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Phone – But Not Telephone!. In the radio world, phone transmissions are voice transmissions by radio . When you hear hams use the word “phone,” it usually has nothing to do with telephones. . Modulation.

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Presentation Transcript
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Phone – But Not Telephone!

  • In the radio world, phone transmissions are voice transmissions by radio. When you hear hams use the word “phone,” it usually has nothing to do with telephones.


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Modulation

  • A transmitter produces RF energy – radio waves – at a particular frequency. But radio waves are not much use unless they carry information. The process of putting information onto a radio wave is called “modulation.” Information can be placed onto a radio wave in several different ways. You don’t need to know a lot about the different types of modulation for the Technician exam, but you do need to understand a little about each one.


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Radio Wave Review

  • When you learned about frequency, you saw that a radio wave can be represented by a sine wave like this:


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Radio Wave Review

  • You also saw that the distance between a point on one wave and the same point on the next wave represents the wavelength of that wave.


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Radio Wave Review

  • The number of waves traveling past a single point in one second represents the frequency of the wave, as the following diagram shows.


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Amplitude

  • Before we can study the different kinds of modulation, we have to look at one more characteristic of a radio wave. The height from the top of a wave to the bottom of that wave is called the “amplitude” of the wave.


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Modulation

  • Again, modulation is the process of placing information onto a radio wave for transmission.

  • Now we are ready to look at some of the different ways a radio wave may be modulated.


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Continuous Wave (CW)

  • Here is an ordinary radio wave. It is represented by our old friend, the sine wave. If we cause a transmitter to transmit a wave like this but do not modulate the wave in any way, it would look something like this. This is called a “continuous wave” or just “CW.”


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How CW Is Used

  • Now take a look at this wave. Do you see the gaps? If you turn the transmitter on and off, you leave gaps in the wave. A properly-equipped receiver at the other end will hear a tone when the CW is being transmitted and nothing when the transmitter is switched off. This is how Morse code is sent. In fact, hams often say they are “working CW” instead of saying they are sending Morse code.

  • Note that this represents the letter “K” or “dah-di-dah”.


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“Keying” the Transmitter

  • When we use a transmitter to send out radio waves, whether we are talking, sending Morse code, or sending data, we say that we are “keying” the transmitter. This goes back to the very early days of radio when telegraph keys were used to turn the transmitter on or off as code was being sent.


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CW – Sending Code

  • Even today, when we use a telegraph key to send code, all we are doing is using the key to turn the transmitter on and off to form the “dits” and “dahs.” (Hams don’t usually call them dots and dashes.) When we press down on the key, the transmitter is turned on and begins sending CW. When we release the key, the transmitter stops sending CW. As you can see, the transmitter is turned on and off many times in a minute when sending Morse code.

  • One big advantage of CW is that it has the narrowest bandwidth of all the modes the Technician uses. It is narrower than AM, FM, SSB or slow-scan TV.


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Amplitude Modulation (AM)

  • We need to be able to do more than turn a radio wave on and off to get a voice transmitted over the airwaves. One way of doing that is to use “amplitude modulation” or “AM.” To understand AM, we need to do a little review and also get a little more background information, so let’s do it!

  • One other thing. This is going to get a little complicated, so take it slow and easy. Much of what you will see in the next few slides is not essential for the test. However, it will help you to better understand what is important once you actually get on the air, and after all, that’s what this test is really all about – getting on the air!


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The Human Voice

  • You may remember that the human voice has an average range of about 300 to 3000 Hertz. Compared to radio waves, the frequency of the human voice is quite low.


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Generating a Voice Signal Using the Microphone

  • When you speak into a microphone, the energy from the sound waves made by your voice is turned into an electrical signal. This signal is an electric current that constantly changes with your voice. This electric current can be represented by a sine wave, just like a radio wave. If it is a steady tone, it will be a smooth sine wave that looks just like a radio wave, except its frequency will be much lower.


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Voice Waveform

  • But your voice is not a steady tone. The sounds you make and the pitch or tone of your voice is constantly changing. A sine waveform that represents your voice might look something like the picture below. This is the signal we want to modulate the radio wave with.


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The Carrier

  • Now let’s suppose we have a radio wave at a particular frequency that we want to modulate with the signal in the last slide. That will be our carrier and the sine waveform for it will look something like this:


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The Carrier and the Signal

  • To modulate the carrier, we have to combine it with the electrical signal representing a voice that was produced by the microphone.


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So How Do We Do It?

  • This signal is applied to the radio wave so that it causes the height or amplitude of the radio wave to change as the signal changes. We call this “amplitude modulation.” On our sine wave it looks something like this:



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Amplitude Modulation

  • If you need to, go back to the last slide and notice that the signal representing the sound wave caused the height or amplitude of the radio wave to change as it changed. This output is an amplitude modulated signal. The radio at the other end will extract the signal from the radio wave and feed it through the speaker at that end so it can be heard.


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Sidebands

  • A modulated AM radio wave also produces two other signals called sidebands. One sideband has a slightly higher frequency than the carrier, and the other has a slightly lower frequency. It works something like this this...


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Modulated Carrier and Sidebands

  • Let’s say you have an audio tone that is 256 Hz. You modulate a radio wave that is 710,000 Hz (710 kHz). You produce an upper sideband that is 710,000 plus 256 Hz and a lower sideband that is 710,000 minus 256 Hz. Keep these sidebands in mind. They will become important in a little bit.


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AM – Not Used That Much

  • Amplitude modulation (AM) used to be used by hams a lot, but it isn’t used all that much any more. The reason is that the modulated wave and two sidebands take up a lot of “bandwidth.” You can only get so many signals on a band, and AM just uses too much space.


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Single Sideband (SSB)

  • The good news is we don’t need all of that modulated AM signal. Each of the two sidebands contains a complete copy of all the voice information! If we strip away the modulated wave and one of the sidebands, we have a signal that is only a third as wide. This is called “single sideband” modulation or “SSB.” Because it uses one of the sidebands of an amplitude modulated signal, SSB is actually a very efficient form of amplitude modulation. Let’s take a look...


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First Start With The Full AM Radio Wave...

  • This is the 710 kHz wave modulated with a 256 Hz tone you saw a few slides back.


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Now Filter The Carrier...

  • We can get rid of the carrier, and we are left with just the two side bands, like this:


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Next, Get Rid Of One Sideband...

  • We can also get rid of one of the sidebands. It doesn’t matter which one, but in this example, we’ll get rid of the lower one.



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Advantages of SSB

  • There are two advantages of SSB over AM. First, we can put all of the transmitter’s power into transmitting the one sideband, so the effect is to make the signal almost three times stronger. The second advantage is that the approximate bandwidth of a single-sideband voice signal is between 2 and 3 kHz. This is about one third of an AM signal. Because the bandwidth is much narrower, more people can use the same amount of band space.


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Uses of Single Sideband (SSB)

  • SSB is the type of voice modulation most often used for long distance and weak signal contacts on the VHF and UHF bands by all amateur license classes. The upper sideband is normally used for VHF and UHF SSB communications. SSB is also the mode most often used by General class licensees and higher on the HF bands


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Frequency Modulation (FM)

  • Another way of placing information on a radio wave is to use the electrical signal generated by a microphone to change the frequency of a radio wave as the signal varies. This is called “frequency modulation” or “FM.”

  • Just as we did for amplitude modulation, let’s suppose we have a tone that has been turned into an electrical signal. When we modulate a radio wave using frequency modulation, it looks something like the diagram on the next slide.


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Frequency Modulation (FM)

  • See how the wave height (amplitude) stays the same? With FM, it is the frequency or distance between the waves that changes.


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AM and FM Compared

  • Compare the two modulation types side by side. The good news is that you won’t have to know that much about either one for the exam, BUT it is still good to understand how they are different!


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FM Bandwidth

  • Now on to some more stuff you really do need to know.

  • The approximate bandwidth of a frequency-modulated voice signal is between 5 and 15 kHz. This is much greater than the 2 to 3 kHz bandwidth of a SSB signal, so it requires a lot of room. However, FM signals are generally very clear and noise free.


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Uses of FM

  • Because of its large bandwidth, FM is generally best suited for local use on VHF and UHF bands. In fact, FM is the type of modulation is most commonly used for VHF and UHF voice repeaters.


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SSB and FM

  • The bottom line is that if you are concerned about voice quality, you want to go with FM. However, if you are concerned about bandwidth, you want to go with SSB. The primary advantage of single sideband over FM for voice transmissions is that SSB signals use much less bandwidth than FM signals.


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Amateur TV – the Biggest Bandwidth Hog

  • Some amateur operators enjoy sending fast-scan TV over amateur radio. Sending an audio and video signal requires a lot of bandwidth. The normal bandwidth required for a conventional fast-scan TV transmission using combined video and audio on the 70-centimeter band is about 6 MHz!


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Amateur Radio and the Internet

  • As we will soon see, amateur radio uses the Internet along with radios to communicate. Some amateur radio stations are set up to allow other stations to access the Internet through these special stations. The name given to an amateur radio station that is used to connect other amateur stations to the Internet is a “gateway.”


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Check-Up Time!

Now let’s try the questions from this group.

You should make a note of any that you miss for later review.


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T6A01

  • What are phone transmissions?

  • A. The use of telephones to set up an amateur radio contact

  • B. A phone patch between amateur radio and the telephone system

  • C. Voice transmissions by radio

  • D. Placing the telephone handset near a radio transceiver's microphone and speaker to relay a telephone call


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T6A01 Answer - C

  • In the radio world, voice transmissions are called "phone" transmissions.


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T6A02

  • Which of the following is a form of amplitude modulation?

  • A. Frequency modulation

  • B. Phase modulation

  • C. Single sideband

  • D. Phase shift keying


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T6A02 Answer - C

  • Amplitude modulation adds information to a radio wave by changing the amplitude or height of that radio wave. In the process, it creates the main carrier wave and two sidebands, an upper sideband, and a lower sideband.


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T6A03

  • What name is given to an amateur radio station that is used to connect other amateur stations to the Internet?

  • A. A gateway

  • B. A repeater

  • C. A digipeater

  • D. A beacon station


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T6A03 Answer - A

  • A station that provides a connection to the Internet is a gateway station.


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T6A04

  • Which type of voice modulation is most often used for long distance and weak signal contacts on the VHF and UHF bands?

  • A. FM

  • B. AM

  • C. SSB

  • D. PM


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T6A04 Answer - C

  • For long distance communication, the modulation choice is always SSB (single sideband). It doesn’t sound as clear as AM or FM, but it packs a lot of power into a narrow bandwidth signal.


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T6A05

  • Which type of modulation is most commonly used for VHF and UHF voice repeaters?

  • A. AM

  • B. SSB

  • C. PSK

  • D. FM


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T6A05 Answer - D

  • FM is always the modulation type of choice for VHF and UHF repeaters. It takes a lot of bandwidth and does not go very far, but it produces a clear voice signal for the repeater to retransmit.


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T6A06

  • Which emission type has the narrowest bandwidth?

  • A. FM voice

  • B. SSB voice

  • C. CW

  • D. Slow-scan TV


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T6A06 Answer - C

  • CW (or continuous wave) is used for sending Morse code. It is simply an unmodulated signal that can be turned on or off. Because CW is such a narrow bandwidth, several code stations can use the same width of frequency as one SSB signal.


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T6A07

  • Which sideband is normally used for VHF and UHF SSB communications?

  • A. Upper sideband

  • B. Lower sideband

  • C. Suppressed sideband

  • D. Inverted sideband


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T6A07 Answer - A

  • Either sideband would work just fine, but for effective communication, everyone has to be on the same sideband. Because of that, by agreement, everyone normally uses USB (upper sideband) for VHF and UHF sideband transmissions.


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T6A08

  • What is the primary advantage of single sideband over FM for voice transmissions?

  • A. SSB signals are easier to tune in than FM signals

  • B. SSB signals are less likely to be bothered by noise interference than FM signals.

  • C. SSB signals use much less bandwidth than FM signals

  • D. SSB signals have no advantages at all in comparison to other modes.


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T6A08 Answer - C

  • The biggest advantage of SSB is that it has a much narrower bandwidth than FM. That means more people can use the same amount of frequency spectrum to communicate.


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T6A09

  • What is the approximate bandwidth of a single-sideband voice signal?

  • A. 1 kHz

  • B. 2 kHz

  • C. Between 3 and 6 kHz

  • D. Between 2 and 3 kHz


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T6A09 Answer - D

  • Bandwidth of a signal is one of those things every radio amateur should know, and not just for the test. A good clean SSB signal should be no more than 2 to 3 kHz (kilohertz) wide


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T6A10

  • What is the approximate bandwidth of a frequency-modulated voice signal?

  • A. Less than 500 Hz

  • B. About 150 kHz

  • C. Between 5 and 15 kHz

  • D. More than 30 kHz


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T6A10 Answer - C

  • Here’s why bandwidth is important. A clean FM signal is 5 to 15 kHz (kilohertz) wide. As you can see, the widest FM signal takes up five times as much bandwidth as the widest SSB signal. (15 kHz compared to 3 kHz.) FM sounds much clearer than sideband, but the price for that nice sound is bandwidth.


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T6A11

  • What is the normal bandwidth required for a conventional fast-scan TV transmission using combined video and audio on the 70-centimeter band?

  • A. More than 10 MHz

  • B. About 6 MHz

  • C. About 3 MHz

  • D. About 1 MHz


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T6A11 Answer - B

  • Yes, hams do television, but it takes a lot of bandwidth – about 6 MHz (megahertz). As you can see, there are four bandwidths you need to know, but knowing them will help you understand the advantages and disadvantages of SSB, FM and fast scan TV.


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Group T6B

Group T6B covers voice communications, as well as the popular digital communication modes, EchoLink and IRLP .


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Echolink and IRLP

  • Many amateur radio operators use the Internet as an additional communications tool using two very powerful software tools, Echolink and IRLP (Internet Radio Linking Project). Both of these tools can put the world at the fingertips of the Technician licensee with a computer or simple handheld radio!


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Echolink

  • Echolink is a program available free to any licensed amateur radio operator. Information is transmitted between stations using Echolink by means of the Internet. When installed on your home computer, it allows you to talk to thousands of other hams around the world via the Internet, similar to AOL instant voice messaging. But it does so much more. As a licensed ham, it also allows you to connect to repeaters and other amateur stations all over the world. Using Echolink, you can log into a repeater in another state or country and chat with hams all over the world.


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Echolink

  • Screenshot of the free Echolink program.


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How Echolink Works

  • Any licensed amateur radio operator may operate on the Echolink system. Echolink allows computer-to-radio linking for voice transmission. All you need is a computer with a sound card and microphone or headset, an internet connection and the Echolink software. You can download the software for free at http://echolink.org/.

  • Once you have downloaded and installed the software, you’ll have to register online. As soon as your license is verified, you will be ready to connect. If you have a computer, Echolink will allow you to get on the air even before you get your first radio.


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IRLP

  • Another very popular use of the Internet for Amateur Communications is IRPL. The abbreviation IRLP means Internet Radio Linking Project. Like Echolink, IRLP describe is a method of linking between two or more amateur stations using the Internet.

  • Unlike Echolink, you use your radio to contact an IRPL station which is usually a repeater. That repeater then uses the Internet to establish contact with another IRLP station, also usually a repeater. When the two repeaters are connected via IRLP, operators on either end can use the local repeaters to communicate with each other .


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How IRPL Works

  • IRLP uses a standard called “Voice over Internet protocol” or “VoIP” to transfer data and voice over the Internet. If you have an IRLP repeater in your area, you can use your portable transceiver to select a specific IRLP “node” by using the keypad to transmit the IRLP “node numbers.”

  • An IRLP node is a station connected to IRLP. The node number is a number that identifies that station to IRLP, and allows IRPL to connect you with that station. For more information, visit www.irlp.net.


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More on Echolink and IRLP

  • Echolink and IRLP both use Voice over Internet protocol (VoIP) to connect amateur stations. This technology allows for fun and inexpensive communications between hams all over the world, as well as providing another link for emergencies. Be sure to give both a try!

  • And next time you are listing to a local 2 meter repeater, you may hear a brief tone and then a station from Russia calling CQ on a 2-meter repeater. If so, you are almost certainly listening to an Internet linked DX station!


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Locating VoIP Nodes

  • You can find a list of active nodes using VoIP in a repeater directory or on the Internet. Be sure to check them out!


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Check-Up Time!

Now let’s try the questions from this group.

You should make a note of any that you miss for later review.


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T6B01

  • How is information transmitted between stations using Echolink?

  • A. APRS

  • B. PSK31

  • C. Internet

  • D. Atmospheric ducting


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T6B01 Answer - C

  • Echolink is a free computer program that allows licensed amateurs to remotely access other stations and repeaters via the Internet. With Echolink, you can use your computer to talk directly to other hams all over the world using the Internet only, or you can log into a remote repeater or station set up for Echolink, and work stations in that area.


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T6B02

  • What does the abbreviation IRLP mean?

  • A. Internet Radio Linking Project

  • B. Internet Relay Language Protocol

  • C. International Repeater Linking Project

  • D. International Radio Linking Project


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T6B02 Answer - A

  • IRLP stands for "Internet Repeater Linking Project." IRLP uses the Internet to link repeaters. Using your radio, you can access an IRLP repeater and by entering a code, you can link that repeater to one of many repeaters worldwide. By linking the repeaters, you can carry on a conversation with other hams all over the world using only your VHF or UHF radio. How cool is that?


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T6B03

  • Who may operate on the Echolink system?

  • A. Only club stations

  • B. Any licensed amateur radio operator

  • C. Technician class licensed amateur radio operators only

  • D. Any person, licensed or not, who is registered with the Echolink system


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T6B03 Answer - B

  • Any licensed amateur operator may use Echolink. If you want to use it with your computer, all you have to do is download and install the program (it's free), and register. The registration process verifies that you are a licensed amateur. From that point, have fun! (By the way, this is an excellent way to put that license to work, even before you get your first radio!)


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T6B04

  • What technology do Echolink and IRLP have in common?

  • A. Voice over Internet protocol

  • B. Ionospheric propagation

  • C. AC power lines

  • D. PSK31


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T6B04 Answer - A

  • Both Echolink and IRLP use VoIP, or "voice over the Internet protocol." VoIP is a standardized system for transmitting speech or data over the Internet.


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T6B05

  • What method is used to transfer data by IRLP?

  • A. VHF Packet radio

  • B. PSK31

  • C. Voice over Internet protocol

  • D. None of these answers are correct


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T6B05 Answer - C

  • VoIP is a standardized system for transmitting data or speech over the Internet. It can transmit data as well as voice because the data is translated into sounds for transmission.


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T6B06

  • What does the term IRLP describe?

  • A. A method of encrypting data

  • B. A method of linking between two or more amateur stations using the Internet

  • C. A low powered radio using infra-red frequencies

  • D. An international logging program.


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T6B06 Answer - B

  • IRLP (Internet Repeater Linking Project) is used to connect two amateur stations with the appropriate software and access to the Internet. Most often, it is used by an amateur to link two repeaters together for long haul communications.


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T6B07

  • Which one of the following allows computer-to-radio linking for voice transmission?

  • A. Grid modulation

  • B. EchoLink

  • C. AMTOR

  • D. Multiplex


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T6B07 Answer - B

  • Echolink allows an amateur to link his or her computer to any IRLP-capable repeater or station worldwide.


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T6B08

  • What are you listening to if you hear a brief tone and then a station from Russia calling CQ on a 2-meter repeater?

  • A. An ionospheric band opening on VHF

  • B. A prohibited transmission

  • C. An Internet linked DX station

  • D. None of these answers are correct


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T6B08 Answer - C

  • If you hear a Russian CQ and call on the local two-meter repeater, you can bet that it is from a ham linked via the Internet. The link could be either through Echolink or IRLP. By the way, "DX" means "distant station.“ (Also bear in mind that calling CQ on a local repeater is not commonly accepted “good amateur practice”!)


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T6B10

  • Where might you find a list of active nodes using VoIP?

  • A. The FCC Rulebook

  • B. From your local emergency coordinator

  • C. A repeater directory or the Internet

  • D. The local repeater frequency coordinator


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T6B10 Answer - C

  • Current repeater directories often indicate whether the repeater is using one of the VoIP protocols. Also, there are many websites on the Internet that show repeaters currently using VoIP.


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T6B11

  • When using a portable transceiver how do you select a specific IRLP node?

  • A. Choose a specific CTCSS tone

  • B. Choose the correct DSC tone

  • C. Access the repeater autopatch

  • D. Use the keypad to transmit the IRLP node numbers


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T6B11 Answer - D

  • Most VHF and UHF transceivers have keypads, either on the radio, or more commonly, on the microphone. If you want to access an IRLP repeater from your radio, you need to key the "node number" of the distant repeater into the keypad. This sends a signal to the local repeater. The local repeater then contacts and links up with the distant repeater via the Internet.


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Group T6C

Group T6C covers several types of non-voice communications, such as image communications, data, CW, packet, and PSK31. It also covers Morse code techniques and amateur radio Q signals.


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Digital Communications

  • Hams use a number of other digital communications methods that do not require the Internet. Some, such as packet, have been around since the early days of computers, while others, such as PSK31 are fairly new. All are lots of fun!


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Packet Radio

  • Packet radio, or simply packet, is one example of a digital communications method. Packet has been around amateur radio since desktop computers became widely available in the 1980’s. It uses special software, a computer connected to a radio, and either a “terminal node controller” or a sound card, to send text or data on a computer over the air. It sends the text or data in “packets” that include information that allows the receiving computer to check the incoming packet for errors. If errors are detected, the receiving station will automatically request a resend of the data to insure 100% error free reception.


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APRS

  • The term APRS means “Automatic Position Reporting System.” APRS is system that automatically tracks the location of an amateur station, usually a mobile or portable station. Along with your normal radio, you’ll need a global positioning system receiver for sending automatic location reports from your station via APRS.

  • APRS has a lot of potential for use during emergencies!


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Fast Scan Television

  • If you want to be on TV, amateur radio gives you the chance. Since the 1960’s, hams have been experimenting with television transmissions. At first, utilizing very bulky equipment, hams used slow scan television to transmit still pictures between stations. Pretty high tech stuff for that time, but not too impressive today.

  • With the advent of inexpensive video cameras, computers and VHF repeaters specially designed for video transmission, hams can use fast scan television. Fast scan television uses the NTSC standard. NTSC, short for “the National Television System(s) Committee,” has developed a uniform standard for fast scan color television signals.


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Point-to-Point Digital Message Forwarding

  • Point-to-point digital message forwarding is yet another method if communications available to the Technician class operator in the 219 - 220 MHz frequency range.

  • The FCC has said that it encourages hams to develop and implement digital message forwarding system networks that can be used for emergency and national defense communications purposes, and to connect local packet nodes for this purpose.


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PSK31

  • PSK31 is a yet another fun digital mode. It requires only a radio and computer with a sound card, along with free software to work the world. PSK31 is a low-rate data transmission mode that works well in noisy conditions. It does not require a lot of power.

  • PSK31 uses the computer and sound card to generate PSK (phase shift keying) signals that are transmitted and decoded at the other end. Unlike packet, PSK31 is not error correcting, but it is still a great mode!


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PSK31 Using Digipan Software

  • Digipan is a free software package that will let you get on the air with PSK. Along with the software, you’ll need a computer with a soundcard, a radio, and a simple interface. For more information, visit www.digipan.net.


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Morse Code – The First Digital!

  • Many aspiring hams are put off from learning Morse code because they believe it is too hard to learn. That is a real shame, because while it does take a little effort to master the code, it also provides some real opportunity for long distance (DX) contacts, as well as special interest operations such as QRP (low power operating).


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Morse Code – How To Learn It

  • This study guide is not intended to teach Morse code. There are lots of ways to learn the code, including other hams, computer programs, or tapes. No matter how you choose to learn, don’t make this too hard for yourself. There are two things you need to remember.

  • First, don’t try to memorize dots and dashes. Instead, memorize the sound of each letter or number.

  • Second, once you have memorized the sounds of just 26 letters 10 numerals and 5 punctuation marks, you will almost certainly be able to pass the five words per minute test.


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Why Learn Morse Code?

  • There are three reasons.

  • First, once you as a Technician are able to pass the code test, you will be given additional HF (high frequency) privileges. You can begin using those privileges to send and receive code right away!

  • Second, when you pass the code, you have gotten the hardest requirement for General out of the way. Pass the General exam, and all the HF bands are yours for the asking.

  • Third, even if you never intend to upgrade or use Morse code, one practical reason for being able to copy CW when using repeaters is to recognize a repeater ID sent in Morse code.


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Sending Morse Code

  • OK, one other thing you may need to know for the Technician exam, is that when you first learn Morse code, you almost always send faster than you can receive. Because of that, you should be careful not to send any faster than the speed you can reliably receive. Why? Because the ham at the other end has no way of knowing that you cannot copy as fast as you send!


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Q Signals

  • Back in the early days of radio when the only form of radio communications was Morse code, operators came up with several abbreviations to move things along. Several of these abbreviations began with the letter “Q” and are still used by hams today. These abbreviations serve the same purpose as “10 codes” for police and emergency workers. Here are some examples. Although they were originally designed for telegraphy, many hams now use them on voice.


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QRM – Interference from other Stations

  • When stations operate on frequencies that are too close to each other, they may interfere with each other’s ability to hear the stations they are trying to communicate with. The "Q" signal you would use to tell another station that you are receiving interference from other stations is “QRM.” Example: “Could you please repeat? I am getting some heavy QRM here.”


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QSY – Changing Frequency

  • If you want to ask another person to change frequency, or announce that you are changing frequency, you use “QSY.” Example: “Jane, we’re close enough that we don’t need to use the repeater. Let’s QSY to 146.52.”

  • A complete list of Q-Signals can be found at www.arrl.org/files/ bbs/general/q-sigs.


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Check-Up Time!

Now let’s try the questions from this group.

You should make a note of any that you miss for later review.


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T6C01

  • Which of the following is an example of a digital communications method?

  • A. Single sideband voice

  • B. Amateur television

  • C. FM voice

  • D. Packet radio


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T6C01 Answer - D

  • Packet radio is a form of digital communications. In digital communications, data is translated into a string of zeros and ones by switching a signal off or on. Off usually represents a zero and on usually represents a one. This series of ons and offs is decoded by the receiver and turned into usable text. Packet radio sends this series of digits in packets along with a checking code so that the receiver can determine if the signal was received correctly. If not, it can signal the same packet to be sent again until it is correctly received.


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T6C02

  • What does the term APRS mean?

  • A. Automatic Position Reporting System

  • B. Associated Public Radio Station

  • C. Auto Planning Radio Set-up

  • D. Advanced Polar Radio System


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T6C02 Answer - A

  • APRS, or Automatic Position Reporting System, uses Global Positioning System (GPS) technology to allow amateurs to track the locations of other hams via radio and computer.


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T6C03

  • What item is required along with your normal radio for sending automatic location reports?

  • A. A connection to the vehicle speedometer

  • B. A connection to a WWV receiver

  • C. A connection to a broadcast FM sub-carrier receiver

  • D. A global positioning system receiver


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T6C03 Answer - D

  • The Global Positioning System (GPS) receiver is required to determine the location of the station to be tracked so that it can send that location out to the APRS system.


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T6C04

  • What type of transmission is indicated by the term NTSC?

  • A. A Normal Transmission mode in Static Circuit

  • B. A special mode for earth satellite uplink

  • C. A standard fast scan color television signal

  • D. A frame compression scheme for TV signal


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T6C04 Answer - C

  • NTSC stands for National Television Standards Committee. This group has developed the standard for fast scan television signals.


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T6C05

  • What emission mode may be used by a Technician class operator in the 219 - 220 MHz frequency range?

  • A. Slow-scan television

  • B. Point-to-point digital message forwarding

  • C. FM voice

  • D. Fast-scan television


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T6C05 Answer - B

  • According to Part 97, operators using this frequency band are limited to data transmissions. All of the transmissions listed in Answers A, C, and D are something other than data transmissions so they are not allowed in this frequency band. Only Answer B mentions a data transmission so this is the right choice.


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T6C06

  • What does the abbreviation PSK mean?

  • A. Pulse Shift Keying

  • B. Phase Shift Keying

  • C. Packet Short Keying

  • D. Phased Slide Keying


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T6C06 Answer - B

  • PSK is short for phased shift keying.


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T6C07

  • What is PSK31?

  • A. A high-rate data transmission mode used to transmit files

  • B. A method of reducing noise interference to FM signals

  • C. A type of television signal

  • D. A low-rate data transmission mode that works well in noisy conditions


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T6C07 Answer - D

  • PSK31 is an excellent mode for working DX (distant stations) with very little power. All you need is a radio with a sound card and PSK31 software, a computer, and a simple interface to connect the computer to the radio.


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T6C08

  • What sending speed is recommended when using Morse code?

  • A. Only speeds below five WPM

  • B. The highest speed your keyer will operate

  • C. Any speed at which you can reliably receive

  • D. The highest speed at which you can control the keyer


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T6C08 Answer - C

  • Most people just learning code can send much faster than they can copy. If you send code faster than you can copy, the person at the other end won't know you can't copy that fast. When it's the other ham's turn to send, you are likely to get code sent back to you at the speed you sent, and you will soon be lost!


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T6C09

  • What is a practical reason for being able to copy CW when using repeaters?

  • A. To send and receive messages others cannot overhear

  • B. To conform with FCC licensing requirements

  • C. To decode packet radio transmissions

  • D. To recognize a repeater ID sent in Morse code


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T6C09 Answer - D

  • Before the code-free license, everyone who wanted to be a ham had to learn Morse code to get a license, so when repeaters sent their ID in Morse code, everyone could understand it. However, learning Morse code will not only let you copy the repeater ID, it will be your ticket to the General Class license and the world of high frequency (HF) communications.


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T6C10

  • What is the "Q" signal used to indicate that you are receiving interference from other stations?

  • A. QRM

  • B. QRN

  • C. QTH

  • D. QSB


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T6C10 Answer - A

  • "Q" signals are used by amateurs to convey a lot of information in a short form. In that way, they are somewhat like the "ten codes" used by police, emergency personnel and CB'ers. One of the more common Q codes is this one - QRM - which means you are receiving interference from other stations near or on your frequency.


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T6C11

  • What is the "Q" signal used to indicate that you are changing frequency?

  • A. QRU

  • B. QSY

  • C. QSL

  • D. QRZ


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T6C11 Answer - B

  • Here is another Q code. QSY means you are changing frequency or that you would like the other operator to do so. Q codes are particularly useful when you are using Morse code since they can convey a lot of information in only three letters, but they are also frequently heard on phone (voice) as well.


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Six Down, Four to Go!

This concludes Study Guide # 6.

Once you are satisfied that you can answer 80% of the questions in this Sub-element, you are ready to move on to Study Guide # 7.


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