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Copyright NVIS Communications, All rights reserved NVIS Communications Training Academy Basic HF Voice Operator 1 Introduction to HF-NVIS Radio Communications.

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Presentation on theme: "Copyright NVIS Communications, All rights reserved NVIS Communications Training Academy Basic HF Voice Operator 1 Introduction to HF-NVIS Radio Communications."— Presentation transcript:

1 Copyright NVIS Communications, All rights reserved NVIS Communications Training Academy Basic HF Voice Operator 1 Introduction to HF-NVIS Radio Communications –Introductory Radio Principles –Why HF radio has become important –Basic HF Radio Technologies

2 Copyright NVIS Communications, All rights reserved Introductory Radio Principles –Electromagnetic (EM) Waves –EM Waves in the Radio Spectrum –High Frequency (HF) in the radio spectrum –Near Vertical Incident Skywave (NVIS)

3 Copyright NVIS Communications, All rights reserved Introductory Radio Principles It all starts with…. However, please feel free to use these wavelengths to watch this presentation. They are a fundamental, observable phenomenon in our universe –Made of electric waves combined with magnetic waves. –They travel through the universe at the speed of light. (they are light) –They range in wavelength from radio waves, to visible light, and beyond. Image courtesy of NASA The Electromagnetic Spectrum from radio waves, through visible light, and beyond We are interested in waves at radio wavelengths MF HFVHFUHF Electromagnetic Waves

4 Copyright NVIS Communications, All rights reserved The radio portion of the EM spectrum “Shortwave”.3 MHz 1000 m 3 MHz 100 m 30 MHz 10 m 300 MHz 1 m 3 GHz.1 m 30 GHz.01 m MF Medium Frequency HF High Frequency VHF Very High Frequency UHF Ultra High Frequency SHF Super High Frequency VHF/UHF waves travel “line of sight” MF waves hug the ground HF waves refract from the ionosphere Special techniques are required beyond here Introductory Radio Principles Although not technically correct, the “HF” radio band is often said to be from 1.6 to 30 MHz. instead of from 3 to 30 MHz. This is because most “HF” radios operate between 1.6 and 30 MHz.

5 Copyright NVIS Communications, All rights reserved About HF (High Frequency) Radio Waves HF radio waves refract and reflect from the ionosphere –If directed toward the horizon they may go long distances –Maybe one hop, maybe many –Maybe short hops, maybe long –Generally includes dead “skip” zones Introductory Radio Principles

6 Copyright NVIS Communications, All rights reserved Instead of: An early NVIS mobile An HF signal directed straight up will rain back down from the sky over hundreds of miles About NVIS (Near Vertical Incident Skywave) Introductory Radio Principles

7 Copyright NVIS Communications, All rights reserved HF Long Distance vs. HF-NVIS Signal toward the horizon High power, often 1KW+ Antennas must be elevated May or may not work Has dead “skip” zones Spills beyond intended area Makes spectrum re-use difficult Signal straight up Low power, 125W is plenty Antennas stay near the ground Virtually always works Blankets entire region Stays in the regional area Re-assign spectrum elsewhere Ionosphere Skip zone Signal zone Signal spilled beyond target area Regional signal blanket Ionosphere Spectrum re-usable elsewhere HF Long Distance compared to HF-NVIS Introductory Radio Principles

8 Copyright NVIS Communications, All rights reserved HF Past and Present Why its use faded and has now come back HF Past and Present

9 Copyright NVIS Communications, All rights reserved Amateur Radio, Shortwave Broadcast, Military The history of our use of the radio spectrum MF Medium Frequency HF High Frequency VHF Very High Frequency UHF Ultra High Frequency SHF Super High Frequency AM Radio Land Mobile Radio – Public Safety, business, government Microwave, satellite, cellular, wireless devices, etc. HF is important again for fallback communications -- Band usage past and present s1940s1930s1950s1960s……… 1910s HF Past and Present

10 Copyright NVIS Communications, All rights reserved HF radiation patterns are complicated (But now we have computers) HF signal paths are very complex –Time of day, frequency, sunspots, … –Historically the operator had to figure this out –That was not ideal for public safety personnel Local government and industry moved to newer technologies –Local communications went to VHF and UHF –Long range went to T-carrier networks and the Internet But the HF-NVIS story is like the “Flying Wing” –Abandoned in 1950s because it was too complicated –Came back with computer control as the B2 bomber HF frequency range HF-NVIS is back under computer control the same way! HF Past and Present

11 Copyright NVIS Communications, All rights reserved Migration from the Past to Today Large, heavy equipment Marketed for the military Few vendors, very expensive Complicated operation Specially trained operators Limited features Not recognized for fallback use Not on the public safety radar Not known to critical infrastructures Smaller lightweight equipment Marketed for govt., public safety Competing vendors, cost effective Simpler, menu operation Your regular operational staff Many voice/data features The new Base Layer Fallback mode Public safety lining up to get it Critical infrastructures want it Today Products from several vendors HF Past and Present The Past

12 Copyright NVIS Communications, All rights reserved Why HF radio is critical for your future It has always been important for military, shortwave broadcast, and amateur radio. Now it is important again for government, public safety, and critical infrastructures

13 Copyright NVIS Communications, All rights reserved Fallback as opposed to Failover Failover preserves the primary operational mode using alternate resources. Fallback replaces the primary mode with simpler modes when the primary mode is not available at all.. Base Layer Fallback is your lowest layer of prepared fallback for when everything else has failed. It must not have components in common with the primary mode. Fallback Modes Primary Operational Mode Failover Modes Why HF radio is critical for your future

14 Copyright NVIS Communications, All rights reserved Fallback for regional and wide-area communications These systems have many complex layers of infrastructure, and this makes them inherently subject to failure regardless of the their capabilities for failover. HF-NVIS systems have no intervening infrastructure between stations, and this makes them immensely more resilient. Modern, automated HF-NVIS networks are taking their rightful place as the Base Layer Fallback Mode for federal, state, and local government and for critical infrastructures. Primary systems: - Microwave, repeaters - Internet, PSTN - Hopefully FirstNet - … Failover Measures Many layers of alternate resources to keep the systems operational – Very important! However… Critically needed Base Layer Fallback HF-NVIS Why HF radio is critical for your future

15 Copyright NVIS Communications, All rights reserved Why HF-NVIIS has become our nation’s Base Layer Fallback Mode We now realize how vulnerable our systems are –Lessons from 9-11, Katrina, Sandy, and others We now understand our need for Base Layer Fallback Modern HF systems are available and easy to use –“Simple menu operation for calling –Automatic frequency selection and call connection –Cost effective for public safety use Leading edge agencies are adopting it! –Federal, state, and local governments –Critical Infrastructure providers –HF-NVIS is becoming our National FallbackNet Why HF radio is critical for your future

16 Copyright NVIS Communications, All rights reserved Plan for these being compromised You can build your own Base Layer Fallback Network Microwave Satellite Internet VHF/UHF Landlines Cellular Normal Operations Operational sites throughout your regional area Why HF radio is critical for your future

17 Copyright NVIS Communications, All rights reserved Have your own HF-NVIS network for selected staff personnel Operational sites throughout your regional area You can build your own Base Layer Fallback Network Why HF radio is critical for your future

18 Copyright NVIS Communications, All rights reserved Interface directly to disaster communications organizations Operational sites throughout your regional area (Licensing restrictions apply) You can build your own Base Layer Fallback Network Have your own HF-NVIS network for selected staff personnel Why HF radio is critical for your future

19 Copyright NVIS Communications, All rights reserved Think of HF-NVIS as a safety net under our infrastructure-heavy primary systems From an article by BBC News This net looks pretty makeshift It’s because they built it after the bear got stuck in the bridge. We should build ours before we get stuck! Why HF radio is critical for your future

20 Copyright NVIS Communications, All rights reserved Basic HF Radio Technology –Single Sideband (SSB) Modulation –HF antennas and the “dipole” antenna –Automatic Link Establishment (ALE)

21 Copyright NVIS Communications, All rights reserved HF Radio Modulation: Single Side Band (SSB) Modulation physics is beyond the scope of this class However, there are several things you should know –Modulation means putting information (voice, etc.) onto a radio wave –VHF/UHF voice systems typically use Frequency Modulation (FM) –FM works great for local, “line-of-sight” communications –But SSB is the most effective modulation for long distances –Unfortunately, SSB does not block out noise the way FM does. –SSB signal rides on top of the noise, so it is not as clear as FM –But for long distances, SSB will get through loud and clear where other modes will simply fail Basic HF Radio Technology

22 Copyright NVIS Communications, All rights reserved SSB vs FM from the user’s perspective A traditional 25 KHz-wide FM signal FM captures its wide bandwidth with a carrier wave of energy For this reason FM blocks out noise within its bandwidth This is why a strong FM signal has no background noise 25 KHz wide 12.5 KHz wide A “narrowband” (NFM) signal is half as wide, but it is still FM Many FM users have been required by the FCC to switch to “narrow band” 3 KHz wide Single Side Band is a sliver of energy vibrating within a 3KHz bandwidth No carrier wave to block out noise, so noise is always there. However… This narrow signal is easier to push long distances than a giant FM signal Basic HF Radio Technology

23 Copyright NVIS Communications, All rights reserved HF Radio Antennas Antenna physics is beyond the scope of this class However, there are several things you should know –Any wire or piece of metal can act as an antenna –But a good antenna is sized for the radio wavelength it will be used for –VHF/UHF antennas can be short because VHF/UHF wavelengths are short –HF antennas must be long because HF wavelengths are long –The wavelength of a 5 MHz HF radio wave is approx. 60 meters. A “dipole” antennas is ideally 1/2 of the wavelength it is used for –So the ideal length for 5 MHz would be 30 meters or 98 feet. –HF antennas are often shorter than ideal for practical reasons. Basic HF Radio Technology

24 Copyright NVIS Communications, All rights reserved The Classic Dipole Antenna Two radiating elements extending in opposite directions. Radiating element Transmission line 1. The radio emits an alternating current at a some frequency. 2. This creates alternating currents in the antenna elements 3. This causes electromagnetic (radio) waves to radiate into space. Radio Dipole Antenna Basic HF Radio Technology

25 Copyright NVIS Communications, All rights reserved Most installations use coaxial cable for transmission line “Balun” Radiating element Coaxial cable To feed a dipole, coaxial feed line needs an interface box called a “balun” –This balances the coax signal equally between the two radiating elements. –The physics of this are beyond the scope of this course Easy to route to an antenna Keeps the radio signal inside until it reaches the antenna Considered “unbalanced” because the two conductors inside it are not the same. –It has an inner conductor and an outer shield. Dipoles as used in most applications Basic HF Radio Technology

26 Copyright NVIS Communications, All rights reserved Common HF-NVIS Base Antennas Basic HF Radio Technology ` ` Single wire dipole ` ` Multi-wire dipole Portable dipole Multi-wire dipole

27 Copyright NVIS Communications, All rights reserved Common HF-NVIS Mobile Antennas Base tuned whip folded over Luggage rack half loopRoof mounted half loop Basic HF Radio Technology

28 Copyright NVIS Communications, All rights reserved Automatic Link Establishment (ALE) A peer-to-peer HF network –Completely inside your radios Site 1Site 2 Site 3Site 4 F1 F2 F4 F3 F5 F6 Your set of authorized HF frequencies that the radios scan Basic HF Radio Technology

29 Copyright NVIS Communications, All rights reserved Scheduled soundings –Every radio, will sound on every frequency –Dynamic models of the optimum frequencies Site 1 testing On F1, On F2, On F3,... recording signal strength Site 1Site 2 Site 3Site 4 F1 F2 F4 F3 F5 F6 A set of authorized HF frequencies that the radios scan Automatic Link Establishment (ALE) Basic HF Radio Technology

30 Copyright NVIS Communications, All rights reserved Place calls by unique radio ALE ID –User picks a contact from the list –The radios pick the best frequency –The receiving radio(s) ring like a telephone. Site 1 calls Site 2 on the best frequency Site 2 rings like a telephone Site 1Site 2 Site 3Site 4 F1 F2 F4 F3 F5 F6 Automatic Link Establishment (ALE) Basic HF Radio Technology A set of authorized HF frequencies that the radios scan

31 Copyright NVIS Communications, All rights reserved Site 2 HFSite 1 HF Gateways Phone patch Internet FAX VHF/UHF Gateways Phone patch Internet FAX VHF/UHF Data modes, gateways, ease of use Voice, , phone, SMS, fax Easy to use - Menu operations - Auto freq. select - Auto connect - Contact lists - Press to call - Rings like phone Third party extensions for ICS form data I C S I C S Basic HF Radio Technology

32 Copyright NVIS Communications, All rights reserved Basic use of your HF-NVIS system –An hypothetical HF-NVIS network –Listening to SSB radio –Talking on SSB radio –Signal reporting on SSB radio –Squelch systems on SSB radio

33 Copyright NVIS Communications, All rights reserved Sacramento San Jose Los Angeles Reno Las Vegas An example HF-NVIS network Direct voice/data among all stations for hundreds of miles Mobile Basic use of your HF-NVIS system

34 Copyright NVIS Communications, All rights reserved Sacramento San Jose Los Angeles RenoLas Vegas “Sacramento now commencing this week’s all station roll call. An Example system test Sacramento places an ALE Group Call All stations stop scanning and ring “After roll call, all stations please send an HF to Sacramento. Next week the test might be conducted by a different station Basic use of your HF-NVIS system

35 Copyright NVIS Communications, All rights reserved Sacramento San Jose Los Angeles Reno Las Vegas During an emergency Any station can call any or all stations Mobile Since the network is tested often, people will know how to use it, and it will work when needed! Basic use of your HF-NVIS system

36 Copyright NVIS Communications, All rights reserved Listening to SSB Radio You may be used to listening to FM radio –Government and public safety radio is typically FM –With FM the voice volume tends to stay the same whether it is a strong or weak signal –If it is a strong signal, then there is no noise along with the voice. (“full quieting”) –If it a weak signal, then the noise raises in volume until it drowns out the voice SSB sound characteristics – opposite from FM –With SSB it is the noise volume (rather than the voice volume) that tends to stay the same –If it is a strong signal, then the voice raises in volume and becomes louder than the noise. –If it s weak signal, then the voice is lower in volume until it can no longer be heard through the noise Basic use of your HF-NVIS system

37 Copyright NVIS Communications, All rights reserved Talking on SSB Radio Use plain language –No 10-codes or other service-specific jargon –Remember, you may be talking with different services who do not know your jargon –If talking with other services, identify yourself with a full, descriptive identifier Example: “ Los Angeles County Sheriff Mobile Command Unit 1” Learn to say “over” before you release the mike –We do not do this on FM because users can hear when your carrier drops –But remember, there is no carrier for them to hear on SSB! –So tell them when you are releasing the mike by saying “over”. Signing off –Say your identifier then say “out” or “clear” –On HF people usually use “out”, but either one describes your intention –Saying “over and out” may earn you some chuckles. Basic use of your HF-NVIS system

38 Copyright NVIS Communications, All rights reserved You may be used to giving signal report s on FM radio: –For example “loud and clear”, “weak and scratchy”, “breaking up”, or “unable to copy”. But remember that SSB characteristics are different –There is always noise, so saying “scratchy” is not informative –Signal would not normally “break up”, but it may fade slowly in and out –Since the characteristics are different, signal reporting is different. A commonly used range for SSB signal reporting : –“Loud and clear”(for a very loud signal) –“Good readable” –“Fair readable” –“Weak readable” –“Unable to copy” Signal reports on SSB radio Basic use of your HF-NVIS system

39 Copyright NVIS Communications, All rights reserved Squelch systems for SSB –they Squelch quiets the speaker when nothing is being received –FM squelch detects the FM carrier of a received signal –SSB has no carrier for a squelch system to detect –SSB squelch therefore has to detect other things Types of SSB squelch –Audio squelch – tries to detect the characteristics of human voice –Signal squelch – detects increased signal level (could be just noise) –Selective Call – activates only when the digital ID for that station is received Using SSB squelch –SSB audio squelch and signal squelch are not as effective as FM squelch –Most people leave their radios on Selective Call to receive only calls to them –After Selective Call activates, it typically leaves the speaker ON (no squelch) –Most people leave the speaker on during calls to hear everything –This is in contrast to FM, which squelches the speaker after each received signal Basic use of your HF-NVIS system

40 Copyright NVIS Communications, All rights reserved NVIS Communications Training Academy Congratulations on completing the classroom portion of: Basic HF Voice Operator 1 Introduction to HF-NVIS Radio Communications. Practical Exercises for this material will now follow. Subsequent courses will present more advanced topics.


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