission...

--
Thanks,
Fred.

It's the extreme low frequency limit of 1/f noise--it happens in optical cables too--

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal

Place a space between the hyphen and the link (as above), otherwise it doesn't work :-(

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |

Same with the "new and improved" digital television. 50dbuV yet ... poof ... no signal :-(

--
Regards, Joerg

http://www.analogconsultants.com/

A year ago I picked up a Netgear 10mb AP for a sale price of $2.95 after rebate ;) Works well, even better with a N card. Thru 2 brick walls to boot.

Cheers

Something about bandwidth-SNR being constant for a given power, I think :-)

That being said, I've seen several instances where some salesdroid is trying to upsell little old ladies 802.11n wireless routers when they only have a couple of computers and only plan to use the router to allow each machine to access their 1.5Mbps or so Internet connection. Sad.

It can also happen with phones. Sell a "modern" 5GHz system to an unsuspecting customer and they can't even walk towards the garage anymore without the phone link breaking up.

--
Regards, Joerg

http://www.analogconsultants.com/

I can talk over 100 feet from the base station with my 5.8 GHz phone even though there is a building with aluminum siding between me and my mail box, and the base is inside another building with aluminum siding.

--
You can\'t have a sense of humor, if you have no sense!

-)

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I think the Shannon theorem comes to play here. However, the 100Mbps wifi falls back to the slower standards, right? Now sometimes when fallback modes are put in comm gear, the quality of the fallback design is poor. That is, someone is addressing a marketing bullet point rather than designing a robust system.

In the dark ages when I worked on a 2400bps analog modem, we satisfied fallback to a stupidly good degree of quality, but only because it wasn't very difficult. For instance, the FSK fallback was done with a coordic computing arcsin to phase unwrap the signal, then a running LMS fit to determine frequency. Insane quality, but all the routines were present for other uses in the target application.

Back to wifi, if you war drive, generally you notice the data rate is down to 1Mbps, presumably due to a more robust (noise tolerant) communications scheme.

Sometimes you can get lucky and there are reflections from other objects to make up for a low signal situation. In this house here (aluminum backed insulation in all walls including interior ones) the old rule applies. The lower the frequency the better stuff works.

--
Regards, Joerg

http://www.analogconsultants.com/

The fallbacks in Wifi are pretty high quality. It's not exactly bleeding edge any more. Link layer is mostly in chipsets, give or take.

-- Les Cargill

The real problem with omnidirectional systems in multiple GHz frequencies is the ridiculously small capture area of the _receiving_ antenna.

The situation gets even worse on higher frequencies. For instance with

60 GHz short range high speed uncompressed video links, some active beam forming (using multiple antenna elements) must be used even with the same room.

Microwave signals bounces around very well in urban areas with hard surfaces, also penetrating through small holes and ducts between rooms. However, vegetation absorbs the signal quite quickly.

phone

.

why do people suddenly reply to 2 year old posts?

Mark

Sometimes Usenet servers regurgitate old posts. Not to say that it is the case here but it can happen. EasyNews coughed-up hundreds of 2-3 year old posts in the s.e.* tree a few weeks ago.

Of course, that just moves the question back one layer: why do Usenet servers suddenly dump two year old posts? ;-)

--
Rich Webb     Norfolk, VA

Usually a wormhole is to blame, but it can also be due to a *very* slow server.

Nothing is ever settled on Usenet, and besides, pulling up a good old thread is sometimes a big help in distracting folks from the default topics of GW and politics. Godzilla vs Rodan was a fun movie, but the Nth repetition gets tedious.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal

GW and politics as default is largely a sign that there just aren't that many people left reading SED, sadly.

There are Mystery Science Theater 3000 versions of Godzilla vs. Meglon and Godzilla vs. the Sea Monster?