UKC

might be wrong forum but...

here's the question.

I've a HUMAX freesat box, and when I set the recorder going on say BBC HD, BBC 1&2, ITV 1 dissapear, they cannot be viewed.

Similar if I set it to record BBC 1 - channels disspear and cannot be watched. Stop recording, they come back.

not tried all channel combinations, but as it's the main ones I want to watch, it's a becoming more annoying.

Is this normal, or as I suspect, there's something wrong somewhere...

any thoughts.

Thanks
Dolbert.

In reply to Dolbert:

Groups of channels are bundled into things called multiplexes, usually shortened to muxes, each mux is broadcast on its own frequency, if you only have one tuner in your box you can only tune to one frequency at a time, which means when you are recording something the tuner is locked to that frequency and you can only see other channels in the same mux. It is the same for terrestrial Freeview, although with different channel groupings.

Here is a list of the channel groupings for the muxes on Eurobird 1 & Astra 2A/2B/2D:
http://www.lyngsat.com/28east.html

In reply to Dolbert:

The way digital works is very different to normal TV. Meaning you cant record one thing while watching another. It is very annoying.

In reply to EddInaBox:

...and if you have a poorly implemented box you won't even be able to watch a different channel on the same mux, just the one you are recording.

In reply to EddInaBox:

Interesting, thanks for that.

I'm not sure I'm understanding it though.

I can certainly watch other channels apart from the one I'm recording. Just not the channels I want to watch. e.g. I can see ITV 4+1 (pish), but not BBC 2, so that would imply more than 1 tuner in the box.

From the link you gave, BBC HD is on a different group or mux (it's with BBC channel Islands and Cambridge) to BBC Scotland.

So by the description BBC Channel Island and Cambridge should remain when I record on BBC HD. Not checked. So why does BBC 1 Scotland go?

Is it using a tuner to fix onto BBC HD and record, another tuner to let you watch other channels. Thus the recording tuner sacrifices what it was picking up as it just looks at the BBC HD group inc Channel Islands and Cambridge only.

But that would leave another tuner available for selecting everything else...or would it?

(No mention of this on the FAQ pages on HUMAX or freesat...)

Only asking for a bit of basic info, as I will be onto HUMAX and Freesat (and the shop I bought it from), to what avail I don't know.

In reply to Dolbert: Which Humax box have you got and how have you got it set up?

Do you have 2 antennae coming from the wall to the box, or do you have it set up with just LNB1-IN connected and LNB1-Out connected to LNB2-IN?

In reply to EddInaBox:

The Humax Freesat recorder has dual tuners. However, it needs two LNBs (two cables from the satellite dish) for both to be able to work. I believe it is possible to daisy-chain from one LNB input to the other but (a) Humax don't officially support that configuration, and (b) it restricts the two tuners to a single mux.

My Dad had a similar problem as the OP with his Panasonic HDD Freesat recorder until I delved behind it and worked out how the installer had cocked up.

Terrestrial digital is different: it only needs one aerial feed for any number of tuners (barring issues with signal degradation).

In reply to JoshOvki:

That is simply not true. Even with analogue you need multiple tuners to be able to record one thing while watching another. Think about the old-fashioned TV+VCR setup: there is one tuner in the TV (for watching) and one in the VCR (for recording). The reason that current digital PVRs typically (but by no means always) have two tuners is so that folks with analogue-only TVs can watch one digital channel while recording another. If your TV has a digital tuner built-in (terrestrial or satellite) then you only need one digital tuner in your PVR, just like it used to be with analogue VCRs. On the other hand, having two tuners does allow more than one programme to be recorded at the same time.

You could argue that digital is actually superior to analogue because it is technically possible to watch-one-record-another with just a single digital tuner, so long as the two channels concerned are on the same multiplex. Not every PVR implements this feature, although I believe the Humax does. I'm pretty sure their terrestrial PVRs allow you to record two and watch a third, provided the one you want to watch is on the same mux as one of the channels that is being recorded.

In reply to Martin W: You can record two and watcha third on the same mux with the Humax HD PVR.

I can't as I only have one LNB and have the jumper lead going from LNB 1 to 2. Works fine.

I have other issues though, but I'm sure I'll find my way to the bottom of them...

In reply to Dolbert:

In theory yes, but satellite tuners (unlike terrestrial tuners) cannot share a single feed to tune in different muxes. So if one is tuned to the mux with BBC HD on it then the other one can only tune to the same mux. A couple of other folks have already noted this as a likely cause of your problem.

This is all down to the much higher frequencies that satellite TV uses compared to terrestrial. The thing on the pole in the middle of the dish that picks up the signal is an active component in the receiving circuit, which has to work in cooperation with the tuner in the TV or PVR to tune in a particular satellite frequency. (The "thing" is called an LNB - see http://en.wikipedia.org/wiki/Low-noise_block_converter - each tuner must have its own LNB in order to be able to tune to different satellite frequencies.)

In comparison, a terrestrial aerial is a wholly passive device which just sends all the frequencies it can receive down the one aerial cable. The tuners in the TV, PVR etc then tune in to the frequency they each want.

In reply to Martin W:

Ahh, I think I'm getting it now. Thanks for the response and the laymans terms.

So with only one LNB on the dish, even if I have two cables (I actually have three, with the third going to a future set in the spare room), if I chose record, I could be fixing the LNB end and one of the tuners in the box to a particular set of channels.

The other cable(s), is connected ultimately to the same LNB on the dish, and so is also fixed to looking at the same group of channels.

Is that it?

The proper solution would then mean an additional satellite dish. (Eh?)

They don't tell you any of this in the shop...

customer: "Can I record and watch different things, like I used to with TV and VCR?"

Trained Shop Assistant; "Yes"

When in fact it's much more complex like the above. Grrrr. There's going to be a riot when we all go digital and analogue telly goes off.

In reply to Dolbert:

That's pretty much it, but you won't need two dishes, just a different LNB set up, sounds like you want a quad LNB, you would have up to four separate cables coming from this, in your case two to the recorder and one or two going to the spare room. Although I wonder if you have two cables coming out of the existing LNB if you might already have a dual LNB.

In reply to EddInaBox:

It's an ex standard Sky dish, as we started out with sky's lump sum pay once free satellite service. You wouldn't happen to know what their standard design is with respect to LNB's?

You're all geniuses by the way.

In reply to Dolbert:

Sky's Freesat is one lnb as they don't offer any way of recording.

You need a aerial engineer to come and change the bit on the end of you dish and then you're up and running. You want a QUAD, that way you can use all three of those cables you've got.

In reply to Philip:

Pretty straight forward to change the LNB. Just did it with mine. It slips off. Plenty of quad LNB's on ebay

In reply to Dolbert: Check this link

http://www.satelliteonline.co.uk/Humax%20Hidden%20Menu%20Info.htm