Will DAT 75 get to the bottom of poor reception on ITV/C4...?

Recently had my old analogue aerial changed for a wideband digital
aerial. Also had omni FM and DAB aerials added to the mast. Got great
reception on BBC but pixellation and spluttering on ITV/C4 (on Reigate
or Crystal Palace). Have Wolsey 6-way amplifier in loft, BUT before you
ask, all the following problems are neither improved nor appreciably
worsened if i connect UHF downlead DIRECT to a TV set - i.e. bypass all
diplexing and amplification).

I noticed on a new Sony 20" LCD TV that the signal information showed
"Level" as green on BBC, amber on ITV/C4, but interestingly, the
post-Viterbi error was 0 on BBC but appreciable (10 to the minus 5) on
ITV/C4. Pre-Viterbi 10 to minus 6 on BBC, 10 to minus 2 on ITV/C4.

So, DAT 45 installed. Much improved but not yet right - still getting
intermittent pixelation. The 'level' is more green on ITV than amber,
but still getting limited post-Viterbi error (now 10 to minus 6, pre 10
to minus 3, compared with previous). Do i need to go the the 75?

Have tried a Tetra notch filter, no difference. All cables are foam
dielectric, double-screened, nickel plated brass screw connection coax
connectors.

Predictions for my OS location are 43 dBuV for Crystal Palace, 39 for
Reigate.

Help...! Thanks in advance!

In article .com,
wrote:
Recently had my old analogue aerial changed for a wideband digital
aerial. Also had omni FM and DAB aerials added to the mast. Got great
reception on BBC but pixellation and spluttering on ITV/C4 (on Reigate
or Crystal Palace).
Predictions for my OS location are 43 dBuV for Crystal Palace, 39 for
Reigate.

CP is HP, Reigate is VP - which way has the aerial been mounted?

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

Hi Charles, the aerial has the two reflectors opened out in the
vertical plane for Palace.

wrote in message
ups.com...
Hi Charles, the aerial has the two reflectors opened out in the
vertical plane for Palace.


?

Bill

What's your question Bill?

wrote:
Hi Charles, the aerial has the two reflectors opened out in the
vertical plane for Palace.

I don't understand what you mean.

For CP it needs to be mounted as in this pictu-

http://www.tlc-direct.co.uk/Images/P..._2/MXDAT75.JPG

For Reigate, turn through 90 degs (but not such that aerial points skyward !
:-) )



--
Mark
Please replace invalid and invalid with gmx and net to reply.

I guess it was the rather unique description of an aerial in the horizontal
position i.e.. with the reflector elements in a vertical plane whilst all
the directors were horizontal ?

Richard.

..
wrote in message
oups.com...
What's your question Bill?

Thanks folks, yes, it is indeed mounted as per the picture.

I don't know if this is relevant, but the signal 'level' fluctuates on
the ITV channels, but not on the BBC ones at all. (This happens on
either the Sony LCD or my Elgato EyeTV box on my apple mac.)

43dBuV is about 140uV absolute, 39dBuV is less than 100uV.

I may be wrong but didn't the BBC used to consider you to be covered
at 1mV (60dBuV) and fringe at 250uV (48dBuv)? Could just be plain old
lack of signal.

Also note that DTTV is more sensitive to phase error - signals that
would cause a ghost on analogue, although at the level required to
upset DTTV you probably wouldn't see it on analogue.


--
Woody

harrogate3 at ntlworld dot com

harrogate3 wrote:
43dBuV is about 140uV absolute, 39dBuV is less than 100uV.

I may be wrong but didn't the BBC used to consider you to be covered
at 1mV (60dBuV) and fringe at 250uV (48dBuv)? Could just be plain old
lack of signal.

Those figures are for analogue transmissions, and ISTR were contour field
strengths for 'primary' and 'fringe', therefore expressed as dBuV/m ?

For noise free analogue reception, most tuner's terminals need to have
delivered 60 dBuV. According to my DTG pocket book the minimum signal level
for reliable DTT reception is 35 dBuV (again as delivered to the tuner) ?

Of course carrier to noise ratio has to be considered if there are any
active devices between aerial and tuner for analogue and DTT situations ?


--
Mark
Please replace invalid and invalid with gmx and net to reply.