Question Freeview signal levels

WhiteEyedGecko

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My freeview reception on the HD channels were a bit spotty. Level/Strength of 30 and Quality of 100 but often going blocky.

I've just had my aerial changed by a professional from a 10 year old grouped one to a high gain wideband with 4G filter.

My levels on HD channels are now level of 70, quality of 100 but my SD channels on Channel 59 are now a level of 44 and quality of 100. Previously these had a level in the 90s.

Is this something to be concerned about? It seems levels have switched.
 
Location (where do you live)?
Transmitter (which one do you receive)?
Exact aerial make/model? (Hopefully on the invoice)
Where is that aerial (roof: chimney/gable end/gutter; loft)?
What is the outlook towards the transmitter from the aerial position (trees, tidal estuary, hills, I see the transmitter mast/lights)?
Any splitters or amplifiers in the chain?
What make/model receiver are you using for the level metering (they all work differently).

BTW <High gain> and <wideband> is an oxymoron... You must trade gain for wider bandwidth. Gain (curves), Again
 
Location (where do you live)?
North Tyneside

Transmitter (which one do you receive)?
Pontop Pike

Exact aerial make/model? (Hopefully on the invoice)
Edit: It's a Fracarro Lp45F periodic log 4g filtered

Where is that aerial (roof: chimney/gable end/gutter; loft)?
Roof height outside on a pole

What is the outlook towards the transmitter from the aerial position (trees, tidal estuary, hills, I see the transmitter mast/lights)?
Clear skies but trees either side.

Any splitters or amplifiers in the chain?
None.

What make/model receiver are you using for the level metering (they all work differently).
Sony Android TV

BTW <High gain> and <wideband> is an oxymoron... You must trade gain for wider bandwidth. Gain (curves), Again

Replies in quote above.
 
Last edited:
Fracarro website indicates it is a log periodic with gain of 10-11dBi (dB ref an isotopic radiator - a theoretical figure used to give a higher number) and that is over the entire old UHF bandwidth (21 to 69). That would be about 8dB ref a dipole (dBd which is a real world, measurable, number and the typical gain figure for any log periodic aerial).

So, that suggests to me, that your 4G filter was an extra device added to the system? Is this accessible to you? Can you remove it from the aerial cable easily? If 'yes' then please do so and repeat the signal level measurements and look for any reception problems.

4G filters are rarely needed. Only if in close proximity to a 4G transmitter, in a fairly weak signal location, and it is in nearly the same direction as the wanted transmitter. 4G would usually affect the highest frequency muxes in the absence of amplification overload... Which would be ch 59 from Pontop.
4G filters come in two flavours: rolling off above frequency ch 60, and above ch59. The 59 variety could well reduce the wanted mux level by a decent amount (oops) even though it is the correct one for Pontop Pike. For example, Filter LTE 5...782MHz 59 channel | Televes has a loss of 6dB at the top end, cf 1dB at lower frequencies.

Do you know you are likely to suffer 4G interference? i.e. Have AT800 written to you? Have they supplied the filter? If no, then I see no reason to require the filter at all! (NB modern aerials are being designed to roll off above ch60 and/or have filtering included.. See the group T aerial on ATV's curves.)

NB Pontop Pike transmits ch58, 54 & 49 @ 100kW; ch 59, 55 & 50 @ 50kW (-3dB); ch 33 &34 @ roughly 34kW (-5dB) and local TV on ch 56 @ 5kW (-13dB).
I would expect all frequencies with the same transmit power should be roughly the same signal level, but there will be differences in the numbers due to the transmitted power levels, of course... and the additional effect caused by the 4G filter perhaps? Quality is usually more important the signal level per se. But I'd be happier to see figures of 60%+ wherever possible.

Check the levels on all received mux frequencies and post the results: with the 4G filter in circuit and again with the filter removed. This might show that the figures you have for ch49 (70) cf ch59 (44) are just how your TV reacts to the signal level presented... or not.

NB if the filter is not accessible (e.g. on the masthead), then you'll need to call back the installer to discuss removal... it can always be re-located to indoors should 4G interference be a real issue at your home. {If it's built into the antenna (aerial) now, in a design update, you'll be stuck with it - but the installer may still be able to do something to improve the signal level on ch59 if required.}
 
The 4G filter is built into the design (it's a new revision) so I wouldn't be able to remove it.

As I said, on the old aerial HD channels such as BBC News HD was on a strength of 30ish but quality was 100. Now, they are on 70ish with the new aerial but the channels that used be in the 90s for strength are in the low 40s such as BBC1 SD etc
 
Give me all the measured numbers and I'll be pleased to comment more on how reasonable they look.

LOCATION would help (knowing how far from Pontop you are) to estimate how strong the signal might be. Not precise, just village/suburb name will do.

Fracarro's UK website has the LP45F LTE... which is designed for 21-60 (LTE being another name for 4G signals). See http://www.fracarro.co.uk/index.php/en/dj-list?format=raw&task=download&fid=1620
That frequency response curve suggests it has no significant loss at ch 60 (f = 786MHz =/- 4MHz) compared to any lower frequency (+2dB max difference). So THAT (new aerial design) is not the cause of any major difference in level. But ch59 is -3dB on transmit power, so must be less than 70... but how much?? {I need the metering numbers for all mux frequencies to determine that!}.

Obviously the older grouped (C/D) aerial gave your set much more signal at ch 59 than the new log does; but also a much worse signal at ch 49... Whether this was due to damage (most probable imo) or simple aging we can't tell.

At the end of the day if there's no reception difficulties now (@ 44 signal strength) it may just be how the TV metering is. Personally, I'd be putting an aerial attenuator or two in line (as a test) to see how close to the digital cliff edge those signals are. If -6dB is still 100% reliable I'd be happy. -10dB, happier still. If 6dB attenuation stops reception, the "I'm in trouble" - well you, rather than me ;) actually.
 
Here we go:

Channel # Signal Strength / Quality

33 71-73 / 100
34 85-86 / 100
49 91 / 100
50 86-88 / 100
54 90 / 100
56 63-65 / 100
58 60-63 / 100
59 43-44 / 100

Location: North Shields, Tyne and Wear
 
ch sig erp(kW) - mode
33 71-73 / 34 - T2
34 85-86 / 34 - T2
49 91 / 100 - T2
50 86-88 / 50 - T
54 90 / 100 - T
55 63-65 / 50 - T (?? 55, I assume 56 is a typo ?? 56 is the local TV mux)
56 ......... / 5 - T ???
58 60-63 / 100 - T
59 43-44 / 50 - T

Those numbers don't look 100% right. Although the only one that is especially worrying is the ch 59 figure being so low cf all the others. So that suggests to me that the receiving aerial may need some fine-tuning position-wise.

It is quite common to find that signals are diffracted off ridges, reflected off water or other foreground land and through or off trees. This results in signals being cancelled out or reinforced on certain frequencies. This can mean, say, that ch59 signal level is reduced cf 58 (NB any other sets of frequencies can be affected the same). Aerials need adjusting higher/lower; crabbed left/right and fore/aft to find the 'sweet spot' where all the frequencies are at more or less the same level (allowing for the emitted power differences). A cranked pole will enable this in most installs. It does take time and need a lot of repetitive measurements (although a graphic display on a spectrum analyser can speed things up).

{Did the installer use a signal meter and/or spectrum analyser display to check all muxes were received at the correct levels? Did (s)he comment on any results observed at all?}

Location: North Shields, Tyne and Wear
26km from the transmitter so not especially near, nor far away. Wolfbane is down at the moment so I can't do a field strength estimate and path profile plot to (say) the Post Office.

It may be worth just going over any hand-made aerial connection(s) with a fine toothcomb... a stray whisker near the centre conductor can give odd frequency-dependent results. If there's a thin moulded-plug type fly-lead between wallplate and TV see if an alternative one gives different results.

Also disconnect and power off any hdmi-connected kit (take out both ends of the cables) to eliminate the (extremely) slight possibility of an interfering signal giving the anomalous reading of signal level on the TV.

If the above makes no difference, do consider using an attenuator to find how much signal you have in hand before losing ch 59 reception. That may give reassurance the signal is good enough, or an incentive to call the installer back to improve it.

Do or did you get any signal at all from Local TV on ch 56? LCN 7 Made In Tyne & Wear ? either with this aerial or with the old one?
 
If those numbers are for the 5kW ERP mux, what do you get for the ch55 com mux which has been omitted? (Mind you

IF 5kW is giving that level, then the 50kW on ch58 and 59 numbers suggest the gain is plummeting like a stone at 57/58 and upwards! Something is seriously wrong if the Fracarro data sheet is to be believed.

Both aerials is a new bit of information - please elaborate.
 
If those numbers are for the 5kW ERP mux, what do you get for the ch55 com mux which has been omitted? (Mind you

IF 5kW is giving that level, then the 50kW on ch58 and 59 numbers suggest the gain is plummeting like a stone at 57/58 and upwards! Something is seriously wrong if the Fracarro data sheet is to be believed.

Both aerials is a new bit of information - please elaborate.

I meant I got the local TV with both my old and new aerial :) sorry
 
If those numbers are for the 5kW ERP mux, what do you get for the ch55 com mux which has been omitted? (Mind you

IF 5kW is giving that level, then the 50kW on ch58 and 59 numbers suggest the gain is plummeting like a stone at 57/58 and upwards! Something is seriously wrong if the Fracarro data sheet is to be believed.

Both aerials is a new bit of information - please elaborate.

I noticed my Sony TV had LNA on. If I turn it off all the levels jump up BUT 59 is now only 55-68 quality and constantly fluctuating, so you may be right on things not looking right before.
 
Sony LNA (low noise amplifier?) aka a booster built in. Not much info on it as a feature via a google, although it appears default is ON.

What are levels/quality showing on all muxes with it off?

Note that quality (received errors) fluctuating is not necessarily a problem (depends where and how the TV measures and display this information). {Some measure before the receiver's error correction circuitry has done its work, and others after. How Sony do it is an unknown.}
 
With LNA off:

Channel # Signal Strength / Quality

33 64-67 / 100
34 72-74 / 100
49 83 / 100
50 76 / 100
54 83 / 100
56 49-51 / 100
58 67-69 / 100
59 40-42 / 49-85 (up and down a lot on quality)
 
Jeez. Arq A (59) only 3dB down on BBC A (58) at the transmitter. 50kW v 100kW (Pontop)

But the received signal is 17 (Post#7) or 27 (post#14) down v ch58. How can that happen on adjacent channels?

I realise that the numbers posted are not necessarily scaled as dB, but its an awful drop.
It appears that your Sony TV has a better sig strength indication than mine, as it gives a 100% sig strength until it falls off the cliff. More like a post error correction reading.
 
OK thanks for the number to summarise the LNA on/off figures:

COM7: ch 33 -5dB: on 71-73 / off 64-67
COM 8: ch 34 -5dB: on 85-86 / off 72-74
BBC B: ch49 0dB: on 91 / off 83
SDN: ch 50 0dB: on 86-88 / off 76
D3/4: ch 54 0dB: on 90 / off 83
ARQ B: ch55 -3dB: NO RECEPTION ??? (at least no numbers given - why not? Pick, Dave, Really, TruTV, Sky News, + others are on this mux)
L-NE: ch 56 -13dB: on 63-65 / off 49-51
BBC A: ch 58 0dB: on 60-63 / off 67-69
ARQ B: ch 59 -3dB: on 43-44 / off 40-42 (Q varying).

LNA off has dropped level (as one would expect) on all except ch58 which has increased a bit, and introduced an issue with quality on the more reduced signal ch 59.

Post#1 said the old group C/D aerial gave 30 level on out of band COM7/8 but 90s for the other channels (L-NE excepted in all probability). So those frequencies do work OK with a suitable aerial.

Other than the ARQB (lack of measurements), if all accessible plugs and sockets have been checked over and are good I can only recommend calling the installer (back). Something just isn't right (it may be a standing wave issue - cancellation/reinforcement referred to in my post #8)? But I can't think of anything else obvious at the moment {Unless installer fitted one of those add-on LTE/4G filters with 6dB loss at top end as well as the one in the aerial design/balun/connection box.}
 
Sorry,

55 is 65 strength and 100 quality with lna off. I'm going to speak to the installer tomorrow about it.
 

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