Sat Signal strength vs Signal quality

[joidevie]

Sat box model METRONIC Touchbox

I've been happily using this in Aude 11 (very South) for two years - sometimes even just popping the dish on a deckchair and tuning in..

I now have it permanently high on a pole and all has been fine for a year or so. On this visit it has begun to break up frequently.. Working fine for a week, now almost dead to the point where an 'auto tune' yields only 12 (rubbish) channels.. I tweaked the dish and got it running at 70-75% signal "strength" (higher than I've had in the past) but am getting a woeful10-30% signal "quality" and no real channels.

I used to be able to tune in so easily!

What is the difference between "strength" and "quality"? The quality seems to vary a bit if i fiddle with the coax connections, but not enough to mak a difference.. Things were deteriorating already, but I did clip the exterior coax to the wall recently.. Coincidence I hope?

Thanks for any suggestions..

[Martin963]

Signal strength tells you very little.   I've often had full strength with the LNB awaiting installation on the dish,  just wired up and lying on the ground.

Signal quality is generally assessed by measuring the number of errors in a given quantity of incoming symbols;  I imagine that's done by counting the number of parity bits that don't tally (putting it simply).   So it is a very accurate indication of how you're doing.

I don't know why you've suddenly got a problem - any trees sprouted recently?   Water ingress into the cable?   Cable clipped too tight?

[joidevie]

No trees here! I'm just reading some other threads which talk of different "clusters" of sats - maybe I 'tweaked' off the important one..

Clips not too tight, how fragile is coax?

[Onion van man]

I have known a tight kink in coax cable to cause a problem. Check it for kinks etc. I changed the coax on my aerial for a better grade and got a much better  signal to noise ratio. Which enabled me to recieve more channels than I could beforehand.

I don't know very much about sat dishes but, I know the cable quality can have an effect.

[Martin963]

You normally have to have quite bad luck to align onto "only" one bird in a cluster.   But it couldn't be it that you've strayed right off Astra 2 cluster and are looking at Astra 1 or Hotbird clusters,  could it?   In addition,   have you twisted your LNB a little clockwise as viewed from the south side of the dish?  It isn't much,  about 20 - 30 deg but it can make a huge difference.

[SC]

[quote user="joidevie"]Sat box model METRONIC Touchbox

[/quote]

I bought three touchboxes 18 months ago. They worked OK for the spring/summer season but when I switched them back on for Christmas guests, one didn't work and the other was dodgy. They were all in dry environments. Metronic replaced them under the guarantee.The third lasted until recently and I replaced it with a different make. Needless to say it won't be a 'touchbox' again as far as I'm concerned.

The strange thing about signal quality/strength was that the old Touchboxes showed only 15% ! signal strength, but 75% quality and received all channels, whereas the replacements with newer setup software (brown background) showed 75/75 on the same dish/lnb/cables, as did another (Strong) box that I have used for several years.

Steve

[Tim]

As I've said on here before - the signal strength/quality indicators on most sat boxes are rubbish. We used to have stickers where I worked for equipment that was not up to date as far as calibration was concerned - the stickers said 'Indicator Only' and I think that sums up most receivers' performance, perhaps a little generously.

I was recently asked to take my receiver round to a friend's house as his box was unwatchable - the picture constantly breaking up. The dish showed a good signal strength but zero quality - this was down to trees, but I've seen similar things happen with (as has been mentioned) kinks in the co-ax and dodgy connectors - water ingress etc.

The postion of the LNB - as Martin has mentioned - also often gets overlooked when people install their own system and is well worth checking.

Tim

[Graham & Brenda]

I have a Metronic box - but a different type, Oursalis Tiny. After about 3 years it wouldn't search for new programmes and I'd lost radio etc. I found an option in the instructions to "Reinitialiser le terminal" Basically it wipes the memory and goes back to the initial setup stage. It means you have to reset any parameters you have changed but it searched and found all the channels again.

[Fridgeman]

Hello Folks

Sounds like a water/cable/dish problem, well that's the way I would approach it, for the cost of a decent bit of coax cable, and making the joints fully water tight (very important) would be where I would start, I would then realign the dish, if no signal try and loan a friends receiver (stb) or you could do a factory reset on your stb, I think on your stb: go into menu / installation / system setup / factory reset, Type in pin (0000 is factory set) this will clear all channels you have setup, turn stb OFF at mains wait 30 seconds and turn ON at mains. This may clear the fault. There should be an option to change the language so it does not have to be in French, if you have not done this previously.

The strength v quality issue .......well as others have stated you can get 70% strength with the lnb sitting on the floor I agree this does not help you in any way but I have to disagree with the quality signal although in fairness I would not put my life on the line for it.  I do feel that as the meter goes up you are getting closer to the point of getting a picture on the tv,  (I have found the sly stb to be the worst) not a perfect solution, you could purchase a proper signal strength but that would cost at least 5 times the cost of the stb!

Back to the problem, if after carrying out the above still no picture come back and let us know, we can then go further

[joidevie]

Well, it's been a couple of months and I'm now back trying to set the system up again.. (in the dark at 5 to nine before the France v England match!) and I've managed to 'tune in' to Astra 2 A the best I can. I re trimmed the coax outside and the box can 'find' the UK channels, but I'm getting things like BBC Parliament and ITV 'superimposed' and very pixelated! And very broken up too..

Could this be a decoder problem?? I eventually managed to catch the second half in Welsh on S4C! But still pretty poor signal mind..

Box or dish/coax problem?

Thanks

[RicandJo]

Sounds like a box problem - but for sure go and beg borrow or steal a friend's box and hook it up just to see.  Unless you've been tinkering with the LNB there's no reason why it should have moved.  Could be LNB water ingress though, even in a dry environment which can actually make the LNB more susceptable to water ingress as the seals inside dry out with the heat then when it rains there's no protection.

 

Good thing is LNB's are cheap, co-ax is cheap hey even a new box is cheap (got my Sony on eblag for 30 quid).

 

As far as strenth vs quality is concerned you can have 25% quality and 100% strength and not get anything.  25% strength and 100% quality however you'lll get a good reception.  Quality is defo the overriding image producer.

 

When I was in the military in Germany I regularly took my Sky box on exercise with us (technical exercises mind not military ones - you know fixing helicopters in a field).  Sometimes we'd move locations 10 times in two weeks - sky set up easily each time.  CO was never too impressed with the dish sticking out through the cam net (satellite communications sir.....) but then he'd always be in our truck to watch the footy if he could!!!

 

So;

1 Borrow a friends box

2 Fit a new LNB and co-ax

3 Get a new decoder box.

 

Ric.

[RicandJo]

One more point to note, make sure you have a 'drop loop' in the co-ax when it comes off the LNB.  The cable should drop down just a little then make sure it goes back up to the LNB arm and cable tie it up, otherwise if you get some water in the connection up there it will capillary all the way down the co-ax and stuff the whole length up instead of just the last section at the LNB.  And be sure to use some self amalgamating tape on the connection, normal electrical insulation tape isn't good enough for lasting protection!

 

Ric.

[powerdesal]

Presumably "black nasty" was tape of choice in Germany. [:P]

[RicandJo]

[quote user="powerdesal"]Presumably "black nasty" was tape of choice in Germany. [:P]
[/quote]

Yes indeed.  Commonly referred to as 'Harry Black'.[:)]

[powerdesal]

I think "black nasty" was Army version and "Harry Black" was RAF, am I remembering correctly?

[RicandJo]

You're probably correct but as we were always attached to the flying side of the Army (Air Corps) I guess our terminologies were quite often the same as for the RAF.  For us it was alway Harry Black, or Harry white (normal masking tape), Harry Icers (blimey it's cold).

 

Man I could go on forever!

[AnOther]

[quote user="RicandJo"]

One more point to note, make sure you have a 'drop loop' in the co-ax when it comes off the LNB.  The cable should drop down just a little then make sure it goes back up to the LNB arm and cable tie it up, otherwise if you get some water in the connection up there it will capillary all the way down the co-ax and stuff the whole length up instead of just the last section at the LNB.  And be sure to use some self amalgamating tape on the connection, normal electrical insulation tape isn't good enough for lasting protection!

 

Ric.

[/quote]Whilst a loop is a good idea to allow water to drip off the outside Ric I can assure you that if you get water ingress anywhere into a coax cable it will eventually capilliary all the way both up and down !

[mick]

Had similar symptoms develop over the last month with the cooler and wetter weather - OK strength, down to 25% signal quality. Clear skies didn't seem to improve matters, and Corsica Rally virtually unwatchable over the weekend, so after checking all the connections, decided to check for water ingress into coax at LNB end as advised elsewhere here. Poked around the hard plastic LNB weatherproof cover to discover wasps nesting inside the cover. After disconnecting Skybox power and spraying wasp killer inside the LNB cover, dozens of wasps made their escape while I watched from a safe distance.

Once the cover had dried, reconnected and checked readings - signal quality now 75% & all missing channels (BBC1 & 2, ITV1, SKY 2 & 3, etc) now restored.

Just got to figure out how to keep those wasps out in future!

[joidevie]

Intersting Mick... But no wasps her right now! I am almost ready to give up... :o(     Bought a new decoder which was unable to tune any channels.. So went back to the Metronic (at least I was getting poor reception.. and that was hugely affected if I yanked the coax connector at the rear of the unit - ie no reception one minute, then almost passable if i yanked it right....) So I thought dodgy input on Metronic so picked up another new box... But, like I said, no tuning on that one!

Old Metronic back on and signal 'strength' is jumping like a yo yo from 30-70% Hop, hop, hop .. up down up down - like a pendulum flickering fast (no in between percentages, just 30% 70%, 30% 70% etc ) .. and I'm moving the dish around to try and find Astra 2A -  Nish. Nada. Rien... Re-done both coax connections at either end. Nothing at all now...

Brand new coax ?

New LNB?

It all worked so easily berfore - I'm not often beaten, but even I'm now getting to the end of it...  :o(

[Martin963]

To be really sure which bit is causing the trouble you need to take your current box round to a friendly neighbour and establish that it's working correctly on their dish.

If it is then I would suspect your cable,  given that you say yanking it makes a difference.   Double check both f connectors,  take them off,  inspect very carefully for stray braid wires touching the inner conductor,  then put them back on.   You don't need much inner conductor sticking out of the f connector and if you have too much it can upset the braid connections or push the plug out altogether as you screw it back.  If yanking still causes problems then your cable has possibly got an internal break of some sort,  or water has got in and corroded something. 

I have had three LNB's go this year at various friends' places;  they're not expensive and you'd have a spare for the future if it isn't that.  If a new LNB doesn't do it and new cable doesn't,  and the box works at a neighbour, then we're back to the dish being misaligned.

Without seeing it it's impossible to be more specific,  you just have to eliminate potential culprits one at a time.

Frustrating though!

[joidevie]

Thanks Martin.. Surely frustrating.. I've now tried new coax, new connectors, and now I've moved the dish around, it's become hard to tune in the new decoder.. And I've not quite worked out how to use a 'sat finder' I bought recently..

... LNB is one more variable I have not yet expolred...

[Martin963]

If you've got a volt meter it's worth checking that you're getting 13V or 18V DC at the dish end of the cable with the receiver switched on.   (13V for vertical pol and 18V for horizontal).

Is the LNB correctly skewed (twisted a little clockwise as viewed from south of the dish).  There are one or two makes (Gardiner for example) where you do not mount the LNB in the expected manner (ie with the cable connector pointing at the ground) - you could check that (I'm getting a bit desperate here!).

If you've checked cable and connectors and LNB  and skew then it really does suggest that dish is not correctly aligned,  but if it's still not the dish you're not going to be able to align it!   A real chicken and egg situation.

Can you get the new box set up with BBC channels in the memory at a friend's house and then use it for lining up your dish (I really find it simplest to have the box,  a TV and the connectors all outdoors -  use a short length of sat cable to make a temporary link - so that you can watch for the slightest twitch on the quality meter on the on screen display.

I'm probably just telling you all the things you know already but without actually coming and doing it myself I'm not sure what else to suggest....