My friend has a Panasonic TV fed via a Humax PVR. The picture quality
is highly variable ranging from 50% to 100% and sometimes shutting
down altogether as inadequate signal. The problem occurs both with
the TV operating direct or operating via the Humax box, though the
Humax is more reliable. For test purposes this is HD channel 40. I
have checked that pass-through for the Humax is enabled. I use the
same transmitter (Blackhill) with no problems whatsoever (constant
100% quality).

My thinking is that there must be something wrong with the aerial. I
replaced the (indoor) aerial cables but the problem persists. The
aerial is in the loft, and is communal. It has probably never been
upgraded for HD but it has worked up to now. It is difficult to see
how it could be so variable. I have suggested getting someone into
the loft to see if the aerial has been dislodged or affected by water
ingress. My friend is reluctant to do this because it is common or
mutual.

Any ideas?

On 07/07/2023 15:42, Scott wrote:
> My friend has a Panasonic TV fed via a Humax PVR. The picture quality
> is highly variable ranging from 50% to 100% and sometimes shutting
> down altogether as inadequate signal. The problem occurs both with
> the TV operating direct or operating via the Humax box, though the
> Humax is more reliable. For test purposes this is HD channel 40. I
> have checked that pass-through for the Humax is enabled. I use the
> same transmitter (Blackhill) with no problems whatsoever (constant
> 100% quality).
>
> My thinking is that there must be something wrong with the aerial. I
> replaced the (indoor) aerial cables but the problem persists. The
> aerial is in the loft, and is communal. It has probably never been
> upgraded for HD but it has worked up to now. It is difficult to see
> how it could be so variable. I have suggested getting someone into
> the loft to see if the aerial has been dislodged or affected by water
> ingress. My friend is reluctant to do this because it is common or
> mutual.
>
> Any ideas?

It may well just be me but I was left unsure if you have by-passed the
Humax totally by plugging the aerial lead into the TV direct.

--
Robin
reply-to address is (intended to be) valid

On Fri, 7 Jul 2023 15:59:45 +0100, Robin <rbw@outlook.com> wrote:

>On 07/07/2023 15:42, Scott wrote:
>> My friend has a Panasonic TV fed via a Humax PVR. The picture quality
>> is highly variable ranging from 50% to 100% and sometimes shutting
>> down altogether as inadequate signal. The problem occurs both with
>> the TV operating direct or operating via the Humax box, though the
>> Humax is more reliable. For test purposes this is HD channel 40. I
>> have checked that pass-through for the Humax is enabled. I use the
>> same transmitter (Blackhill) with no problems whatsoever (constant
>> 100% quality).
>>
>> My thinking is that there must be something wrong with the aerial. I
>> replaced the (indoor) aerial cables but the problem persists. The
>> aerial is in the loft, and is communal. It has probably never been
>> upgraded for HD but it has worked up to now. It is difficult to see
>> how it could be so variable. I have suggested getting someone into
>> the loft to see if the aerial has been dislodged or affected by water
>> ingress. My friend is reluctant to do this because it is common or
>> mutual.
>>
>> Any ideas?
>
>It may well just be me but I was left unsure if you have by-passed the
>Humax totally by plugging the aerial lead into the TV direct.

What I meant to say was that the aerial lead goes first to the Humax
box then there is a coaxial cable from the Humax to the TV. The Humax
has an option for pass-through to be on or off in standby and I have
selected on. I have not tried plugging the aerial direct into the TV,
which I should perhaps have done.

On 07/07/2023 15:42, Scott wrote:
> It has probably never been
> upgraded for HD

There is nothing intrinsically about HD that requires changes in the
aerial, although it might be on channels outside the design range of the
aerial, or signal levels may be weaker.

If you are daisy chaining through the Humax, there will be some
degradation in signal to noise ratio, compared with what the Humax has
to work with, but basically it sounds like your signal strength is marginal.

In article <qc8gaipbo31e0djnblhbi00t61m0pp649v@4ax.com>,
Scott <newsgroups@gefion.myzen.co.uk> wrote:
> My friend has a Panasonic TV fed via a Humax PVR. The picture quality
> is highly variable ranging from 50% to 100% and sometimes shutting
> down altogether as inadequate signal. The problem occurs both with
> the TV operating direct or operating via the Humax box, though the
> Humax is more reliable. For test purposes this is HD channel 40. I
> have checked that pass-through for the Humax is enabled. I use the
> same transmitter (Blackhill) with no problems whatsoever (constant
> 100% quality).

> My thinking is that there must be something wrong with the aerial. I
> replaced the (indoor) aerial cables but the problem persists. The
> aerial is in the loft, and is communal. It has probably never been
> upgraded for HD but it has worked up to now. It is difficult to see
> how it could be so variable. I have suggested getting someone into
> the loft to see if the aerial has been dislodged or affected by water
> ingress. My friend is reluctant to do this because it is common or
> mutual.

> Any ideas?

If the aerial is communal, there's probably a distribution amplifier to
feed the various outlets.
Check with neighbours - do they have the same problems?
If so, bypass the amplifier to feed just one point. See how that works.

Get an aerial instaler in to sort the problem.

--
from KT24 in Surrey, England - sent from my RISC OS 4té
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
<david@ex.djwhome.demon.invalid> wrote:

>On 07/07/2023 15:42, Scott wrote:
>> It has probably never been
>> upgraded for HD
>
>There is nothing intrinsically about HD that requires changes in the
>aerial, although it might be on channels outside the design range of the
>aerial, or signal levels may be weaker.
>
>If you are daisy chaining through the Humax, there will be some
>degradation in signal to noise ratio, compared with what the Humax has
>to work with, but basically it sounds like your signal strength is marginal.

It seems to be quite high (I cannot remember the figure) and it is the
quality that fluctuates. The fluctuation puzzles me especially with
an indoor (loft) aerial.

On 07/07/2023 17:04, Scott wrote:
> On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
> <david@ex.djwhome.demon.invalid> wrote:
>
>> On 07/07/2023 15:42, Scott wrote:
>>> It has probably never been
>>> upgraded for HD
>>
>> There is nothing intrinsically about HD that requires changes in the
>> aerial, although it might be on channels outside the design range of the
>> aerial, or signal levels may be weaker.
>>
>> If you are daisy chaining through the Humax, there will be some
>> degradation in signal to noise ratio, compared with what the Humax has
>> to work with, but basically it sounds like your signal strength is marginal.
>
> It seems to be quite high (I cannot remember the figure) and it is the
> quality that fluctuates. The fluctuation puzzles me especially with
> an indoor (loft) aerial.
>
Remove the Humax box completely with its HDMI lead and plug the aerial
directly into the TV. If he still has a problem its the aerial.

On 07/07/2023 16:19, Scott wrote:
> On Fri, 7 Jul 2023 15:59:45 +0100, Robin <rbw@outlook.com> wrote:
>
>> On 07/07/2023 15:42, Scott wrote:
>>> My friend has a Panasonic TV fed via a Humax PVR. The picture quality
>>> is highly variable ranging from 50% to 100% and sometimes shutting
>>> down altogether as inadequate signal. The problem occurs both with
>>> the TV operating direct or operating via the Humax box, though the
>>> Humax is more reliable. For test purposes this is HD channel 40. I
>>> have checked that pass-through for the Humax is enabled. I use the
>>> same transmitter (Blackhill) with no problems whatsoever (constant
>>> 100% quality).
>>>
>>> My thinking is that there must be something wrong with the aerial. I
>>> replaced the (indoor) aerial cables but the problem persists. The
>>> aerial is in the loft, and is communal. It has probably never been
>>> upgraded for HD but it has worked up to now. It is difficult to see
>>> how it could be so variable. I have suggested getting someone into
>>> the loft to see if the aerial has been dislodged or affected by water
>>> ingress. My friend is reluctant to do this because it is common or
>>> mutual.
>>>
>>> Any ideas?
>>
>> It may well just be me but I was left unsure if you have by-passed the
>> Humax totally by plugging the aerial lead into the TV direct.
>
> What I meant to say was that the aerial lead goes first to the Humax
> box then there is a coaxial cable from the Humax to the TV. The Humax
> has an option for pass-through to be on or off in standby and I have
> selected on. I have not tried plugging the aerial direct into the TV,
> which I should perhaps have done.

It would rule out the problem being with the Humax.

--
Robin
reply-to address is (intended to be) valid

On Fri, 7 Jul 2023 20:13:28 +0100, MikeS <MikeS@fred.com> wrote:

>On 07/07/2023 17:04, Scott wrote:
>> On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
>> <david@ex.djwhome.demon.invalid> wrote:
>>
>>> On 07/07/2023 15:42, Scott wrote:
>>>> It has probably never been
>>>> upgraded for HD
>>>
>>> There is nothing intrinsically about HD that requires changes in the
>>> aerial, although it might be on channels outside the design range of the
>>> aerial, or signal levels may be weaker.
>>>
>>> If you are daisy chaining through the Humax, there will be some
>>> degradation in signal to noise ratio, compared with what the Humax has
>>> to work with, but basically it sounds like your signal strength is marginal.
>>
>> It seems to be quite high (I cannot remember the figure) and it is the
>> quality that fluctuates. The fluctuation puzzles me especially with
>> an indoor (loft) aerial.
>>
>Remove the Humax box completely with its HDMI lead and plug the aerial
>directly into the TV. If he still has a problem its the aerial.

I shall do this tomorrow when I visit my friend (though not during
Wimbledon coverage!!!).

On 07/07/2023 17:04, Scott wrote:
> On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
> <david@ex.djwhome.demon.invalid> wrote:
>
>> On 07/07/2023 15:42, Scott wrote:
>>> It has probably never been
>>> upgraded for HD
>>
>> There is nothing intrinsically about HD that requires changes in the
>> aerial, although it might be on channels outside the design range of the
>> aerial, or signal levels may be weaker.
>>
>> If you are daisy chaining through the Humax, there will be some
>> degradation in signal to noise ratio, compared with what the Humax has
>> to work with, but basically it sounds like your signal strength is marginal.
>
> It seems to be quite high (I cannot remember the figure) and it is the
> quality that fluctuates. The fluctuation puzzles me especially with
> an indoor (loft) aerial.

The problem is that there are two parameters that affect glitches or "no
signal". TVs and PVRs tend to report both, but the way they do varies a
lot - from numerical dBm and dB to bars and arbitrary "3 out 5" ratings.

One parameter is the signal strength - ideally expressed in dBm. The
other is signal quality or signal-to-noise ratio expressed in dB.

You want both figures to be as high as possible - but beware that signal
strength is a negative number, so -50 dBm is worse than -40 dBm.

Suppose you have an aerial that is picking up a weak signal - or one
with a lot of reflections or interference from a distant transmitter
that happens to use the same frequency. With a really powerful aerial
amplifier this can feed the TV with a strong signal. But it will be a
"loud" version of the signal you want plus a lot of background noise.
That's where the SNR comes in: it measures how much stronger the wanted
signal is than the background crap. Some TVs report BER (bit error rate)
which measures how well the decoder is decoding the signal (where
background noise will cause a lot of decoding error and hence a high BER).

I live about 50 miles due north of Belmont. Normally my terrestrial
reception is pretty damn good (in terms of errors that actually cause
picture glitches) despite a hill 1/2 mile away that is the only thing
between me and Belmont.

But when there is atmospheric "lift", signals from Crystal Palace,
several hundred miles away, manage to propagate as far as me, whereas
normally they are so weak as to be negligible. And CP shares the all the
same frequencies as Belmont :-( Unfortunately when it happens, the
signal is so bad that the TV won't even lock and so doesn't even report
strength and SNR.

On 07/07/2023 16:45, charles wrote:
> In article <qc8gaipbo31e0djnblhbi00t61m0pp649v@4ax.com>,
> Scott <newsgroups@gefion.myzen.co.uk> wrote:

>> My friend has a Panasonic TV fed via a Humax PVR. The picture quality
>> is highly variable ranging from 50% to 100% and sometimes shutting
>> down altogether as inadequate signal. The problem occurs both with
>> the TV operating direct or operating via the Humax box, though the
>> Humax is more reliable. For test purposes this is HD channel 40. I
>> have checked that pass-through for the Humax is enabled. I use the
>> same transmitter (Blackhill) with no problems whatsoever (constant
>> 100% quality).
>
>> My thinking is that there must be something wrong with the aerial. I
>> replaced the (indoor) aerial cables but the problem persists. The
>> aerial is in the loft, and is communal. It has probably never been
>> upgraded for HD but it has worked up to now. It is difficult to see
>> how it could be so variable. I have suggested getting someone into
>> the loft to see if the aerial has been dislodged or affected by water
>> ingress. My friend is reluctant to do this because it is common or
>> mutual.
>
>> Any ideas?
>
> If the aerial is communal, there's probably a distribution amplifier to
> feed the various outlets.
> Check with neighbours - do they have the same problems?
> If so, bypass the amplifier to feed just one point. See how that works.
>
> Get an aerial instaler in to sort the problem.

Actually indoor aerials are remarkably good for digital. I have a
communal system, and, a little while ago when it lost power I tried
connecting a simple, unamplified, log-periodic antenna and it was good
enough to use, despite the fact that I live on the ground floor not very
near the transmitter. With analogue I expect it would have been snowy at
least.

--
Max Demian

On 07/07/2023 20:13, MikeS wrote:
> On 07/07/2023 17:04, Scott wrote:
>> On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
>> <david@ex.djwhome.demon.invalid> wrote:

>>> If you are daisy chaining through the Humax, there will be some
>>> degradation in signal to noise ratio, compared with what the Humax has
>>> to work with, but basically it sounds like your signal strength is
>>> marginal.
>>
>> It seems to be quite high (I cannot remember the figure) and it is the
>> quality that fluctuates.  The fluctuation puzzles me especially with
>> an indoor (loft) aerial.
>>
> Remove the Humax box completely with its HDMI lead and plug the aerial
> directly into the TV. If he still has a problem its the aerial.

Or the fly-lead.

--
Max Demian

On 07/07/2023 17:04, Scott wrote:

>
> It seems to be quite high (I cannot remember the figure) and it is the
> quality that fluctuates. The fluctuation puzzles me especially with
> an indoor (loft) aerial.

Local electrical interference getting in from an inadequately screened
down lead or fly-lead between a wall plate and the box/TV?

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Friday, 7 July 2023 at 17:04:23 UTC+1, Scott wrote:
> On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
> <da...@ex.djwhome.demon.invalid> wrote:
>
> >On 07/07/2023 15:42, Scott wrote:
> >> It has probably never been
> >> upgraded for HD
> >
> >There is nothing intrinsically about HD that requires changes in the
> >aerial, although it might be on channels outside the design range of the
> >aerial, or signal levels may be weaker.
> >
> >If you are daisy chaining through the Humax, there will be some
> >degradation in signal to noise ratio, compared with what the Humax has
> >to work with, but basically it sounds like your signal strength is marginal.
> It seems to be quite high (I cannot remember the figure) and it is the
> quality that fluctuates. The fluctuation puzzles me especially with
> an indoor (loft) aerial.
No, you'd expect it. Remember that digital TV needs a tiny change in signal level to radically affect reception quality, if the signal levels are marginal.
Bill

On Friday, 7 July 2023 at 22:15:13 UTC+1, Max Demian wrote:

> Actually indoor aerials are remarkably good for digital. I have a
> communal system, and, a little while ago when it lost power I tried
> connecting a simple, unamplified, log-periodic antenna and it was good
> enough to use, despite the fact that I live on the ground floor not very
> near the transmitter. With analogue I expect it would have been snowy at
> least.

You shouldn't really generalise from one specific incident.
Bill

On Fri, 7 Jul 2023 21:36:26 +0100, NY <me@privacy.net> wrote:

>On 07/07/2023 17:04, Scott wrote:
>> On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
>> <david@ex.djwhome.demon.invalid> wrote:
>>
>>> On 07/07/2023 15:42, Scott wrote:
>>>> It has probably never been
>>>> upgraded for HD
>>>
>>> There is nothing intrinsically about HD that requires changes in the
>>> aerial, although it might be on channels outside the design range of the
>>> aerial, or signal levels may be weaker.
>>>
>>> If you are daisy chaining through the Humax, there will be some
>>> degradation in signal to noise ratio, compared with what the Humax has
>>> to work with, but basically it sounds like your signal strength is marginal.
>>
>> It seems to be quite high (I cannot remember the figure) and it is the
>> quality that fluctuates. The fluctuation puzzles me especially with
>> an indoor (loft) aerial.
>
>The problem is that there are two parameters that affect glitches or "no
>signal". TVs and PVRs tend to report both, but the way they do varies a
>lot - from numerical dBm and dB to bars and arbitrary "3 out 5" ratings.
>
>One parameter is the signal strength - ideally expressed in dBm. The
>other is signal quality or signal-to-noise ratio expressed in dB.

It's percentages. I think R has higher general strength than me but
variable quality. Mine is 79% strength and solid 100% quality, this
coming from the same transmitter at Blackhill.
>
>You want both figures to be as high as possible - but beware that signal
>strength is a negative number, so -50 dBm is worse than -40 dBm.
>
>Suppose you have an aerial that is picking up a weak signal - or one
>with a lot of reflections or interference from a distant transmitter
>that happens to use the same frequency. With a really powerful aerial
>amplifier this can feed the TV with a strong signal. But it will be a
>"loud" version of the signal you want plus a lot of background noise.
>That's where the SNR comes in: it measures how much stronger the wanted
>signal is than the background crap. Some TVs report BER (bit error rate)
>which measures how well the decoder is decoding the signal (where
>background noise will cause a lot of decoding error and hence a high BER).

I have heard it can be better to remove amplification for digital TV.
It's a very old communal system, but it has worked up to now, which
makes me think something has changed.
>
>I live about 50 miles due north of Belmont. Normally my terrestrial
>reception is pretty damn good (in terms of errors that actually cause
>picture glitches) despite a hill 1/2 mile away that is the only thing
>between me and Belmont.
>
>But when there is atmospheric "lift", signals from Crystal Palace,
>several hundred miles away, manage to propagate as far as me, whereas
>normally they are so weak as to be negligible. And CP shares the all the
>same frequencies as Belmont :-( Unfortunately when it happens, the
>signal is so bad that the TV won't even lock and so doesn't even report
>strength and SNR.

This is interesting. Our first thought was atmospheric pressure
during the extreme heat, but not the heatwave is over, we have
experienced lower pressure and the problem continues. Also, my TV
(same transmitter) has experienced no problems whatever. We are c40.
I see there are other low powered transmitters using this. The oddity
is that this is a recent phenomenon. What has changed?

"alan_m" <junk@admac.myzen.co.uk> wrote in message
news:kgredcFufntU1@mid.individual.net...
> On 07/07/2023 17:04, Scott wrote:
>
>>
>> It seems to be quite high (I cannot remember the figure) and it is the
>> quality that fluctuates. The fluctuation puzzles me especially with
>> an indoor (loft) aerial.
>
>
> Local electrical interference getting in from an inadequately screened
> down lead or fly-lead between a wall plate and the box/TV?

Now there's a possibility. When we moved into our new house I replaced a lot
of the tungsten GU10 downlighter bulbs with LED ones. I noticed very poor
quality recordings on the PSB1 (BBC) mux while others were fine. It only
happened in the evening. It took a long time before I correlated the poor
reception to the lights being turned on in my study which is directly below
the TV aerial. I changed each GU10 in turn in the study and found the duff
one. It seems that it was giving out RF noise that only affected 482 MHz
(PSB1 for Belmont) and not the nearby 490 (COM5). So I moved the bulb to the
other end of the house where it is far enough away that I can't detect any
change in sig or SNR readings, and can't see any continuity errors in
recordings, when it is turned on. I've marked the bulb in case we ever move
it in the future!

If you are seeing poor reception on one mux and not any others, RFI from a
bulb or other electronic device *might* be the cause.

On Sat, 8 Jul 2023 10:51:30 +0100, "NY" <me@privacy.invalid> wrote:

>"alan_m" <junk@admac.myzen.co.uk> wrote in message
>news:kgredcFufntU1@mid.individual.net...
>> On 07/07/2023 17:04, Scott wrote:
>>
>>>
>>> It seems to be quite high (I cannot remember the figure) and it is the
>>> quality that fluctuates. The fluctuation puzzles me especially with
>>> an indoor (loft) aerial.
>>
>>
>> Local electrical interference getting in from an inadequately screened
>> down lead or fly-lead between a wall plate and the box/TV?
>
>Now there's a possibility. When we moved into our new house I replaced a lot
>of the tungsten GU10 downlighter bulbs with LED ones. I noticed very poor
>quality recordings on the PSB1 (BBC) mux while others were fine. It only
>happened in the evening. It took a long time before I correlated the poor
>reception to the lights being turned on in my study which is directly below
>the TV aerial. I changed each GU10 in turn in the study and found the duff
>one. It seems that it was giving out RF noise that only affected 482 MHz
>(PSB1 for Belmont) and not the nearby 490 (COM5). So I moved the bulb to the
>other end of the house where it is far enough away that I can't detect any
>change in sig or SNR readings, and can't see any continuity errors in
>recordings, when it is turned on. I've marked the bulb in case we ever move
>it in the future!
>
>If you are seeing poor reception on one mux and not any others, RFI from a
>bulb or other electronic device *might* be the cause.

Good idea. She lives in a ground floor flat so it could be the antics
of one of the neighbours. I suppose we need to check a range of
channels rather than the HD one only.

On Fri, 7 Jul 2023 16:49:45 -0700 (PDT), "wrightsaerials@aol.com"
<wrightsaerials@f2s.com> wrote:

>On Friday, 7 July 2023 at 17:04:23 UTC+1, Scott wrote:
>> On Fri, 7 Jul 2023 16:36:02 +0100, David Woolley
>> <da...@ex.djwhome.demon.invalid> wrote:
>>
>> >On 07/07/2023 15:42, Scott wrote:
>> >> It has probably never been
>> >> upgraded for HD
>> >
>> >There is nothing intrinsically about HD that requires changes in the
>> >aerial, although it might be on channels outside the design range of the
>> >aerial, or signal levels may be weaker.
>> >
>> >If you are daisy chaining through the Humax, there will be some
>> >degradation in signal to noise ratio, compared with what the Humax has
>> >to work with, but basically it sounds like your signal strength is marginal.
>> It seems to be quite high (I cannot remember the figure) and it is the
>> quality that fluctuates. The fluctuation puzzles me especially with
>> an indoor (loft) aerial.
>No, you'd expect it. Remember that digital TV needs a tiny change in signal level to radically affect reception quality, if the signal levels are marginal.

Thanks. Would a cheap signal meter (sub £20) be of any assistance? I
believe some of them may not work where there is an aerial amplifier.
I keep telling R she needs one of your professional colleagues.

On 08/07/2023 10:51, NY wrote:
> Now there's a possibility. When we moved into our new house I replaced a lot
> of the tungsten GU10 downlighter bulbs with LED ones.

There is a well known story of a Y Service site in WWII (North Wales I
think).

They were getting interference with lots of theories about the cause
including enemy action.

It was found to be caused by a light bulb in WAAF's toilet I think.

On Sat, 8 Jul 2023 12:45:48 +0100, MB <MB@nospam.net> wrote:

>On 08/07/2023 10:51, NY wrote:
>> Now there's a possibility. When we moved into our new house I replaced a lot
>> of the tungsten GU10 downlighter bulbs with LED ones.
>
>There is a well known story of a Y Service site in WWII (North Wales I
>think).
>
>They were getting interference with lots of theories about the cause
>including enemy action.
>
>It was found to be caused by a light bulb in WAAF's toilet I think.
>
I installed 12 volt LED spotlights in the kitchen and this obliterated
DAB reception. Mains voltage are okay. I assume this was because the
current was nearly 20 times greater.

On 07/07/2023 16:36, David Woolley wrote:
> On 07/07/2023 15:42, Scott wrote:
>> It has probably never been
>> upgraded for HD
>
> There is nothing intrinsically about HD that requires changes in the
> aerial, although it might be on channels outside the design range of the
> aerial, or signal levels may be weaker.
>
> If you are daisy chaining through the Humax, there will be some
> degradation in signal to noise ratio, compared with what the Humax has
> to work with, but basically it sounds like your signal strength is
> marginal.

Some communal systems have filters intended to only let through the
channels broadcast by the mast the aerial is pointed at.

--
Brian Gregory (in England).

On 08/07/2023 12:54, Scott wrote:
> I installed 12 volt LED spotlights in the kitchen and this obliterated
> DAB reception. Mains voltage are okay. I assume this was because the
> current was nearly 20 times greater.

More likely the back street place in China, that made them, saved a few
pence by not fitting any filtering. There have often been reports of
things with provision on the PCB for components to filter out
interference but they were not fitted.

"Scott" <newsgroups@gefion.myzen.co.uk> wrote in message
news:vdgiaidtnn77l70ceegctqn6eukvnv2rql@4ax.com...
> Good idea. She lives in a ground floor flat so it could be the antics
> of one of the neighbours. I suppose we need to check a range of
> channels rather than the HD one only.

Yes. I'd check a selection such as:

- BBC One (SD) [LCN 1] (mux PSB1)
- ITV1 [3] (PSB2)
- BBC One (HD) [101] (PSB3)
- Drama ([20)] (COM4)
- Really [17] (COM5)
- Talking Pictures [82] (COM6)

That covers all six of them.

"Brian Gregory" <void-invalid-dead-dontuse@email.invalid> wrote in message
news:kgtj6bFafbjU2@mid.individual.net...
> On 07/07/2023 16:36, David Woolley wrote:
>> On 07/07/2023 15:42, Scott wrote:
>>> It has probably never been
>>> upgraded for HD
>>
>> There is nothing intrinsically about HD that requires changes in the
>> aerial, although it might be on channels outside the design range of the
>> aerial, or signal levels may be weaker.
>>
>> If you are daisy chaining through the Humax, there will be some
>> degradation in signal to noise ratio, compared with what the Humax has to
>> work with, but basically it sounds like your signal strength is marginal.
>
> Some communal systems have filters intended to only let through the
> channels broadcast by the mast the aerial is pointed at.

Hopefully those filters are updated if a transmitter changes the UHF
channels it uses ;-)

Do any communal aerial systems remodulate a mux onto a different UHF
channel? For example to group all the muxes into a tight block that can be
covered with a single wider band-pass filter rather than a series of
single-mux filters. I remember in the days of Bracknell Cable TV (analogue!)
they moved all the broadcast signals from Crystal Palace (BBC, ITV Thames
etc) and Hannington (ITV Meridian) onto unused UHF channels, presumably so
any leakage from the cable wouldn't affect people with their own aerial.