Hi Bob,
> For Scenario #1, by far the simplest, I wonder about the degradation of
> signal over 50' of category 5 cable to the upstairs computer. I also
wonder
> about the potential RFI problem of transmitting legal limit power and
having
> the 50' cable run act as an antenna. I know that I can use ferrite beads
to
> reduce the effects of RFI but I still wonder about the signal degradation
> over such a long length of cable.
50 feet of CAT5 is nothing. The official specifications state a limit of
100 meters, but 10 Mbit Ethernet can go much further and 100 Mbit has even
been known to exceed 100m without trouble.
QRM to CAT5-based Ethernet is minimal because of the design of the signals
on the wire. Ethernet over twisted-pair (10BaseT, 100BaseT, ...) uses
differential encoding. The signals on each wire of the twisted pair are 180
degrees out of phase. The RX is a differential amplifier. Any QRM is
injected on both wires in phase. This is cancelled out by the differential
amplifier. Also, the wires are twisted upon each other to minimize
reception of noise in the first place. Is QRM still possible? Certainly,
but I use CAT5 and have yet to cause problems, even with the Acom amp
blowing full steam. My Peet Bros. WX station, on the other hand, always
gets scrambled and requires a reset after every contest!
> What about the RFI to the router located 10' away from the transmitter.
Is
> this an issue that anyone has in their station? If so, how is it solved?
Of course, this is always a concern, but this stuff tends to be pretty good
with RFI, mainly because they will GENERATE a ton of RF if improperly
shielded (decent 30m QRP XMTRs).
> Scenario #2
>
> If I go wireless, will the legal limit RF create a problem with the
router
> and the wireless signals?
They run spread spectrum in the 2.4 GHz range, so probably not.
> Also, if there is a wireless signal now, wouldn't it be easy for anyone in
> close proximity to my qth to access either or both computers and get data
> from my files? Security is a real concern to me.
Encryption is available in most devices. While insufficient for the CIA and
commercial banking, it's fairly good and way more than most of us would
need.
> I currently use Zonealarm ver 2.6 as a firewall on both computers but my
> understanding is that this is excellent protection against people trying
to
> invade from the "outside" but I don't know if it will protect against
> invasions against interecepted wireless signals and my transmissions by
the
> wireless router.
ZoneAlarm will do nothing to protect from QRM. QRM is beyond the scope of
what this class of products does. I also use ZoneAlarm and its VY FB. If
you install a wired router, the router will likely have similar firewall
features, rendering ZoneAlarm redundant. If you use wireless networking,
ZoneAlarm will indeed provide an extra level of protection, although the
encryption will likely be enough.
Here is a worst-case scenario for wireless networking that is unlikely, but
nevertheless posssible. You do not enable encryption and your neighbor
tasps into your wireless network and essentially uses you as a free ISP.
You tell ZoneAlarm that your "local" network is safe and any IP addresses
beginning with 192.168 are local. Your neighbor grabs a 192.168 address and
can then access shared files on your PCs. ZoneAlarm CAN protect against
this, but you have to be very specific about which addresses are "trusted"
and monitor it carefully. The best option is, of course, to use encryption.
This would keep you neighbor out unless he somehow discovered your
encryption key.
CONTEST RELEVANCE:
Since this is the contest reflector, how does this relate to CONTESTING?
Multi-ops and some SO2R ops will want to use such networking. With
WriteLog, CT, and other logging software supporting Ethernet networking now,
it handily beats the old COM port serial networks. Also, this is of crucial
importance for family harmony. If the XYL and harmonics want to surf the
Internet during the big contest, it's best to understand these issues.
VY 73 de Glenn K3PP
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