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Radio Free Amerika The ins and outs of the radio frequency spectrum, including scanners, trackers, building your own transmitters, mixers, and antennas, station formats, frequencies, favorite pirate radio stations, the FCC, radio stories, working at radio stations, and more.

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 #1 
Old 2007-12-17, 11:54
SephirothAngelus SephirothAngelus is offline
Regular
 
Default Cable TV amplification

I recently went from full cable service (minus pay stations like HBO) to basic service.

I'm supposed to have like local stations, and such.

I ended up having 2-14, 23, a fuzzy looking and sounding 24, 24-48 are pretty bad, 49 is very snowy and bad sounding but is ALMOST watchable, 50-60 are not usable, 61-65 or so are watchable with a little fuzzy sound and a pretty fuzzy picture, 66-74 are worthless I think, 75 is watchable (although fuzzy) 76-77 are garbage (always have been I think) and 78 comes in crystal clear.

These are channels like SPIKE, the "sell jewelry channel" and other shit like that. I don't understand why I have such a random assortment of channels..

I did a little bit of research, and I think that my cable company uses a negative trap system. Reason being, the day they unhooked my cable, they didn't even come in the house, just went over to (possibly up) the telephone out front.

It seems odd that I would have almost watchable channels like this.

I've been contemplating putting a channel amplifier on the line, and seeing what happens. Some TV's in the house get a couple more channels than others (like one gets 75, another doesn't).

The channels are almost watchable. I mean, I ended up watching the twilight zone on one of the higher channels. It was just an even snow all over the picture really, and a very fuzzy sound. Very viewable.

I don't want to incur the cable companies wrath, so going out on the pole and taking the traps out is probably not a good idea.

If I put an amplifier on the line, do you think it'd make these channels much better? Why would the channels be so close to usable? Any other tips or tricks I could do? (terminating the ends of the 75 ohm coax with caps, perhaps?) Would a VCR or another type of tuner work better?

Thanks so much!:D
 #2 
Old 2007-12-17, 17:37
Super Moderator
 
In a nuclear crater
Default Re: Cable TV amplification

Moving to RFA, and yes -- if you have noticeable signal at all an amplifier (assuming it's low-noise) should help significantly.
 #3 
Old 2007-12-17, 20:08
Moderator
 
Kelso, Washington, USA
Default Re: Cable TV amplification

Quote:
Originally Posted by oddballz194
Moving to RFA, and yes -- if you have noticeable signal at all an amplifier (assuming it's low-noise) should help significantly.


Well, this is almost not RFA as well. But I will offer that an amplifier will be of significant help. I'm going to make a copy of this of T&T.
 #4 
Old 2007-12-17, 23:39
Regular
 
If she's easy, take'r twice.
Default Re: Cable TV amplification

Is it Digital cable or old fashioned? If you can upgrade to digital cable, it's the only thing available around here (bumfuck montana) and comes in quite clear. You get a reciever unit instead of just plugging directly into the TV, plus there's a lot of features that were usually associated with sattelite TV like on-screen menus and instant PPV.
 #5 
Old 2007-12-18, 05:59
SephirothAngelus SephirothAngelus is offline
Regular
 
Default Re: Cable TV amplification

uhh did you read my post? I had the "good cable" (we had digital at my fathers house, but I moved out.. living with my parents was getting annoying..) and downgraded to super basic cable... and can still get an almost watchable signal from a lot of the "good" package.

I'll have to get an amp and see what happens.
 #6 
Old 2007-12-18, 19:14
Super Moderator
 
In a nuclear crater
Default Re: Cable TV amplification

Now that I'm thinking of it, IIRC, the typical scrambling system for analog cable works the opposite way of what you're thinking -- they remove a filter to *disable* the signal, and add a filter to enable it -- it has a secondary signal encoded over it (well, with a freq shift IIRC) to make it "scrambled". It mainly screws up the sync, although it can also screw up the luminance/chrominance channels. If you add a filter for each channel, you can make it watchable. My father used to do this for his employer (a TV dealer), but that was a while ago -- don't tell anyone though ;). It was probably a simple RC or LC filter.
 #7 
Old 2007-12-20, 09:06
SephirothAngelus SephirothAngelus is offline
Regular
 
Default Re: Cable TV amplification

what is an RC or LC filter?

And I think that's a positive trap system, whereas what I am describing would be a negative trap system.
 #8 
Old 2007-12-21, 19:18
Super Moderator
 
In a nuclear crater
Default Re: Cable TV amplification

Quote:
Originally Posted by SephirothAngelus
what is an RC or LC filter?

And I think that's a positive trap system, whereas what I am describing would be a negative trap system.


RC= Resistor-Capacitor
LC=Inductor-Capacitor (Inductor being a coil of wire, typically -- for some reason L is the typical symbol for an inductor)

They're tuned circuits.

With negative traps, they typically filter out the sync signal, and then they reconstruct it by taking the sync from channel 2 (typically) in the cable box. This is almost always not done on the line.

With either type of scrambler, they would typically not bother entering the premises. The filters involved would be on the line where it branches out to your house.

Typically, if they add a filter to disable the channel they disable it entirely -- the filter is designed to reduce the signal level to near-zero on the frequency.
 
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