TV and radio broadcast receivers

Transcription

1 TV and radio broadcast receivers Lindsay Cornell Principal Systems Architect, BBC

2 Some Key Challenges No existing standards to upgrade from EG still being developed for most of the initial technical work RE-D HEN skeleton template changed several times during the drafting stages Short lead time compared to typical consumer electronics development cycles 2

3 Working groups Part of ERM TG17 Separate WGs for TV and radio WG1: TV - John Wilson, Sony WG2: Radio - Lindsay Cornell, BBC Thanks to John for contributing to this presentation 3

4 EN : RE-D for DTT Broadcast Receivers Receivers fitted with an external antenna input (tuner port) capable of receiving DVB-T and/or DVB-T2 signals Set-top boxes Integrated TVs 4

5 Agreeing constraints The timeframe for RE-D introduction was shorter than the timescales required for new TV hardware development ~ 3 years from stable silicon requirements to introduction in TV sets too long for new silicon to be developed to meet initial RE-D However some tuner software optimisation assumed possible within RE-D timeline 5

6 Interference LTE was considered the most critical Based on previous LTE 800MHz experience, bursty LTE interference was considered the biggest challenge to tuner performance 700MHz UE is close to TV CH48 and UE could have very low duty cycle bursts if on light load tuner AGC challenge! 6

7 How to test against interference? No standard 3GPP reference test signals were suitable Recordings of bursty UE interference traffic loadings were made and receiver measurements carried out to find suitable worst case UE recording This recording was processed and formatted as an I/Q sample file for popular laboratory vector signal generators used by the TV industry This I/Q sample test waveform approach was an ETSI first now being considered by other RE-D standards 7

8 UE test waveform This was recorded from an LTE UE to represent a very bursty UE transmission (ACKs from a large download) 1 s 8

9 BS test waveforms Bursty LTE BS and fully loaded LTE BS signals were also included in the standard 50 ms 50 ms This is similar to the LTE idle signal used by DTG testing for UK D-Book testing 9 This is used for blocking and overload tests as it has the highest carrier density

10 Process Initial draft went for approval before the EG RE-D guide was stable ENAP comments requested additional performance parameters (such as sensitivity) Seven intensive resolution meetings were needed to resolve all the comments and create a revised draft for national vote Some G2M calls were held before normal working hours very early in the morning in order to accommodate all interested parties from across the globe and busy schedules 10

11 Overall timeframe 23 0 Don t underestimate the proportion of time taken by the various administrative, editing and approval processes ~(61%) But still much faster than some other standards organisations months 6

12 EN : RE-D for Broadcast Sound Receivers All receivers which include any of AM, FM, DAB and DRM demodulation 12

13 Agreeing scope Radios come in many, many, different forms Portable In-car Beat-box Mobile phone Hi-fi Different power sources battery, mains Different demodulation systems in various combinations 13

14 Agreeing test requirements For digital demodulation, already material available Introduction of DAB is ongoing and industry understanding of necessary performance requirements is established; DRM at an earlier stage but similar outlook For analogue demodulation, no performance testing previously required But AM and FM are well established and have not suffered market failure due to poor products Actual performance variation extremely large 14

15 First draft Very limited participation in working group despite many attempts to recruit members from manufacturers, regulators and others Initial draft went for approval in order to garner feedback and with the hope of increased interest and participation ENAP comments requested additional performance parameters (especially for FM) but were very vague about what would be satisfactory 15

16 Some comments Comment There is no rationale given for the limits and requirements as well as for the test signals. All tested receivers were much better than required. If this standard is in force, it is possible that the next generation of receivers is getting a worse quality in relation of sensitiveness and selectivity. Proposal Improve the requirements according to the state of the art. Issue no test data was provided; no information as to which demodulation system(s) the comment applies to 16

17 Some comments Comment The receiver adjacent channel selectivity and blocking values do not match the international planning criteria in Recommendation ITU-R BS.412. The values in the harmonised standard should better match or be better than the protection ratios used in the planning criteria. Proposal The values in Table 4 should be modified to better reflect the protection ratios in Recommendation ITU-R BS.412. Issue ITU-R BS.412 applies to FM only; better reflect is rather imprecise! Other comments suggested five other ITU-R documents should be used as references 17

18 Some comments Comment The sensitiveness for AM and FM receivers should be defined because is one parameter for the planning of broadcasting coverage. Proposal Define requirements for sensitiveness for AM and FM receivers Issue no suggestions of what limits should apply 18

19 Some comments Comment Why are the tests for receivers with inbuilt antennas and without any connector for an antenna mandatory? Such kind of receiver is often cheap equipment. But the effort for testing is much higher as for receivers with an external antenna connector. For example to produce a defined level for the wanted signal is very difficult. Proposal Issue excluding equipment based on sale price is interesting! 19

20 Some comments Comment For integrated receivers without access to internal measurements points for BER, measurement for blocking, according to IEC 62104, chapter is not possible. Proposal Use methods that not only are possible for technology providers, but also for market surveillance. Issue no actual methods are suggested. 20

21 Second draft Unfortunately participation did not improve Six resolution meetings were held to address all comments and to generate the new draft The desire for a more generic testing procedure and simple go / no-go requirements led to a complete rewrite Extensive laboratory work was carried out to develop and assess test methods 21

22 Second ENAP ENAP comments concern details and inconsistencies First resolution meeting has been held All comments have been reviewed Some have already been resolved Others require further action to fully assess Expectation that revised draft will proceed to National Vote in due course 22

23 Conclusions From a standing start, producing HSs for RE-D is difficult! A lot has been understood in the process By those who produce the standards By those who assess the drafts 23

24 Thank you