High Latitude HF Comms Testing LT Mike Grochowski Bill Jankowski USCG RDC What’s the Frequency, Kenneth? •WiFi – 2.4 GHz (2400 MHz) •AM Radio - ~1000 kHz (~1 MHz) •FM Radio - ~100 MHz (0.1 GHz) •Cell Phones (850/900/1,800/1,900 MHz) What Does HF Mean? HF stands for HIGH FREQUENCY These are the frequencies from 1.8* to 30 MHz or the 160 meter to 10 meter bands. HF is also known as shortwave. *160m is actually a Mid Frequency (MF) band but it is included in the Amateur HF bands for ease of discussion. Ok, if HF is so Great, why doesn't everyone use it?? –HF propagation is impacted by the actions of the Sun via “Sunspots” –Data throughputs from 75bps->19.2kbps under poor-> very good conditions, –From 2-10MHz, the noise environment can rise 33 – 70dB ABOVE thermal noise (kTB) due to manmade and atmospherics„ (fluorescent lights, T- storms, fish tanks, electric fences, Xmas lights, old electric motors, etc) –Common perception is that data rates are “low” and antennas are LARGE •Breaking NEWS: MIL-STD-188-110C Appendix D Data Waveform Suite (approved Sept 2011) supports HF Channel bandwidths ranging from 3 – 24KHz in 3kHz steps, allowing 75bps -> 120Kbps. How is HF different other communications methods? •No “machine” or infrastructure is used. HF Takes advantage of atmospherics •Allows communication beyond line of sight WITHOUT Satellites or repeaters. Links can be a couple of hundred miles to over several thousand miles. •Propagation is strongly effected by solar activity. •Several communication modes are available to use. SSB, CW, RTTY, SSTV, Digital, AM Hearing Signals Out of Thin Air The Role of Sol How the Sun Opens and Closes The Bands Why HF Works (The Atmosphere) The Earth’s atmosphere is made up of several layers or regions. D-Layer – Strong absorber of low-frequency HF energy during the day E-Layer – Reflects mid frequencies of HF (10-30 MHz) during the day F-Layer – Strong reflector of lower-frequency HF Radio waves change direction when they enter the ionosphere Sunspots / Solar Activity •More sunspots, the higher the ionization of the F2 Layer –11 year cycle •Solar storms (intense cosmic activity) can change the critical frequency in a matter of minutes -> hrs – One minute the link is fine, in a matter of minutes, its GONE •Sunspot maximum - 10,000miles commonplace using 10watts or less with frequencies in the 20 – 30MHz range. –Sunspot Activity has stayed well below maximum •During short summer evenings, the MUF can stay above 14 MHz and it can support communications to some point in the world around the clock. –Similarly, during long winter evenings, MUF plummets and HF Distances shorten Propagation There are three basic types of propagation of HF radio signals: 1.Sky-wave 2.Ground wave 3.High Angle Radiation (NVIS) Sky-Wave Provides Single (<4000km) or Multihop (7 hops, 15,000km) communications via ionospheric reflections * * Very, very old picture – D Layer attenuates; it’s the E and F layers that reflect The Gray Line The transition are between daylight and darkness is called the gray line. This area offers some unique and special propagation to the radio operator. Ground Wave Ground wave is the signal that radiates close to the ground from the Earth’s surface up to the lower atmosphere or troposphere and is reflected or diffracted by the terrain. - ~200-300 NM NVIS - Near Vertical Incidence Sky-wave Like squirting a hose at the ceiling, this technique allows you to blanket your signals over a significant area close to your station. OK, Physics, Great – Why does the USCG Care? GMDSS – Global Maritime Distress and Safety System Uses DSC (Digital Selective Calling) tied to ship’s MMSI GOTHAM and COTHEN HF ALE (Automated Link Establishment) networks HF Secure Voice Network Got it. Why does HEALY 1403 care? RDC study of existing Alaska HF sites identified areas where coverage could be improved Temporary deployment to Barrow this summer Considering additional fixed sites Multiple Measurements using existing fixed sites and Healy allow for better modeling in future efforts More about HF Amateur Radio ARRL Web Site -http://www.arrl.org/what-s-ham-radio ARRL PowerPoint “Discover The Magic of HF Radio” http://www.barriearc.com/CBSS_ARES_files/HF-Radio.pdf http://www.emergencyradio.ca/course/HF-Radio.ppt Low Band Dx‟ing – probably the best source of ALL THINGS HF you‟ll ever need http://vss.pl/lf/00.pdf HF Propagation and Propagation Prediction – VOACAP Website http://www.astrosurf.com/luxorion/qsl-perturbation6.htm HF Radiation - Choosing the Right Frequency http://www.weather.nps.navy.mil/~psguest/EMEO_online/module3/module_3_2b.html Learning about Space Weather and Predicting HF Propagation http://www.spacew.com/ HFALE http://www.navymars.org/central/reg4/al/ALE%20Introduction.pdf Useful HF Noise Models complete with Formulas http://ftp.rta.nato.int/public//PubFullText/RTO/TR/RTO-TR-IST-050///TR-IST-050-02.pdf NVIS Questions? Publications ARRL General Class License Manual http://www.arrl.org/catalog/lm Morse Code Study Materials http://www.arrl.org/catalog/lm Publications ARRL Handbook http://www.arrl.org/catalog/?item=9280 Publications ARRL Antenna Book http://www.arrl.org/catalog/?item=9043 Publications ON4UN's Low-Band DXing Antennas, Equipment and Techniques for DXcitement on 160, 80 and 40m http://www.arrl.org/catalog/7040/ Publications The Complete DX'er by Bob Locher, W9KNI http://www.arrl.org/catalog/?item=9073 Publications On the Air with Ham Radio By Steve Ford, WB8IMY http://www.arrl.org/catalog/?item=8276 Publications RF Exposure and You By Ed Hare, W1RFI http://www.arrl.org/catalog/?item=6621