Can I feed multiple signals into a single coax cable?

[James Hawkins]

I have coax between a TV antenna in the loft, two upstairs points and two downstairs points. This allows for all points to use the loft antenna signal.

I would like to "add" a few signals to the cable (layman-speak here). I would like to feed in the analogue output from the cable box (downstairs) as well as add a radio antenna in the loft and add that to the mix. The idea is then that I could use the signal coming out of any of the sockets for radio, normal (terrestrial) TV and for whatever the cable box is set to.

I would add the cable signal on the cable side of the filter in the socket if there is one, and I suppose I might need a filter to e.g. exclude the non-FM signals for the radio and v.v.

My limited electronics knowledge suggests that this should be fine, in the sense that the additional signals should not interfere in any significant manner with each other or the existing TV signal; can anyone confirm or deny?

[Andy Wade]

You need a 4-way distribution amplifier with FM and UHF inputs. The TV aerial needs to go to the cable STB (and any other STBs, VCR etc.) first. Then split the output of the loop-through chain with a 2-way 'Y' splitter, one leg to the local TV and the other to the UHF input of the amplifier. Radio aerial can go straight to the VHF input. Then all four outputs of the D/A carry all off-air plus all looped-thro UHF signals. Choose STB modulator channels carefully to avoid interference.

[Dave Plowman (News)]

Snag is that devices like VCRs etc that have an RF output so any TV set in the chain can pick them up need to be daisy chained into the start of the system - ie aerial in, system out. You can daisy chain more than one such device if it has adjustable output frequency - with care and luck. However, I'm not sure you could *add* this RF signal at any point in the chain - or rather not without specialist equipment. And your STB is unlikely to be the first thing on the aerial circuit?

You can diplex in an FM aerial, but in general this isn't as successful as multiple TV outlets. Should be ok for local reception, though.

[Dave Fawthrop]

|I have coax between a TV antenna in the loft, two upstairs points and |two downstairs points. This allows for all points to use the loft |antenna signal. | |I would like to "add" a few signals to the cable (layman-speak here). |I would like to feed in the analogue output from the cable box |(downstairs) as well as add a radio antenna in the loft and add that |to the mix. The idea is then that I could use the signal coming out |of any of the sockets for radio, normal (terrestrial) TV and for |whatever the cable box is set to. | |I would add the cable signal on the cable side of the filter in the |socket if there is one, and I suppose I might need a filter to e.g. |exclude the non-FM signals for the radio and v.v. | |My limited electronics knowledge suggests that this should be fine, in |the sense that the additional signals should not interfere in any |significant manner with each other or the existing TV signal; can |anyone confirm or deny?

Yes it is done with a "Loft Box"