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S4C's Transmitter Gripe


S4C has revealed that it is getting numerous complaints from viewers in Wrexham who can't get S4C Clirlun, its HD channel on Freeview. In an email from S4C, posted on the Digital Spy forums by forum member Phil Owens, the broadcaster states that viewers can't receive programmes from the "Welsh transmitters" due to signal stengths from "English transmitters" having been recently increased. It states it is bringing the matter to the attention of Ofcom.

So is there any truth to this rather sweeping statement? 

Looking at the frequencies used in the area, there is one possible frequency clash.

The Wrexham area lies just outside of the coverage area of the Midlands-based Sutton Coldfield transmitter, however some weaker signals do reach some areas, especially elevated parts.

Sutton Coldfield's commercial multiplex SDN co-channels on UHF channel 42 with the BBC-B multiplex carrying S4C Clirlun from Moel-Y-Parc. The SDN multiplex was operating at a lower than intended power following last year's switchover, but commenced transmitting at full power (200kW Effective Radiated Power) during the last week of April following a transmission parameter change being rolled out on the SDN multiplex throughout the UK, which requires a higher powered signal to maintain a similar coverage area.

However, the standard definition S4C service on multiplex D3&4 (PSB2) from Moel-Y-Parc does not co-channel with any high powered transmitter in nearby England. 

This is set to change next year when the signals from the Welsh Moel-Y-Parc transmitter starts using a frequency already used by the English Sutton Coldfield transmitter following clearance of the frequency band ready for 4G/LTE mobile broadband. D3&4 will move to UHF channel 39 - the frequency used by Arqiva B at Sutton Coldfield.

Based on the the current issue with the co-channelling of one service, the additional proposed co-channel allocation between Sutton Coldfield and Moel-Y-Parc could create a potential reception problem for S4C's standard definition service in the future.

Reception of Moel-Y-Parc has been traditionally poor in many parts of the Wrexham area due to the hills - so for some, S4C reception would have been borderline, and any additional interference would quickly hinder reception.  Some households around Wrexham are actually not in the official coverage area of Moel-Y-Parc due to the local terrain. For many, the strongest TV signals come from Winter Hill in Lancashire. Some households can receive TV services from The Wrekin in Shropshire. But neither of these transmitters uses frequencies used by S4C in North East Wales so as to disrupt S4C reception.

A relay transmitter operates in the area which carries S4C and Clirlun - Wrexham-Rhos, which is in fact just outside of Rhos. However its position does not lend itself to full coverage in the area. That relay fills the transmission gap created by Hope Mountain and was, according to local history, originally installed in haste in order to be on air for the Eisteddfod at Rhos. A better site to cover the area, near a quarry was turned down, for fear of affecting work at the quarry. The quarry has since closed. 

It appears local political reasons stopped a better site being used, but many years later the outcome of events continues to be felt as without satellite distribution of Clirlun, viewers in parts of Wrexham can not receive the HD version of S4C. 

S4C states that it cannot bring Clirlun to satellite due to the costs involved. S4C's funding is in the process of being cut, with the bulk of funding coming via the licence fee from 2013-14

So, in summary, what of the claim that 'English transmitters' are affecting the S4C service? 

Rather than loads of 'English transmitters'  blocking the service to a number of 'Welsh transmitters' as you might think, there's just the one possible conflict at the moment, just affecting the HD version, with the main Welsh transmitter at Moel Y Parc moving in turn to a frequency already used in England next year, posing potential problems with the standard definition version of S4C. 

In addition, many of the affected viewers are in a marginal reception area for Moel-Y-Parc, which doesn't help. And of course, Moel-Y-Parc itself has created interference in England, due to the fact that Moel-Y-Parc signals travel right across to the Manchester area and into Cheshire. If the transmitter network was being built now, Wrexham might have had a better sited relay to provide better coverage of Clirlun...


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