Author Topic: Terrestrial TV non-reception - what to replace?  (Read 1154 times)

Terrestrial TV non-reception - what to replace?
« on: January 08, 2021, 06:28:21 pm »
Probably a stupid question but, whilst I'm reasonably technically literate, I've not really tried to keep up well with all the changes in TV transmission in recent decades, and just done the minimum.

We've got an old "portable" TV in a bedroom. We're in a decent reception area in range of Sandy Heath (which is about 15 flattish miles away). The TV has an oldish Philips PACE TV freeview box attached. The odd thing is that we get good signal for many channels, but some, including BBC1 and BBC2, are missing entirely. The box "knows" that they should be there, but just says "No signal". I had to replace the loft aerial for the downstairs TV when everything went digital, but that's about it.

I tried replacing the (indoor) aerial without success. We're not really interested in sticking things on the outside of the house for a second TV. But why would a basic channel such as BBC be missing, and not others? I'm vaguely aware of channels being multiplexed now and frequencies changing, but not really well-enough up to date on this stuff to think where to start. Is it worth looking at the PACE box? Is something using an out-of-range frequency for something else? All pointers, including to the Web pages that I ought to have read up on, welcome!

jiberjaber

  • ... Fancy Pants \o/ ...
  • ACME S&M^2
Re: Terrestrial TV non-reception - what to replace?
« Reply #1 on: January 08, 2021, 06:32:03 pm »
Well it could be a change in format of transmission which the box capabilities might predate but I am not sure if you've tried it already connected to the main aerial to rule out the antenna you've been using so far?
Regards,

Joergen

Feanor

  • It's mostly downhill from here.
Re: Terrestrial TV non-reception - what to replace?
« Reply #2 on: January 08, 2021, 06:37:20 pm »
Firstly, do a re-tune on the box.
There will be a menu option to do a re-scan somewhere.
The channels have moved around a fair bit over the years, and your box has no way of knowing that till you force a re-tune.

Yes, the channels are multiplexed.
So several channels share a single 'mux', which is broadcast on a single UHF channel.
There will be several muxes broadcast from the transmitter, each carrying several TV channels.
The act of 'tuning' a digibox basically involves it scanning through each of the UHF channels, looking for a digital mux.
Then it interrogates that mux for what TV or radio channels it contains.
It then builds up a table of channels to display to you, and when you select one of the TV channels, it knows what mux to go to and which stream in the mux to decode.
If the box has not been re-tuned in many years, the table will be out-of-date, and when you select some channels it looks in the wrong place because it's moved.

If that doesn't help, then the digibox is probably past it's use-by date.

The terrestrial digital TV system has evolved, and many of the earlier boxes were not particularly compliant with the spec.
One thing that changed was the NIT ( Network Information Table ) got split some years back.
This was always in the spec, but many original boxes didn't support it because they didn't need to at the time.

Then HD got added.

jiberjaber

  • ... Fancy Pants \o/ ...
  • ACME S&M^2
Re: Terrestrial TV non-reception - what to replace?
« Reply #3 on: January 08, 2021, 06:44:18 pm »
Regards,

Joergen

Re: Terrestrial TV non-reception - what to replace?
« Reply #4 on: January 08, 2021, 06:49:15 pm »
If you need a new box, can I recommend a Manhattan product. I have a T3-R, which also records, but also has the “catch-up” services like iPlayer, All4, etc..  It a British company with very good support.

https://manhattan-tv.com/
We are making a New World (Paul Nash, 1918)

Re: Terrestrial TV non-reception - what to replace?
« Reply #5 on: January 08, 2021, 07:57:58 pm »
I'm feeling a bit dumb because my wife reminded me that BBC1 comes out at channel 803 on this box. That's so high that it's past the radio channels and, before them, the "exotic" ones  :hand: and I stopped looking before that point. I've no idea why it's that high. But yes, I'm wondering whether it's time for a new digibox. Would need to be fairly low end. We wouldn't be in this position if we used this TV heavily, so it would be hard to justify spending much.

Some good information so far, thanks. I feel like I've got a starting point to read up on it, anyway, but more comments welcome. And I'll look at rafletcher's recommendation too.

Re: Terrestrial TV non-reception - what to replace?
« Reply #6 on: January 08, 2021, 08:05:38 pm »
on my reasonable new digital TV I have bbc1 on channel for one region but another region on 802 if this explains why your box is putting bbc on 803

Re: Terrestrial TV non-reception - what to replace?
« Reply #7 on: January 08, 2021, 08:10:08 pm »
I'm feeling a bit dumb because my wife reminded me that BBC1 comes out at channel 803 on this box. That's so high that it's past the radio channels and, before them, the "exotic" ones  :hand: and I stopped looking before that point. I've no idea why it's that high. But yes, I'm wondering whether it's time for a new digibox. Would need to be fairly low end. We wouldn't be in this position if we used this TV heavily, so it would be hard to justify spending much.

Some good information so far, thanks. I feel like I've got a starting point to read up on it, anyway, but more comments welcome. And I'll look at rafletcher's recommendation too.

It sounds like it might just need you to redo the channel search. They put normal channels up high if they find duplicates. Presumably the original BBC One it found is gone.

Feanor

  • It's mostly downhill from here.
Re: Terrestrial TV non-reception - what to replace?
« Reply #8 on: January 08, 2021, 08:10:37 pm »
Yep, reigonal variant most likely.
Did doing a re-tune from the setup menu change anything?

Re: Terrestrial TV non-reception - what to replace?
« Reply #9 on: January 08, 2021, 09:40:17 pm »
I've redone channel search loads of times. Always ends up with non-working BBC at 1 and 2, and the working versions in the 800s.

Edit: I reckon the set-bottom box (the TV is on a stand) is ancient. It's a Philips DTR22/05. I can't find specific reference to it but, looking at some references here and Googling a bit, the sense is that the addition of lots more channels overwhelmed the memory and other capacities of some boxes. There were changes to the Network Information Table, whatever that is. This thread has a post on 16/09/2008 talking about channels getting shunted to the 800s, which is what we've seen. Unfortunately the linked page is long gone.

So we need a new, basic box that's as future-proof as reasonably possible. I think. Unless anyone has a better idea?

Thanks all. With your help, I'm learning a bit.

Feanor

  • It's mostly downhill from here.
Re: Terrestrial TV non-reception - what to replace?
« Reply #10 on: January 08, 2021, 10:05:37 pm »
Yep, as I mentioned upthread the NIT issue was A Thing many years back.

Sounds like the digibox is past it's use-by date.

I've not bought a standalone DTV box for years, but back in the day I'd have said Humax.

<rummages>
Would you like a SCART cable to go with that?
</rummages>

Re: Terrestrial TV non-reception - what to replace?
« Reply #11 on: January 08, 2021, 10:24:04 pm »
Thank you. SCART cables we do have - the Philips box uses them :thumbsup:

Re: Terrestrial TV non-reception - what to replace?
« Reply #12 on: January 08, 2021, 11:13:12 pm »
some  (mostly older) freeview tuners respond to local news broadcasts on BBC1 by 'finding a new  channel' and giving it an 800 sized number. If you have an antenna which receives more than one local variant of any given channel, there is likely to be a duplicate somewhere in the channel list.

Note that there is often a difference between 'install new channels' (which merely adds to whatever is there) and 'replace all channels'.  The latter is what you want if your 'old' channels don't work.

Pointless getting a HD receiver to drive an old portable with, however non-HD boxes have gone from being sub £20 in tescos to NLA in the last couple of years.  They most recently did a 'dion' one which is cheap and cheerful, and since folk are constantly  upgrading, these (and similar) appear on ebay.  I'd suggest you get one of those if you want a cost-effective solution.

Past that getting a new TV will probably pay for itself in lower electricity costs.  A good 22"-32" set will consume a similar number of watts whereas even a small old CRT TV will be using many times more than that.

cheers

Re: Terrestrial TV non-reception - what to replace?
« Reply #13 on: January 09, 2021, 10:44:43 am »
Might be worth an ask on Freegle / Freecycle to see if anyone has an unused Freeview box. As people gradually upgrade to full smart TVs with built in Freeview I expect there will be a lot of perfectly good digiboxes going to landfill/recycling. You might get one for free.

Also, you can watch BBC live on a laptop/PC etc.  I’m assuming the old TV has no capability to receive input from a Chromecast or similar?

Re: Terrestrial TV non-reception - what to replace?
« Reply #14 on: January 09, 2021, 04:23:07 pm »
Thanks all. On rafletcher's recommendation, I've got a used Manhattan one on the way. I'll report back in a week or so.

Re: Terrestrial TV non-reception - what to replace?
« Reply #15 on: January 09, 2021, 04:26:06 pm »
Freesat works if you have terrible terrestrial reception, provided you have line of sight to Astra 2A.  Unfortunately the current Freesat boxes are rather buggy and you don't get Channel 4 in HD, because Freesat wanted too much money from Ch4 to include it in the EPG.

I like satellite TV as a technological concept but hate its association with $ky.

In practice broadband streaming is probably going to take over in the future.  It's expensive to launch satellites or to maintain terrestrial transmitters.  You do lose synchronous transmission, though, which is occasionally irritating.  Digital terrestrial already has lag, satellite about 250ms more, but broadband can introduce a lot more than that.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

Re: Terrestrial TV non-reception - what to replace?
« Reply #16 on: January 09, 2021, 04:42:39 pm »
In practice broadband streaming is probably going to take over in the future.

This is probably why current Humax support is worse than ever for their PVR’s. After all, why bother recording anything when you can (theoretically at least) get it from a catch-up service.

One of the reasons I recommended Manhattan was a recent experience. One evening the box I have refused to wake up. It only recovered when I did a power cycle reboot. All the scheduled recordings for that evening failed as a result. I emailed their support, and got a response in 24hrs asking for some details. Shortly after I got another, asking me to download a special debugging and logging firmware onto a USB stick, and, in the event of it happening again, instructions on how to dump the logs and send to them. Oh, and in case I didn’t have a suitable USB they offered to send one with the software pre-loaded.
We are making a New World (Paul Nash, 1918)

Re: Terrestrial TV non-reception - what to replace?
« Reply #17 on: January 09, 2021, 06:18:37 pm »
Unfortunately the current Freesat boxes are rather buggy and you don't get Channel 4 in HD, because Freesat wanted too much money from Ch4 to include it in the EPG.

If your Freesat box has a non-Freesat mode (ours does), you can tune Channel 4 in HD.

Feanor

  • It's mostly downhill from here.
Re: Terrestrial TV non-reception - what to replace?
« Reply #18 on: January 09, 2021, 06:36:47 pm »
Unfortunately the current Freesat boxes are rather buggy and you don't get Channel 4 in HD, because Freesat wanted too much money from Ch4 to include it in the EPG.

If your Freesat box has a non-Freesat mode (ours does), you can tune Channel 4 in HD.

I'm pretty sure my Humax can do that too, but it's an either/or thing.
If I take it out of Freeview mode to tune any arbitrary channel, then I loose the Freeview EPG, and that's really the whole point of it.

Are there any boxes which allow a 'hybrid' mode where they let you use the Freeview EPG, and also add manual channels to it?
I expect Freeview don't allow that as it would undermine their business.


Re: Terrestrial TV non-reception - what to replace?
« Reply #19 on: January 10, 2021, 01:04:50 pm »
Well it could be a change in format of transmission which the box capabilities might predate but I am not sure if you've tried it already connected to the main aerial to rule out the antenna you've been using so far?

The OP mentioned a 'Pace' freeview box, which I think were one of the first on the market back in the early 2000's, however since then there have been technical changes to the transmission standard which means a lot of the early freeview boxes and tv's with freeview built in will be stuck receiving either a limited selection of the available channels or no channels at all. Also the original frequency plan will also have changed, so your antenna might no longer be optimal for the frequencies now being used, and because of frequencies cleared to make space for 4G, some areas will only have access to a bare minimum of channels simply due to the lack of available radio spectrum for television services.


Re: Terrestrial TV non-reception - what to replace?
« Reply #20 on: January 10, 2021, 01:12:45 pm »
Unfortunately the current Freesat boxes are rather buggy and you don't get Channel 4 in HD, because Freesat wanted too much money from Ch4 to include it in the EPG.

If your Freesat box has a non-Freesat mode (ours does), you can tune Channel 4 in HD.

+1,  for years I had two dishes, one for 28.2E  and another for 13E/19E (dual LNB),  using a Humax Foxsat dual tuner, I was able to receive not only UK tv but French, German,  Italian, Spanish, Portuguese, Polish, Russian, Iranian, Azerbaijani and Armenian TV

Re: Terrestrial TV non-reception - what to replace?
« Reply #21 on: January 10, 2021, 02:32:08 pm »
I don't think that box has options, dual tuning or anything :-) I changed the aerial as my first step, as I think I mentioned. Let's see what the Manhattan box does!

Re: Terrestrial TV non-reception - what to replace?
« Reply #22 on: January 10, 2021, 11:08:49 pm »
You do lose synchronous transmission, though, which is occasionally irritating.


Flashback to the early 80s now, where they'd broadcast a concert on BBC TV, and you could listen to it in stereo on Radio 1.

I'm guessing you mean moving between rooms with the same programme on.

Re: Terrestrial TV non-reception - what to replace?
« Reply #23 on: January 11, 2021, 10:10:51 am »
even (DAB) radio isn't synchronous any more; the BBC still broadcast 'the pips' but they are no longer as meaningful as they once were.

For the last few years I have viewed F1 using RTL satellite coverage for the pictures, with radio five live for the commentary. The latter is usually a couple of seconds ahead of the former.  No FTA satellite coverage of F1 next year, so I might bother pointing my dish setup (which has done well considering it cost me about £20 all in) at a different satellite instead.

cheers

Re: Terrestrial TV non-reception - what to replace?
« Reply #24 on: January 11, 2021, 11:36:29 am »
Even if it was a synchronous broadcast it wouldn't help. What you actually hear or see has a delay introduced by the buffering on the digital TV or radio for its DAC as well.
We have tow Sony TVs in the lounge and dinner kitchen and they are different ages and models. If you have them both on the same TV channel they aren't quite in synch and makes for a weird echoey effect.
To get synchronous results and accurate PIPs etc there would need to be an agreed delay period and buffering between reception and display / sound broadcast across all makers of TVs and digital radios. Technically possible especially with how cheap accurate clock chips are now but would be hard to get agreement.
I think you'll find it's a bit more complicated than that.