[HATS] Digital DX, it can be done!

[KB9FOHAM@aol.com]

Digital DX, It can be Done
by Henry Ruh AA9XW (KB9FO)

With the controversy surrounding 8VST-T modulation, and the generally gloomy 
outlook for its acceptance for indoor reception, vs having outside antennas, 
and the various questions of is it going to work, here is a little excitement.

While my ATV friends may think I am absent from the airwaves, I in fact have 
just been very busy on the commercial side of TV. Recently I completed a 
study (600+ pages) comparing UHF reception in Chicago. The study involved 5 
NTSC UHF stations and 1.25 DTV stations. That's one full data and one with 
partial data. Recently more stations in Chicago have joined the DTV world, 
and 1 will be conducting another study shortly that will document the DTV 
reception. I'm using my own personal "ENG" truck, mast and a slew of test 
gear that almost makes my ham shack look light. 

Meanwhile, there are now some 60+ DTV stations operating full time in several 
markets. You can obtain a current list by visiting the NAB [www.NAB.ORG/dtv] 
site and going to the DTV station page. There they list by market the DTV 
operating stations and the list is updated as quickly as stations become 
operational. 

You can receive ATSC digital TV fairly inexpensively. A WinDTV card for your 
computer (by Haupaggue Electronics) is available for $299 at most computer 
stores or by Internet. The NTSC is only about $49. I purchased 8 of the 
NTSC/DTV cards to pass around station staff to monitor our own Channel 45 DTV 
signal which is a half million watts from the top of the Sears tower. I have 
one in my home computer, and it is hooked to my master house antenna system. 
The antenna is a typical mid range Wineguard UV combo on the roof top, about 
25 feet above ground. A rotor lets me move it to view adjacent markets. 

>From my home south of Crown Point, IN, (about 45 airline miles from the Sears 
Tower) I can usually watch South Bend P4.  about 50% of the time Milwaukee 
from the Lake inversion effect, and frequent glimpses of Indianapolis, 
Lafayette, Ft Wayne, Madison, and more distant locations. Needless to say, 
these coincide with the 440 MHz ATV band openings. The VHF stations in these 
markets are also similarly viewable under the same atmospheric conditions.

The obvious question is, "Are the DX DTV stations also able to be received?"  
The answer is yes, and to some extent, more easily than the NTSC stations!

Sunday morning 10-28-00, between shopping, making meals and training dogs, I 
managed to squeeze in a few minutes of regular TV and noticed a band opening. 
Milwaukee, Indianapolis were fairly strong and South Bend a bit iffy. in 
Milwaukee there is a rather low powered DTV-8 that carries NTSC 10 WMTV. It 
is best known in Broadcasting for interference to Muskegon, MI viewers of 
WOOD TV 8 in Grand Rapids. The shot being about 65 miles directly across the 
lake between Milwaukee and Muskegon. The Channel 8 Milwaukee station has 
decreased its power and changed to a directional antenna to reduce the 
problem, but as we hams know, when the band is up, power is meaningless with 
10 watt 300 mile contacts on ATV possible. 

Sure enough, from Milwaukee, channel 10 was visible, channel 6 was there but 
had two other CO-channel signals beating with it. A scan of the DTV mode 
found channel DTV8. At first, much like rain fade DBS, the signal was blocks, 
intermittent and audio bits here and there, but as the band improved, the 
signal got better until there was full reception.  I snatched a few frames in 
the WinDTV 2000 program, and E-mailed them off in hopes of a reception 
confirmation. The scan also picked up a DTV 25 station. I did not know where 
that was, and so a search was made by rotating the antenna while watching the 
DTV 25 channel on the computer. When I got to the Indianapolis direction, it 
popped in and came in just fine. Full reception. So I captured a few frames 
of DTV 25 which is the parallel of WRTV channel 6 Indianapolis.  I could also 
get 13 NTSC from Indianapolis just fine. DTV pictures are either "perfect" or 
nothing, albeit, there is a 1 dB range of signal level where the error rate 
may produce partial pictures, blocks, or broken sound. DXing the usual NTSC 
signals often is difficult because of the co channel interference. This is 
clearly seen in the channel 6 NTSC pictures. The closest channel 25 NTSC 
signal to me is Peoria, IL, about 100 miles, the DTV 25 signal is about 150 
miles away. There was no trace of the Peoria signal, but the Indianapolis 
signal was certainly P5, or perhaps we should say D5! The NTSC 13 pictures is 
a good P4+, some co-channel signal can be seen from a local (6 miles) LPTV 
channel 13 that runs video juke box. Although not visible in this pix, there 
is also a 13 in Grand Rapids, that when the band is open, gets competition 
from the local LPTV 13. If I turn the antenna today, I can see it also. 
While the Indianapolis channel 25 DTV signal was easily received, there was 
only P1 to P2 signals from one Indianapolis NTSC UHF stations, and the others 
were not visible at all. So in this one instance, UHF DTV was perfect while 
UHF NTSC was basically not watchable from 150 or so miles. 

The Milwaukee low power DTV 8 signal was also visible, but the more powerful 
NTSC VHF channels in Milwaukee was a full P5 perfect reception, except for 
some co-channel interference. So even low power VHF DTV can make it, albeit 
not as well as full power VHF NTSC. 

I did not receive any of the DTV signals from South Bend, and the NTSC 
signals were at best P3 (16, 22, 28), quite a bit less than "normal."

Also included is the ID shot from my own Channel 44N/45D station that has a 
half million watts from the Sears building 24/7. Its the most powerful DTV 
station in Chicago. For those watching DTV, Chicago has D31 WFLD fox at 200 
kW ERP, D43 WCPX (with 6 multiplex channels of programming) at 100 kW ERP, 
D45 WSNS with 467 kW ERP.  All are at the same antenna height (but not the 
same antennas) from the top of the Sears building. Soon NBC 29 and ABC 52 
will be operating (they have been testing on air for the past week) and WGN 
DTV 19 is supposed to be on in December. Pix of 31 and 38 are also included. 

The WinDTV board is quick in locking in to the DTV signals.  The board itself 
doesn't have a lot of buffer memory, and will, on perfectly good signals, 
occasionally drop frames, or block defect the picture. But for the money, its 
perfectly fine in these early days of DTV. 

The WinDTV board receives all VHF and UHF channels, in NTSC M, NTSC N or ATSC 
8VSB-T mode. It also has two inputs, one for an antenna and one for cable. It 
can scan both and selects the demodulation mode automatically between analog 
and DTV. The board also has lots of nifty features to capture video input 
from an external source, i.e., your baseband video and audio from an ATV 
receiver, TV set, camera, VTR, etc., and has a good tuner.  I have not yet 
tried to see if using the cable input for cable channels 56-60 will net ATV 
signals, but it would be a natural thing to try. The capture mode lets you 
snatch off air frames, and there is also a movie mode, however, you need lots 
of disk space to store the JPEG pix files!   

So here are the pix, and happy DXing the new DTV world. 




The new KGB:
Klinton
Gore
Janet "Bang" Reno



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