On Jun 20, 2009, at 2:47 AM, Neil wrote:
Okay, a small, offtopic question. (I figured you guys were a far more
reliable source than my local ${electronics_store} salesperson...)
Consider the following setup:
internet pipe -> wired network -> (wireless router) wireless network
->
computer1, computer2
Suppose the signal coming in on the pipe is good, but the signal
deteriorates rapidly in wired network (old & bad wiring). Now, the two
computers are connected via the wireless network only. computer1 has
a great
connection (it's in the same room as the wireless router), but
computer2 is
far away and drops the wireless connection frequently.
Now, a former electrical engineer is claiming that if we improve the
wired
network so that the signal comes across better, then computer2 won't
drop
the wireless connection so frequently. (He says that the signal
emitted by
the wireless router will be improved by feeding it a better source
signal.)
If you are running a digital network, no. Digital doesn't work like
that. The
packets get through intact, or they are dropped. Dropping the wireless
connection means that
you are having trouble communicating between the wireless router and
computer 2.
Since computer 1 is close and works and computer 2 is far away, that
strongly suggests that you have
a SNR problem. To fix that, you need either a stronger
access point (wireless router), another access point closer to
computer 2, or a wireless repeater. Note that the AP also has
to receive the signal from computer 2, and you probably can't boost
computer 2's power, so you may
not be able to fix this by just boosting the access point's power.
There is a possibility that the problem is with computer 2. You might
try swapping
computer 1 and 2 to confirm that the problem is distance related, or
(what I generally do)
use a laptop as a test probe to confirm a good signal at computer 1,
and a poor one at computer 2.
I argue that there are two separate signals: the internet connection
signal
coming in on the pipe, and then the wireless network signal being
emitted
from the wireless router; and their strengths are independent. In
other
words, if we improve the wiring, the wireless signal will not get any
stronger.
In the spacecraft world, what the wireless router is doing is called
regeneration. It is
not just amplifying the wireline signal it receives, it receives it,
decodes it, turns it into
bits, and then puts those bits out as a radio encoding. Any noise in
the signal
received is irrelevant, as long as it is not enough to cause the
entire packet to be dropped.
Regards
Marshall
So...basically, who's right? (Or are neither of us?) Any thoughts,
comments,
corrections?
