Cannot get Mux A at all from Sandy Heath in Northampton

In article , Sn!pe
wrote:
PMFJI, but I wonder whether I know you from a former existence;*
does "TA28" mean anything to you?

It was a long time ago in a galaxy far away....

Well, Worcestershire anyway.

Do I know you? Do you have a name other than "spambin"?

Rod.

"Sn!pe" wrote in message
o.uk...
Roderick Stewart wrote:

PMFJI, but I wonder whether I know you from a former existence;
does "TA28" mean anything to you?

It was a long time ago in a galaxy far away....

Well, Worcestershire anyway.

Do I know you? Do you have a name other than "spambin"?

If you were on TA28 then yes, you do; and I do indeed have a name
other than spambin, it's in an email to you.

--
^Ï^ ---{ Sn!pe }---

Mourning my shed of yore.


Men have landed on the moon? you jest yes?

I now have an Advantest Spectrum analyser on loan to me.

This is the 1st part of three news postings I am doing, the other two will
relate to my Mux A problems from both of my Sandy Heath aerial arrays....

To recap, I have three seperate Aerial arrays here at my house in
Northampton

The one I end up using all the time is the one aligned to Oxford.

This comprises a Wideband Triax Unix 52, followed by a Antiference UBF1
bandpass filter (blocks Tetra and GSM), followed by a Maxview MHA23US
masthead amplifer (23dB gain, Noise figure is 2.0dB).

This then feeds a 3 input (all 3 inputs have individual gain controls)
Antiference ATA3MP headend which then combines this with the DAB aerial and
an FM aerial. The gain for the UHF input is set to minimum. The gain for DAB
and FM aerials is set to around 20dB

The output of this then feeds a Triax TMS5x16P multiswitch and then onward
to 16 outlets around the house. A Sky Quattro LNB hangs off this
Multiswitch.

Each wall outlet is a Labgear PSF410 Quadruplexor that then provides four
outputs, FM, DAB, UHF and SAT from the single downlead

Heres the web address for the spectrum analyser output at the TV wall socket
for 470MHz to 860MHz

http://tubeimage.com/viewer.php?file...l-Spectrum.jpg

Reading from left to right, the 1st 3rd of the image is Sandy Heath's
Analogue along with Oxford's Mux 1 and D.

The middle 3rd is Hannington's analogue as well as Oxford Mux C at UHF 48

The right 3rd is Oxford's analogue. as well as Oxford Muxes A, B and 2 at
Ch's 51, 52 and 68.


The Oxford analogue channels are coming out as:

BBC1 62.5dBµV
BBC2 69.8dBµV
ITV 66.3dBµV
Ch 4 69.8dBµV
Ch 5 64dBµV
Oxford Ch 6 57.6dBµV

The digital muxes are coming out as:

Mux 1 56dBµV
Mux 2 51dBµV
Mux A 44dBµV
Mux B 44dBµV
Mux C 47dBµV
Mux D 55.46dBµV

The main problems I have with Oxford:

All 6 analogue TV channels are very noisy so obviously a poor S/N ratio
rather than inadequate signal levels. The noise floor seems to be around
20dBµV.

I have not yet worked out how to measure analogue C/N or S/N ratio on the
analyser so thats why I have given the noise floor level in case someone is
able to work out what my analogue C/N or S/N ratios are.

All Freeview channels are rock steady except for adverse weather conditions.
details given below.

Mux A and Oxford Ch 6 get trampled all over by Wenvoe (42º off axis) and
the Big 4 analogue get trampled by Carmel (58º off axis) during certain
weather conditions.

Hannington Analogue (9º off axis), and Sandy Heath (101º off axis) are
coming in as well via the Oxford array. I know I could use a group C/D
filter, but Muxes 1 and D are in Group A.....

Comments welcome....

Two more postings to follow....

Stephen


"Mallory" wrote in message
...
Yes I have, but Hunsbury Hill is in the way between me and Sutton
Coldfield.

I can get Oxford, but the trouble is it often gets trampled all over from
Wenvoe and Carmel's transmitters.

I often lose Mux A at the same time when S4C appears on top of Oxford's
Channel 6.

There is a fire station with a metal Telecoms mast between me and Waltham
so blocking my view of Waltham.

I have clear line of site to Sandy Heath, and can get Analogue Channel 5
here without too much trouble.

I already have TWO tetra filters in my system but still cannot get Mux A
from Sandy Heath.

Have youn tried actually pointing a suitable aerial at Sutton Coldfield
to see whether you can get the digital muxes from there rather than Sandy
Heath?
--
Cheers,
Roger

Now for the Log Periodic array aligned to Sandy Heath....

The as measured Analogue signal strengths a (Tx power is 1,000kW)

Ch 21 Channel 4 50dBµV
Ch 24 ITV 52.3dBµV
Ch 27 BBC 2 53.3dBµV
Ch 31 BBC 1 55.44dBµV
Ch 39 Channel 5 20dBµV

The digital Mux strengths a (TX power is 20kW for all 6 muxes, so 17dB
down on analogue)

Ch 40 Mux C 18.6dBµV
Ch 42 Mux 1 13.4dBµV
Ch 43 Mux A 6 to 10.5dBµV across Mux A with a single spike in it at
16dBµV at 647.26MHz
Ch 45 Mux 2 15dBµV
Ch 46 Mux D 17.5dBµV
Ch 67 Mux B 10dBµV

The noise floor appears to be -10dBµV (yes negative) and the digital muxes
are over 30dB down on the big four analogue TV channels which is more than
would be expected for Sandy Heath. Mux A is over 40dB down alone vs analogue
and about 8dB to 12dB down when compared to the 2 lots of adjacent muxes.

Muxes C,1,A,2 and D at Ch's 40, 42, 43, 45 and 46 are shown in
http://tubeimage.com/viewer.php?file...hs-5-muxes.jpg

Mux A in greater close up detail is shown in
http://tubeimage.com/viewer.php?file...aths-Mux-A.jpg

Regards

Stephen

"Mallory" wrote in message
...
Yes I have, but Hunsbury Hill is in the way between me and Sutton
Coldfield.

I can get Oxford, but the trouble is it often gets trampled all over from
Wenvoe and Carmel's transmitters.

I often lose Mux A at the same time when S4C appears on top of Oxford's
Channel 6.

There is a fire station with a metal Telecoms mast between me and Waltham
so blocking my view of Waltham.

I have clear line of site to Sandy Heath, and can get Analogue Channel 5
here without too much trouble.

I already have TWO tetra filters in my system but still cannot get Mux A
from Sandy Heath.

Have youn tried actually pointing a suitable aerial at Sutton Coldfield
to see whether you can get the digital muxes from there rather than
Sandy Heath?
--
Cheers,
Roger

Now for the Triax Unix 52 array aligned to Sandy Heath....

The as measured Analogue signal strengths a (Tx power is 1,000kW)

Ch 21 Channel 4 44.5 dBµV
Ch 24 ITV 46.4 dBµV
Ch 27 BBC 2 53.45 dBµV
Ch 31 BBC 1 51.76 dBµV
Ch 39 Channel 5 13.25 dBµV

The digital Mux strengths a (TX power is 20kW for all 6 muxes, so 17dB
down on analogue)

Ch 40 Mux C 14 to 18dBµV with a single spike in it at 21dBµV
Ch 42 Mux 1 13.5dBµV
Ch 43 Mux A 7 to 12 dBµV across Mux A with a single spike in it at
20.9dBµV
Ch 45 Mux 2 10 dBµV
Ch 46 Mux D 7 to 12dBµV with a single spike in it at 24.6dBµV
Ch 67 Mux B 12 dBµV

The noise floor appears to be -10dBµV (yes negative) and the digital muxes
are over 30dB down on the big four analogue TV channels which is more than
would be expected for Sandy Heath. Mux A is over 30dB down alone vs analogue
and about 8dB to 12dB down when compared to the 2 lots of adjacent muxes.

When I was on this array, I could not recieve Muxes C or D in addition to
Mux A, hence the reason I tried a pair of Log periodics

The three spikes in Sandy Heath's Muxes C, A and D are the Sutton Coldfield
Analogue (204º off axis)

Muxes C,1,A,2 and D at Ch's 40, 42, 43, 45 and 46 and the three spikes are
shown in
http://tubeimage.com/viewer.php?file...andy-Heath.jpg

Ever since I fitted the pair of log periodics, reception of Mux C and D is
now robust compared to the Triax Unix 52. However I still continue to have
problems with Mux A.

It is interesting to note that on BOTH the Log Periodic and on the Triax
Unix 5, that Mux A appears to be weaker than Muxes C, 1, 2 and D and also
appears to reduce in power across itself, its as if there is a null
somewhere between the transmitter and the Spectrum analyser.

The two aerial arrays are on two seperate poles each with seperate downleads
and the Mux A problem is common to both, so does anyone have any ideas on
whats causing the Mux A problems?

Regards

Stephen

"Mallory" wrote in message
...
Yes I have, but Hunsbury Hill is in the way between me and Sutton
Coldfield.

I can get Oxford, but the trouble is it often gets trampled all over
from Wenvoe and Carmel's transmitters.

I often lose Mux A at the same time when S4C appears on top of Oxford's
Channel 6.

There is a fire station with a metal Telecoms mast between me and
Waltham so blocking my view of Waltham.

I have clear line of site to Sandy Heath, and can get Analogue Channel 5
here without too much trouble.

I already have TWO tetra filters in my system but still cannot get Mux A
from Sandy Heath.

Have youn tried actually pointing a suitable aerial at Sutton Coldfield
to see whether you can get the digital muxes from there rather than
Sandy Heath?
--
Cheers,
Roger

"Mallory" wrote in message
...
This comprises a Wideband Triax Unix 52, followed by a Antiference UBF1
bandpass filter (blocks Tetra and GSM), followed by a Maxview MHA23US
masthead amplifer (23dB gain, Noise figure is 2.0dB).

This then feeds a 3 input (all 3 inputs have individual gain controls)
Antiference ATA3MP headend which then combines this with the DAB aerial
and an FM aerial. The gain for the UHF input is set to minimum. The gain
for DAB and FM aerials is set to around 20dB

Comments welcome....

So the masthead amp lifts the signals 23db and adds noise, then the signals
are attenuated 20dB in the ATA3MP. So you've added noise for no reason. If
you really need a masthead amp use one with the lowest gain possible.

The reality is that the ATA3MP will be adding a lot of noise as well. The
'gain' control will be at the front end I expect.

Any system with more than 6dB of attenuation is a design failure.

Personally I'd design this around the signal level I could get from UHF, and
make the VHF fit in. You're doing the opposite.

Bill

"Mallory" wrote in message
...
Muxes C,1,A,2 and D at Ch's 40, 42, 43, 45 and 46 are shown in
http://tubeimage.com/viewer.php?file...hs-5-muxes.jpg

What's the response notch centred on 652MHz then? It's right across that
part of the band. I've seen that effect when there's been a big tree in the
way, but not at this time of year. The whole thing looks a bit crap really.
If you can put the analyser on 'store' and leave it for a few minutes you
might get a clearer picture.


Mux A in greater close up detail is shown in
http://tubeimage.com/viewer.php?file...aths-Mux-A.jpg

Fairly obvious analogue CCI.

Bill

Given that my analogue signals from Sandy Heath were low on both the Log
periodic and the Triax Unix 52, I then fitted a bandpass filter followed by
a masthead amplifier and the big four analogue channels are now in the
region of 70 to 75dBµV. The digital muxes should therefore be around 20 to
25dB lower, giving 50 to 55dBµV

I then repeated the spectrum analysis for Group B, taking in Ch's 38 to 47
inclusive. This was done so each channel fits nicely with the black vertical
markers:

The signal levels thus a

UHF 40 Mux C 39dBµV
UHF 42 Mux 1 34dBµV
UHF 43 Mux A 20 to 30dBµV with a spike at 36dBµV
UHF 45 Mux 2 30 to 36dBµV
UHF 46 Mux D 36dBµV

The image is at
http://tubeimage.com/viewer.php?file...plifcation.jpg

So why is Mux A at around 10 to 20dB down when compared to the other 4 muxes
considering when all 5 are Tx'ed at 20kW from Sandy Heath?

I can't really use more amplication as the analogue channels would start
going above 80dBµV and causing overloading/intermodulation problems........

any comment?

Stephen






"Mallory" wrote in message
...
Now for the Triax Unix 52 array aligned to Sandy Heath....

The as measured Analogue signal strengths a (Tx power is 1,000kW)

Ch 21 Channel 4 44.5 dBµV
Ch 24 ITV 46.4 dBµV
Ch 27 BBC 2 53.45 dBµV
Ch 31 BBC 1 51.76 dBµV
Ch 39 Channel 5 13.25 dBµV

The digital Mux strengths a (TX power is 20kW for all 6 muxes, so 17dB
down on analogue)

Ch 40 Mux C 14 to 18dBµV with a single spike in it at 21dBµV
Ch 42 Mux 1 13.5dBµV
Ch 43 Mux A 7 to 12 dBµV across Mux A with a single spike in it at
20.9dBµV
Ch 45 Mux 2 10 dBµV
Ch 46 Mux D 7 to 12dBµV with a single spike in it at 24.6dBµV
Ch 67 Mux B 12 dBµV

The noise floor appears to be -10dBµV (yes negative) and the digital
muxes
are over 30dB down on the big four analogue TV channels which is more than
would be expected for Sandy Heath. Mux A is over 30dB down alone vs
analogue
and about 8dB to 12dB down when compared to the 2 lots of adjacent muxes.

When I was on this array, I could not recieve Muxes C or D in addition to
Mux A, hence the reason I tried a pair of Log periodics

The three spikes in Sandy Heath's Muxes C, A and D are the Sutton
Coldfield Analogue (204º off axis)

Muxes C,1,A,2 and D at Ch's 40, 42, 43, 45 and 46 and the three spikes are
shown in
http://tubeimage.com/viewer.php?file...andy-Heath.jpg

Ever since I fitted the pair of log periodics, reception of Mux C and D is
now robust compared to the Triax Unix 52. However I still continue to have
problems with Mux A.

It is interesting to note that on BOTH the Log Periodic and on the Triax
Unix 5, that Mux A appears to be weaker than Muxes C, 1, 2 and D and also
appears to reduce in power across itself, its as if there is a null
somewhere between the transmitter and the Spectrum analyser.

The two aerial arrays are on two seperate poles each with seperate
downleads and the Mux A problem is common to both, so does anyone have any
ideas on whats causing the Mux A problems?

Regards

Stephen

"Mallory" wrote in message
...
Yes I have, but Hunsbury Hill is in the way between me and Sutton
Coldfield.

I can get Oxford, but the trouble is it often gets trampled all over
from Wenvoe and Carmel's transmitters.

I often lose Mux A at the same time when S4C appears on top of Oxford's
Channel 6.

There is a fire station with a metal Telecoms mast between me and
Waltham so blocking my view of Waltham.

I have clear line of site to Sandy Heath, and can get Analogue Channel
5 here without too much trouble.

I already have TWO tetra filters in my system but still cannot get Mux
A from Sandy Heath.

Have youn tried actually pointing a suitable aerial at Sutton
Coldfield to see whether you can get the digital muxes from there
rather than Sandy Heath?
--
Cheers,
Roger

On Mar 26, 2:35 am, "Mallory" wrote:

So why is Mux A at around 10 to 20dB down when compared to the other 4 muxes
considering when all 5 are Tx'ed at 20kW from Sandy Heath?

Don't assume that all six muxes from Sandy are omni-directional, and/
or they share the same HRP template. ERP might well be 20kW, but in
the case of directional transmissions this is often just the maximum
lobe.

Unfortunately the broadcasters seem to want to keep exact HRP data for
TV transmissions out of the public domain (unlike HRP data for
commercial radio transmitters, which is readily available on the Ofcom
web site)

"Mallory" wrote in message
...
I now have an Advantest Spectrum analyser on loan to me.

This is the 1st part of three news postings I am doing, the other two will
relate to my Mux A problems from both of my Sandy Heath aerial arrays....

To recap, I have three seperate Aerial arrays here at my house in
Northampton

The one I end up using all the time is the one aligned to Oxford.

This comprises a Wideband Triax Unix 52, followed by a Antiference UBF1
bandpass filter (blocks Tetra and GSM), followed by a Maxview MHA23US
masthead amplifer (23dB gain, Noise figure is 2.0dB).

This then feeds a 3 input (all 3 inputs have individual gain controls)
Antiference ATA3MP headend which then combines this with the DAB aerial
and an FM aerial. The gain for the UHF input is set to minimum. The gain
for DAB and FM aerials is set to around 20dB

The output of this then feeds a Triax TMS5x16P multiswitch and then onward
to 16 outlets around the house. A Sky Quattro LNB hangs off this
Multiswitch.

Each wall outlet is a Labgear PSF410 Quadruplexor that then provides four
outputs, FM, DAB, UHF and SAT from the single downlead

Heres the web address for the spectrum analyser output at the TV wall
socket for 470MHz to 860MHz

http://tubeimage.com/viewer.php?file...l-Spectrum.jpg

Reading from left to right, the 1st 3rd of the image is Sandy Heath's
Analogue along with Oxford's Mux 1 and D.

The middle 3rd is Hannington's analogue as well as Oxford Mux C at UHF 48

The right 3rd is Oxford's analogue. as well as Oxford Muxes A, B and 2 at
Ch's 51, 52 and 68.


The Oxford analogue channels are coming out as:

BBC1 62.5dBµV
BBC2 69.8dBµV
ITV 66.3dBµV
Ch 4 69.8dBµV
Ch 5 64dBµV
Oxford Ch 6 57.6dBµV

The digital muxes are coming out as:

Mux 1 56dBµV
Mux 2 51dBµV
Mux A 44dBµV
Mux B 44dBµV
Mux C 47dBµV
Mux D 55.46dBµV

The main problems I have with Oxford:

All 6 analogue TV channels are very noisy so obviously a poor S/N ratio
rather than inadequate signal levels. The noise floor seems to be around
20dBµV.

I have not yet worked out how to measure analogue C/N or S/N ratio on the
analyser so thats why I have given the noise floor level in case someone
is able to work out what my analogue C/N or S/N ratios are.

All Freeview channels are rock steady except for adverse weather
conditions. details given below.

Mux A and Oxford Ch 6 get trampled all over by Wenvoe (42º off axis) and
the Big 4 analogue get trampled by Carmel (58º off axis) during certain
weather conditions.

Hannington Analogue (9º off axis), and Sandy Heath (101º off axis) are
coming in as well via the Oxford array. I know I could use a group C/D
filter, but Muxes 1 and D are in Group A.....

Comments welcome....

Two more postings to follow....

Stephen


"Mallory" wrote in message
...
Yes I have, but Hunsbury Hill is in the way between me and Sutton
Coldfield.

I can get Oxford, but the trouble is it often gets trampled all over from
Wenvoe and Carmel's transmitters.

I often lose Mux A at the same time when S4C appears on top of Oxford's
Channel 6.

There is a fire station with a metal Telecoms mast between me and Waltham
so blocking my view of Waltham.

I have clear line of site to Sandy Heath, and can get Analogue Channel 5
here without too much trouble.

I already have TWO tetra filters in my system but still cannot get Mux A
from Sandy Heath.

Have youn tried actually pointing a suitable aerial at Sutton Coldfield
to see whether you can get the digital muxes from there rather than
Sandy Heath?
--
Cheers,
Roger






Why don't you just abandon analogue, and concentrate on the DTT from Oxford?
Going by your results, there's not much hope for a decent MuxA from anywhere
else, so why not start again (with Oxford in mind) with something a bit
better than a wideband high gain and too much amplification? You could move
the array to maximise shielding from other transmitters. What about a nice
LP with a lower gain masthead amplifier or a GRP A and GRP C/D with low gain
mastheads, combined, then into some channel fiddlers to cherry pick & level
the Oxford DTT channels. Would clean up a lot of noise at the same time.

As Bill said it's a bit silly to whack up the signals with a 23db masthead,
then put them through another launch amp with max attenuation, then into the
multiswitch. The Antiference amp probably adds about 6db of noise?