I had to go down to Oban on Monday, I noticed that DAB reception in the
car was terrible as I left the town.
Too strong around here to notice but I went up to Inverness today and
was not able to receive DAB most of the way.
Wondering what to do, if I ask the VW dealership to take a look then
they will just switch on the radio, find reception OK in Inverness so
say there is nothing wrong.
The only thing I have changed in the last week is putting in a new
memory card with updated maps. I can't think of any reason it should be relevant but the radio, Sat Nav etc all tend to linked up on modern cars
so I will have to get myself back to somewhere with poor signal and put
the old memory card back in. I doubt it will make any difference.
I had to go down to Oban on Monday, I noticed that DAB reception in the
car was terrible as I left the town.
Too strong around here to notice but I went up to Inverness today and
was not able to receive DAB most of the way.
Wondering what to do, if I ask the VW dealership to take a look then
they will just switch on the radio, find reception OK in Inverness so
say there is nothing wrong.
The only thing I have changed in the last week is putting in a new
memory card with updated maps. I can't think of any reason it should be relevant but the radio, Sat Nav etc all tend to linked up on modern cars
so I will have to get myself back to somewhere with poor signal and put
the old memory card back in. I doubt it will make any difference.
Are there some DAB transmitters out of service? I’ve no idea how you’d find
out these days.
Have you tried doing a scan update of late? If you are listening to
national stations like the BBC or ClassicFM you may need to do a scan periodically as even some 'national' stations are carried on local muxes.
On 28/01/2022 17:10, Tweed wrote:
Are there some DAB transmitters out of service? I’ve no idea how you’d find
out these days.
I don't think so I had started out in range of one then a different one.
Both were OK close to the site but lost as got further away.
Failed antenna connection?
I had to go down to Oban on Monday,
I noticed that DAB reception in the car was terrible as I left the town.
Too strong around here to notice but I went up to Inverness today and
was not able to receive DAB most of the way.
Could be one of the transmitters has fallen out of GPS lock, and is
punching a hole in coverage with its mistimed signal.
Happened at Reigate once, and at another site in Portsmouth more recently.
On 29/01/2022 14:06, Mark Carver wrote:
Could be one of the transmitters has fallen out of GPS lock, and is
punching a hole in coverage with its mistimed signal.
Happened at Reigate once, and at another site in Portsmouth more recently.
It is happening in the overlap area between Oban and Fort William & Fort William and Rosemarkie.
Obviously no way of checking except going further afield and little
chance of explaining that on the form for reporting complaints!
I tried putting the Sat Nav back on its original memory card, I know extremely unlikely to be the cause but wanted to check.
I wondered if the car aerial has a separate fuse but no mention in the handbook.
If I can think of a reason to go up to Kingussie / Aviemore then can see where I start to hear Kingussie.
The map on the ukfree.tv site seems very optimistic, lots of "COMING
SOON" sites" and the map data claims to be 2022!
On 29/01/2022 14:06, Mark Carver wrote:
Could be one of the transmitters has fallen out of GPS lock, and is
punching a hole in coverage with its mistimed signal.
Happened at Reigate once, and at another site in Portsmouth more
recently.
It is happening in the overlap area between Oban and Fort William &
Fort William and Rosemarkie.
On 29/01/2022 17:50, Mark Carver wrote:
Then I'd put money on the Fort William Tx having lost its GPS clock
reference...
I will have a think about where to have a drive to find somewhere I
can compare with past reception quality.
Then I'd put money on the Fort William Tx having lost its GPS clock reference...
The clue will be to find a place where reception of FM services from
Fort William and one or other of the other two sites is also good.
It'll follow that the DAB signal from FW and the other site is equally
as good. With no decodable DAB at that location, it's a fairly safe bet destructive (rather than combinive)Â reception is present
There's a lot of ruggedness round them parts though, and DAB is twice
the frequency of FM. I should perform the experiment at a number of
locations in case of propagation differences caused by screening and reflections.
On 30/01/2022 02:09, williamwright wrote:
There's a lot of ruggedness round them parts though, and DAB is twice
the frequency of FM. I should perform the experiment at a number of
locations in case of propagation differences caused by screening and
reflections.
DAB tends to perform better than VHF FM in the "rugged" terrain, the reflections can enhance the signal whilst causing distortion on VHF FM.
On 30/01/2022 08:56, MB wrote:
On 30/01/2022 02:09, williamwright wrote:
There's a lot of ruggedness round them parts though, and DAB is twice
the frequency of FM. I should perform the experiment at a number of
locations in case of propagation differences caused by screening and
reflections.
DAB tends to perform better than VHF FM in the "rugged" terrain, the
reflections can enhance the signal whilst causing distortion on VHF FM.
I think we might get into standing waves any moment now.
On 31/01/2022 22:17, williamwright wrote:
On 30/01/2022 08:56, MB wrote:
On 30/01/2022 02:09, williamwright wrote:
There's a lot of ruggedness round them parts though, and DAB is twice
the frequency of FM. I should perform the experiment at a number of
locations in case of propagation differences caused by screening and
reflections.
DAB tends to perform better than VHF FM in the "rugged" terrain, the
reflections can enhance the signal whilst causing distortion on VHF FM.
I think we might get into standing waves any moment now.
On every individual carrier within the mux ?
On 01/02/2022 08:21, Mark Carver wrote:
On 31/01/2022 22:17, williamwright wrote:
On 30/01/2022 08:56, MB wrote:
On 30/01/2022 02:09, williamwright wrote:I think we might get into standing waves any moment now.
There's a lot of ruggedness round them parts though, and DAB is twice >>>>> the frequency of FM. I should perform the experiment at a number of
locations in case of propagation differences caused by screening and >>>>> reflections.
DAB tends to perform better than VHF FM in the "rugged" terrain, the
reflections can enhance the signal whilst causing distortion on VHF FM. >>>
On every individual carrier within the mux ?
What I'm getting at is the way reflections can arrive at the aerial with varying phase relationships as a vehicle travels, resulting in nulls if
the two signal paths result in almost identical signal strength with an 180deg phase difference at the aerial. Of course DAB should deal with
that effectively because it will be of short duration, and in any case
it is likely to be a rare occurrence. But what happens when you stop at
the lights and things just happen to drop wrong? Maybe diversity
reception is a good idea!
Incidentally I assume that this is unlikely to be much of a problem with
SFNs because, again, it is unlikely that the two signals will arrive at
equal strength.
On a related topic, a partial or complete solution to tidal fading is to simply mount two aerials at different (random) heights, and combine by
means of a simple splitter.
There is usually some buffering inside your receiver which covers the
signal holes.
Yes, there's a local short tunnel near me that the SDL mux doesn't
penetrate. At the right speed the reception mutes from the point I exit
the tunnel for about 4 seconds.
In terms of tidal fading, in the late 70's we did a 1500MHz link from
Winter Hill to the top of Snaefell but I won't say for whom. The path
was predicted at 99.8% reliable. The 4ft dishes at WH were 50
wavelengths apart or about 10m, but there was a single 6ft dish at Snaefell.
In the 10 years or so I was involved with it it only dropped out once
that we knew about*. It went out in both directions for about an hour
one July morning, then came back one way only for almost 14 hours.
No-one that I asked could explain it.
*When we first installed the link we put a multi-channel pen recorder on
the signal level circuit and as we were only using one input we got a
dot on the trace about every 6 seconds. The link could drop out and
restore between two dots! Given however that it was an analogue link
carrying analogue channels (12 of them) it was never noticed, thankfully!
On 01/02/2022 08:21, Mark Carver wrote:
On 31/01/2022 22:17, williamwright wrote:
On 30/01/2022 08:56, MB wrote:On every individual carrier within the mux ?
On 30/01/2022 02:09, williamwright wrote:
There's a lot of ruggedness round them parts though, and DAB is twice >>>>> the frequency of FM. I should perform the experiment at a number of
locations in case of propagation differences caused by screening and >>>>> reflections.
DAB tends to perform better than VHF FM in the "rugged" terrain,
the reflections can enhance the signal whilst causing distortion on
I think we might get into standing waves any moment now.
What I'm getting at is the way reflections can arrive at the aerial
with varying phase relationships as a vehicle travels, resulting in
nulls if the two signal paths result in almost identical signal
strength with an 180deg phase difference at the aerial. Of course DAB
should deal with that effectively because it will be of short duration,
and in any case it is likely to be a rare occurrence. But what happens
when you stop at the lights and things just happen to drop wrong? Maybe >diversity reception is a good idea!
Incidentally I assume that this is unlikely to be much of a problem
with SFNs because, again, it is unlikely that the two signals will
arrive at equal strength.
What I'm getting at is the way reflections can arrive at the aerial
with varying phase relationships as a vehicle travels, resulting in
nulls if the two signal paths result in almost identical signal
strength with an 180deg phase difference at the aerial. Of course DAB
should deal with that effectively because it will be of short
duration, and in any case it is likely to be a rare occurrence. But
what happens when you stop at the lights and things just happen to
drop wrong? Maybe diversity reception is a good idea!
I think Mark Carver was referring to the fact that a DAB multiplex
consists of very many carriers, of close but slightly varying
frequencies across the band slot allocated to the multiplex - such that
any given physical situation will not null out more than one or two of
the multitude of carriers. It may null out a few completely and
permanently, but the data coding across the multiplex is robust enough
to survive the loss - even permanent - of a few of them.
On Tue, 1 Feb 2022 at 19:46:38, williamwright <wrightsaerials@f2s.com>
wrote (my responses usually follow points raised):
On 01/02/2022 08:21, Mark Carver wrote:
On 31/01/2022 22:17, williamwright wrote:
On 30/01/2022 08:56, MB wrote:Â On every individual carrier within the mux ?
On 30/01/2022 02:09, williamwright wrote:I think we might get into standing waves any moment now.
There's a lot of ruggedness round them parts though, and DAB is
twice
the frequency of FM. I should perform the experiment at a number of >>>>>> locations in case of propagation differences caused by screening and >>>>>> reflections.
DAB tends to perform better than VHF FM in the "rugged" terrain,
the reflections can enhance the signal whilst causing distortion on >>>>
What I'm getting at is the way reflections can arrive at the aerial
with varying phase relationships as a vehicle travels, resulting in
nulls if the two signal paths result in almost identical signal
strength with an 180deg phase difference at the aerial. Of course DAB
should deal with that effectively because it will be of short
duration, and in any case it is likely to be a rare occurrence. But
what happens when you stop at the lights and things just happen to
drop wrong? Maybe diversity reception is a good idea!
I think Mark Carver was referring to the fact that a DAB multiplex
consists of very many carriers, of close but slightly varying
frequencies across the band slot allocated to the multiplex - such
that any given physical situation will not null out more than one or
two of the multitude of carriers. It may null out a few completely and permanently, but the data coding across the multiplex is robust enough
to survive the loss - even permanent - of a few of them.
There is usually some buffering inside your receiver which covers the
signal holes. Try listening to something off Clifton and unplug the
aerial - you will find the sound does not stop immediately.
Also the data interleaved across all the carriers, In essence it's the
same with your ADSL or VSDL broadband connection, where you're likely to
have permanent(ish) nulls in the spectrum on your particular phone line.
On Thu, 3 Feb 2022 08:38:12 +0000, Mark Carver <mark.carver@invalid.invalid> wrote:
Also the data interleaved across all the carriers, In essence it's theMine are caused by MW TX interference. Primarily Clevedon, but I could
same with your ADSL or VSDL broadband connection, where you're likely to
have permanent(ish) nulls in the spectrum on your particular phone line.
see lots of others - even Droitwich made a small dip in the spectrum.
Can't see it on VDSL like I could on ADSL now though.
On Tue, 1 Feb 2022 20:26:17 +0000, Woody <harrogate3@ntlworld.com> wrote:
There is usually some buffering inside your receiver which covers the
signal holes. Try listening to something off Clifton and unplug the
aerial - you will find the sound does not stop immediately.
And if you then plug it in again, do you still not get a hole?
Of course you do. You can't get back (from the buffer) what you never >received.
Buffering doesn't cover holes unless you can request re-transmission,
which of course you can't.
Bit like the delay system used on phone-ins, that builds up the delay in pauses in the presenter's or caller's speech. (Do they still use those?)
Bit like those portable CD players that were aimed at joggers (i. e.
where the playing mechanism was subject to lots of knocks): I think I've encountered those where there was up to tens of seconds of buffering,
but they built it up - if you started them up lying on the table, you
didn't have to wait that long after pressing play before you heard
anything. (If they _didn't_ work like that, there'd be no point in
_having_ the buffer.)
the grill of my bedroom storage heater as a handy earth.
Then the window pane got a crack in it, and ice formed on the inside.
I hated getting up for school in the winter...
On Sat, 5 Feb 2022 17:25:10 +0000, Mark Carver
<mark.carver@invalid.invalid> wrote:
the grill of my bedroom storage heater as a handy earth.
Oh, a softy southerner :-)
Whilst we had CH upstairs, it was warm air based, but my room was the >furthest from the boiler and it was almost always cold by the time it
got there.
Then the window pane got a crack in it, and ice formed on the inside.
I hated getting up for school in the winter...
On 05/02/2022 14:08, Paul Ratcliffe wrote:
On Thu, 3 Feb 2022 08:38:12 +0000, Mark Carver <mark.carver@invalid.invalid> >> wrote:I've never lived anywhere near an MF or LF site, when I was mucking
Also the data interleaved across all the carriers, In essence it's theMine are caused by MW TX interference. Primarily Clevedon, but I could
same with your ADSL or VSDL broadband connection, where you're likely to >>> have permanent(ish) nulls in the spectrum on your particular phone line.
see lots of others - even Droitwich made a small dip in the spectrum.
Can't see it on VDSL like I could on ADSL now though.
about as a very young lad old with electronics sets, and building
radios, it was always a struggle to get anything other than R3 Daventry
(647 kHz) or R4 Brookmans Park (908 kHz). Consequently, I ended up
listening to unhealthy amounts of Radio 4, using a croc-clip on the
grill of my bedroom storage heater as a handy earth.
I remember taking my electronics set along on a family holiday on
Anglesey, two miles from Penmon. The crystal earpiece almost jumped off
the table. No need for an earth there !
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