Optical LNB

On Thu, 28 May 2009 12:28:43 +0100, Johnny B Good
wrote:

The message
from Petert contains these words:

====snip====

Just checked - the LNB at
http://www.triax.co.uk/Products/Fibr...cal%20LNB.aspx

transmits a 7dBm which should be plenty!

(Some will correct me if I'm wrong, but I make that to be about 8mW)

Wrong! +7db mW approximates to a power level of 5mW (it's 3db shy of 10mW)

Consider yourself corrected! ;-) However, your figure is well within
"The Ball Park".

My excuse is that I worked backwards from 30dBm = 1 watt (in my head -
must rmember head not too good at this)
--
Cheers

Peter

"Ian Jackson" wrote in message
...
In message , R. Mark Clayton
writes

"Petert" wrote in message
. ..
On Mon, 25 May 2009 16:20:30 GMT, "Brian Gaff"
wrote:

SNIP

In addition it is a relatively simple matter to split and amplify the
optical signal.

Are there any optical amplifiers for 1310mn? The LNB will need a 1550
laser. And optical amplifiers are definitely not cheap.

Well not yet anyway...


I expect this may get developed, since the power for the LNB is fairly
low,
so visible light could be transmitted the other way to provide sufficient
energy to run the LNB. They will also connect direct to receivers.

An AM laser carrying a full channel loading between 1 and 5GHz is going to
need a fair amount of electrical power. To transmit 'optical line power',
you're going to need a 'James Bond' laser . [Bear in mind that anything
more than an apparently piddling 20dBm is getting 'quite scary'.]

It does not need to be a laser going the other way, but I can see your
point.

As an LNB is bound to be in the sun during daylight, one could use a solar
cell on the back. Even run continuously you probably only need to capture
less than 1kJ per day.


I will certainly be looking seriously at them to fit on a Wavefrontier
SMATV
for two blocks of flats - a doddle compared to long lossy multiple runs
between the blocks.

--
Ian