Multi-dwelling with scr - intermittent skyq dropouts across all channels

[nimo70]

I'm the building manager for a 7 unit multi-dwelling. Setup as per tag. Experts have been called in, but we still have the issue. My only experience is domestic terrestrial tv. I'm looking to make decisions on the best way forward and have better informed conversations with IRS engineers and/or Sky. Apologies for length (too long; didn't read at the bottom of the post).

A tenant is reporting intermittent issues with signal reception on SkyQ - either all channels are ok, or none are available. Lasts hours and a receiver reset needed. The building's Integrated Reception System is out of warranty. IRS engineers inspected system twice on 'good signal' days - clean bills of health (barring very minor dish realignment). An engineer has suggested the system is sitting at the top of a digital 'cliff-edge', with something (meteorological?) tipping it over intermittently. FWIW terrestrial via the IRS has no issues.

This bit may or may not be relevant:

Prior to SkyQ installation in the flat, Sky were unable to get their meters to give the go-ahead (I believe I should have had a PDF from Sky via the tenant with data on the failure for each visit. Is this the case, and would the PDFs still be available months down the line?) On the third visit (with our IRS engineers giving the system a clean bill of health between visits) Sky sent an IRS engineer as well as the domestic installer. Having told Sky the system was SCR every visit, on this last occasion the IRS engineer told the domestic engineer (after watching me tighten every connector on the dSCR units in the riser cupboard) to test the tenant's socket again "in SCR mode". At the time I wondered why the engineer added the 'SCR mode' bit, surely that went without saying having been told it was an SCR system?! The test unit gave the go-ahead this time leading me to question whether the tenant's socket test had been done in SCR mode previously (it could have been the tightening - yes, but that was about the third time I'd done it and there was nothing left to tighten!) This, to me, casts doubt on whether or not the system had any issues prior to installation, and we have no data from Sky on the failed installations to help.

A few questions I can think of below, but any other ideas/comments welcome.

Testing

Whilst the IRS engineers tested the system at a time when the issue was not apparent, are there any tests that could have been done at that time that perhaps weren't and would have identified a problem waiting to happen. e.g. SNR? Or do we just need to try some things to see if they work, or get lucky with testing when the issue is apparent?

Termination

The multi-dwelling unit has 7 flats all wired with faceplates for Sky/SkyQ. Only one flat is using them. So for the other 6 flats we have probably over 100m in total of cabling attached to the two dSCRs (1 per floor) with, I assume, nothing other than a faceplate at the other end. Documentation for the dSCRs states : Unused ports to be terminated with 75Ω Terminators. There is one port unterminated at the dSCRs, which we can terminate, but it strikes me, unqualified as I am, that the cabling to the other 6 flats with no receivers attached could possibly be causing issues as well. Is that likely, and if a possible cause, is there any merit in either unhooking the 6 flats at the dSCR end and fitting terminators (telling tenants that they will need to notify us to hook up FreeSat or Sky; obviously not ideal, but I am on-site) or providing tenants with terminators for faceplates?

Dish size

We have a 60cm dish. Would 78-80cm (larger?) be more suitable for multi-dwelling IRS? AFAIK we have good elevation and sightline, and coverage (~52N,0E) and signal on a 'good day' is fine.

Sky

Sky won't touch our IRS system, which is understandable. The tenant has suggested we could try and organise a Sky engineer visit to coincide with an IRS engineer commissioned by us. What benefits would you see in this - i.e. what can Sky tell the IRS engineer that the IRS engineer can't find out for themselves?

SKY have so far only talked to the tenant. We are happy to arrange this engineer meetup if necessary, but are obviously not keen to employ an IRS engineer to wait around for Sky engineers to no-show (they have no-showed the tenant previously). Sky so far have given the tenant wide slots of several hours for visits and we'd be keen to nail them to a specific time. Is there a Sky department that would be willing to speak to a building manager/landlord about this issue, given that Sky's relationship is with the end-user i.e. the tenant?

Receiver

Are there any diagnostics on the SkyQ receiver that the tenant can check, perhaps both when the signal is received ok and when it isn't, that would be useful to Sky and/or an IRS engineer?

tl;dr - intermittent loss of SkyQ signal on all channels. Sitting on a 'digital cliff-edge'? Should Sky provide tenants with data PDFs of test results with installation failures, and how long do they keep them? Any IRS engineer tests on a good reception day that would be useful? or do we need to just try solutions? Any receiver tests on good & bad days that would help? 100s of metres of cabling to flats that have no receivers, also unterminated output on dSCR - possible issues? 60cm dish too small for 7 flats? Worth getting Sky and IRS engineers on the same day? What can a Sky engineer tell the IRS engineer that they cannot find out for themselves? Sky department for landlords to talk to?

2 dSCRs (with unterminated connection highlighted FWIW).

 

[Terryl]

You keep mentioning "Good and Bad" days, this would in my mind indicate that the main dish maybe too small, and the dish/LNB only provides signals to the distibution amp/switches, not directly to the flats them selves, can you go to at least a one meter dish? This could provide up to an additional 6 dB of signal at the LNB and improve your possible signal drop outs at the dish it's self.

What satellite(s) are you looking at? If they are at a certain low angle to the horizon you could be getting temperature inversion problems, this would at certian times of the day/night cause the signals at the dish to drop, this due to an out of phase signal reflecting off the inversion layer and mixing with the main. (dishpointer dot com can help you with the angles)

And I would go and terminate all unused outputs as the manufacture says, this would eliminate that as a possible problem.

 

[ozumo]

Terryl - it's a system for Sky on 28.2e, elevation is around 23 degrees.

nimo70 - There is a signal strength/quality check somewhere in the Sky Q settings menu, I've never used Sky Q so can't be too precise, but it's definitely there somewhere.

 

[rolfw]

First things first, the incoming signal from the dish needs to be sufficiently robust, I tend to use a 70 or 80cm dish, the slightly smaller dish size helps to bring in the weaker slightly offset beams of some of the lesser used channels, 60cm is on the small size, but can be OK. The 28.2 cluster is quite powerful in the UK and I can see that a 5 wire Televes amplifier is being used before the two way splitter, so sat signal level should be OK. Sky will measure the legacy satellite signal first, as if that is low or bad quality, the SCR signal will be low quality as well.

I've not used the LEM units, but if they are anything like the Whyte dSCR units, providing too much terrestrial signal UHF/VHF can swamp the satellite signals and they will show as no signal or quality on a sky box. The non-terminated subscriber outlet will not cause the problems your system is experiencing, but a faulty or under specified power supply could. This sort of problem is sometimes difficult to sort even when on the premises, it requires a logical approach and pretty much starting from basics, intermittent problems are the most difficult for obvious reasons.

Whereabouts are you nimo70 ?

 

[nimo70]

Many thanks for the replies all.

Some further thoughts -

The tenant mentions rebooting the SkyQ receiver - whether this was actually needed or just done anyway, I'm not sure. It has been suggested to me that if a reboot was required that might point to a receiver issue as the receiver should see the signal return to a good strength/quality without requiring a reboot. Any thoughts on that?

In reviewing emails with the tenant, the issue appeared to have initially only affected certain channels before progressing to affecting all channels. So there seems to have been a degredation over time.

Any concerns with placing the two SCRs back to back as per picture in original post? Heat? EMF (though surely shielded if prone to that)? Any difference between 2 x 4way or 1 x 8way?

Terryl - Astra 28.2E (as per ozumo). Dishpointer.com suggests elevation of 24.9° at our building. We do have space for a larger dish if bigger is better.

I have sourced terminators, but understand links to commercial sites not allowed. Would any F-type 75ohm terminator from a reputable store do or are there brands that are worth sourcing? I know not to short the end of the connector when fitting the terminator, but is it ok to fit when the system is on (given turning the sytem off would involve prior arrangement with tenants - don't want to interrupt their recordings of Homes Under The Hammer!) It seems a simple job, system on or off, but if there's other factors or too much risk of damage involved I'd of course get someone in.

ozumo - How useful would the tenant logging these numbers when reception is both good and non-existant be for an IRS engineer? I could suggest this is done ASAP if it'll be useful at any point. Any particular channels that would be more use than others (given the tenant is not going to want to log every channel)?

rolfw - the LEM dSCRs each have a LEM plug-type PSU, so one would assume not under-specified, unless LEM do several and the wrong ones have been used. The amp also has a PSU. I will look into the power specs of the PSUs, and see if I can find the requirements for the equipment connected. I may also be able to check their output is as spec. I can look into replacements as a step towards solving this puzzle.

Re the amp and signal strength - I note that you think that it should be ok, but I'd be interested in thoughts on whether the topology might have any impact on signal strength reaching the dSCRs (if only for curiosity):

The topology is:

dish -> amp -> splitter -> multiswitch 1 -> dSCR 1
. . . . . . . . . . . . . . . . . . . . . . -> multiswitch 2 -> dSCR 2

Would putting the dSCRs before the multiswitches increase the signal strength to the dSCRs or is that not a topology that would work?

Re your comment "providing too much terrestrial signal UHF/VHF can swamp the satellite signals and they will show as no signal or quality on a sky box" - I'm not sure if that is linked with the possible faulty or under specified power supply, or is a separate issue (and if so, what would be the solution).

We're in North Herts, UK.

 

[rolfw]

Only way to solve this is on site with a spectrum analyser in the hands of a competent IRS engineer, anything else will be trial and error and in the long run, more costly. The nearest of my IRS contacts is in Stansted.

 

[ozumo]

Anything can help with diagnosis, logging levels will also give a real world reference as to whether any work done is actually improving anything. I would suggest:

BBC NEWS HD ch.503 - one the strongest transponders
Smithsonian HD ch.173 - one of the weakest.

General weather conditions at the time may be useful too - sunny/clear, cloudy, light rain or heavy rain should cover it.

 

[rolfw]

Anything can help with diagnosis, logging levels will also give a real world reference as to whether any work done is actually improving anything. I would suggest:

BBC NEWS HD ch.503 - one the strongest transponders
Smithsonian HD ch.173 - one of the weakest.

General weather conditions at the time may be useful too - sunny/clear, cloudy, light rain or heavy rain should cover it.

Agree, that sort of info won't hurt, but only as an aid to onsite diagnosis.

 

[ozumo]

Slightly OT, is there any advantage by going dish -> amp -> splitter -> 2x switches, rather than dish -> multiswitch 1 -> multiswitch 2?