[PVRCNC] -SPAM- (5.6) What! No Voltage?

[Jim Jordan, K4QPL]

Mike,

Fantastic! I never knew that!  And they can parcel out those deci-bels and 
send them down the wires with no voltage. Absolutely amazing.

I thought the term came from somewhere else. There used to be this big 
telephone company called Ma Bell. In the old days, it made lots of money, 
had no bailouts but was considered  "too big to succeed".   So it got broken 
up into seven or eight baby Bel's--most of which have either failed or been 
eaten by others, mostly their parent.  The short form for the now decimated 
Bel's is the deci-bel.

Jim


----- Original Message ----- 
From: <mike at bentwire.net>
Cc: <pvrcnc at mailman.qth.net>
Sent: Monday, June 15, 2009 4:41 PM
Subject: Re: [PVRCNC] -SPAM- (5.6) What! No Voltage?


>
> The cable TV world operates a little differently than what we hams are
> used to. In the cable TV arena, they transmit signals down the cable
> using a signal quantum called Bels. Bels are quite large units of
> signal, and correspondingly very expensive to create and transmit.
> Hence they feed them out very frugally, using only the minimum amount
> necessary. Thus, they measure them in deci-bels, 1/10 of a Bel. To
> avoid wasting these deci-bels, they install hardline coax, and
> adequate, but crappy, F-connectors on their system.
>
> In the ideal world, if they had no losses in the cable, they could
> transmit the signals with zero Bels of signal. This is the ultimate
> goal of the industry. Whoever manages to accomplish this will be given
> the No Bel Prize by the cable TV industry.
>
>
>
>
> "Jim Jordan, K4QPL" <k4qpl at nc.rr.com> wrote:
>
> Cable repairman down at the coast came to investigate on Saturday why
> the
> cable modem kept dropping out causing erratic internet access. Having
> nothing better to do I thought I'd learn something about how the bits
> and
> bytes get to us from the cable.
>
> As he was cleaning up and replacing connectors corroded by the salt
> air, I
> made the innocent comment: "I can see where corrosion on those
> connectors
> could cause voltage drop and loss of signal"
>
> To which he set me straight:  "There is NO voltage on a digital cable-
> --only
> decibels".
>
> After replacing some cables, connectors, lightning protector, splitter
> and
> anything else readily to hand and the system was working again, he
> then
> pulled up the analysis software on his laptop and said that everything
> was
> now fine at our end except the "Receiving SNR line".  "Minimum
> decibels on
> the 'Receiving SNR line'  should be >33 and we were only getting
> 30db". I
> looked at the screen and while trying to keep a straight face on that
> explanation of the signal to noise ratio analysis being done by the
> software, I asked what was the problem with "the receiving SNR line"?
> Response: "We're having some issues with that in the system". End of
> explanation.
>
> I wanted to ask if they had anyone out looking for those lost decibels
> that
> should have been on the 'Receiving SNR Line' but thought better of it.
> As
> there's no voltage involved, I shouldn't be concerned.
>
> Painting by numbers applied to tech service     ;-)
>
> 73,
>
> Jim, K4QPL
>
>
>
>
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