Analysis: Freeview TV Services in Sydney, Australia (27th December 2018)

It’s been a while since my last analysis of the Freeview services on air in Sydney – in fact, the last time I did it was after SBS moved to MPEG-4 for its HD services back in 18th April 2017. Part of the reason for this is simply because of a change of habit – we no longer consume as much TV as we used to. Another reason is that I had moved into a different location, which had poor reception as a consequence. But as I recently returned back to my other house to fix a few things, I thought I’d bring along my TBS 5220SE and record some multiplex .ts files to analyse on my return home.

Multiplexes on the Air & Their Constellations

From the test location, doing a whole scan of the band, it is fairly quiet except for the strong signals from Gore Hill, comprising of five DVB-T multiplexes as expected. Another hump is seen above 750Mhz and represents the new LTE base stations using the “digital dividend” spectrum (e.g. Telstra 4GX, Optus 4G Plus).

The multiplexes all averaged about 37dB SNR which is a lot better than at my regular location. Of note is that all of them have the same DVB-T transmission parameters of 64QAM, 3/4 FEC, 8K FFT, 1/16 Guard Interval, thus all broadcasters have the same amount of bandwidth to deliver their services (23.050Mbit/s). Constellation plots are fairly well resolved with a sprinkling of noise which may be due to non-linearities of the splitting amplifier that I had used (e.g. when encountering impulse noise).

Overall, the signal strength was adequate enough to record 32GiB TS files (just over three hours) on 27th December 2018 for averaged bitrate analysis.

Summary of Services

The new service summary table is as above. Key changes are highlighted in red and summarised below:

  • The first DSM-CC PIDs previously allocated have mostly been removed, so where a broadcaster had two streams, now they have just one, etc.
  • Channel 7 has gained Channel 74 7food network, which broadcasts in MPEG-4 H.264 [email protected] 640x576i with MPEG-4 HE-AACv2 Stereo audio, similarly to RACING.COM, which will require more modern televisions to receive. The quality offered is likely to be limited.
  • SBS’s loss of the Food Network branding results in their channel being changed to SBS Food. SBS also offers their DAB digital radio offerings over their TV multiplex, especially gaining SBS Chill (replacing Radio 3’s PMT entry), SBS Radio 3, SBS PopDesi and SBS PopAsia – the latter two using MPEG-4 HE-AACv2 Stereo encoding for higher bitrate efficiency.
  • Channel 9 has changed EXTRA to be called Your Money. Seems like an odd rebranding.
  • Channel 10 have renamed most of their services, opting for the digits “10” instead of Ten possibly to try and show up higher if sorted alphabetically. The naming is rather nondescript – “BOLD”, “Peach” … am I expecting to see peaches on TV now?
  • ABC has also renamed ABC News 24 to just ABC NEWS, with ABC 2 becoming ABCComedy/Kids. The radio servies get a bump up in their bitrate to 256kbit/s.

The per-PID rates are provided in the image above.

Multiplex Usage

Multiplex utilisation appears to have improved, with Nine, Ten and SBS being very close to filling their multiplex and Seven being quite acceptably close. The only broadcaster not making full use of their multiplex seems to be ABC which has left almost enough bitrate for a whole new service. I wonder if that is their eventual intention?

TV Service Bitrates

The above graph summarises the TV service total bitrates sorted descending. HD services are highlighted in light green, while MPEG-4 SD services are in teal green. MPEG-4 or AC3 audio is highlighted in purple to distinguish from the baseline MPEG services.

On the whole, it seems that 10 HD has a sizeable lead in bitrate over all other broadcasters’ services. HD services occupy mostly the higher bitrate echelons, with the exception of ABC which seems to prioritise its SD bitrate ahead of its HD service bitrate.

Rather unexpectedly, the newly launched 7food network occupies bottom spot for total service bitrate – even falling behind RACING.COM and all the “rubbish” shopping channels. This suggests that the channel may not have significant viewership or is not of a high priority for the network at this time.

Variations between most mainstream MPEG-2 channels don’t seem to be too significant, with some secondary channels enjoying higher bitrates than the primary channels (as those may also be simulcast in HD). The progression to MPEG-4 technology seems to be slow and cautious as viewers take time to update to newer TVs (or perhaps, ditch the whole broadcast TV paradigm altogether).

Bitrate Evolution Trends

It seems that over time, the bitrates for Seven have mostly stabilised with only minor changes. The exception would be 7HD Sydney which launched with high bitrates, only to have that clawed back for the rise of 7flix, 7food network and RACING.COM.

A look at SBS shows barely any bitrate movement at all compared to previous measurements. If anything, it seems any differences may just reflect statistical multiplexing and the type of content being aired at the time.

Nine’s bitrates have mostly remained stable as well, with a slight loss in the main SD channel being offset by gains in 9Life and 9HD Sydney.

Network Ten’s bitrates seem to have only seen minor changes as well, with 10 BOLD getting a bump up, at a slight cost to the remainder of the channels. Again, we might be seeing content-based effects causing minor skew in the values.

Finally, ABC sees a surprising drop in ABC NEWS and ABC HD bitrate, where the others mostly remain stable. Due to the inefficient multiplex utilisation, this bitrate reduction has only led to the emission of null padding packets in the multiplex.

Conclusion

Freeview TV is becoming less and less a part of my life, thus this analysis comes well overdue. Due to a fortuitous situation which allowed me to access a good quality signal, I took the opportunity to make some recordings for analysis.

While there have been a few minor renaming of services and the launch of a new channel, there seems to be less of an emphasis on quality as we continue to squeeze more from our limited bandwidth while using older MPEG-2/MPEG-1 suite of baseline codecs and DVB-T modulation to ensure maximal compatibility. HD MPEG-4 services which launched with high bitrates, enabled by the “large” bitrate allocation formerly needed to carry HD MPEG-2 services, have given way to more moderate allocations in order to squeeze in another SD MPEG-2 service.

The big disappointment seems to be 7food network which has launched using MPEG-4 codecs (limiting viewer access to some degree) while also being extremely deprived of bitrate even compared to shopping channels.

But in a world with increasingly good internet access, live streaming possibilities coupled with video-on-demand catch-up, the reasons to maintain a TV and aerial are beginning to diminish. Even satellite and pay TV providers have embraced the move to IPTV, so it seems that Freeview may be living on borrowed time.

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
This entry was posted in Radio, Satellite, Telecommunications and tagged , , , , , . Bookmark the permalink.

4 Responses to Analysis: Freeview TV Services in Sydney, Australia (27th December 2018)

  1. Very thorough work. The gradual evolution of TV standards, but still some woeful resolutions and content.

    SBS seems to be moving toward a streaming service with a lot of streaming content not shown free to air.

    I suspect you are using a VHF antenna and may miss some UHF services intended for outside greater Sydney or as fill-in.

    I live on the Gold Coast with all UHF services, although Brisbane is VHF, for which I do not have an antenna. We get the northern NSW services as well.

    The program mix is much the same as for Sydney, just with different advertising. Apparently many stations do all their advertising out central locations like Sydney. This allows less staff at regional stations.

    Almost all media is done via networks now. The local radio club ended up with a heap of SDI video and balanced twin-wire audio gear. Would have been worth a fortune in its day.

    • lui_gough says:

      Hi Andrew VK4ZXI,

      In fact, at the place where I did the analysis, I have a multiband Yagi of the “regular” sorts pointed towards Gore Hill in Sydney. We have four or so fill-in UHF repeaters around the outskirts which are actually quite a way off to the sides – so I suspect the beam pattern of the antenna does not capture them. To me, this is a good thing as some of the “dumber” TVs aren’t smart enough to know on an autoscan which “version” of a given channel they should memorise. The current use of UHF for fill-ins exploits the fact many TVs will memorise the last-scanned-frequency for a given LCN, and due to the normally ascending frequency scan, they will choose the fill-in every time which should be the right thing to do assuming your antenna is pointed to the fill-in. This breaks down when the fill-in is off-axis but just enough gets in to get a decode of the PMTs – the TV will choose the fill-in even though it has very high BER/low SNR. As a result, I make it a habit to decide which transmitter site to aim for and manually scan the known mux frequencies.

      Part of the issue is with legacy – a lot of the antennas that are still around were installed in the analog days when SFNs were not really possible and fill-in repeaters were fewer especially around Sydney. The UHF fill-in and SFN situation is really a byproduct of the introduction of DVB-T and mandatory switch-over to ensure sufficient coverage is maintained.

      However, analysis of the trial DVB-T2 broadcasts at my other house did capture a majority of the fill-in UHF carriers around the Sydney area such as the one in Kurrajong Heights (https://goughlui.com/2018/05/30/analysis-dvb-t2-australian-television-networks-test-transmission/).

      In this day and age, using VHF to cover the majority of the Sydney basin still seems to be the strategy, but leads to quite a bit of pain as larger antennas tend to fail progressively thanks to wind loading, birds, etc. Also, not so easy to get decent gain/get away from impulse noise on VHF, but alas, it propagates well. Smaller and lighter antennas for UHF are nice, but UHF likes line of sight. In the past when our local community station (TVS) was still broadcasting, they were not available on any UHF fill-ins, so I was always adamant to receive from the main Gore Hill site in Sydney as we got one more multiplex. Now that TVS is off the air, I suspect there is no disadvantage of tuning into the UHF fill-ins. My original fear was that there was whole-chain signal reprocessing done at some of these sites which might change the program availability or quality (e.g. by re-encoding), but it seems this is not the case.

      A lot of things have migrated to IP or private fibre networks – satellite feeds have occasionally been replaced by (noticeably poorer) 4G-LTE based field news-gathering video/audio relay links. Satellite feeds have also given way to fibre based digital media networks which shuffle MXF containers from site to site without re-encoding losses and faster than realtime. Now, consumers have the choice of watching things over the internet – streaming live, video on demand or in some cases still, offline download. The whole broadcast paradigm along with a lack of ‘free time’ will probably continue to erode their popularity.

      – Gough

  2. Hi Gough

    Most interesting, certainly a complex evolving industry.

    The VHF TV antennas are large, especially the legacy ones that go down to channel 0 or 2. However the newer antenna for the current TV band plan would be smaller, only needing to cover ~150 MHz up. VHF is preferred for propagation especially in the huge area of our capital cities.

    With analysis of DVB-T you might have a look at the Decontis software. I use it for amateur digital TV. The software is professional grade but quite inexpensive, plus it runs on a USB TV dongle. Search VK4ZXI Decontis for my blog post on it. I have used Crazyscan2 but prefer Decontis.

    – Drew

    • lui_gough says:

      Thanks Drew,

      I’ll probably take a look into it when I have the time, but I have a tendency to stick to the software and workflow I know best which is a hodge-podge of CrazyScan2, TsReader, ffmpeg, Twinhan TS Recorder (for my older cards) and some Excel magic. It may not be very streamlined, but that’s never stopped me :).

      – Gough

Error: Comment is Missing!