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Assumptions
• Today’s presentation assumes you are An Introduction to HF familiar with VHF/UHF from your EMCOMM work. Communications
Gordon Good, KM6I
About KM6I Outline
• Licensed since 1975 1. The HF Bands • Previously WN8YVI, WB8YVI, KC8ES 2. Modes • Active on HF 1975-1981, some contesting 3. HF Propagation Basics at Univ Michigan ARC W8UM 4. HF Antennas • Inactive on HF for many years 5. Operating Practices • Became active in MTV CERT/ARES 6. Having Fun on HF around 2001 • Got back into HF + contesting in 2008
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Unit 1: The HF bands HF Amateur Bands
• HF Amateur Bands • HF = High Frequency = 3 MHz – 30 MHz • Amateur allocations at: • Sub-bands: license class, mode – 1.8 – 2.0 MHz (160 meters) • Sub-bands: considerate operators – 3.5 – 4.0 MHz (80/75 meters) – ~ 5.3 MHz (60 meters – 5 channels only) • Special Considerations: – 7.0 – 7.3 MHz (40 meters) – Primary vs. Secondary users – 10.1 – 10.15 MHz (30 meters) – 14.0 – 14.35 MHz (20 meters) – WARC – 18.068 – 18.168 MHz (17 meters) – 60 meters – 21.0 – 21.45 MHz (15 meters) – 24.89 – 24.99 MHz (12 meters) – 28.0 – 29.7 MHz (10 meters)
Sub-bands: license class, mode Sub-bands: considerate operators
• Within each HF band, • Band plans lay out “gentleman’s operator privileges, agreements” about specific frequencies modes, and power are for specific modes, activities, etc. limited by license class.
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Primary vs. Secondary Users WARC bands, 60 meters
• Not all “ham bands” are exclusively for our use. • WARC = World Administrative Radio • In some bands, amateurs are secondary users. Conference (an ITU technical conference - Must not interfere with primary users and are now World Radiocommunication afforded no protection from primary users. Conference - WRC) • 1900-2000 kHz shared with radiolocation (FCC • Additional bands authorized for amateur considering returning entire band to hams) use at WARC-79 • 30 m shared with fixed services in other parts of • 30m, 17m, 12m, gentleman’s agreement the world for no contesting, some international • 60 m shared with mobile and fixed services power limits • 60 meter band = 5 specific channels at about 5.3 MHz, non-interference basis
Unit 2: HF Modes Overview of HF Modes
• Overview of Modes • HF bands much narrower than VHF/UHF • CW – implies narrower bandwidth modes • SSB • Main 3 modes are CW, SSB, and Digital • Digital Modes • CW – morse code • New Digital Modes • SSB – Single Sideband Voice • Other Modes • Digital – catch-all for RTTY, PSK-31, and other digital modes • New digital modes • Other modes you may hear
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CW SSB
• AKA Morse Code • SSB = an amplitude-modulated signal with • CW = “Continuous Wave” one sideband and carrier suppressed • Not actually continuous. Carrier wave is • Carrier conveys no information. keyed on and off Sidebands are redundant • Is a digital mode in the strictest sense. • Allows all transmitter power to go into Data rate slow enough for human brain to conveying information copy it • Very narrow bandwidth. Depends on • Receiver re-injects carrier speed and keying envelope, but roughly 4x speed in WPM. 20 WPM ~= 80 Hz
SSB Digital modes
• All - low b/w compared to WiFi, 3G/4G • But low b/w is useful, esp in emergency • RTTY –5-bit baudot code. No error correction or retry. Popular for contesting. • PSK-31. No error correction or retry • 300-baud packet • PACTOR • Many others: see
Source: http://en.wikipedia.org/wiki/File:SSB_bandform.svg http://www.kb9ukd.com/digital/
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New Digital Modes JT65A, JT9
• Implemented in software • Excellent weak-signal performance • Enables rapid innovation. No new • Written by Joe Taylor, W1JT, astrophysicist hardware. Runs on PC sound card and Nobel Prize winner • Older radios may need isolation • Worldwide communications with low transformers + special cables power and simple antennas • Newer radios (e.g. Elecraft K3) plug • Latest WSJT-X software is extremely easy directly into sound card with 1/8” cables to set up and use • Newest radios (Kenwood TS-590sg) have USB audio interfaces built in 17
Other Modes
• Digital Voice – Example: FreeDV • 1600 bits/sec • 1.25 MHz bandwidth (similar to SSB) • Tuning around the bands, you may hear: • AM - Amplitude Modulation, just like AM broadcast band. About 4 KHz wide • ESSB - Extended SSB. Wider bandwidth with wider audio frequency range
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Unit 3: HF propagation basics The Sun and the Ionosphere
• The Sun and the Ionosphere • Ionosphere can refract HF signals, allows • Sunspots and Solar Flux consistent over-the-horizon propagation • More sunspots -> higher HF bands (typ. 14 Mhz • Rules of Thumb: what band, what time and above) experience refraction • MUF • Sun has an 11-year cycle ( • K index, A index • At a good solar peak in the 11-year cycle, 10m • Refraction Angles and higher produce amazing propagation (e.g. California -> Europe S9+), but... • NVIS and EMCOMM • In mid 2016 we are on the downswing of cycle • Propagation Predictions 24 (began in 2008), which turned out to be a dud.
The Ionosphere Sunspot Numbers, Solar Flux
• Layers change day • Ionizing radiation from the sun ionizes the vs. night ionosphere, enhances F layer propagation • D absorbs 10 Mhz • SSN (Smoothed Sunspot Number) from and below observations. • When F layer highly ionized, refracts • Solar Flux – proxy for SSN, measures higher frequencies, 2800 Mhz radiation from sun. e.g. 14 Mhz + • Ranges from 0 to ~200 at highest peaks.
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Historical Sunspot Numbers Cycle 24 Underperformance
Ground Wave, Sky Wave Rules of thumb: band/time of day
• Daytime = more ionization = higher frequency bands (20m+) open (lower frequencies are absorbed and not refracted) • Nighttime = less ionization = lower frequency bands (40m-80m) open (higher frequencies not refracted) • Example: recent DX contest at KM6I – early afternoon local time: Japan on 15m, 80m dead – 2am local time: 20m dead, Japan on 80m • 30m and 40m often offer some interesting propagation at all times
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Maximum Usable Frequency K-Index, A-Index
• Highest frequency that will allow • Both measure geomagnetic activity. communication between two points (via • A-index linear, K-Index logarithmic skywave) • High values -> geomagnetic storm, propagation may be compromised. • Best conditions when K <= 3, A <= 15 • Solar flares and coronal mass ejections can cause a geomagnetic storm, which can cause an HF radio blackout. Often sudden onset.
Refraction Angle NVIS and EMCOMM
• Longer-path propagation implies lower • NVIS = Near-Vertical Incidence Skywave takeoff angle from antenna. • Signal goes pretty much straight up, • Close-in propagation implies high takeoff refracted back to close-in targets. angle. • Useful for regional EMCOMM, e.g. Silicon Valley to Sacramento • A half-wave dipole close to the ground exhibits very high takeoff angle = good NVIS antenna (but a poor DX antenna) • More in next section
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Propagation Predictions Example VOAAREA plot from "Tactical Use of Propagation Predictions for HF Contesting", (Dean Straw, N6BV). Available from http://nccc.cc/webinars.html • We now have a good physical model of how the ionosphere behaves, and how radio waves interact with it. • VOACAP engine (from US gov) implements this model. • Takes into account sunspot number, time, produces estimate of propagation from one
point to another S5
S9+20dB S9 • VOAAREA program feeds model for many S9+10dB S7 receiver points, produces graphs, e.g.
Three different bands at 2200 UTC Unit 4: HF Antennas (3 pm PST), moderate sunspot # • Antenna Gain • Basic HF Antenna Types: – Wire dipoles – Ver tic als – Directional arrays 20 meters 15 meters • Antenna Modeling
40 meters
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Antenna gain Wire dipoles
• Isotropic Radiator: a theoretical antenna • A ½ wavelength wire, fed in the center, that radiates equally in all directions (e.g. exhibits about a 50 ohm impedance (good a sphere). match for amateur equipment that happens to have 50 ohm impedance) • Practical antennas have asymmetrical • Easy to construct patterns, and also interact with the earth. • Can be large (1/2 wavelength on 80 • Antenna gain usually in reference to meters is about 120 feet long) isotropic, e.g. an antenna with 3 dBi has 3 • Unless about ½ wavelength above db more gain than an isotropic radiator. ground, tend to shoot straight up (NVIS) • Typically 1 S-Unit is 6 dB • When higher, exhibit some directivity
Verticals Directional arrays
• Omnidirectional • Most common – yagi. Driven element plus • Performance highly dependent on quality of parasitic elements (reflector, directors) turned by ground. Normal soil does not provide a good a rotator. ground plane, so you need radials (wire on the • Typical gain for a 3-element yagi is 7-9 dB. ground). With a good radial field, verticals can have a low takeoff angle – good DX antenna. • 9 dB is like going from 100 watts to 800 watts • Raised radials are more effective, but must be w/same antenna (1.5 S-Unit improvement) resonant • Yagis for lower bands (40, 80) can get big (75 • Salt water is a good ground plane (at that foot boom for a 4 el 80 meter yagi), and need to beachfront villa you own) be very high (120 ft on 80m) • Some “no radials required” verticals are actually dipoles, mounted vertically
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Typical HF Yagi A 160 meter (1.8 MHz) Yagi?
It may end badly... Antenna Radiation Patterns
• You can plot the gain of an antenna, either in 2d or 3d. • A 2d elevation plot shows the gain at various elevations, e.g. looking at the antenna from the side • A 2d azimuth plot shows the gain around the compass headings, e.g. looking down. • A 3d plot shows both.
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2d Elevation Plot 2d Azimuth Plot
3d Plot Antenna Modeling
• You can model antennas using free or inexpensive software • NEC-2 engine (Numerical Electromagnetic Code) was developed in 1970s, and is freely available • A number of GUIs exist that make it easier to use. EZNEC by W7EL exists in both free and paid versions • NEC-4 engine is more sophisticated, but is proprietary
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Angle of elevation Unit 5: Operating Practices
• Generally, an antenna with a lower angle • Telling time of radiation will produce better results for • Calling/Answering CQ long-haul contacts. • Phonetics • Q-codes • Passing traffic on HF voice • Sharing the bands • Signal quality • RFI • The Kenwood TS-870 at K6MTV
Tel l i ng Ti m e Calling CQ
• Since HF signals cross many time zones, • Pick a frequency that’s: UTC time is used (time in Greenwich, – Not in use England) – On a frequency you’re licensed for • CA is UTC -8 hours, -7 hours during – Is not one with a gentleman’s agreement daylight savings time. • Listen for a while • Example: 1100 local time today is 1800 • If nothing heard, say “Is this frequency in UTC (6 pm). use” (phone) or send “QRL?” (CW) • Call CQ
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Example CQs Answering a CQ
• Phone: “CQ, CQ, CQ 40 Meters. this is • Be sure you’re on the other station’s KM6I, Kilo Mike Six India calling CQ 40 frequency Meters and listening.” • Be brief, e.g. “W1AW, this is K6MTV, Kilo • CW: “CQ CQ CQ DE KM6I KM6I KM6I K” Six Mike Tango Victor” • Digital: (same as CW) • Several short CQs (with listening time between) are better than one long one
Typical QSO Exchange Signal Reports: RST
• First round: Signal report, QTH, name • RST = Readability, Strength, Tone • Second round: gear, occupation, etc. • Readability: 1 = unreadable, 5 = perfect copy • Strength: 1 = very faint, 9 = very strong. Many report S-meter reading • Tone: Not used on phone. On CW: 1 = 60 Hz harsh tone, 9 = perfect sine wave. On digital, has come to mean quality of transmitted digital signal, e.g. how much inter-modulation distortion • In contests, everyone is 59 or 599
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Phonetics Q-codes
• Same as we use in ARES, but some • Discouraged on VHF latitude. • Good for CW, also used on HF SSB • Especially in DX contests, some • Common: “alternate” phonetics are common: – India -> Italy – QRZ? who is calling me – Mike -> Mexico – QRM interference – Zulu -> Zanzibar – QRN noise • Sometimes these seem to “cut through” – QRS send slower QRM a bit better, but don’t use these on – QSY change frequency the ARES nets.
Being a good sport about operating Passing traffic on HF voice frequencies • ARRL Radiogram format is the “Lingua • No one “owns” a frequency. Franca” for messages traveling a long • Listen before transmitting. Then listen some distance more. • If a net frequency is occupied, net control will • Otherwise, procedures are just like we politely ask others to vacate, and they usually teach in local ARES (spell phonetically, do. pause every 5 words, etc) • Be aware that on HF, because of propagation, you might not hear a station on a frequency. • Always ask: “QRL?” on CW, “Is the frequency in use?” on voice. • Respect informal band plans (e.g. stay away from beacon frequencies).
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HF and "good ears" Transmitted signal quality
• HF just sounds a lot different than VHF- • It’s your responsibility to make sure your FM signal is clean. • Know how to use your radio’s features to • Ideally, all of us would have a monitor eliminate interference. Tools: scope, but… – Narrow filters • Often signal reports from other amateurs – IF shift/passband tuning are the tool we have. – Notch filters • However, there are some rules of thumb, – Noise blankers for each mode.
SSB: mic gain/processing/splatter CW: key clicks • CW keying waveform – if rise or fall is too • Avoid background noise: use a good fast, you’ll get key clicks. Generally quality microphone, speak close to it. requires rig mod to fix. • Don’t overdrive the audio – you’ll end up with a very wide signal. • Speech processing can improve the “punch” but too much and you’ll produce splatter. • Ask others how your signal sounds.
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Station at 1460 hz is occupying approx 700 hz bandwitdh and interfering with stations at 1240 and 1710 hz. Digital mode and overdriving PSK-31 is supposed to occupy 31.25 hz. Don’t be this guy! BAD GOOD BAD • When using a computer sound card to generate digital signals (PSK31, RTTY), you need to avoid overdriving the rig. • General rule of thumb: adjust sound card output level so that rig’s ALC meter just barely moves. • Too much drive causes Intermodulation Distortion (IMD – extra signals above/below the desired signal) • Can observe overdriven stations in receive waterfall display
RFI RFI Resources
• RFI – Radio Frequency Interference • ARRL RFI Handbook • Just plan for it, and approach it methodically • A Ham’s Guide to RFI, Ferrites, Baluns, • RFI received by amateur: and Audio Interfacing – Jim Brown, – Many consumer electronic devices emit stray RF K9YC, on web – Chokes, shielding often help • RFI “caused” by amateur: – Devices act as unintentional receivers – Chokes, shielding, shortening long wires are often helpful
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Meter Power (S-Meter, Power K6MTV’s TS-870 Unit 6: Having Fun on HF SWR) USB/LSB VFO A Frequency VFO B Frequency • It’s magic! • DXing • Contesting • Weird stuff (e.g. “K” beacon) • The missing Q codes
AT Tune Mic Gain (Inner) Up/Down Power (Outer) AF/RF gain Main Tuning Knob Squelch
It’s Magic! DXing
• Using about as much power as a light • DXing = making contacts over long bulb, you can transmit a signal that will distances induce enough current in a piece of wire in • Awards granted for things like 100 Japan so that a ham there can countries (DX Century Club) etc. communicate with you. • On HF, you really feel connected with what’s going on with the Sun, the Earth, and the ionosphere.
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Casual DX vs. pileups Split mode
• For “non-rare” DX stations, you may be able to • Used often in pileups ragchew • DX station transmits on one frequency, • Rare countries produce pileups: many stations calling at once and listens on another. • DX station’s goal is to make as many contacts • Calling stations expected to spread out as possible, esp. for dxpeditions. across a few KHz, DX station tunes • Typical report during a pileup is only a signal across callers and picks them out. exchange • Good DX ops can do hundreds of QSOs per • Very easy to goof and transmit on top of hour DX station!
Contesting Contest Exchanges
• My favorite aspect of the hobby • Each contest will have its own exchange. Need • General Objective: as many contacts as to read the rules possible in a given time period • Field Day exchange is
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A Field Day QSO Asking for repeats
• Station W8UM is calling CQ, and is answered by • Need whole exchange again: “Again?” K6MTV – W8UM: “CQ Field Day. This is W8UM, • Need only class: “Your class?” Whiskey Eight Uniform Mike, Field Day” • Need only section “Your section?” – K6MTV: “W8UM, Kilo Six Mike Tango Victor” • If asked for a fill, only give the requested – W8UM: “K6MTV, Three Alfa, Michigan” information. Probably good to give it twice, – K6MTV: “Roger. One Foxtrot, Sierra as there’s probably QRM that caused it to Charlie Victor” – W8UM: “Thanks and Good Luck. Whiskey be missed the first time. Eight Uniform Mike, Field Day”
Computer Integration Field Day GOTA Stations
• Computer logging programs can handle all • GOTA = Get On The Air logging and duping tasks • Also can send CW and canned Phone • Encourages hams to jump into contesting exchanges at Field Day • Most programs will interface with radio. Read frequency from radio and log it • Usually mentored • Other nice features: visual cues for dupes, pre- • Local clubs have Field Day GOTA stations fills, bandmap/DX cluster integration (click to S&P) • Show up - you’ll be welcome! • First time I used N1MM, I thought I’d need scratch paper to jot down calls. Never used it!
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Contest Stations A “modest” contest station
• It’s possible to have a lot of fun with a modest station: – 100 watts, wire antenna – special challenges in QRP (< 5 watts) • some people take this very seriously, e.g.
http://www.arubaqth.com/index.html
A not-so-modest station (N0NI) K3LR Multi-Op Station
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SO2R SO2R Station
• Single Operator 2 Radios • Two radios on different bands. Typically, one radio is the “run” radio and the other is used for S&P. • While the run radio is calling CQ, operator tunes the other radio. • Audio switching allows op to listen to run rig, S&P rig, or both (one in each ear). • If no answer to CQ, make an S&P contact on the other radio. • It’s rub-tummy-and-pat-head to the extreme!
Thanks! SO6V Any Questions?
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