Module 12 - Data Modes
- Reading Assignment
- INTRO to DATA MODES
- DATA STATION SETUP
- DATA SOFTWARE
- MFSK & MORE
- HAM RADIO DELUXE
- TERMINAL NODE CONTROLLER
- INTERNET GATEWAY
- IRLP & ECHOLINK
- Quiz 12
- Recommended Reading
Read Chapter 5, Pages 5-8 to 5-13 Chapter 6-19 to 6-20 in your text before you continue.
Introduction to Data Modes
Amateur radio is a hobby with many facets and attracts people with a wide range of interests. Many amateurs begin with a fascination of radio communication and then find different areas of the hobby that make the hobby more interesting to them.
Some of the focal areas amateurs pursue include radio contesting, radio propagation study, public service communication, technical experimentation, and computer networking.
Demonstrating a proficiency in International Morse code was for many years a requirement to obtain amateur licenses. Internationally regulations dropped the requirement for code proficiency in 2003. The U.S. FCC did not follow suite until 2007.
CW (code)has advantages over many other modes because it has a narrow bandwidth and can effectively communicate over long distances with little power and in less than perfect conditions. However, learning CW was an arduous task that many did not want to pursue. Many were concerned that the hobby would react negatively to this change. This has not seemed to have occurred, in fact just the opposite, more people are getting their licenses now than ever before.
Data modes have helped to feed that wave of interest. Data modes also have very small bandwidth requirements, some considerable more narrow than CW! Modern personal computers have encouraged the use of digital (or Data) modes. Personally I believe these modes have provided a modernized CW kind of communication.
DATA STATION SETUP
We are going to explore how equipment is connected to use the data modes, but not in detail. If you wish to use the data modes there is considerable information available. Also don't forget to ask for help from your Elmers and fellow hams.
Any communications using the personal computer requires several connections and accommodations. The receiver audio output of the transceiver must be connected to the mod input (mike) of the computer to allow the computer access to the received signal. Also, the demod (speaker) audio output of the computer from needs to be connected to the microphone (or transmitter)audio input of the transceiver to allow modulation of the transmit signal. Both of these audio connections should be electrically isolated from each other and the impedances matched if needed.
The (computer) sound card provides audio to the microphone input of the transciever and converts received audio from the transceiver to digital form.
Figure M12-2 shows the typical hookup for basic data modes, while figure M12-3 shows a typical commercially available data interface. It is a rather simple circuit and can easily be built in a short time with minimum cost by anyone familiar with electronics construction. Even if you decide to go the commercial route, the cost is very modest.
Note: Unless mentioned to the contrary the following data modes all use this same interface.
Software is necessary to code and decode the digital signals. There are many software programs available that will do the job.
The software also includes a user interface on the PC, which is used to display the decoded text and manage the software configuration.
The software does much more than displaying just the decoded text.
Signals are displayed two ways. One, usually on a waterfall display that shows frequency and a time slot several seconds long that shows the undecoded signals. Two, a window or strip will show the decoded signal along with the call sign associated with that signal.
Data modes use the single sideband mode and modulate that signal with specific audio signals at specific bandwidths. A typical SSB bandwidth is around 3 KHz wide. The data modes occupy much less bandwidth, so multiple signals of the same data mode can be displayed and demodulated at the same time!
Yep, that's right, you can monitor multiple stations' signals and decode them at the same time.
Data mode software has many features to manage those signals. Probably the neatest of these features are the Macros (previously typed messages which are able to be recalled and used with the click of a mouse.). These Macros will call CQ, respond to replies to your cq, brag files - which are lists of your rigs, and much more.
There is a transmit window that has any text that is scheduled, being sent, and has been sent.
There is a receive window that has received text and keeps it until you erase the window
There are many more features and tweaks in the data modes, too many to list here. I would suggest you download, at your leisure, one of the programs listed below and check it out. And/OR go to their websites and glean the information about what they offer.Talk to an Elmer (ham helper). Go onto their user forums. Go onto our forum and ask questions.
Click Here to go to wb8nut.com for more information on digital modes. An audio playback of each mode is available so you can hear what they sound like.
These are some of the several data software programs available, most are a suite of digital modes which contain with many data modes including all the following unless exceptions are noted.
The following is a list of several software programs, you can do an internet search on them for more information. Many are free or very inexpensive.
- Digipan - Great PSK31 Software (Freeware)
- FLDigi - Great Multi Mode Application and it runs on Windows, MAC OSX, and Linux. Plenty of add-ons and a messaging package (NBEMS) which is very useful for emergency communication (Freeware)
- Hamscope - PSK31, RTTY, ASCII, MFSK, Packet and CW (Freeware)
- IZ8BLY Hellschreiber - All popular Hell modes (Freeware)
- MixW - The soundcard based software that does all the modes! (Shareware - Reasonable)
- Stream by IZ8BLY for MFSK (Freeware)
- Ham Radio Deluxe - Free and has so much you won't believe it. More on this program later.
RTTY, also known as Radioteletype, a legacy data mode, is still popular. It allows communication using two radios and a modulation technique such as frequency shift keying (FSK).
RTTY previously required cumbersome mechanical equipment. However, now many ham radio operators enjoy using modern PCs and soundcard software to communicate using the RTTY mode.
The particular code used in RTTY is the Baudot code. More specifically, on the Amateur bands, it's 5 bit Baudot meaning that every character consists of five bits, either mark or space (in actuality Baudot is 8 bits because a start bit and two stop bits are added for synchronization). In general, a baud rate of 45.45 baud is used, which is the equivalent of 60 wpm (words per minute, each word containing 5 letters). RTTY uses two alternating tones.
Specialized digital modes such as PSK31 allow real-time, low-power communications on the shortwave bands.
A PSK31 operator typically uses a single sideband transceiver connected to the sound card of a PC running special. When the operator enters a message for transmission, the software produces an audio tone which sounds, to the human ear, like a continuous whistle with a slight warble. This is then fed into the transceiver, where it is transmitted.
The received audio whistle from the transceiver's audio output is fed into the sound card's audio input, and the software decodes it.
PSK31 can often overcome interference and poor propagation conditions in situations where voice or other data methods of communication fail.
However, PSK31 was only designed for leisure use by amateurs, and due to its relatively slow speed and no error control, is not intended for the transmission of large blocks of data, text, or critical data requiring high accuracy. The errors are similar to those encountered when using Morse Code and easily filled in by human interpretation.
PSK31 uses very little bandwidth and is therefore very effective at low power levels and gives big bang for the buck, however, it is a low-rate data transmission mode.
MFSK & Other Modes
Multiple frequency-shift keying (MFSK), an improvement over FSK, is a variation of frequency-shift keying (FSK) that uses more than two frequencies.
Each symbol in the MFSK alphabet is sent as a pair of tones, one from each of two distinct frequency sets. Perhaps the most widely used 2-tone MFSK system is dual-tone multi-frequency (DTMF), better known by its AT&T trademark of "Touch Tone". (It is important that each tone appears in only one set.) These signals are distinctive when received as a rapid succession of tone pairs with almost musical quality when they are heard by the user.
MFSK is ideal for HF operation since it has good noise rejection and good immunity to most propagation distortion effects which adversely affect reception of other modes that only use a single tone.
There are several other modes that are popular. Each mode has advantages and disadvantages.
Some of these modes are: MFSK8, MFSK16, Olivia, Coquelet, Piccolo, DominoF, DominoEX, THROB, & CROWD-36. Some are more robust than others (better accuracy). But the more robust, usually the slower the transmission rate.
Also, these modes take up more bandwidth than PSK31 and are slightly harder to tune as being slightly off frequency is more critical.
HAM RADIO DELUXE/DM780Why single out one program of all those available. Two reasons it does so much and I am very familiar with the program.
Ham Radio Deluxe includes DM780 which is a digital software program that employs a superbrowser. The PSK screen in DM780 decodes the signal in windows like other software, but it also includes the decoded text in a ribbon adjacent to the frequency signal trace for that station. This allows for several signals to be decoded at the same time and viewed easily.
Other software will decode multiple signals at the same time but each signal is displayed in its own window box limiting the viewing areas.
With DM780 you can follow many stations and move to their frequency to transmit simply be clicking on that particular trace. The call sign appears at the beginning of the trace and by clicking on it you can receive information such as location, name etc of that call sign.
DM780 supports almost any known digital mode and you can easily switch to the one you desire. DM780 also supports Slow Scan TV, RTTY, CW and more. It can control your rotator for your beam antenna and automatically point the antenna to the calling stations location.
Different tabs in the program will look at QRZ (to look up call signs), propagation prediction sites, a world map showing day and night zones, and much more.
Ham Radio Deluxe (HRD) itself will via a data cable actually control most modern transceivers with the computer. HRD displays a screen that shows any of the transceiver's modes and functions on one screen. This is a great feature, as one of the problems with complex transceiver is that many controls are buried in menus and sub-menus. This is necessary because there simply isn't enough room to have them all on the front panel. HRD makes it possible to do so with its easily customizable screen.
In order for your computer to control the transceiver, an interface to address the different logic voltages is necessary. The computer uses +/-5VDC logic, while the computer relies on +/-12VDC logic. All it takes is a simple interface easy to build, and commercially available. In face many of the interfaces necessary to process the audio for digital modes also have the circuitry built into to allow controlling the transceiver in one moderately priced interface. Custom cables that match your brand and model of transceiver are readily available also.
HRD also will facilitate the remote control of your transceiever. That's right you can, with your laptop, use a wi-fi connection to remotely control your transceiver from locations anywhere.
Bottom line there are many options available to you as a ham to do many thing with ham radio digital modes.
Most of the data modes discussed so far have no error correction. MFSK by virtue of using 2 discrete tone for each character does minimize errors, but it is not really good enough for data. Sometimes there are errors in the received bits. The acronym 'BER' is the bit error rate and refers to the number of errors in digital communications systems.
Packet radio is a form of packet switching technology used to transmit digital data via radio. It uses the same concepts of data transmission that are fundamental to communications via the Internet.
As you can read in your textbook, messages are broken into pieces and included into packets along with other information. Each packet contains a header, data & error checksum.
Packets are transmitted from your computer to your transmitter (via a device called a terminal node controller - TNC). Packets are transmitted using FSK (frequency shift keying) over the air. The packet(s) is then received by a far station receiver where the process is reversed. First the receive, then the TNC, then the computer to display the message(s). A parity bit is sent along with the message which will be used to detect errors in the received data. If an error is detected by the checksum (parity bit), the receiving station sends an automatic repeat request, thus the final packet is error free because of the error correction protocol.
Simple Packet communication can be performed just by using a computer software program and a transceiver. However more complex Packet communication requires a discrete TNC (Terminal Node Controller) between the computer and the transceiver.
PACTOR is a radio modulation mode used by amateur radio operators, marine radio stations, and radio stations in isolated areas to send and receive digital information via radio. A robust network of PACTOR stations has been established to relay data between radio stations and the Internet, extending Internet access to sea based and other isolated users. PACTOR utilizes an almost ideal combination of simple FSK modulation, and the ARQ protocol for robust error detection and data throughput.
PACTOR I is open technology and modems can be purchased in the $150 price range and are in ample supply.
Two enhanced modes, PACTOR II and PACTOR III, are much faster but have been kept proprietary by the German company, SCS, that developed them. As a result, SCS is the only source for TNC modems capable of these modes.
Voice Over Internet Protocol (VOIP) commonly refers to the communication protocols, technologies, methodologies, and transmission techniques involved in the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet.
VOIP or Voice Over Internet Protocol is becoming more popular and hams use it in many ways. VOIP is what Ham Radio Deluxe uses for remote operation for both the data path and the audio paths.
You are probably most familiar with VOIP as used by SKYPE, Magic Jack and others.
We will discuss other services that use VOIP just a little later in this module.
An internet gateway is a station that receives your radio signal, converters it to digital and connects it to the internet, thereby connecting other amateur radio stations to the internet.
You can look up a list of active nodes that use VOIP from a repeater directory available from many sources. You can even obtain a repeater directory that will reside on your GPS unit. It will tell you the milage to repeaters in your area. It is a great asset if you are traveling out of your home territory.
Internet radio gateways can use the internet is several ways: to connect a radio station to the internet, to relay information from the internet to a radio station, or to join repeaters or simplex stations together, using the latest voice over Internet protocol (VOIP) technology. There are several systems now in operation and we will discuss some of them next.
IRLP & Echolink
Operating an internet gateway with is easy. Two of the most popular are IRLP & Echolink
Both of these systems are a way to access remote repeaters so you can expand your area coverage exponentially
IRLP - Internet Radio Linking Project
The aim of this project is to reliably and inexpensively link amateur radio systems without the use of RF links, leased lines, or satellites.
The IRLP uses Voice-Over-IP (VOIP) custom software and hardware. Coupled with the power of the Internet, IRLP will link your repeater site or simplex station to the world in a simple and cost effective way.
IRLP operates a worldwide network of dedicated servers and nodes offering very stable worldwide voice communications between hundreds of towns and cities.
So for example on IRLP if you wanted to call a ham in Sydney Australia using your hand held you would use the keypad to transmit the IRLP node ID. Here's how, press the PTT and then press the DTMF key numbers 6 0 0 0 then release and listen.
You would hear a voice announcement telling you that the link was connected. You would then talk and carry on a QSO normally as you would if you were working a local station. When you have finished you press the PTT and the press DTMF 7 and then 3 which closes the link. You will then hear another voice announcement informing you the link has been closed.
You should always listen first on a gateway frequency to see if it is in use. You can also send a `0' to see if it connected to anywhere.
The node software used in IRLP is Linux. IRLP allows the linking of repeaters to provide a greater coverage area. IRLP requires a radio to access the linking and at each end of the conversation to work.
Echolink also uses Voice over IP technology to enable amateurs to communicate through local Internet-connected repeaters and radio nodes Automatic link establishment (ALE) has enabled continuous amateur radio networks to operate with global coverage.
EchoLink is designed specifically to run under Microsoft Windows. Currently, there are no plans to offer versions of EchoLink for other platforms.
EchoLink allows licensed Amateur Radio stations to connect to one another over the Internet. You can use EchoLink to connect your station (or your computer) over the Internet to other amateurs using the same software, and carry on a voice QSO (contact). This greatly enhances the range and utility of mobile and portable VHF/UHF-FM stations, and also allows computer-equipped hams to access distant repeaters directly.
You can access EchoLink either with a radio or a computer. If you are in range of an FM repeater or simplex station equipped with EchoLink, you can use DTMF commands from your radio to access the EchoLink network.
If you are a licensed amateur with an Internet-connected PC, you can access EchoLink stations directly from your PC.
There is a good functional diagram (Fig 5-10)in the textbook on page 5-11.
Winlink, also known as the Winlink 2000 Network, is a worldwide radio messaging system that mixes internet technology and appropriate amateur radio technologies.
The system provides radio interconnection services including: email with attachments, position reporting, graphic and text weather bulletins, emergency/disaster relief communications, and message relay.
Winlink was built and administered by volunteers without pecuniary interests. (recognize that term?) Winlink 2000 is a project of the Amateur Radio Safety Foundation, Inc. (ARSFI), a charitable entity and non-profit organization. Winlink networking started by providing interconnection services for amateur radio.
The system runs several central message servers around the world for redundancy. During the past decade it increasingly became what is now the standard network system for amateur radio email worldwide. Additionally, in response to recent needs for better communications disaster response, the network has been expanded to provide separate parallel radio email networking systems for MARS(military affiliate radio system).
The system is used continuously by maritime users. To locate lost and overdue vessels, the US Coast Guard frequently requests the assistance of over 7,500 Winlink users who are at sea,and positive results are very common.
In addition, during the Asian Christmas Tsunami, maritime users played an important role in communications in the aftermath. This was also true of the Chilean/Peruvian storms, the failure of INTELSAT 804--which left hundreds of Islands without reliable communications--and many other hurricane-related episodes in the Caribbean and Atlantic
Winlink 2000 is a worldwide radio messaging system that takes advantage of the Internet wherever possible while retaining the ability to function without major parts of it. It combines the best attributes of wireless communications and the internet to allow remote users to send and receive email to and from correspondents on the internet as well as other users of the system. The synergy of this combination provides fast internet message forwarding worldwide with the long reach of radio links to places without normal internet service, like out to sea in the middle of the ocean.
The Automatic Packet Reporting System was designed to support rapid, reliable exchange of information for local, tactical real-time information, events or nets.
The idea is to transmit all relevant information to everyone in the net in a consistent manner. APRS established standard formats not only for the transmission of POSITION, STATUS, MESSAGES, and QUERIES, it also establishes guidelines for display so that different systems will still see the same information displayed in a consistent manner.
The two images below should give you an idea of the kinds of information available to the mobile operator on his APRS radio. On the left is the Kenwood D710 radio showing the station list, and on the right is the attached GPS with map display showing the location of other APRS stations.
Each station in the list has three more pages of information on it. The objects can show Repeater frequencies in an area, meetings, nets, events, hamfests, Echolink and IRLP nodes and frequencies, traffic speeds, accidents, emergency situations.
The attached GPS can show the location of each of these items.
There also is a lot of comprehensive information to be found at http://www.aprs.org/ , although it is a lot more technical.
D-STAR (Digital Smart Technologies for Amateur Radio) is a Digital voice and data protocol specification developed by the Japan Amateur Radio League. D-Star offers digital voice and slow and high-speed data communications
While there are other digital on-air technologies being used by amateurs that have come from other services, D-Star is one of the first on-air and packet-based standards to be widely deployed and sold by a major radio manufacturer that is designed specifically for amateur service use.
Other non-digital voice modes such as amplitude modulation, frequency modulation, and single sideband have been widely used since the first half of the 20th century. By comparison, digital D-STAR signals offer clearer signals and use less bandwidth than their non-digital counterparts. As long as the signal strength is above a minimum threshold, and no multi-path is occurring, the quality of the data received is better than an analog signal at the same strength.
D-Star compatible radios are available on VHF, UHF, and microwave amateur radio bands. In addition to the over-the-air protocol, D-Star also provides specifications for network connectivity, enabling D-Star radios to be connected to the Internet or other networks and provisions for routing data streams of voice or packet data via amateur radio call signs.
D-Star is capable of connecting repeater sites using the Internet and forms a world-wide radio network.
You will receive instant feedback to your answers and
you will be able to see how you did on the quiz overall.
Also you will be able to view a detailed summary of the
All answers, whether right or wrong, will be referenced back to your text so you can review and correct any wrong answers.
Tips on how to remember the correct answer are included.
You can take the quiz as often as you wish.
No one but you will see the quiz results.
Information about data communications was the focus of this module. If your head is not bursting with the possibilities available, I am surprised.
Don't be dismayed if it is a bit muddled at this time. Use the links in this module to delve a bit further into any mode or service mentioned in the module. Ask you Elmers, ask the forum, go to YouTube and do a search.
View the complete Technician Question Pool in Chapter 11 of your Ham Radio License Manual.
Review the complete Technician Question Pool with Hints to help you to remember the answers for the test available by clicking the last item on the left hand select menu.
Read, Read, Read. Many books are available from the ARRL. Many articles are also readily available on the internet.
Use the links in this module to delve a bit further into any mode or service mentioned in the module. Ask your Elmers, ask the forum, go on YouTube and do a search.
There are several videos on You Tube. Do a search on Amateur Radio, Ham Radio Technician License, variations of these or on the exact subject matter in which you are interested.
Review the Term Glossary in Chapter 10 of your Ham Radio License Manual
Practice Exams are available at www.arrl.org/exam-practice and there are links to many other test practice sites also.