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AndersG
Posted: Fri Sep 28, 2012 8:22 pm Reply with quote
Joined: 23 Jul 2012 Posts: 21 Location: Åland Islands
Ie, when you hit the info button on a PVRc5100? There are two bars, "strength" on top and "quality" below. Normally I see the strenght one about 50% and quality 100%, but some days quality hovers between 50..75% and those days I see plenty of pixelation.

The manual says precious little about what those indicators indeed show, and what are to be regarded as normal values. Can someone enlighten me?
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alan_m
Posted: Fri Sep 28, 2012 9:19 pm Reply with quote
Frequent contributor Joined: 18 Oct 2006 Posts: 3511
AndersG wrote:
Ie, when you hit the info button on a PVRc5100? There are two bars, "strength" on top and "quality" below. Normally I see the strenght one about 50% and quality 100%, but some days quality hovers between 50..75% and those days I see plenty of pixelation.

The manual says precious little about what those indicators indeed show, and what are to be regarded as normal values. Can someone enlighten me?


The quality figure is the important one.

On a 5800/5810 a signal strength greater than 60% is OK

A QUALITY figure of less than 98% is likely to give unreliable reception. Ideally the quality figure should be rock solid at 100%.

In general the signal strength figure is a crude indication of the level of the signal reaching the tuner. The quality figure indicates the number of errors (or no errors) detected in the decoded digital signal.


Last edited by alan_m on Sat Sep 29, 2012 9:24 am; edited 1 time in total

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AndersG
Posted: Sat Sep 29, 2012 9:00 am Reply with quote
Joined: 23 Jul 2012 Posts: 21 Location: Åland Islands
Quote:
The quality figure is the indicates the number of errors (or no errors) detected in the decoded digital signal.


OK. So it basically indicates bit errors and they can be caused by a multitude of things.
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albertd
Posted: Sat Sep 29, 2012 9:15 am Reply with quote
Frequent contributor Joined: 01 Jul 2010 Posts: 574
Anders:

In your part of the world, you might sometimes be suffering from interference caused by reflections of distant transmitters anywhere in N. Europe by the aurora borealis.

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alan_m
Posted: Sat Sep 29, 2012 9:36 am Reply with quote
Frequent contributor Joined: 18 Oct 2006 Posts: 3511
AndersG wrote:
Quote:
The quality figure is the indicates the number of errors (or no errors) detected in the decoded digital signal.


OK. So it basically indicates bit errors and they can be caused by a multitude of things.


Yes

Local electrical interference from domestic equipment getting into poorly screened aerial leads. This can be minimised by using CT100 (equivalent) cable that has 100% copper screening. http://www.wrightsaerials.tv/articles/coax-cable-quality.shtml

Electrical interference from passing vehicles that have poor, or no, suppression on their electrical systems. Usually 'boy racers' on scooters or on 50cc bikes with exhausts modified to give the impression that it's a 200mph (322km/h) drag racing bike running on Nitro. Wink

In my part of the world often caused by the weather. A high pressure causing a lift and signals from my preferred transmitter going missing and those from distant transmitters appearing. Often it's just 1 or 2 MUXs that are affected.


The Signal Monitor TAP may work on your Toppy model
http://www.tapworld.net/index.php?option=com_content&task=view&id=318

A signal LEVEL of 50% may just be marginal and an aerial signal amplifier (low gain/low noise) may raise the signal level to a point where the quality figures are more stable. On the other hand, an amplifier may make no difference Sad
http://www.amazon.co.uk/PROception-Professional-digital-Amplifier-Booster/dp/B002GT7TBQ

http://www.blake-uk.com/downloads/pdf/catalogue/Blake%20UK%20and%20PROception%20Page%2026.pdf

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AndersG
Posted: Sat Sep 29, 2012 10:59 am Reply with quote
Joined: 23 Jul 2012 Posts: 21 Location: Åland Islands
Yes. This is a domestic CATV, installed less than 10 years ago. Everything in the house should be done per specs and the installation was checked (measured) before we moved in.

I am also suspecting some sort of interference, but we are on a quiet dead-end with no through traffic.

As you said, it is only the lowest mux at 130MHz that is affected and only so at weekends an evenings. Never during the daytime when the cable guy has been over to measure. I have rigged up a crude spectrum analyser, consisting of an old TV tuner that is swept at a rate of approx 6Hz over 100-160MHz, followed by a decoder and I can clearly see that the 130MHz mux is lower in amplitude than the other Muxes. This can be part of the problem as well,

I will try the TAP in our unit, never installed a single tap in my life though Smile

As for weather, Disturbances seem to coincide with rain, not high-pressure Smile
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alan_m
Posted: Sat Sep 29, 2012 11:33 am Reply with quote
Frequent contributor Joined: 18 Oct 2006 Posts: 3511
AndersG wrote:
Yes. This is a domestic CATV, installed less than 10 years ago. Everything in the house should be done per specs and the installation was checked (measured) before we moved in.

I am also suspecting some sort of interference, but we are on a quiet dead-end with no through traffic.

As you said, it is only the lowest mux at 130MHz that is affected and only so at weekends an evenings. Never during the daytime when the cable guy has been over to measure. I have rigged up a crude spectrum analyser, consisting of an old TV tuner that is swept at a rate of approx 6Hz over 100-160MHz, followed by a decoder and I can clearly see that the 130MHz mux is lower in amplitude than the other Muxes. This can be part of the problem as well,

I will try the TAP in our unit, never installed a single tap in my life though Smile

As for weather, Disturbances seem to coincide with rain, not high-pressure Smile


99.9% of the posters to these forums are in the UK and own a 5800/5810 terrestrial TV box with the input via an aerial/antenna (470 to 850Mhz)

Is your box cable or satellite? If either ignore the advice about an amplifier.

Rain fade is usually associated with satellite reception and often the only way of improving the situation is a larger dish. If there is a recent degradation of performance it may indicate that the dish may have moved slightly.

Installing a TAP
http://www.toppy.org.uk/documents/Installing%20TAPs%20-%20Windows.pdf

On a Topfield installing a TAP is simply copying the TAP file (and maybe some support files) across to the Toppy's hard disk.

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Geoff Bacon
Posted: Sat Sep 29, 2012 11:54 am Reply with quote
Frequent contributor Joined: 12 Jan 2007 Posts: 4422
water in the lead from aerial/dish to toppy?

Geoff

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albertd
Posted: Sat Sep 29, 2012 12:37 pm Reply with quote
Frequent contributor Joined: 01 Jul 2010 Posts: 574
I think we are talking about a cable system here, bearing in mind the references to a Mux at 130 MHz - nowhere in the world has over the air TV at that frequency as it is bang in the middle of the globally used aircraft communications band. Also Anders mentioned CATV.

So the thoughts we have been having about aerial/dish problems and various forms of interference probably do not apply.

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AndersG
Posted: Sat Sep 29, 2012 1:12 pm Reply with quote
Joined: 23 Jul 2012 Posts: 21 Location: Åland Islands
Quote:
I think we are talking about a cable system here,


Yes. I also said PVR5100c Smile That ia a DVB-C unit.

Edit:
Tried the tap, but it did not work so I assume it si not compatible with the 5100


Last edited by AndersG on Sat Sep 29, 2012 1:40 pm; edited 1 time in total
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juwlz
Posted: Sat Sep 29, 2012 1:16 pm Reply with quote
MyStuff Team Joined: 12 Aug 2005 Posts: 10802 Location: Wokingham, Berkshire (Hannington transmitter)
AndersG wrote:
Yes. I also said PVR5100c Smile That ia a DVB-C unit.
You did, but that doesn't mean much to most people on this forum, who are only familiar with the 58xx Freeview models.

Julie

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AndersG
Posted: Sat Sep 29, 2012 1:41 pm Reply with quote
Joined: 23 Jul 2012 Posts: 21 Location: Åland Islands
Quote:
You did, but that doesn't mean much to most people on this forum, who are only familiar with the 58xx Freeview models.


OK. Sorry about that. I saw posts here from people all over the world, regarding all sorts of topview units.
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AndersG
Posted: Mon Oct 01, 2012 9:06 am Reply with quote
Joined: 23 Jul 2012 Posts: 21 Location: Åland Islands
Anyway. For the lurkers.... The installation is done as a star topology, with 12-15dB attenuation at the hub and 1dB at the wall socket. The bloke that installed originally had installed two four-way splitters, one with a -3dB passthorugh. When I looked at the input signal:


Ie, the muxes are distinct and well formed. But after the splitter:



Ie, the signal is attenuated 15,5dB as it should, but the frequency response is off. Took out that splitter and used the other one, alone. Signal looks a lot cleaner now.

I have not ruled out external interference though so I have an old 14" TFT TV that can tune the analogue range and, lo and behold, has a scale in MHz! It is now set to 130MHz on preset 99, so I can check there,if and when, I have problems next time.

Lesson learned: Never assume something is right, just because you paid someone to do the job. Never assume something is OK, even if it once was Smile
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alan_m
Posted: Mon Oct 01, 2012 11:48 am Reply with quote
Frequent contributor Joined: 18 Oct 2006 Posts: 3511
AndersG wrote:
Lesson learned: Never assume something is right, just because you paid someone to do the job. Never assume something is OK, even if it once was Smile


Often splitters don't give the correct results if the unused outputs are not terminated correctly with (75 ohms???). Unused outputs should be fitted with a terminating load.

http://www.ebay.com/itm/Lot-10-F-TYPE-75-Ohm-TERMINATOR-75Ohms-Coax-/360294264240

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AndersG
Posted: Mon Oct 01, 2012 12:48 pm Reply with quote
Joined: 23 Jul 2012 Posts: 21 Location: Åland Islands
Good point, yes. But they were. Terminated that is. I have now obtained a new 8-port splitter and intend to bring order to the snake-nest Smile
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