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WITH ACTIVITY.  PERIODS OF SUNSET AND SUNRISE ENHANCEMENT ACTIVITY AT NDB
FREQUENCIES NEAR 630 AND 2200 METERS ARE SHOWN IN TABLE 1.  THE GRAYLINE
NEAR LOCAL SUNSET AND SUNRISE AT NDB FREQUENCIES IS LIKE THE WELL KNOWN HF
GRAYLINE.  HOWEVER, ON NDB FREQUENCIES, THE INDIVIDUAL BEHAVIORS OF SUNSET
AND OF SUNRISE PROPAGATION ARE CLEARLY DIFFERENT FROM EACH OTHER.  FIRST,
AFTER APPROACHING AND PASSING THROUGH SUNSET, THE NUMBER OF BEACONS
INCREASED TENFOLD FROM SEVEN AT 0100 020

OPTIMIZING PROPAGATION ON 630 AND 2200 METERS  THIS STUDY OF OUR NEW MEDIUM
AND LOW FREQUENCY BANDS YIELDED INTERESTING RESULTS.  ROBERT S. LOGAN, NZ5A
PROPAGATION ON OUR NEW FREQUENCY BANDS AT 630 AND 2200 METERS CAN BE QUITE
DIFFERENT FROM WHAT MOST AMATEURS ARE ACCUSTOMED TO EVEN 160 METER
OPERATORS.  TO BETTER UNDERSTAND THE CONDITIONS ON THOSE BANDS, I CONDUCTED
A STUDY OF LOW FREQUENCY STATIONS CALLED NONDIRECTIONAL BEACONS NDBS FOR
THREE WINTER SEASONS FROM 2014 THROUGH 2017.  IN THE UNITED STATES, NDBS
HAVE SERVED AVIATORS AND MARITIME VESSELS AS IMPORTANT AVIGATIONAL AIDS
SINCE 1932, WHEN THE DEPARTMENT OF COMMERCE INSTALLED 83 BEACONS ACROSS THE
COUNTRY.  NDBS TYPICALLY TRANSMIT SLOW SPEED CW MESSAGES AT VARIOUS
FREQUENCIES FROM 190 KHZ TO 535 KHZ, ALTHOUGH THEIR ALLOCATION RANGES UP TO
1750 KHZ.  OTHER COUNTRIES NDB SYSTEMS GENERALLY FOLLOW SIMILAR FREQUENCY
ALLOCATIONS.  FOR EXAMPLE, AUSTRALIAN NDBS TRANSMIT FROM 200 TO 490 KHZ.
NDBS ARE RELEVANT TO THE AMATEUR COMMUNITY FOR THREE REASONS.  FIRST, THEY
PROVIDE REAL TIME PROPAGATION INFORMATION ON FREQUENCIES VERY CLOSE TO THE
NEW BANDS.  FOR EXAMPLE, 630 METERS IS ABOUT 60 KHZ BELOW THE UPPER
FREQUENCY LIMIT FOR DOMESTIC NDBS, WHILE 2200 METERS IS ABOUT 50 KHZ BELOW
THEIR BOTTOM LIMIT.  IN TERMS OF PROPAGATION, THEN, CONDITIONS ON NDB
FREQUENCIES AT ANY GIVEN MOMENT ARE PROBABLY SIMILAR ON THE TWO NEW BANDS,

EXCEPT PERHAPS FOR DISTANCE BECAUSE 630 METER SIGNALS PENETRATE HIGHER INTO
THE IONOSPHERE THAN 2200 METER SIGNALS, RESULTING IN LONGER DISTANCES.
SECOND, NDBS PROVIDE INFORMATION FOR LOWER FREQUENCIES LIKE THE HF BEACON
NETWORK DOES FOR HIGHER FREQUENCIES.  BOTH SYSTEMS REPEATEDLY TRANSMIT CW
MESSAGES IN CERTAIN SEQUENCES FROM FIXED LOCATIONS AT PUBLISHED POWER
LEVELS ON A 24/7 BASIS.  HEARING AN HF BEACON MEANS SOME LEVEL OF
PROPAGATION EXISTS BETWEEN YOU AND ITS LOCATION THE SAME GOES FOR HEARING
AN NDB STATION.  HOW WELL YOU HEAR THEIR SIGNALS GIVES YOU A SENSE OF THE
PROBABILITY OF MAKING CONTACTS ALONG THE SHARED PATH.  SO, WHETHER ON 20,
630, OR PERHAPS EVEN 2200 METERS, EACH SYSTEMS INFORMATION CAN BE USEFUL.
THIRD, JUST AS CONTESTERS AND OTHERS USE SOFTWARE PROPAGATION MODELS TO
MAKE HF OPERATING MORE ENJOYABLE, REAL TIME NDB DATA CAN ENHANCE YOUR
ENJOYMENT OF THE TWO NEW BANDS AS WELL.  NO PROVEN PROPAGATION MODELS EXIST
YET FOR AMATEUR OPERATION AT 630 AND 2200 METERS.  HOWEVER, WITH IMPROVED
DATA COLLECTION AND ANALYSIS TOOLS, ITS JUST A MATTER OF TIME UNTIL THE
WIZARDS AMONG US DEVELOP USER FRIENDLY PROPAGATION MODELS.  PERHAPS THE

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