Wednesday, April 25, 2012

TV DXing in the Digital Age

In the 29 years I've been seriously DXing television, no adjustment has been as major as the transition here in the United States from analog to digital television three years ago. Many of us remember the "nightlight" operations by several TV stations of their analog signals broadcasting public service announcements on the conversion to digital for one month. In my home state, the stations that did this included KSDK 5 St. Louis, KRCG 13 Jefferson City, KYTV 3 Springfield and KMBC 9 Kansas City. Of course, KSDK now operates on UHF Channel 35, KYTV on UHF Channel 44 and KMBC on UHF Channel 29. KRCG remained on VHF, operating on Channel 12. Via E-skip, I pulled in such operations from WGBH Boston, WPBT Miami and KPRC-TV Houston (both on VHF Channel 2), as well as the TV stations run by the University of North Carolina.

It was well worth the money I paid for my first digital TV tuner, a Digital Stream HD3150. I bought it in 2005. I used this for DX for the first three years of my DXing digital TV signals. The tuner is now part of my entertainment system, but is still hooked to the same Radio Shack VU-210XR that my pair of Zenith DTT-901 tuners are hooked to. Some of my early DTV DX was received on the HD3150. My best log came in November 2006, when I pulled in WJHL Johnson City, TN operating in digital on UHF Channel 58. They're now in digital on VHF Channel 11. This was how their main channel came through.

Digital TV also allows for the capacity to transmit multiple channels on a 600 kHz chunk of spectrum that an analog television signal occupied. The most sub-channels I've seen on one station has been five, for the stations owned and operated by Trinity Broadcasting Network (TBN). Many stations use one channel for a full-time weather channel. On that same night, I pulled in WJHL's weather channel.

One thing that doesn't change, however, is E-layer skip propagation. A handful of digital TV stations in the U.S. operate on VHF Channels 2 through 6. The first E-skip signal that was steady enough to do a video capture of is WRGB Schenectady, NY, which operates in digital on VHF Channel 6. This was pulled in after the completion of the digital transition in 2009.

VHF low-band DTV signals can also be received by tropospheric enhancement. This is from the summer of 2011, pulling in WHBF on VHF Channel 4 from Rock Island, IL. This is the closest VHF-low band digital TV station, at 185 miles.

Many of the VHF digital TV stations operate on Channels 7 to 13. This is my closest VHF High band DTV station, WCIX in Springfield, IL on VHF Channel 13.

My ability to video capture my DX is greatly enhanced with a video card on my computer. In 2004, I bought a Hauppauge Win-TV-Go video card. It's a vital piece of equipment for any DX shack. It does better with digital signals than analog signals. Sometimes, an analog signal can hold long enough to get a video capture. Some countries are still broadcasting in analog, such as Mexico. This one is XHAE on VHF Channel 5 from Saltillo, Coahuila. You can barely read the "Televisa Saltillo" ID in the top left hand corner of the screen. This was received in the summer of 2011.

TV DXing, as far as I've found, hasn't been that much different in the digital age than it was during the analog era. It's just that you need more patience to pull in DX. Give it a try, regardless of whether you have a DTV tuner hooked to an analog TV set, or a new HDTV set. You would need a top-of-the-line antenna to receive DX, though.

Thursday, April 12, 2012

Locating Your DX Shack in a Metropolitan Area

Today, I'm going to talk about the subject of locating your DX shack in a metropolitan area. A large metropolitan area is usually considered an "RF jungle"; a term coined by an AM (medium wave) broadcast band DXer to refer to one such place (Denver, CO).

For most of my life, I've lived in the St. Louis area. More specifically, I have DXed from the city of Hazelwood, in northwestern St. Louis County. It is a community of 25,000 residents located north of Lambert-St. Louis International Airport. Since 1992, I've DXed from my current location in back of McNair Elementary School (this one is named after Alexander McNair, the first Governor of Missouri, who served from 1821 to 1825). My first DX location, two blocks to the southwest of my present location, was annexed into Hazelwood the year I started DXing in earnest (1981). Before that, it was in unincorporated St. Louis County. From 1988 to 1992, I DXed on the Cobb-Cherokee county line in Georgia; in this case, I was close to a major military installation (Dobbins Air Reserve Base and Naval Air Station Atlanta, now a Joint Base, in Cobb County, near Marietta and Smyrna).

One of the best locations to locate your DX shack in a metropolitan area the size of St. Louis is near a major airport. When I started DXing, St. Louis was one of the ten busiest airports in the country. Now, it's more like an airport in a smaller city, such as Springfield, MO. If you enjoy monitoring the VHF Aviation Band (which is AM mode, unlike most VHF communications, which is FM), an airport provides the best location for this purpose. You're far enough away from local AM, FM and TV transmitters to adequately DX with even a portable receiver (like a Crane CCRadio). Depending on the ground conductivity in your area, you can null out nearby AM stations to pull in DX. My current location is 15 miles northwest of downtown St. Louis; most of the AM transmitters are on the Illinois side of the river, around East St. Louis, East Carondelet, Madison, Granite City and Pontoon Beach. I can get decent signals out of the St. Louis stations at night, with the sole exception of 18-watt KSTL (690 kHz). On most channels except 1120 kHz (where 50 kW blowtorch KMOX resides), I can put tight nulls on the St. Louis stations to pull in DX. The closest AM transmitters to me are both ten miles away: KFUO (850 kHz) in Clayton (a 5 kW limited time operation, on from sunrise to one hour after sunset, to coincide with sunset at KOA Denver) and KHOJ (1460 kHz) in St. Charles (5 kW day, 210 watts at night). Before sign-off, KFUO, which broadcasts in digital, takes out 840 to 860, so those channels are lost for sunset DX. When KHOJ cuts to night power, I can pull in DX with the station nulled. I can even put a tight null on KTRS (550 kHz) on some nights to pull in KTSA in San Antonio, TX. When I was living in Georgia, my DX location was 25 miles northwest of downtown Atlanta, and 75 miles southeast of Chattanooga, TN. The night signals of the full-time Atlanta stations, with the exceptions of WSB (750 kHz), WGST (640 kHz), WAFS (920 kHz-now WGKA) and WKHX (590 kHz-now WDWD) were barely audible or totally inaudible. Most of the Atlanta AM transmitters were in the northeast part of the city (around I-85 and Georgia 400), with a few exceptions. For example, WSB's transmitter is in Tucker, in DeKalb (pronounced "De Cab") County. WDWD's transmitter is in Cobb County, near Austell. The best Chattanooga signals at night were WGOW (1150 kHz) and WDEF (1370 kHz). One night, I even put a tight null on WSB to hear KJEL (now KBNN) Lebanon, MO at Lebanon's sunset. The difference is the ground conductivity. In much of metro Atlanta, the ground conductivity value is the lowest on the scale, 1 (very poor). In Cobb County, the ground conductivity value is a 2 (poor). Much of Tennessee has a ground conductivity value of 4 (fair), including Chattanooga and Nashville. The St. Louis area's ground conductivity value is 15 (very good), except around Warrenton, where the ground conductivity value is 8 (good).

On the FM and TV sides, my current location is 17 to 20 miles from local FM transmitters. Most of the St. Louis area's most powerful FM and TV transmitters are in southern St. Louis County, in communities like Affton, Shrewsbury, Sappington, Webster Groves and Oakville. With even modest equipment, I've been able to put nulls on some of my 100 kW locals to pull in DX. For example, I've pulled in KPRS 103.3 Kansas City with KLOU nulled, and even WBVN 104.1 LeRoy, IL through WHHL (then licensed to Jerseyville, IL). The closest powerful FM transmitter is six miles north of my QTH; the Radio One tower north of Florissant, which serves as a backup for WHHL (now licensed to Hazelwood, although it should have a "K" call) and the main transmitter site for WFUN-FM (95.5 MHz). Five miles from my QTH is 100-watt KCFV (89.5 MHz), where I worked in the late '80s and early to mid-'90s. During the analog era, I could null down most of my locals to pull in DX. For example, a visit by KMBC 9 Kansas City with KETC on was pretty much an annual event; the same with WHAS-TV 11 Louisville with KPLR on. By contrast, the late Rich Eddie DXed from the middle of the FM-TV RF jungle, in Webster Groves. His TV DXing was limited to UHF, even though he used a Winegard UHF antenna. For FM DX, he had to use a McIntosh MR-78, which had a super-narrow bandwidth setting. I checked it out when I visited his Webster Groves QTH in 1987. When I was in Atlanta, I was over 30 miles from most of the powerful Atlanta FM and TV transmitters. The nearest powerful FM transmitter was also six miles away; the WCHK-FM (105.7 MHz-now WWVA-FM) site in Holly Springs, halfway between Woodstock and Canton. Even with that 50 kW station blasting away, I could still occasionally get WLAC-FM (105.9 MHz-now WNRQ) out of Nashville. Even most of the 100 kW Chattanooga stations were semi-locals. For example, WMBW (88.9 MHz) has their tower atop Lookout Mountain on the Tennessee-Georgia border. I used modest equipment while I was in Georgia.

Your location in a metropolitan area won't affect shortwave listening as much, unless you're within, say, five miles of an AM radio transmitter, especially a 50 kW blowtorch like KMOX or WSB. I've had success on shortwave from Hazelwood and suburban Atlanta using simple homebrewed antennas, including one made of a metal coathanger and speaker wire. My shortwave listening took a big leap when I purchased a G5RV antenna (engineered for Amateur Radio) in 1997. With an antenna tuner, it can be adapted for use as a shortwave broadcast antenna. I don't know how well it would do near an AM transmitter facility, however.

If you live in a metropolitan area, the best place to set up your DX shack, even if you have modest equipment, is at least 10 miles away from AM transmitters, at least six to eight miles from an FM transmitter of up to 50 kW, and at least 15 miles from 100 kW FM transmitters and high-powered TV (digital or analog, depending on what system your country uses) stations. If you're in an RF jungle, you would have to try DXing using top-of-the-line equipment, if it's even worth trying.

If you're looking to buy a home in a metropolitan area, it's best to buy near a major airport or far away from the powerful AM, FM and TV transmitters.