Saturday, 1 November 2014

Achieving 4K UHD DATV- very draft


Achieving 4K UHD DATV- very draft

Perhaps a little early, but 4K DATV may be more achievable than I first thought. It would be a bit of a technological coup if amateur radio can do 4K before regular free-to-air broadcast TV. 4K video cameras and monitors are already relatively inexpensive. 4K TV capture/switchers are available and not too expensive. The missing link are modulators, transmitters and receivers, but may be possible using inexpensive SDR TRX; they can already do DVB-T/S.

As far as I am aware, broadcast TV is still struggling with Full HD digital TV in some countries, notably the USA with a very large number of small TV stations and the not insignificant cost of having to replace virtually everything, other than their antenna. I suspect the same across some of Europe and Asia. For both terrestrial and satellite, while they may have digital TV, most of it is SD (standard definition) or HD (high definition 720p), rather than wide-screen Full HD (1080i; wish it was 1080p).

While I raise the possibility of 4K DATV, the other technology for the future that I raise, networked, internet-linked DATV is probably a greater personal objective. However, others may be interested in low-cost 4K. I can see a real need for 4K in CCTV, where definition matters; it is not just technology bling.

4K DATV is a good use of the numerous UHF bands/spectrum that amateur radio has, but only makes limited use of. In many countries there is pressure to take amateur radio spectrum and use it for other purposes. Use it or loose it?
I will start with the easy bits and progress toward the more difficult aspects.

4K UHD TV Standards: 2160p

Fortunately there is a 4K UHDTV standard, 2160p, (3840 x2160)  http://en.wikipedia.org/wiki/Ultra-high-definition_television, http://en.wikipedia.org/wiki/2160p. It is similar but not the same as the video standard used in cinemas with digital projectors.
It is interesting that it is progressive, 2160p, not interlaced, 2160i. While those who developed digital TV standards a couple of decades ago, 1080i would have been virtually unachievable, but like so many computer standards, it has been surpassed. Further, I suspect that the step will be straight to 2160p TV, with 1080p languishing. 1080p is needed for recording, but not likely to be used live. It is difficult to buy a 1080p to 1080i converter, well, relatively expensive at $600+ per camera; my current dilemma.

4K UHD Displays/TVs

4K PC 28” displays are common and fairly cheap, about $600. I have a Samsung one, but don’t use it as a PC monitor. They use older-style TN LED screens that are good straight on, but are poor for angle viewing. Sitting 500mm from the PC monitor, the sides are blurry.  Tried it for a month, great for reading PDF magazines, but tiring otherwise. I went back to my 28” 2K IPS LED monitor. Still much better than Full HD 1080p!

I use a Panasonic plasma for the little bit of TV I watch, and have a Full HD projector, that gets even less use. Both get around the side-view problem of LCD.

Apple has announced a 5K monitor since I started writing this post. 4K IPS LCD panels are available, but still a bit expensive.

4K UHD cameras

There are a range of 4K UHD cameras on the market, starting with the Hero action cameras, about $450, a number of consumer 4K DSLR, the cheapest currently  Panasonic Lumix DMC-GH4, about $1500 body only, BlackMagic Studio Camera 4K, about $3000 body only. The costs are likely to drop quickly, as it did for the 1080p cameras.
One caveat with 4K UHD cameras is that while they can record at 4K, I am not sure what they stream live. It may be 2160p, but it wouldn’t surprise me if it is still 1080p, with the exception of the BM Studio Camera 4K, it has no record function and will stream live 4K. The GH4 streams 4K too. To be investigated further.  All the same, the cheaper cameras can record at 4K. An amateur 4K system is likely to start with recorded media then move to live.

4K Production switcher

Perhaps not essential, but likely kit even for a Full HD DATV station, the BM ATEM Production Studio 4K, about $1700, allows the use of multiple HDMI and SDI cameras and other devices (recorded media, PC) https://www.blackmagicdesign.com/products/atem/techspecs/W-APS-04.

HDMI devices negotiate connection standards that can be problematic when connecting devices in ways other than what the manufacturer intended. The switchers handle those problems well.
HDMI is not the preferred interface for 4K, the switcher can output UHD SDI, potentially making the interface with the modulator much simpler.

4K Compression standards

There is a 4K compression standard: H-265: http://en.wikipedia.org/wiki/High_Efficiency_Video_Coding. Not a simple subject, but amazing technology.

Compression is a key to usable 4K, to reduce the storage space and data rate but keep the quality; a contradiction. There has been considerable progress in compression, the move from MPEG-2 to H-264 for Full HD being a recent example.

4K Transmitter/amplifier

Compressed 4K UHD will fit in a standard 6, 7 or 8 MHz ATV channel. I think DATV in some countries are restricted to 2 MHz, but that may only be for lower UHF bands such as 70cm. The bandwidth and modulation parameters determine the necessary data rate, which clearly will be higher than for Full HD. In Australia we can use 7 Mhz on 70cm up, at the same standards as free-to-air broadcast TV.

DVB-T at 7 MHz bandwidth has the capacity to handle 4K UHD, but always needs a very linear amplifier. I am not sure what data rates are possible with DVB-S.
As such any good DVB-T transmitter/amplifier should be able to handle 4k; to a point the content is not relevant, although modulation parameters can make greater demands on the TX linearity.

4K modulator/encoder

Ok, now we are into the curly stuff. Current 4K modulators are expensive broadcast devices ($10000+).
However, Nuand BladeRF SDR TRX, a FPGA-based device, may be able to be programed for 4K UHD, linked by USB3 with a PC, networked to the BM ATEM TV Studio for digital and audio inputs. As noted in my last post, the BladeRF has been used for DATV DVB-T: http://yo3iiu.ro/blog/?p=1191, http://www.irrational.net/2014/03/02/digital-atv/. They may be interested in the challenge of 4K UHD DATV with GNU radio. Developing the modulation/encoding It is beyond me.

4K UHD CCTV with dedicated chips per HiDes/ITE DVB-T devices??

optical-astronomy: reducing interference: noise cancelling

…. To be continued ….

My journey in DATV and the future: 4K UHD or internet-linked DATV repeaters; Not that crazy? Draft


My journey in DATV and the future: 4K UHD or internet-linked DATV repeaters; Not that crazy? Draft

In this post I want to briefly outline my DATV journey and a quest for Full HD DVB-T. I have achieved this in a relatively short time and out of some of my difficulties, have wondered if first, 4K UHD DATV and, second, network-linked DATV repeaters, are possibly not that distant.

In this post I will outline my journey, as the future is path dependent, history matters!
In the following two posts I will consider ways to achieve 4K UHD and internet-linked DATV repeaters.

My DATV journey: Live Full HD DVB-T

Personally, coming late to DATV at the beginning of 2013, with a 40 year break in my amateur radio activities (see my first post), I have not had to put in the extreme effort and expense of either analogue TV or digital TV, particularly over the last decade, such as by the DATV Express team, among many others.

Before returning to amateur radio I had spent considerable time and money on home cinema, both PC-based and stand-alone, with both terrestrial and satellite TV, together with an interest in photography and video. As such, I had some knowledge of digital TV, particularly its reception.

After briefly wondering if anything had changed in amateur radio in my 40 year absence, with Japanese-made TRX on HF, I found software-defined radio (SDR) and a place to re-start my adventures. While I enjoy working with SDRs, there were some pauses as I waited for new hardware and software to be released, notably BladeRF (which I will return to), that lead me to find DATV.
After paying a couple of thousand for a good HF TRX, I was reluctant to spend much on DATV, but came across the HiDes DVB-T dongles from Taiwan. I bought the cheapest dongle for less than $200. Getting it going was a bit of a challenge, recorded video was fairly easy, as were webcams, but HDMI capture from a digital SLR camera (DSLR) was very difficult. However, I wanted high quality video, as that is what I had pursued in home cinema and I saw composite analogue video with digital TV as a bit of a contradiction. After spending quite a bit of time and money on PC-based video capture, I thought there must be a better way.

I achieved live, Full HD DVD-T quite quickly with the HiDes DC-100, a Full HD CCTV-based DVB-T camera and modulator, at a very modest cost of $250 plus lens. The DC-100 must be the most over-looked device in DATV. It is simple and cheap to get good quality Full-HD; the lenses have to be higher quality just to match the quality from the camera sensor. HD-CCTV may be an important path to 4K, to be discussed later. As good as the DC-100 is, I was working alone, so wasn’t too concerned only being able to transmit a few hundred metres, I still wanted DSLR quality video.

The HiDes HV-200E, at $660, my third DVB-T modulator in less than a year finally did everything I wanted. With HDMI and SDI (Serial Didital Interface- http://en.wikipedia.org/wiki/Serial_digital_interface), the broadcast TV standard interface, I could TX live, Full HD DVB-T at the highest quality I was prepared to pay for a camera and lens (lens are dearer than camera bodies!).

The HiDes devices use dedicated video chips from ITE Technology, also in Taiwan (see my post on the HV-200E where I describe each chip in the box). The boxes use firmware upgrades. ITE's main market is HD CCTV and consumer electronics, but through HiDes are very helpful to amateur DATV. Dedicated chips, while expensive to develop, are cheap in large volumes.  The alternative is a FPGA and a CPU/PC. HD CCTV uses either coaxial cable or network, so modulators need to cater for DVB-T on coax and network streaming; a win-win for DATV.
At around the same time I came across the BlackMagic Design ATEM TV studio 19” rack hardware, about $1100, but worth every penny. I had dabbled with PC-based TV production switching, as I fancied being able to TX live and recorded video, while working with the DVB-T USB dongle. The ATEM device is incredible; PC-controlled network-based, broadcast TV quality, multiple HDMI and SDI camera inputs, the HDMI inputs doubling as inputs for any HDMI devices, specifically a Western Digital TV live media player for recorded media and HDMI video from a PC. See my earlier posts. The device has HDMI, SDI and network outputs, all of use to DATV.

However, the BM ATEM TV Studio has a significant glitch, all sources must use the same broadcast TV video standard, fair enough, but only the most common, most problematic being 1080i but no 1080p. The big problem is that all digital cameras output 1080p and can’t be plugged into the device! It is a complete mystery why, as even BM’s own cameras can’t be connected. I used everything at 720p, requiring converters for each camera. The cameras can be connected directly to the HV-200E as it supports 1080p. Not all Full HD monitors or TVs support 1080p.
I started looking around for solutions, the simplest being the BM ATEM Production Studio 4K at $1800. I though, sell the old one for $1000 and it’s only an extra $800… It was then that I realised 4K may not be too hard.

Other approaches to DATV I have examined

I have a DATV Express, with external analogue video capture. I tried it briefly and suggested to the group to try digital input via HDMI, but they want to run it on cheap Linux computers instead. Without digital cameras, it was not what I wanted.

I have a “consumer grade” $600 HDMI-in DVB-T modulator from a very large Chinese manufacturer of broadcast DVB equipment, a Digicast DMB-9592. I haven’t needed to try it, but it is based on a FPGA, like the DATV Express, but includes a built-in input for HDMI and analogue inputs. It is stand-alone and does not require a PC, similar to the HiDes HV-200E.

Another approach to DATV, that I have the hardware, but have not pursued the DATV software, is the Nuand BladeRF. I use it with SDR software as a spectrum analyser. I use improvised test equipment as I have little dedicated gear. However, others have programmed it as a modulator for most of forms of DVB with GNU radio, DVB-T, DVB-S etc. See http://yo3iiu.ro/blog/?p=1191, http://www.irrational.net/2014/03/02/digital-atv/

The BladeRF a FPGA-based device, similar to that used by DATV Express and the Chinese Digicast modulator I have. It may be possible to program it for 4K UHD, linked by USB3 with a PC networked to the BM ATEM TV Studio for inputs.

Conclusion

So in one year, I have five or six DVB-T modulators, the three from HiDes, a DATV Express, a Chinese device, plus a BladeRF SDR TRX. I achieved my initial goal with the HiDes HV-200E, and went to a full DATV DVB-T studio with the BlackMagic ATEM TV Studio, allowing the best cameras I could afford.

In terms of the future, 4K UHD may be achievable with the BladeRF and BlackMagic 4K Production Studio, and both the HiDes HV HV-220E and the BlackMagic ATEM TV Studio are capable to network streaming out and possibly in.