After DSO will masthead amps need removed?

Digifriendly

This is maybe a shot in the dark and possibly no real answer until Oct 24th but here goes anyway. Quite a lot of viewers here in NI who receive ROI stations via an aerial have signal boosted through masthead amplifier (witness multitude of red boxes attached to aerials colouring skyline in much of Belfast and many other places). When DSO takes place and signal from e.g. Clermont Carn is increased will be there an overload of signal and masthead amps needing to be removed to get decent DTT reception of ROI channels?

FREETV

Digifriendly wrote: »

This is maybe a shot in the dark and possibly no real answer until Oct 24th but here goes anyway. Quite a lot of viewers here in NI who receive ROI stations via an aerial have signal boosted through masthead amplifier (witness multitude of red boxes attached to aerials colouring skyline in much of Belfast and many other places). When DSO takes place and signal from e.g. Clermont Carn is increased will be there an overload of signal and masthead amps needing to be removed to get decent DTT reception of ROI channels?

Possibly in a lot of cases where the signal may be strong, anyway I think that the red masthead amps are possibly old unshielded Fringe models which mightn't do any harm if they were replaced or removed if not needed anymore. Peter would be probably the best person to reply or Watty as he knows Antrim very well and has family/relations there I believe.

Ronnie Raygun

Digifriendly wrote: »

... When DSO takes place and signal from e.g. Clermont Carn is increased will be there an overload of signal and masthead amps needing to be removed to get decent DTT reception of ROI channels?

Probably no need to remove the amps. There is a difference in recommended min. & max. signal levels at the receiver, wrt analogue v. digital, with the minimum analogue level (~60dBµV) being the same as the maximum recommended for digital receivers.

I'm not sure how to relate the analogue & digital transmitter ERPs, but certainly "on paper", the 160kW digital output seems a lot less for the amps to handle than 300kW analogue (or whatever proportion of this goes northwards).

mrdtv2010

Ronnie Raygun wrote: »

Probably no need to remove the amps. There is a difference in recommended min. & max. signal levels at the receiver, wrt analogue v. digital, with the minimum analogue level (~60dBµV) being the same as the maximum recommended for digital receivers.

I'm not sure how to relate the analogue & digital transmitter ERPs, but certainly "on paper", the 160kW digital output seems a lot less for the amps to handle than 300kW analogue (or whatever proportion of this goes northwards).

Amps should be taken out afterwards. Overloading usually manifests as very high signal strength and zero quality on stbs. A cheap way to do it is to buy a variable gain attenuator and insert it in line. This allows for contingencies and prevents having to go on the roof. For equivalent coverage digital ERPS are 1/5th of analogue ERP because of the lower decode threshold required for perfect pictures.
CC was always a bit of a fringe signal in many parts of NI so it was generally amped, particularly in Belfast.

winston_1

mrdtv2010 wrote: »

Amps should be taken out afterwards.

Not necessarily true. The new digital signal will be the equivalent, strength wise, as the analogue signal being switched off. If the old analogue signal did not cause overloading, the new digital signal shouldn't either.

12 element

What about when they get rid of channels 52-69 and start using them frequencies for broadband etc. Some of the older wideband amplifiers might have some problems then.

winston_1

It's only channels 60 to 69 that are going at present. Nobody knows how any individual amplifier or situation will react to LTE. Best wait and see.

Capt'n Midnight

Do RTE have a teletext test page ?

http://www.bbc.co.uk/news/uk-scotland-11621911

BBC Ceefax and ITV/C4 Teletext Page 284 currently carry a test page to check if the signal is robust enough.

Ronnie Raygun

TG4 had it at one stage (maybe TV3 too), there wasn't much point it being on RTE, as a lot of the country is served by VHF band III analogue transmissions.

STB

Digifriendly wrote: »

This is maybe a shot in the dark and possibly no real answer until Oct 24th but here goes anyway. Quite a lot of viewers here in NI who receive ROI stations via an aerial have signal boosted through masthead amplifier (witness multitude of red boxes attached to aerials colouring skyline in much of Belfast and many other places). When DSO takes place and signal from e.g. Clermont Carn is increased will be there an overload of signal and masthead amps needing to be removed to get decent DTT reception of ROI channels?

There have already been reported cases of RF overload within Ireland most likely due to old analogue setups pulling in nearer sites/stronger signals that didn't exist before resulting in distortion of BER.

Sponge Bob

mrdtv2010 wrote: »

A cheap way to do it is to buy a variable gain attenuator and insert it in line. This allows for contingencies and prevents having to go on the roof.

I like this solution, anyone recommend any models for Bands A or B or C only that reject 'out of band' signals as well as attentuate within their own band??

Peter Rhea

An attenuator after the amp isn't much use if the amplifier itself is being overloaded. All kinds of bandpass, band stop, single channel pass & notch filters are available, though I'd doubt there's much demand for a device that also attenuates all of the wanted band (unlike a single channel filter/leveller in some distribution systems), although, having said that, the level control on adjustable amps is usually by variable attenuation on the input or between stages.

Capt'n Midnight

Digifriendly wrote: »

When DSO takes place and signal from e.g. Clermont Carn is increased will be there an overload of signal and masthead amps needing to be removed to get decent DTT reception of ROI channels?

Aren't RTE going to be on UK Freeview in NI ?

Ronnie Raygun

Peter Rhea wrote: »

All kinds of bandpass, band stop, single channel pass & notch filters are available

Examples of single channel pass & notch filter in use here, along with attenuators to control the output of fixed gain amps.

Mightn't be a particularly relevant example in the context of this thread, but it shows how different devices can be combined to good effect.

Ronnie Raygun

Capt'n Midnight wrote: »

Aren't RTE going to be on UK Freeview in NI ?

RTE & TG4 will be on the so called NIMux, no TV3 channels & I believe there will be rights issues & blacked-out content, unlike the full Saorview service available from southern transmitters.

Digifriendly

Ronnie Raygun wrote: »

RTE & TG4 will be on the so called NIMux, no TV3 channels & I believe there will be rights issues & blacked-out content, unlike the full Saorview service available from southern transmitters.

Spot on. That's why it will be a major advantage to have Saorview. As I pointed out on another thread 'Premier Soccer Saturday' on RTE2 is being blacked out on Sky here in NI so this almost certainly will be the case with the mini-mux.

formerly scottish paddy

Ronnie Raygun wrote: »

RTE & TG4 will be on the so called NIMux, no TV3 channels & I believe there will be rights issues & blacked-out content, unlike the full Saorview service available from southern transmitters.

And no RTE 2HD on the NIMux

JoeDunne

First time poster, long time lurker. Comreg say amps need to be removed when the Lte comes along:
http://www.comreg.ie/lte

The Cush

JoeDunne wrote: »

Comreg say amps need to be removed when the Lte comes along:
http://www.comreg.ie/lte

This from the Dept of Communications earlier this year, their position on masthead amplifiers

Mast Head Amplifiers

Installations which use a mast head amplifier for TV reception (irrespective of the frequencies to be received) will most likely need a filter. This is because mast head amplifiers are prone to an "overload" condition if the signal level from either DTT or other sources (on frequencies either above or below the TV signal) is very strong. In these overload conditions unintended signals called “intermodulation products” can be radiated causing interference to other users of the spectrum.

Mast head amplifiers should only be used for reception of DTT where there is a clear need to do so. Excessive amplification of a DTT signal can cause set top boxes to appear not to be able to decode the DTT service.

There is a lot to be done between now and the cessation of analogue television services in the UHF band. The Department will fully engage with ComReg and the other stakeholders involved in order to deliver the best results for Ireland.

http://www.dcenr.gov.ie/Communications/Business+and+Technology/Digital+Dividend/