On 6/9/2011 10:38 AM, Jeff Liebermann wrote:
On Wed, 08 Jun 2011 21:48:45 -0500, wrote:

On 6/7/2011 11:46 PM, Jeff Liebermann wrote:

That would be the MU (Multi-Unit) system.
http://www.netlinkweb.com/solutions/motorola/BPL-applications/BPL-MU.asp
I have no experience with that one. Did you look at it on a spectrum
analyzer? Motorola is one of the few BPL vendors that supplies
devices that intentionally filter out "sensitive" bands, such as ham
radio. My understanding (possibly wrong) is that since the entire
building shares the same wiring, the bandwidth per user is limited
during peak times.


I looked at it band by band for the US amateur bands. I believe I also
check out of band here and there, but it was 5 or 6 years ago. And that
was straight from the transmitter level with a 1 meter cable and a 75 to
50 ohm mismatch.

I also swept our area 30 to 30 on HF with a not great hunk of wire and
heard nothing beyond the normal ethernet, PC, printer and other office
furniture. But nothing from the BPL which had a noticeable pattern.

Well, maybe you're right. Lets's do the math.

On Pg 54, Motorola says the power spectral density is about -50dBm/Hz.
If your receiver was set for SSB with about a 3KHz bandwidth, that's:
-50dBm/Hz + 10log(3000Hz) = -50 + 34.7 = -15dBm
You should have been able to hear that when directly connected.

Assuming S9 is 50uv into 50 ohms, that's
P = E^2/R = (50*10^-6)^2 / 50 = 125 uWatts = -9dBm
You should have seen noise at 6dB over S9 on your guess meter
(ignoring the 50/75 ohm mismatch and ham radio band notch filters).

Shared bandwidth is an issue, but it is also split up by phase, and that
helps somewhat.

Good point. However, even commodity DSL (1.5Mbits/sec) download is
considered old technology by many broadband users. With 42.5Mbit/sec
aggregate bandwidth, that would minimally supply 28 typical
residential customers at 100% utilization, about double that if
overloaded, and maybe one user doing file sharing. Splitting phases
will increase that by x2 or x3, assuming there's no crosstalk between
phases. That's more than adequate for residential service, assuming
the building owner wants to pay for a T3 line or one third of an OC3
plus service.

I found 3ea X10 lamp modules and one controller. There are more
buried somewhere.


One thing most people can't appreciate the advantage of is having your
own email server. I helps a lot when you have a low bit rate connection.

I don't need lamp modules, they are less satisfactory.

Which controller do you have?

And maybe we should move this offline.

tom
K0TAR