Digital TV Technical Discussion


#556

So, now I’m waiting for the ABC to launch the state radio services on DVB-T


#557

If the ABC wanted to run it’s radio services on DVB-T, perhaps something like the following could work?

Mono 64kbps:

*ABC Local Radio (Capital City, Digital/Online/Satellite feed with alternative programing in place of Sport)
*ABC Local Radio (Statewide Regional Feed, which does run Sports coverage IIRC)
*ABC Radio National
*ABC NewsRadio
*ABC Grandstand

Stereo 128kbps:

*ABC Classic FM
*ABC Country
*ABC Jazz
*ABC KIDS listen
*Double J
*Triple J
*Triple J Unearthed

Ideally each and every region would have their local ABC station available via DVB-T but since it’d be a logistical nightmare to achieve, I figured that having the Digital/Online/Satellite version of the capital city station + whatever regional station is designated as the “Statewide” feed on satellite (don’t know about other states but here in NSW it’s the Western Plains station from memory) would be a decent enough compromise.


#558

I think statewide feeds would probably be a bad idea. It would mean some people would become reliant on TV for radio broadcasts, which in the event of local emergency warnings would mean some people would miss out.


#559

The DVB-T2 test licences for Sydney have been issued to Free TV Australia.

https://web.acma.gov.au/rrl/client_search.client_lookup?pCLIENT_NO=1219571




#560

I see that they’ll be using VHF-10 from Gore Hill and UHF-29 for Kings Cross and Mosman.


#561

Thanks!

At 82kw, the VHF-10 signal is stronger than the 50kw for the others?

Don’t know why this is so…


#562

82Kw. God that is a lot of power. Now I will wonder if I can receive it from Melbourne during ducting.


#563

It’s on air now. H265 video, AAC audio. Network is ‘FreeTV’. Program now playing: ‘NOT REQUIRED’. Mux bitrate about 7Mbps. Video is 1920x540p at 50 fps. Playing a demo loop at a restaurant. Channel name is ‘TEST TRANSMISSION’ on LCN 401.

Screenshot:


#564

About time.


#565

There’s also the issue of certain sports being made available via FTA TV when Foxtel has the rights. If you were to have, say, NRL commentary over a FTA signal of a game that is exclusive to Foxtel, one can imagine the tiff Foxtel would have it. Of course, you’d alleviate the issue by not transmitting ABC Grandstand and the ABC Statewide Regional Feed and sticking to the Capital City, Digital/Online/Satellite feed with alternative programing in place of Sport.

I like the idea but I can see certain rights holders getting shitty for the most insignificant of reasons.


#566

My Sony 4K Tv can pickup the signal and displays it at 100% on the metre but as the quality is 0% nothing will decode.


#567

Yeah, fair point: Re, the issues with local emergency and sports broadcasts if the ABC were to expand it’s audio offerings via DVB-T.

Personally I almost never listen to the radio stations via Digital TV. But if the ABC and SBS are going to do this sort of thing, they might as well transmit as many radio services on DVB-T as they can (within the limitations of bandwidth and content rights) so people who live in areas without DAB+ can still enjoy the digital radio offerings from the public broadcasters without having to use online streaming.

Ahh good to hear.

Not that I would’ve been able to scan it in anyway but for what it’s worth, VHF-10 came up with an OK signal strength but no signal quality on a DVB-T set top box.


#568

I imagine it’s so that they can test how the signal will behave at higher powers. It’s a maximum that they’re allowed to run it at, not the power they’ll actually be using all the time (if at all).

Is your TV DVB-T2 compatible?

They could just put all emergcy warnings for the state on the DTV offering.
The high power TV transmitters (which feed the lower power sites) also line up somewhat with the ABC Local areas, so they could possibly offer local stations if they wanted to (or the choice of 2 local stations where TV coverage covers 2 areas).

I wouldn’t expect that to be a problem. Despite being over the FTA signal, they are still legally considered to be radio services. They also wouldn’t be providing vision and the audio is already broadcast to the area.


#569

It says it is Dvb-t2 compatable.


#570

My 2017 Sony 4K DVB-T2 compatible TV is showing 0% signal and 0% quality, even though other Sydney VHF channels are 100% signal and 75% quality :tired_face:

Maybe it’s just not running full power right now, but may get ramped up as the tests progress?


#571

It is now being received on the Sony Tv in Stanhope Gardens, with a 10 element band 3 yagi antenna, 30db matchmaster vhf / uhf / Fm masthead amp set at 15db VHF gain.

Signal information from TV-
Test Transmission - no Video 401
Not required

Signal quality metre 100%
Signal Level 100%
Frequency 212.499mhz
Pre ldpc 2.0e-04 average
Post ldpc 0.00e+00
C/n 40
Guard interval 1/32
T2 System ID 0x006F
Channel 10
AGC 166


#572

Does your TV decode H265 (aka HEVC)? The video comes up OK for me.


#573

Could not find The codecs you mentioned in the specs of my tv.
What Tv do you have, and what is the test transmission they are showing?


#574

I’m watching it on my computer.

The test transmission is a loop of some scenery and then some scenes from a restaurant.


#575

The ERP (effective radiated power) of the transmission is still 50kw. The EIRP (effective isotropic radiated power) for a 50kw VHF station is 82kw. So the other VHF stations would be transmitting the same amount of power.

ERP measures the combination of the power emitted by the transmitter and the ability of the antenna to direct that power in a given direction. EIRP is the total power that would have to be radiated by a hypothetical isotropic antenna to give the same signal strength as the actual source in the direction of the antenna’s strongest beam. (Source: Wikipedia)