SW Wireless Interference
 

On Sun, 27 Mar 2005 19:00:47 GMT, Monroe wrote:

I'm not up on the tech side of 2-way wireless comm's. Solely Rx only
of the shortwave and longwave frequencies. But I am considering a
wireless alternative to my slow dial-up for internet connectivity.
The system is based around this device:


http://www.packetgods.com/store/prod...roducts_id=127

The wireless ISP rep indicated that the power over ethernet line had
resulted in intereference for some local HAM users, and suggested a
shielded cable and/or selective routing may solve the problem.

I use random wire and long wire antennas for most of my listening.
All of the antennas have/will have a common mount on my metal TV tower
with a feedpoint into the house located near the base of the tower
(I'm also using the tower to support an FM antenna; no TV reception
required). Antenna lines run down alonside or a short distance ( 1
m) from the metal tower. I have an outdoor 1:9 balun for connection
to the wire antennas, a coax feed into the house to a switchbox
feeding the Rx's. The balun is grounded to an 8 ft. ground rod about
1 m from the base of the antenna tower.

Given this environment, will there indeed be a problem with
interference? If so, are there any options to eliminate it?
I think they're talking about cheap CAT 5 wiring. Not the 2.4 gig
stuff. Good Cat 5 wire has twisted pairs that inherently reduce
interference. If there's a problem, I'd use ferrite beads every 6
feet or so (or just wherever practical).

Monroe wrote:
I'm not up on the tech side of 2-way wireless comm's. Solely Rx only
of the shortwave and longwave frequencies. But I am considering a
wireless alternative to my slow dial-up for internet connectivity.
The system is based around this device:


http://www.packetgods.com/store/prod...roducts_id=127

The wireless ISP rep indicated that the power over ethernet line had
resulted in intereference for some local HAM users, and suggested a
shielded cable and/or selective routing may solve the problem.

I've not heard of any problems with power-over-ethernet causing
interference to hams. (that said, this is the first I've heard of
power-over-ethernet period!)

I think he may have had it confused with the opposite system,
broadband-over-power-lines (BPL) which DOES cause severe shortwave
interference.

I suppose there is some possibility that the provided 12v DC power unit
is not adequately filtered and that it radiates interference. I would
think a ferrite choke core (available at Radio Shack), placed as close
to the power unit as possible, would probably take care of the
interference. You *might* need another one at the wireless box itself.

But I wouldn't be all that worried about it.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

In article ,
Doug Smith W9WI wrote:

Monroe wrote:
I'm not up on the tech side of 2-way wireless comm's. Solely Rx only
of the shortwave and longwave frequencies. But I am considering a
wireless alternative to my slow dial-up for internet connectivity.
The system is based around this device:


http://www.packetgods.com/store/prod...roducts_id=127

The wireless ISP rep indicated that the power over ethernet line had
resulted in intereference for some local HAM users, and suggested a
shielded cable and/or selective routing may solve the problem.

I've not heard of any problems with power-over-ethernet causing
interference to hams. (that said, this is the first I've heard of
power-over-ethernet period!)

Snip

Think of small switching power supplies running on 24 to 48 volts and
switching from 100 to 500 KHz. Bad news. Bad, bad, bad.

The idea is to be able to connect networked devices and also power them
over the ethernet cable.

Not popular yet and I hope it stays that way. It's been around a few
years now. Besides the noise generation potential its a lame idea anyway.

--
Telamon
Ventura, California

Telamon wrote:

In article ,
Doug Smith W9WI wrote:

Monroe wrote:
I'm not up on the tech side of 2-way wireless comm's. Solely Rx only
of the shortwave and longwave frequencies. But I am considering a
wireless alternative to my slow dial-up for internet connectivity.
The system is based around this device:


http://www.packetgods.com/store/prod...roducts_id=127

The wireless ISP rep indicated that the power over ethernet line had
resulted in intereference for some local HAM users, and suggested a
shielded cable and/or selective routing may solve the problem.

I've not heard of any problems with power-over-ethernet causing
interference to hams. (that said, this is the first I've heard of
power-over-ethernet period!)

Snip

Think of small switching power supplies running on 24 to 48 volts and
switching from 100 to 500 KHz. Bad news. Bad, bad, bad.


Not always bad. They were developed for industrial use to interface
with other systems. A poorly designed linear power supply can generate
a lot of noise if the diodes are cutting off fast enough to create
noise. A lot of designs use a small capacitor across the diode to swamp
the oscillation at the switching point. A well designed and shielded
switching supply can be very quiet. Just because it has a long power
line doesn't mean it has to create and radiate noise.

The idea is to be able to connect networked devices and also power them
over the ethernet cable.

Not popular yet and I hope it stays that way. It's been around a few
years now. Besides the noise generation potential its a lame idea anyway.

--
Telamon
Ventura, California


--
?

Michael A. Terrell
Central Florida

In article ,
"Michael A. Terrell" wrote:

Telamon wrote:

In article ,
Doug Smith W9WI wrote:

Monroe wrote:
I'm not up on the tech side of 2-way wireless comm's. Solely Rx only
of the shortwave and longwave frequencies. But I am considering a
wireless alternative to my slow dial-up for internet connectivity.
The system is based around this device:


http://www.packetgods.com/store/prod...products_id=12
7

The wireless ISP rep indicated that the power over ethernet line had
resulted in intereference for some local HAM users, and suggested a
shielded cable and/or selective routing may solve the problem.

I've not heard of any problems with power-over-ethernet causing
interference to hams. (that said, this is the first I've heard of
power-over-ethernet period!)

Snip

Think of small switching power supplies running on 24 to 48 volts and
switching from 100 to 500 KHz. Bad news. Bad, bad, bad.


Not always bad. They were developed for industrial use to interface
with other systems. A poorly designed linear power supply can generate
a lot of noise if the diodes are cutting off fast enough to create
noise. A lot of designs use a small capacitor across the diode to swamp
the oscillation at the switching point. A well designed and shielded
switching supply can be very quiet. Just because it has a long power
line doesn't mean it has to create and radiate noise.

The idea is to be able to connect networked devices and also power them
over the ethernet cable.

Not popular yet and I hope it stays that way. It's been around a few
years now. Besides the noise generation potential its a lame idea anyway.

Well, it's supposed to be cheap way of doing things and you know what
that means. Poor filtering due to cost and no space to put the
components anyway in those little bricks.

--
Telamon
Ventura, California

In article ,
"Michael A. Terrell" wrote:

Telamon wrote:

Well, it's supposed to be cheap way of doing things and you know what
that means. Poor filtering due to cost and no space to put the
components anyway in those little bricks.

--
Telamon


"Cheap" in industrial settings means not having to run conduit, new
power lines and put up with low data rates or pay for several days labor
to install this stuff. In a pinch they can stick a hub at the nearest
computer or other item on the network and add the DC power to the Cat 5E
wire and be in service in a few minutes instead of expensive downtime
while a more conventional system is installed.

And don't forget hot plug-able.

Let's hope this stuff does not find its way into the consumer market.

--
Telamon
Ventura, California

Well,there is Road Runner (I subscribe to www.twcjam.com Road Runner
for my computer (and I can prove it too,you come here and see for
yourself if you don't believe me) and DSL and www.starband.com and
many other Broad Band internet access providers.Look in your phone
book.Computers are made for Broad Band and I would never accept anything
less than Broad Band high speed internet access for my computer even
though it does cost more money.It is well worth it to me.Just my
opinionated opinion.
cuhulin

If you go wireless for your computer(s),you definatley need the best
encryption for your computer(s) www.linksys.com sells some good
hardware routers that can be used as hardware firewalls.If there is a
www.compusa.com store in your area,I recommend going there and talk to
someone in their computer repair department.Them other computer
stores,stay away from them! they don't know anything about
computers,their job is to sell computers and that is all they know! I
will never go wireless with my computers!!!
cuhulin