3. Analysis

The results achieved by ANACOM’s probe network, the graphic records of which were sent to MEO by letter of 24 July 2014, clearly demonstrate that, in the week from 14 to 20 July 2014, the network showed a marked instability, which was more predominant on the 16 July, all the more so as, for most of these cases, in the preceding and subsequent weeks, technical parameters assessed remained stable as a whole (for example, electric field and MER).

It is stressed that ANACOM’s probes were designed, developed and manufactured by the consortium UBIWHERE/WAVECOM, in full conformity with technical requirements laid down in specifications, which were made publicly available when the respective international tender was launched, and always under the scientific supervision of university researchers and teachers from the Instituto de Engenharia de Sistemas e Computadores - Tecnologia e Ciência (INESC-TEC - the Institute for Systems and Computer Engineering - Technology and Science) and from the Faculdade de Engenharia of Universidade do Porto (FEUP - the Faculty of Engineering of the University of Oporto).

These probes were later subject to a wide range of tests, to comply with radio interface requirements (arising from the R&TTE Directive¹  regime), as well as with requirements imposed by the low voltage directive² and the electromagnetic compatibility directive³, the respective EC declaration of conformity having been issued.

All probes used by ANACOM were subject to a strict quality control, throughout the process of manufacturing, and, in particular, in the post-production stage, having undergone individual laboratory tests and checks, using reference equipment that was calibrated and screened under internationally acknowledged standards. All these procedures were monitored, accompanied and validated by the project’s scientific coordination team, consisting of 3 PhDs in electrical engineering from INESC-TEC and FEUP.

As a consequence, there is no doubt as to the integrity and reliability of data collected by ANACOM’s probe network and, as such, as to the diagnosis of instability in the SFN network.

It is further clarified that, in most of the cases where ANACOM registered instability, reception conditions had been validated ex ante, on site, with mobile means, and in some circumstances echoes were registered outside the guard interval, which already suggested some potential for interference, under more adverse conditions of the propagation channel. Results obtained during the reported period were as such not surprising.

It is therefore reiterated that, in the period concerned, interference phenomena did effectively occur, which are clear from the inverse correlation electric field vs MER, which caused instability to the DTT SFN network and a consequent loss of service.

As conveyed to MEO, ANACOM cannot rule out the possibility that the verified instability may occur again, taking into account the changes in propagation conditions that take place every year, especially during the summer season.

Under these circumstances, and in the light of the above, ANACOM was of the opinion the recurrence of problems that occurred in the week from 14 to 20 July 2014 should be prevented, in the framework defined in the decision of 16 May 2013.

By letter dated 14 August 2014, ANACOM notified MEO to identify transmitters - to be included in the temporary licenses to be granted - that were required for the resolution of problems occurred in areas not covered by the MFN network (which were indicated), in order to ensure the provision of the service with the necessary levels of quality, taking into account the instability already demonstrated and with a view to prevent a recurrence of problems verified from 14 to 20 July 2014.

In its letter of 22 August 2014, MEO failed to identify any transmitters, as it did not acknowledge the existence of any problems in those areas, although it did inform the locations identified in ANACOM’s letter that were likely to be covered by a theoretical coverage of the 4 MFN transmitters the license for which had been required.

As referred above, ANACOM, by determination of 11 September 2014, granted to MEO a temporary network license, for a period of 180 days, consisting of 4 stations. Subsequently, by determination of 13 March 2015¹, this Authority decided to renew the referred temporary license.

Restating that it was necessary to prevent a recurrence of problems occurred during the week from 14 to 20 July 2014, in the framework defined in decision of 16 May 2013, ANACOM analysed the behaviour of probes installed in areas not covered by the MFN network or by the 4 transmitters the temporary license for which was granted, from the week from 20 June 2014 up to 20 July 2015, and in this context it was found that it cannot unquestionably be said  that any of the probes had been unavailable for longer than 1% of the time²,  as a result of transmission failure of any of the network’s transmitters and/or due to interference generated by transmitters of the network.

As such, ANACOM takes the view that, for now, there seem to be no reasons to order MEO to present a plan for the installation of main transmitters as provided for in point 6. of determination of 11 September 2014, that is, in areas not covered by the current MFN network or by the 4 temporarily licensed transmitters.

Nevertheless, it is stressed that in the final decision on terrestrial coverage obligations and on the amendment of the RUF³, published on the date of this decision, objective criteria are defined allowing for the assessment, with a greater degree of certainty, of possible and future periods of unavailability of service reception.