High Latitude HF Comms Testing

High Latitude HF Comms Testing

LT Mike GrochowskiBill 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 FREQUENCYThese 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 dayE-Layer – Reflects mid frequencies of HF (10-30 MHz) during the dayF-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-wave2.Ground wave3.High Angle Radiation (NVIS)

Sky-Wave

Provides Single (<4000km) or Multi-hop (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 LineThe 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 SystemUses DSC (Digital Selective Calling) tied to ship’s MMSI

GOTHAM and COTHENHF 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 improvedTemporary deployment to Barrow this summerConsidering 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 needhttp://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 Frequencyhttp://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 http://tcares.org/tcares/images/presentations/nvis%20propagation%20theory.pdf

Questions?

PublicationsARRL 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 forDXcitement on 160, 80 and 40m

http://www.arrl.org/catalog/7040/

Publications

The Complete DX'erby Bob Locher, W9KNI


PublicationsOn the Air with Ham RadioBy Steve Ford, WB8IMY


Publications

RF Exposure and YouBy Ed Hare, W1RFI


Documents

High Latitude HF Comms Testing