Thursday, June 26, 2008

Situational Awareness


Soldiers and law enforcement types refer to "situational awareness" as being keenly aware of the environment that you're operating in. Alert to possible opportunities to gain a tactical advantage.

If you're operating with indoor antennas, it becomes even more vital. Fortunately, there are lots of ways to get this vital "intel".

The best way is also the easiest...use your ears. Park your radios on the weak signal calling frequencies when you're working in the shack. 50.125mhz for six meters, 144.200mhz for 2 Meters, 222.100 for the 222 band, 432.100 for 70cm, and 1296.100 for 1.2ghz. All in USB mode. Obviously, you're listening for CQ's...but also other subtle "cues".

For example "Sporadic E" has a bubbling sound that is very different from other types of noise. You'll usually hear this on six meters and 2 meters just prior to an opening. Sometimes you may hear it, and the opening will never come, but often it will.

You may also want to program in the National Weather Service NOAA Weather Radio frequencies. They're in FM mode, and spread out over seven channels:

162.400
MHz
162.425
MHz
162.450
MHz
162.475
MHz
162.500
MHz
162.525
MHz
162.550
MHz

I made a simple chart that noted each of the four major beam headings, North, South, East & West, and listed which stations I could usually receive under "normal" conditions. Depending on the direction, I average about five channels out of seven. Those with outdoor and larger beams will likely get stations on all seven frequencies.

During enhanced conditions, tropo, and rarely even Sporadic E events, you'll suddenly have new stations dominating the frequency or two stations competing for the FM Capture Effect! This is a sure sign that 2 Meter is open! Get on 144.200 and make some noise!

Here in Central Alabama, it's easy to tell when the band is open to the West. NOAA stations in Mississippi use a female "text to speech" computer voice, while Alabama is an all male voice state. If I hear a female voice, then I know the band is open! Just remember these are in FM mode, not USB.

Another great source of information is the Internet. I can't recommend installing a high speed Internet connection in the shack enough. Cable modems, DSL, or satellite can provide high speed connections to the web. For VHF Men, there is nothing like it. Here are some of the sites that I often keep opening while operating:

  • DX Sherlock VHF-UHF Real Time QSO Maps: This pulls data from the DX Spotting networks and displays them as points on a map of North America. There is a lag in the information of several minutes, but it can give you a great idea of where the band is open to. Very useful for 6 Meters and 2 Meters...less so on the higher bands.
  • 144 Mhz Propagation Logger: Kind of a combination DX Spotting tool and "chat room" for weak signal 2 Meter operators.
  • VHF (APRS) Propagation Map: The technology here is very cool. This map uses the 2 Meter APRS network to detect signals that are being propagated past the normal range of digipeaters (LOS) and plots them in shades of yellow, orange, and red. Areas of red usually indicate tropo or Sporadic E openings. There are "false positives" from time to time, but in general it's a great tool. I only wish that the page would update itself every few minutes, instead you have to remember to "refresh" it if you want real time information.
  • Bill Hepburn's Tropospheric Ducting Forecast: Basically a "weather forecast" for tropo propagation. Like your weatherman, Bill's map are not always accurate forecast, but they are reliable enough to make them daily viewing for most VHF DX'ers.
  • Sidewinders On Two (SWOT) Radar Map: Sidewinders on Two is the oldest organization for 2 Meter DX'ers and membership is highly recommended. Their web site also contains instructions and a real time map of NWS radar. Unlike your local TV station, the NWS maps don't filter out "ground clutter" or "false returns". This ground clutter often amounts to tropo or strong backscatter openings on VHF
There's lots more to learn on the web about VHF DXing, but these sites cover most of the real time information sources used by DX'ers. There are others...such as "PingJockey" for WSJT mode, and I highly recommend them for that mode. There are EME (Moonbounce) chat rooms and six meter specialty sites as well, but these are the most used tools.

Remember though, nothing beats "chair time" and your ears!

73 DE N1LF

2 comments:

Rod Scott - N1YZ said...
This comment has been removed by the author.
Vince - N9VN said...

Les, with your determination, you should have no problem getting the indoor VUCC... I'm also trying to accomplish the same feat. I've worked 67 grids on 6m so far this summer from my dorm room using only a tuned random wire and 30-40 watts. I guess when the band is open, its open... For 6m ops, you may also wanna check out the ON4KST 6m chat page. I see alot of the big guns on 6m hanging out there. It's good for passing the time in between openings. There's also alot of good articles at the UK six meter group webpage. Maybe I'll get to work ya one of these openings. Good VHF DX,

Vince - N9VN