How to view full fidelity HDTV without great expense

To navigate to my Home Page click here.

 When HDTV came to the San Francisco Bay area, I wanted to view it at home at full fidelity without spending an enormous amount of money. I had my system up in time to view the Winter Olympics broadcast by a local NBC station and the outdoor scenes just sparkled! The resolution was just amazing compared to standard NTSC.

There are two major hurdles to overcome: how to display the 1920x1080 at full bandwidth, and how to decode the digital 8VSB transport stream. There is a big difference in being able to address the 1920 pixels, and being able to resolve the 1920 pixels. I decided to go the computer display route to keep the cost low. I chose the Sony GDM-FW900 which has a 16:10 form factor. Since HDTV is 16:9, and the Sony has the bandwidth to resolve the 1920 pixels, (I think it takes about a 350 MHz DAC to do it) I went with it. The FW900 has two input ports, so I took the obvious route and tied the other port to my PC. This is a great monitor. It doesn't get blindingly bright without defocusing, but it is very adequate.

At the time I started this project, there were no consumer 8VSB decoders available. I went for a professional decoder made by Harris for the broadcast industry. The model number is ARX-H100 which has since been superseded by a later model. This decoder was intended to be set on one channel and left to monitor the station's broadcast signal. Therefore, the user interface is a farce. It is slow to respond to a button push and the display is a couple line LCD. In its favor however, is it's ability to decode the 19.3 megabit transport stream and convert it to a full bandwidth RGB video signal. I had a lot of trouble with Harris' initial entry decoder for ATSC and had to send it back for service four times after which they were still unable to fix it. I finally fixed it myself after tracing the problem to the RF tuner. The decoder was actually made for Harris by Samsung and so when a consumer decoder from Samsung came on the market, I bought one. It is the model SIR-T165 and has all of the user interface the Harris lacks, but when I A/B compare the video output of the T165 with the ARX-H100, the Harris is clearly sharper and crisper. It could be my particular unit, but I suspect the T165 does not have the full video bandwidth that the professional unit has.

There are two additional requirements to be met before one can sit back and enjoy the programming. One is obtaining a high quality RF signal for off-air reception and the other is decoding the sound. Since there are many consumer products to decode the audio I won't waste space with that. I am physically located in several television station market areas and the transmitters I need to receive, span almost 360 degrees, which means I needed an outdoor antenna with a rotator. San Francisco's Sutro tower which houses many of the San Francisco stations is about 35 NMi from my home. Sacramento's stations have to traverse a mountain range and are about 65 NMi in range. The San Jose stations come from numerous directions, but unfortunately, channel 52, (NTSC channel 36) is about 20 degrees off of the Sacramento station direction and is only 12 NMi in range. In order to get the best directivity I chose a Yagi design UHF antenna and a homemade preamp mounted at a 35 foot elevation. I still have trouble receiving one of the Sacramento stations which is weaker than the others, but since it is a repeat NBC station, it isn't a big loss. I often hear that you can either receive an ATSC station or not; it is either perfect or non-existent. I find that for the weaker, distant stations, that I may receive a perfect signal for an hour or so and then have it interrupted by decoder errors for many seconds. This is most annoying, and I would rather watch an NTSC station with some snow in it, than an HDTV station that disappears altogether for a few seconds every once-in-awhile. The point is, don't skimp on the antenna system.

 

 

To navigate to my Home Page click here.