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Post by GTCGreg on Feb 1, 2016 2:26:26 GMT
It actually may be better this way. AS we talked about earlier, it was behaving like the modulator was overpowering the cable signal. I have it installed on the tap connection. The tap may be working in reverse to limit the power of the RF modulator coming into the device to something reasonable and preventing it from killing the other signals. So yea, I've got what I want, so I'll leave it alone. Guess I don't have to order the new splitter and attenuators after all. One question. Is there anyway that the camera signal that I am putting into my household cable system is leaking out to other houses nearby? If they tune to channel 4, would they get my feed? Probably not. I doubt the signal from the modulator will make it backwards through the RF amp. There is also a "tap" type splitter between your drop and the main cable system that would greatly attenuate any signal coming from your house. But you may want to check with a neighbor just to make sure. |
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Post by wvengineer on Feb 1, 2016 2:27:00 GMT
Thinking about it some more, the cable company has some sort of filter on the line coming into my house that blocks channels 1-68 since I don't pay for cable TV. However it allows channels 69 and up with poor reception on 69-73. I guess they can't block everything when I am paying for internet service. So I get a couple cable channels and a bunch of digital broadcast channels. That filter should block my channel 4 from being visible from anyone outside. Right?
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Post by GTCGreg on Feb 1, 2016 2:30:10 GMT
Thinking about it some more, the cable company has some sort of filter on the line coming into my house that blocks channels 1-68 since I don't pay for cable TV. However it allows channels 69 and up with poor reception on 69-73. I guess they can't block everything when I am paying for internet service. So I get a couple cable channels and a bunch of digital broadcast channels. That filter should block my channel 4 from being visible from anyone outside. Right? It's highly unlikely your signal will make it out of your house. But again, check with a neighbor to make sure. |
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Post by c64 on Mar 13, 2016 10:52:41 GMT
Here is how your "in/out/tap" box works. It is a so called "directional coupler".  A directional coupler has two main paths with 2 exits each. Technically it is a so called "4-port network". The main signal runs through the upper part of the box in the picture. The main path can be inside the street running from house to house or inside the house running from room to room (or both). The major part of the RF fed into the top left port (IN) comes out of the top right port (OUT) and vice versa. A fraction of the RF fed into the top left port will come out on the lower left port (TAP). So each box removes only a fraction of the RF power on the main bus line without interfering with the shape of the signals. This is very important! Whatever is sent into the top right port (OUT) will be forwarded into the top left port (IN) and a fraction of it is tapped into the bottom right port which is a resistor in those boxes with 3 connectors. This RF is then lost. Whatever you feed into the bottom left port (TAP) is manly fed into the resistor as well, only a fraction of it will come out the top left port (IN). A good RF modulator contains a directional coupler already so it can only feed its RF to the TV-port (which would be the top left "IN" port in the picture). If your RF modulator doesn't contain a coupler, it would be a very good idea to add your box, the "IN" port towards your TVs and the "OUT" port towards the street with your RF modulator hooked to the "TAP" port. This would make sure not feeding your pictures into the street and reduce the chance to tamper with your modem. |
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Post by c64 on Mar 13, 2016 11:05:22 GMT
The best strategy here would be buying a Raspberry PI along with the PI-cam and an USB Wifi interface if there is no copper network available. Use the Pi-cam without IR filters and by adding a bunch of IR-LEDs or a ready to use IR-spotlight it can also see in the dark. There are ready to use video surveillance programs available, all you need to do is to download an image from the internet and copy it onto an SD card. Assemble everything and it is ready to use. There are also nice Pi-cam casings available, even with IR-LEDs built in.  Or just buy a Pi-cam IR module and scavenge an old halogen spotlight to use as a casing:  The system then feeds live images into your network you can watch with most smart-TVs and all smartphones. If you want, you can access the life feed using your cell anywhere. It can also sound an alarm e.g. if the baby is crying and send you an SMS or your video app on your cell pops up. |
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Post by c64 on Mar 13, 2016 11:23:01 GMT
Here is a true 4-port directional coupler:  This is the kind you use for ham radios. Connected between your transmitter and your antennae, one port gives you a fraction of the power rushing out of the transmitter and the other one a fraction of what's returning from your antennae. By connecting a special meter to the two output ports of the coupler, you can measure your transmitting power and by comparing the two readings you can calculate the SWR ratio which tells you how efficient your antennae is. There are two strategies. One is a "cross-coil" meter where the fields of the two meter coils interfere with each other so the needle is indirectly affected by the SWR ratio and points it out on a scale directly. I like the "cross-needle" versions better but those are more expensive:  You can observe your "forward" and "reverse" power independently and the SWR ratio is where the needles meet. This allows you to find a spot in your setup where you get much more power out of your transmitter with a slightly greater SWR so your overall range is greater than just trying to find the best (lowest) SWR possible. |
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