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>> DOUG: This video will describe in detail how to use the spectrum analyzer function
on the 360 DSP. It is in the Troubleshoot menu, if I go into
the spectrum icon, [pause]
What I would use this function for is to essentially check the existing cable at a customer�s
house. In other words, I would go to the tap, disconnect
the drop from the tap, and connect the drop to my meter so that I am looking in towards
the house. I am looking at what should be dead cable.
[pause]
The noise floor of the meter is around -55 I believe.
I should not see any energy above -30, in that range, anything below -30 should be fine.
[pause]
So in the upper left part of the screen, if I do not see a trace on the graph, I need
to lower my reference level. [pause]
I can do this by highlighting that field, just hitting the up and down arrows, or I
can hit the enter key and just type in my reference level.
Minus 25, and it will set it for me. The reference is the value at the top of the
screen. [pause]
If I hit my right arrow, one time, I am at the resolution field.
This is 10 dB per division. That just tells me how many dB is it for each
horizontal line. So if I am at -25 at the top one line below
that would be -15, one line below that would be minus, I am sorry, -35, one line below
that would be -45, and then as you can see I am at about -50 where my current trace is
roughly. [pause]
I can set the stop frequency, the start is always four.
I can set my stop by highlighting that field using my up down arrows.
I can select 42, 65, 85, or 110. If I am checking existing wiring, 110 is a
good value to use because I know there is energy in the environment.
FM Stations. FM stations broadcast 88 to 109 MHz roughly.
If I have got a faulty cable, and anything is going to bleed in, I am probably going
to pick up some FM stations. So this is a way for me to quickly test the
integrity of the existing wiring. [pause]
This display here is pretty much what I want to see.
I want to see no energy on that existing cable. [pause]
If I see anything like this, I have got some energy bleeding in, that is an indication
that I have got a maybe a staple through a coax, maybe I have
got some other issues, loose connections, but I do not want to see any energy on that
existing coax. This would be a failure.
A passing test in a perfect world would be a completely flat spectrum.
[pause]