Samsung and Freeview

mubdigit

Novice Member
Might be a well asked question, since I can't be the only one!

We have a multi outlet spidering from the loft amp into 4 outlets, from which 2 are split 4 ways to multiple outlets around the home. We have previously tested all the outlets and noise levels well within the limits. However, recently, CH35 (Winter hill) and a few select or mux's have dropped, particularly Freeview HD. The funny thing is that the old Samsung TV (2018) in the play room continues to received the channels, and will receive them when connected to other outlets. All the other TV's are Samsung but are newer models (2019/20/21) and all refuse, except for a very brief moment, to receive CH35 at all.

Since I've stripped and tested all combinations of connections, its not the cabling internally, but must be the aerial masthead out of alignment or similar (maybe even the old protected Oak tree out front has gotten a little top heavy). However, anyone else noticed the Samsung DVB-T1/2 tuners becoming more 'picky'?
 

Rodders53

Distinguished Member
Noise levels is actually very tricky to measure and expensive Pro metering is needed - what did you use?

BUT location is key (ideally a postcode within 100m of your home of a shop/pub/church etc.,.).
Then what aerial (for the gain and directivity curves)?
Where is it sited (outside, loft)?
How old is it?
What masthead amp (make/model for gain/noise figs) and where located? How is it powered?
What 4-way splitter distribution in the loft (make/model) and what is the make/model of the other two 4-way splitters?

Passive 4-way splitting is -8dB cf the input. Cascading amplifiers is never ideal due to the added noise, so if you have three amps in series... ?

Possibly overload?????? Rare but not unknown.
What do the different TVs' tuners report on f.ch35 and a few other multiplex frequencies for signal level and quality / error rates?

Trees can and do affect reception. With leaf-fall reception may well change for the better if it's the problem. It's sometimes possible to relocate an aerial to miss the tree(s) or to see the transmitter from underneath the canopy (i.e. lower down) rather than going higher to see over.

Winter Hill until recently was group C/D and is now group A (apart from the temporary HD COM 7 on f.ch55 and one Local TV mux on 40). This may (or may not be relevant.
 

mubdigit

Novice Member
Postcode: CW57BQ

The aerial itself I can't speak too, sited on the roof on a mast well above the roofline (3 story house). No masthead amp, aerial feeds into a slx4b, two of which output to sac 4-way splitters, other two outputs are direct to face plates.

Yes originally it was a noise problem! previous owner cascaded several amps. Removed those and left the slx4b in place which was sufficient (back then) to provide db well within the bounds. checked at the face plates as well).

Different TV's for f.ch35, older Samsung 2018 gives 90+% signal, quality ~50%, bit error rate 0. All newer devices pretty much 0%/0% on f.ch35. This is in every combination! directly connecting the cable to the amp, disconnecting all other outputs from the amp, etc. (Even moving the old Samsung to other rooms to check the cable into the face plate from the amp, with and without the splitter intervening, same result).

At this point I really am pointing the finger at the aerial alignment or the tree, other indications its that are testing late last night, I did manage to get a newer Samsung to discover f.ch35, badly, but it wasn't flat lining 0%, just intermittent.

As such, I'll ask an old neighbour (old radio/aerial guy) who doesn't mind the heights to align and check the damn tree.... leaf coverage would explain it being gradual and never noticing the lack of HD.

Just curious if others have noticed gradual reduction in Samsung's DVB tuners over time, as every newer model refuses to pick up f.ch35...
 

Rodders53

Distinguished Member
Wolfbane suggests clear line of sight an 42dBuV/m field from Winter Hill (old C/D frequencies tho). So allow 10dB aerial gain = 52dB - amp gain 11dB = 63 dB:
Cable and termination losses say -2dB = 60-61 dB on amplifier outlet fed to sets.
Receivers need between 45 and 65 dB for reliable reception (CAI / Digital UK guidelines).
4-way split -8dB so 52/53 dB to those.
So the basics look good.

The 2018 having 50% quality worries me - suggesting there's a lot of correctable errors (giving 0 ber after correction)?

It may be enough errors to tip the newer ones into rejecting it as unusable?

Different tuners will have differing sensitivity, overload protection and ability to correct errors in the received signal data. The way the metering is shown will also differ, even in the same maker's range(s).

FYI my Humax pvr gives me 81%S and 100%Q on my HD mux... and if I rely on direct cable pickup by unplugging from the wallplate 31%S with 100%Q still. I am close-ish to Sandy Heath though and room aerials work well in the bedrooms.
I've even had a look at a bedroom Panny that has a bit error rate indication. That too is 100%Q unless I really mess with the aerial and it'll drop to 60% - but still with 0 ber, after correction.

What numbers do yours give on f.ch 32 (BBC SD) and 34 (ITV/C4 SD) and the other SD channels? Do you get anything on f.ch55

Any idea on age of aerial? Old enough it would have been C/D grouped. A few might work OK at group A but most won't? Wideband / grouped TV aerials - A.T.V. Poles, Brackets, Clamps & Aerials

A picture of it (as close as possible via a zoom lens) or identifying its' style from a site like ATV aerials would be next best.

Certainly worth discussing with your neighbour. He may even have access to a pro meter to help to diagnose the problem without climbing up to the aerial. Or remember when that aerial went up?

NB external aerials and cables will degrade over time by exposure to the elements (UV, hot/cold, wind and rain). They don't last forever.

It may also be worth taking one of the 'new/problem' sets to another aerial install (e.g. that neighbour, if willing) to tune in and store (then never retune again - disabling any auto update features! - to use as a test unit on your house distribution).

Finally The Wrekin (Central ITV) is also predicted to work at your location, but is approx 180 degrees off the bearing for Winter Hill. If the tree can't be avoided and is the sole cause of problems, then it might provide better signals?
 

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