Saturday, 1 November 2014

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.

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