Freesat & FTA channels on Tp D10S - probs

dowtchaboy

For ages I've been getting probs on certain channels - PopGirl, TinyPop - always when small kids are visiting and the CBeebies ones have gone off!
Freeezing, blocky, etc.
Just noticed it on True Entertainment (which has some good stuff like The Vice) - and noticed the signal level goes from 100% to 0, and quality from reasonably high to nothing - all this over a few seconds.

On lyngsat I see that these are all one particular transponder (Tp D10S) as well as True Movies, True Movies2, NME, Falva, Bliss, Scuzz, and The Vault.

This morning it's perfect on all these channels - but last night they were poor - and the weather was much the same - no rain or anything.

Receiver is bottom of the range Goodmans Freesat box, and Sky dish and (relatively new) quad LNB.

Any ideas? LNB orientation? Water in coax?

greendom

Cordless phone in the vicinity ?

dowtchaboy

greendom wrote: »

Cordless phone in the vicinity ?

Well - yes there is (about 4 metres away), and there is a 2.5Ghz video-sender type unit, and a Wii. Usual lots of WiFi about the place, a doorbell (also on 2.5 GHz I think), and our neighbour has a weather-station on the fence that likely uses WiFi frequencies). We've always had a lot of probs with getting the doorbells and the video-sender to work reliably yet cannot show a connection (ouch!). Nearby is also an unshielded house alarm panel... I suspect an afternoon with an RF meter would be useful!

Is that Tp frequency subject to interference from DECT phones in particular? Note the phones were in the same place during good and bad reception.

watty

Sat IF is 950 to 2100MHz, L.O is 9750 or 10600, for RF 10,700 to 12,700 (switched at 11,700MHz between 9750 and 10600 L.O.)

So Transponder 11.642GHz Tp D10S is 1880 to 1904 approximately
11642 - 9750 = 1892 MHz

DECT phone is 1900MHz is likely culprit
Mobile GSM is 880MHz to 960MHz, 1800MHz

Also
1900 + 10600 = 12,500MHz is Honey, Dirty Talk, Active Channel (tp F3L) Plus some Sky pay TV.

The Ghana TV on 12599MHz is Nigerian Beam.


So culprit is likely DECT cordless phone

not going to interfere
3G is 2100MHz
WiFi is 2450MHz
Cordless Weather station is 433Mhz
Door bell usually 433MHz
Video Sender is 2450 MHz for Video (FM) and 433Mhz for IR remote back channel (ASK/OOK)

dowtchaboy

These channels are on 11642 MHz - why would that particular frequency alone (or the resultant IF) be affected?

watty

Because on the coax between dish and sat box (the IF) it's 11642 - 9750 = 1892MHz
But sat channel is 15 MHz to 30MHz wide depending on symbol rate rate and some other stuff..
So channels are 1880 to 1904 approx. Same band as DECT cordless phone.

The channels at 12,500MHz approx should be affected too.

dowtchaboy

OK - thanks watty for the clear explanation.
I thought DECT phone was not a likely culprit as it was well away from the TV and sat box - but now I realise the coax from the LNB runs near enough the DECT basestation and as you point out it's the IF that's running down the coax that is subject to EMI. Also this coax was installed many years ago by someone who knew shag-all about RF, TV or satellite so there are coax cables (one from RTE aerial, one from South Coast (analogue), one from Sat - and a rats maze of cables and a 4 way amp (was 2 x 4-way amps in series....) under the floorboards.
As it happens I checked the dish end of things and found a not very tight F plug (slightly rotate-able in fact) which won't have helped matters. Must investigate skew at some stage too.....

I'll go play about with the cable connections and the DECT basestation location and see if matters improve (and stay improved).

watty

you may have to replace the coax. Maybe it has not got heavy briad + solid foil screen.

Ordinary TV cable is no use even for TV. Spiderweb screen braid lets everything in and out.

dowtchaboy

Just an update - I finally got round to turning off everything electronic in the rooms between the sat dish and the sat receiver and have identified the culprit - it is, as Greendom and Watty suggested, the DECT phone.
If I switch it back on, within a few seconds the reception on True Entertainment, PopGirl and all the other channels on this transponder start to go odd, stutter or stop. I have found a short-term solution is to place a broad layer of kitchen foil under the phone base-station i.e. between the base-station and where I suspect is a poorly shielded join in the satellite (actually old TV quality) coax cable. Her Indoors will not stand for bits of foil lying about the house so I'll have to find a better solution, better coax and so on.
Thanks for the suggestions.

PeterDuggan

I have a similar problem interfering with True Entertainment but I've turned off every wireless device in the house (and my neighbour's) and still can't clear it.

Any ideas what I'm missing?