We all knew it was coming. The government did a good job of warning us, and today the day has arrived. As I write this, I feel some sort of sadness that a technology which has served us, incrementally improved upon since the black and white era, will now be laid to rest. Powerful transmitters switched off. Modulators with no more work to do. Old TVs, TV radios and VCRs with nothing but static. I grew up with analog, and now analog is no longer. I felt it was part of my duty to preserve some of it for posterity.

Living with Analog

As a child, I was already into science and technology. One of the first devices I was fascinated with, was the VCR. VHS tapes, spools and drums turning round and round and mechanical noise. It was the business. This naturally lead me to have an interest in Analog TV, as recording TV was a big part of the role of a VCR.

Analog TV was always a chore. From our former residence at Cabramatta, our rooftop antenna experienced frequent damage and pointing failure due to winds and storms. There came a point where it wasn’t worth fixing, and instead we relied on rabbit ears. The signal was only barely adequate, regardless of the type of rabbit ears in use.

If there’s anything that Analog TV taught me, it was that there is no perfection in analog. The defects are all part of the technology. You wouldn’t expect a vinyl LP to be pop-free, nor shortwave radio to be perfectly quiet. Likewise, snowing (white spots scattered around the image, still or moving), ghosting (quite apparent when aircraft are flying overhead due to multipath), ringing (on edges) and banding were considered normal. Judicious placement of the antenna made a small difference – but even people walking around the room could be enough to make the signal fade out to near disappearance behind the noise. Worse still, the use of poorly shielded appliances, switching appliances on and off or using appliances which create impulse noise (brushed motors) caused loud popping in the audio, snowing or sometimes picture “rolling” as sync was lost. The term “VHold” comes to mind, as old sets had adjustments to allow for drifting frequency references inside the set, and fine tuning knobs for getting the best picture.

Even colour had its own special look – edges were never sharp. Colours bleeded and “crawled” around. Interlaced scanning meant line twitter as well (things jumping up and down between scan-lines). Motion blur was an expected thing thanks to the persistence of the phosphor.

It was an experience. I always wanted to make it better – once it was recorded, it was “kept” in that quality, so it led me to be patient and to tweak and refine. Despite all its failings, having not known any better (and knowing that VHS was inferior to a good broadcast signal), we were very content. Now, 1080p seems to be the expected level of quality.

Being a relatively young person, I never experienced black and white, nor kinescope film replays. I experienced the true heyday of analog. Mass produced, inexpensive TV sets. Not much repair, alignment or modular design. Mostly computerized digital control, with only a few knobs. And towards the end, even on-screen displays on the TV sets and VCRs.

Analog also came with its curse of different systems, while Australia used PAL, others used SECAM or NTSC. These were incompatible, and might display in black and white with the wrong number of lines (squashed) or end up rolling. Different colour carrier frequencies, encoding methods and scanning lines/rates made these hardware incompatible.

Broadcasts also had their characteristic full-screen appearance, and were watermark free until late in the game. Once digital arrived on the scene, analog was merely a “compatibility” mode, often with black letterboxing to accommodate a slightly less pan-scanned 16:9 image.

The Analog Neighbourhood

All radio transmissions in Australia happen with the permission of the Australian Communications and Media Authority (ACMA), formerly ACA. Analog TV in Australia follows a frequency band-plan which is unique to us. Ultimately, this is the reason why international receivers, like TV tuner cards, need the country to be set correctly, so they tune to the right frequencies.

In Sydney, we have five analog stations. We know them as Channel 2 (ABC), Channel 7 (Seven), Channel 9 (Nine), Channel 10 (Ten) and Channel 28 (SBS). Formerly, there was a Channel 31 Community TV Sydney, however, it lost its license to operate due to advertising dispute with the ACMA. The earliest channels began broadcasting at the end of 1956, 57 years ago.

All of the broadcasts are made in PAL B format which has 625 scanning lines, of which 576 are visible. The frame rate is 50 fields per second interlaced. Apparently, earlier systems (e.g. 405-line) were forbidden, and thus never took off.

I still don’t have a clear idea of what the transmit power was, but it’s definitely some large number. I consulted the Radcoms database of ACMA, and made PDF archives of the data there for future reference (in case you can’t find the licenses in the future). The data is © Commonwealth of Australia (Australian Communications and Media Authority) 2013 and is attributed as requested according to their license.

License 1139424 ATN7

License 1139425 ATN7-S

License 1150082 ABC

License 1150091 SBS

License 1384570 TCN9

License 1384571 TCN9-S

License 1384572 Ten10

License 1384573 Ten10-S

What have we lost?

Some of the readers would, at this point, be totally convinced of Digital TV’s superiority in image quality, bandwidth efficiency, transmission power utilization/coding gain and error correction ability. They might feel that nothing has really been lost. To some extent, this might be true.

One thing we have lost is the ability to pick out and hold onto even very weak distant transmissions. Analog is likely to be much easier to DX, because even when it’s not good – say, snowy, interference bars, ghosting, the brain is still able to make out some of the imagery. With higher order modulation modes and reduced FEC and guard intervals, digital TV is almost an all-or-nothing proposition.

Analog transmissions could and were used as a source of frequency reference, as their field/frame rates were very stable. When viewed on a regular CRT, these signals produce a whistle at 15625hz, which is due to magnetostriction in transformer cores inside the TV. This signal did cause annoyance to me (as I can hear them), but it was useful for use with Spectrumlab. I can definitely attest to the stability of the signal when it lasted.

Analog TV also carried Teletext, a text and primitive graphics information system, which was encoded into the “vertical blanking interval” lines not directly seen by viewers. The system itself discontinued broadcasting earlier than the removal of analog TV, and there is a Digital TV replacement (MHEG-5) which allows for a similar service, although only used for closed captioning at the moment.

In fact, Analog TV’s signal was related to the PAL signal format (composite) and itself, a product of the limitations of scanning CRTs of the time. No longer will such non-visible lines need to be sent, and no longer can we “bury” data in them as such.

Due to the way the audio in Zweikanalton A2 broadcasts, it is a medium width FM signal, and certain TV audio radios were produced which allowed an extended tuning range so you could “hear” (but not see) the TV. The switch-off will render those sets no longer capable of this, and will also render older portable TVs to be obsolete (if not already). In fact, my Icom IC-R20 has a TV mode … it’s not going to be useful for long.

We’ve also lost, and possibly for good, the very dominant 4:3 aspect ratio presentation. Digital systems are almost universally opting for 16:9 format instead, which, took me a while to get used to. We might have also finally lost the PAL/SECAM/NTSC format issues, as progressive “any-rate” scan systems become the norm – technically there’s less reason to need to conform strictly to these standards anymore.

I suppose, to the ordinary TV watcher, they may find the digital services preferable for their high reliability given sufficient signal, better programming/more variety even though there is slight image degradation, higher resolution, and positive identification of signal. Tuners are also quite cheap, and recording doesn’t have to involve further losses in quality (necessarily), or use of VHS tapes and their associated annoyances (rewinding, tape chew, head cleaning).

The irony is, despite the digital, we still have some nasty analog legacy which follows through – for example, interlaced instead of progressive scan, and the standard definition resolution of 720×576.

Waiting for the moment …

Since we were well warned about this, I tried my best to be as well prepared as I could. My ankle really slowed me down when it came to gathering and setting things up, however. I settled on monitoring the spectrum using rtl-sdr dongles, rtl_power and heatmap.py to see when they all went off air. I grabbed an old Samsung 6-head VCR, 10 years old at this stage, and plugged that in via composite (aka CVBS) to a Empia EM2800U USB 2.0 capture card (supported under Windows 7 x64 by drivers from Windows Update). Audio would be captured by an onboard Realtek sound card. Using Virtualdub, I would capture video from the air as tuned by the VCR into a huffyuv lossless compressed file for later processing.

This let me monitor the video from one channel. I settled that I would monitor Channel 7 (ATN), as I had a feeling they would deliver something before going off the air entirely.

Before the moment, I took the time to capture frame grabs which illustrate the messages which were displayed to viewers warning of the “impending doom”. Interestingly, no such messages appeared on ABC or SBS.

Channel 7 opted to have a scrolling banner. Click to see full size, without the sides cropped.

Channel 9 had fixed text, although it had some strange corruption to the left side which remained constant.

Channel 10 had fixed text as well, although a bit small. All of the texts refer viewers to the digitalready.gov.au services at (freecall) 1800 20 10 13. Just for completeness, I gave the service a few calls and recorded the automatic voice systems (apologies for VoIP packet losses):

Having documented all of this, the next step was to wait until the signals were turned off. There was no precise time given, we were told that it “may” go off tomorrow (said the operator on the phone). I stayed up till midnight.

I watched. Midnight came and went, 12:10am, signal was still there!

I reasoned, no broadcast engineers would be around at that hour to pull the plug. Instead, it would be first thing in the morning on Tuesday which I reasoned to mean 9am.

It goes off …

The signals went off at 9am Eastern Daylight Savings Time on the 3rd December 2013 (2013-12-02 2000UTC). Almost simultaneously, the channels all “switched off” leaving no trace of their carriers within the 10 seconds prior to 9am.

We can see this in the rtl_power waterfall plots – here’s a time span from 8am to 10am, with 9am being right in the middle. The vision carrier peak is on the left, and the A2 stereo’s “dual mono” carriers on the right side. Forgive the frequency inaccuracy – none of the three dongles used were ppm corrected as I was in a hurry.

Above is ABC. Extinguished at 9am.

Here’s ATN7, also extinguished at 9am.

TCN9, bordering the 9A DAB service. TCN is gone by 9am, DAB service rolls on.

Network Ten, also gone at 9am.

Finally, SBS, gone at 9am, while its digital DVB-T counterpart continues on to the side.

I was monitoring the vision from ATN7, and they broadcast a special farewell, which in itself is poignant due to the use of the song Tommy Leonetti – My City Of Sydney which was the station identification music for ATN7 in the 80’s. Note that the initial silence is for audio synchronization, and the first video frame represents exactly 8:55:00am, the sign-off begins at 1:11 into the video.

It also featured archive film footage, although somewhat anachronistically pillarboxed in a letterboxed format, rather than filling the 4:3 screen as “traditional” analog broadcasting would have done. The scrolling banner was “removed” during the morning program, and changed to a static one for the farewell. I don’t think it aired in digital, although I didn’t check.

After the old ATN7 logo is put to bed, and a final goodbye is said, the screen “shrinks” to a point like the old black and white CRTs of the day. The audio develops some hiss. Then the carrier goes. The VCR puts up its “blue” no-signal background, having lost lock with the carrier, freewheeling from its internal clock source. My capture cards timing diagram shows that the solid stability of broadcast TV is lost.

I didn’t get a chance to receive the other stations, so I don’t know if they prepared any sign-off message or not. I’d be quite interested to see them if there are any (please leave me a comment!).

Bye bye analog. You were good for so long. Even when you were weak, you were still there in the shadows. You will be missed by those who remember having you around. You were the first TV they knew.



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