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RF Switching Question

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JohnS_AZ:
I an certainly NOT an RF geek.

I have 3 satellite receivers in my house, each with their own TV monitor. I also have another TV monitor on our back deck.
I do not want to add another sat receiver for the deck, so I would like to be able to switch that set between the three existing receivers. Note: all of the coax is already in place, two RG6 runs to each room (I went a little nuts when I remodeled a few years ago)  :)

Each receiver outputs an RF signal modulated to channel 3 (or 4), so on the deck I'll have three coax cables that each have a different channel 3 signal and I need to switch between them. I also have a boat load of 5vdc DPDT mini relays I'd like to use and avoid having to buy new parts for this. Obviously what I am trying to avoid is having the multiple signals interfere with each other.

Soooo ... is the following sketch a decent way to switch between the three signals?

sonicj:
maxim max4545

easy to implement, easy to interface, high quality, free samples.
-sj

jahonen:
In principle, that relay schematic works just fine for antenna signals. However, the magic is in the construction how good that is in practice. But I guess that you are not after a top of the line isolation or matching figure, and frequency is still relatively low. Go ahead and try it.

A microstrip construction on a double-sided PCB should do it if you want to build it on a PCB. With one side as solid contiguous ground plane, 75 ? microstrip trace is approximately as wide as the dielectric thickness.

Regards,
Janne

TechGuy:

--- Quote from: JohnS_AZ on October 12, 2010, 06:36:13 pm ---
Each receiver outputs an RF signal modulated to channel 3 (or 4), so on the deck I'll have three coax cables that each have a different channel 3 signal and I need to switch between them. I also have a boat load of 5vdc DPDT mini relays I'd like to use and avoid having to buy new parts for this. Obviously what I am trying to avoid is having the multiple signals interfere with each other.

Soooo ... is the following sketch a decent way to switch between the three signals?

--- End quote ---

Go with SonicJ's solution. a Relay is likely to attenate the signal and cause interference since some of the signal will leak out.

Perhaps as a completely different solution, there is a DVR that supports multiple TVs, where the SAT connects to a master server and distributes out meda (recorded and perhaps live TV) to multiple TVs. FWIW: I am setting up a Media server to host stored content and distribute it to multiple digital media players (set-top box). The Digital Media players are set-top boxes that play digital media from a server or URL (ie you-tube, hulu, netflix) and play it on your TV. You can also RIP DVDs and play them from a Digital Media Player. Unfortunately, I don't know of commerical digital media player that will also handle Live TV yet.

The only system that I know of that can stream live TV is MythTV (Linux), but your set-top box would need to be media PCs since I don't think there is a digital Media player that supports MythTV. MythTV can play live TV using a server with DTV/Analog capture cards, converting live TV to a Stream (MPEG4) and sending to a remove client to play the content. The idea would be to install multiple capture cards in the server (one for each SATTV settop box) and then relay the output to remote MythTV boxes to play. You can use a regular remote to change the channel, On the server side, the server would send IR signals to the SatTV box to change the channel. You would be limited to the number of SatTV boxes for the number of concurrent streams, ie two SatTV boxes = two live streams. You can view recorded material on all systems concurrently, unless you run into network bandwidth performace issues. The data would be streamed using ethernet or WiFi.

sonicj:
i attempted a couple of mythbox builds, but never got it 100% polished. thats about the only thing i like about windows... XP MCE was pretty good as a analog DVR! i do have a couple of old xbox's setup with XBMC. i think they will function as a mythbox front end for sdtv.... controlling them from my droid over wifi is pretty slick!

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