why this modem is so powerful?

Hi Why this 802.11b radio modem

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can transfer date up to 6 miles but my 802.11b router can only 50meters? thanks from Peter ( snipped-for-privacy@hotmail.com)

Reply to
cmk128
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Aren't there legal restrictions on transmit power and the use of external antennas in the US?

Reply to
Bert Hyman

Transmits more power, and has a more sensitive receiver. Probably uses directional antenna to get the 6 miles.

Reply to
Dana

snipped-for-privacy@hotmail.com hath wroth:

What make and model 802.11b router do you own? Some of the older stuff is really junk.

My guess(tm) is that it's a matter of speed. Very roughly, for every

4 times increase in speed, you lose half your range. Look at the speed versus thruput chart in the FAQ at:

It's not perfect, but it gives you the idea. Note that the BER (bit error rate) is assumed to be constant of all speeds and ranges (usually at BER=10^-5 reference).

Another apples and oranges comparison are antennas. Antennas make a HUGE difference in range. For every 6dB of antenna gain, you get double the distance. Something like: +6dB = 2 times as far +8dB = 2.5 times as far +12dB = 4 times as far +24dB = 16 times as far

Of course, the marketing department never specifies test conditions so there's no way to know. They mumble 54Mbits/sec and 10 miles, but they don't bother to mention that this can't be done at the same time. The correct specs would be 54Mbits/sec up to perhaps 10ft range, or 10 miles range at 1Mbit/sec using two 24dBi dish antennas.

Fastlinc is also apparently using 200mw (+23dBm) xmit cards, so there's about a 6dB improvement (twice the range) due to higher xmit power.

I think (not sure) that if you look inside the FastLinc box, you'll find a very conventional MiniPCI or PCMCIA wireless card.

Reply to
Jeff Liebermann

Yes. But you can still use external antennas. And the link the OP posted shows that the external amp that could be used with the modem had a 1watt output. That kind of power with directional antenna would have no problem going the distance advertised.

Reply to
Dana

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