Presentation on theme: "Soundcard Digital Modes"— Presentation transcript:
1 Soundcard Digital Modes Soundcard Digital CommunicationsSoundcard Digital ModesTyler GriffithsN7UWXScott Honaker- N7WLO
2 Soundcard Digital Communications Evolution of AcronymsHuman transmitted digitalCW – Operator determines performanceMachine sent digitalRTTY – Baudot 5-bit codeMachine sent corrected data packetsPacket – APRS – TCP/IPHigh noise immunity RTTY replacementsPSK31 – QPSK – MFSK – MT63Intermittent channel weak-signal modesHSCW – FSK441 (WSJT)Extreme weak signal modeJT44 (WSJT)CW is the first and oldest digital mode, sent and received by humans. Performance is determined by the skill of the operator.RTTY provides basic text but is wide bandwidth, uncorrected, slow and limited in charactersPacket provides full 8-bit ASCII data to be sent in corrected packetsAPRS is an application that runs on packet and provides position and message transfer capabilities ( )TCP/IP is also implemented over a packet connection for Internet connectivity over radio at 1200 or 9600 baud (half duplex)PSK31 provides keyboard to keyboard chat functionality like RTTY but very narrow bandwidth (31Hz vs. 350Hz) with high noise immunityQPSK error-corrected version of PSKMFSK error-corrected with a slightly wider bandwidthMT63?High Speed CW at WPM used for meteor scatter contacts but machine-inefficientFSK441 very efficient high speed with many repetitions for meteor scatter contactsJT44 very slow speed data sent repeatedly to create a signal that can be copied 26dB+ BELOW the noise floorTyler Griffiths - N7UWXScott Honaker- N7WLO
3 Sound Card Digital Modes Connecting your Radio to your ComputerYou can purchase an interface to connect your transceiver to your computer, OR you can make your own for a few $.
4 Computer/Radio Interfacing Soundcard Digital CommunicationsComputer/Radio InterfacingLine or Speaker OutputLine or Mike InputInterfaceCOM PortCOM PortThe Rascal interface shown here is not necessary. There needs to be an audio connection and some method for PTT. This is normally done via a simple transistor switch off the serial port. Some packages also support switching via the computer control port for some radios.You have a laptop with no real COM port. There are USB to serial adapters that can be used. This is occasionally tricky because they may not support the RTS and DTR lines properly to handle the switching.Push-to-talk (PTT)Receive AudioTransmit AudioComputer Control CI-V or CATTyler Griffiths - N7UWXScott Honaker- N7WLO
5 Sound Card Digital Modes Connecting your Radio to your ComputerReceive Audio Connection:Connect an audio cable between the transceiver audio output and the soundcard LINE IN jack.
6 Sound Card Digital Modes Connecting your Radio to your ComputerTransmit Audio Connection:Connect a shielded audio cable between the transceiver MIC input and the soundcard LINE OUT jack through a 40 db attenuator. If your transceiver has a LINE input, no attenuation is required. (eliminate the 2 resistors)
7 Sound Card Digital Modes Connecting your Radio to your ComputerT/R Connection:CWPSK31RTTYPACKETAPRSFSK411JT44EMEPTT is controlled via the RTS and/or DTR outputs of the computer’s RS-232 serial port.
8 Sound Card Digital Modes Connecting your Radio to your ComputerT/R Connection:CWPSK31RTTYPACKETAPRSFSK411JT44EMEPTT is controlled via the RTS and/or DTR outputs of the computer’s RS-232 serial port.
9 Soundcard Digital Communications Soundcard PacketAGW Packet Engine for 1200 or 9600Supports Terminal, TCP/IP, DX Cluster, DigipeaterAPRS Software support via APRSPoint, UI View and WinAPRSSupports multiple simultaneous connectionsAllows remote use over a network/InternetThe software was written by SV2AGW. The basic features are free and he charges a small registration fee for more advanced features and higher speed (still a fraction of the cost of a hardware TNC).Tyler Griffiths - N7UWXScott Honaker- N7WLO
10 Soundcard Digital Communications PSK 31Designed by Peter G3PLXBased on the RTTY mode of operation useful for live keyboard to keyboard QSOWorks at baudsUses varicode character coding providing 50wpmGive very good copy under low Eb/No numbers and is thus suitable for QRPThat instead of using FSK or on/off keying uses BPSK or QPSK with a Viterbi decoderUses advanced DSP and narrow band (31 Hz!!) techniquesPSK31 is not a digital mode that will make Pactor, Pactor-2, Clover-II or Gtor obsolete, offers error free links, can be used to transmit files or access mailboxes...Tyler Griffiths - N7UWXScott Honaker- N7WLO
12 Soundcard Digital Communications QPSKQuadernary Phase-Shift KeyingFour phases instead of 2 for PSKExtra capacity used for error-correctionImprovements of up to 5 fold in error-rateNot as good for QRP (3dB hit)Extra transmission delayMore frequency sensitive (within 4Hz)Must use correct sidebandStart BPSK and switch to QPSKPSK31 operators find QPSK can be very good but is sometimes disappointing. In bench testswith white noise, it is actually worse than BPSK, but in real band conditions with fading andinterference, improvements of up to 5 times in the character error-rate have been recorded. Thisdoesn't come free, however. Apart from the transmission delay, which can be a bit off-putting,QPSK with four phases instead of two, is twice as critical in tuning as BPSK, and needs to bewithin 4Hz. This could be a problem with some older radios. What tends to happen is thatcontacts start on BPSK and change to QPSK if both stations agree. There is one aspect ofQPSK that has to be kept in mind - it is important for both stations to be using the correctsideband - on BPSK it doesn't matter.Tyler Griffiths - N7UWXScott Honaker- N7WLO
13 Soundcard Digital Communications MFSK 16Multiple frequency-shift keying (MFSK) is a variation of frequency-shift keying (FSK) that uses more than two frequencies.Sixteen tone carriers, ~16Hz apart42 WPM in 316Hz with FECHigh rejection of pulse and broadband noise due to narrow bandwidth per toneLow baud rate for sensitivity and multi-path rejection - data bit rate higher than symbol baud rateTolerance of ionospheric effects such as doppler, fading and multi-pathMFSK is a technique for transmitting digital data using multiple tones, extending the RTTY two-tone technique to many tones, usually, but not always, one tone at a time.MFSK means Multi - Frequency Shift Keying, and should not be confused with MSK (Minimum Shift Keying). There are a number of different techniques, using concurrent (or parallel) tones, sequential (one after another) tones, and combinations of tones. MT-Hell can be either concurrent or sequential, DTMF tones used for telephone signaling are concurrent tone pairs, while Piccolo and Coquelet, although using tone pairs, are decidedly sequential.MFSK transmissions have a unique sound, almost musical, which is why Piccolo and Coquelet received their names (Coquelet means rooster).MFSK uses relatively narrow tone spacing, so remarkable data rates are achieved for a given bandwidth - 64 bps in a signal bandwidth of 316 Hz is typical. The following picture is a waterfall display of an MFSK16 signal (16 carriers) with a spacing of Hz and operating at baud. The transmission operates at 62.5 bps (about 80 words per minute!) and occupies about 316 Hz of bandwidth. MFSK16 is always operated with FEC, so the text throughput is actually only about 42 WPM (31.25 bps).Let's be fair - there are disadvantages to MFSK! The main disadvantages are related to the narrow spacing and narrow bandwidth of the individual tone detectors - drift can be a problem and accurate tuning is essential. Good tuning indicators and AFC are necessary at the slower speeds. It is important that the radio transceiver be very stable, and also that it has very small frequency offset between transmit and receive (preferably less than 5 Hz).MFSK also uses more bandwidth for a given text speed than a 2FSK or PSK system, but by the same token it is therefore more robust. This wider bandwidth means that you will not have the same QRP performance advantages as an extremely narrow band mode like PSK31.Tyler Griffiths - N7UWXScott Honaker- N7WLO
14 Soundcard Digital Communications HamScope SoftwareHamScope is a FREE multi-mode communications interface for amateur radio that supports:PSK31 (BPSK and QPSK, see PSK31 Home Page )RTTY (HamScope uses Makoto Mori's MMTTY Engine)ASCII (both 7 bit and 8 bit protocols using MMTTY)MFSK16 (see MFSK16 Home Page )PACKET (HamScope uses George Rossopoulos' AGWPE Engine) CWHamscope also offers an advanced user interface with a multitude of features to provide optimal control and convenience during operation:a wide, multifunction panoramic displaya radio control interface for several ICOM, TenTec, Kenwood, and Yaesu transceivers42 user-programmable macro buttonsuser definable function key mappingsHamScope 1.51 has added data links to several logging and/or radio control programs:DXbaseLOGic 6RYLogitTRX-ManagerYPLOGHamScope also supplies a DDE server for users who wish to connect to the programHamScope is designed to run under Windows 95, 98, and NT, and requires a 133 MHz Pentium-class or better machine. 16 bit SVGA color (or greater) is also necessary for the panoramic waterfall display to function correctly.Tyler Griffiths - N7UWXScott Honaker- N7WLO
15 Soundcard Digital Communications DigiPan SoftwareDigiPan stands for "Digital Panoramic Tuning" and brings the ease and simplicity of PANORAMIC reception and transmission to PSK31and PSK63 operation. DigiPan provides a panoramic display of the frequency spectrum in the form of an active dial scale extending the full width of the computer screen. Depending upon the transceiver IF bandwidth, it is possible to "see" as many as 40 to 50 PSK31 stations at one time. DigiPan1.0 forever changed how PSK31 tuning was done, from manually tuning the transceiver, to "point-and-click" mouse tuning, in which a signal on the waterfall is clicked with the mouse button to find out the station's callsign and decide whether or not to contact that station..Tyler Griffiths - N7UWXScott Honaker- N7WLO
17 Soundcard Digital Communications fldigi SoftwareFldigi - Digital modem program runs on many different flavors of operating system Linux, Free-BSD, OS X, Windows XP, NT, W2K, Vista and Win7.flarq - Automatic Repeat reQuest program.Tyler Griffiths - N7UWXScott Honaker- N7WLO
19 Soundcard Digital Communications APRS SoftwareUsing programs like UI-View and APRSISCE along with AGWpe you can run APRS.Scott Honaker- N7WLO
20 Digital Modes Waterfall’s Soundcard Digital CommunicationsDigital Modes Waterfall’sCW PSK QSPK PACKET RTTYScott Honaker- N7WLO
21 Interesting Waterfall! Soundcard Digital CommunicationsInteresting Waterfall!Scott Honaker- N7WLO
22 Soundcard Digital Communications FSK WSJTFrequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave.[100% duty cycle, so no extra energy wasted by On/Off keyingMore user-friendly interface--like RTTY or PSK31 modesMuch better S/N than HSCW at same speedEach character takes about 2.3ms to send with four tones. That’s 441 baud.WSJT was created by Joe Taylor – K1JT, Nobel Prize winning Astronomer.Most popular bands are 144 and 50MHz. There is growing activity on 222MHz, and a few 432 MHz QSO’s have been made.More is better, but “brick and yagi” are sufficient on 144 and 222 any time of year.Brick and yagi has worked on 432, but more operation is needed to draw conclusions.Preamp—you don’t know what you’re missing!On 144MHz, the average “brick and yagi” station should be able to work a similar station in the mi range fairly consistently, any time of year.Geometric limit of ~1400mi (based on the height at which meteors ionize sufficiently)Limits, schlimits! Records are meant to be broken!Rovers can stray to distant grids and still make contacts—that means new grids and more multipliers.“Big guns” should be able to work anyone within 1200mi on 144Mhz.Fills the “dead time” in the small hours of the morning with valuable mulipliers.Tyler Griffiths - N7UWXScott Honaker- N7WLO
23 Soundcard Digital Communications JT 44 - WSJTUses long term signal averaging to recover a signal that is up to 30dB below the noise floor!Humans have “short ears” limited by their sensory memory—they can only analyze a signal in a small timeframeComputers can analyze in relatively large timeframesInspired by the PUA43 mode (with dedicated hardware)Uses 44 tones, one for each character in the PUA43 alphabet (same as FSK441), plus a synchronization tone. Each character is assigned a unique frequencySlow transmission speed: 5.38 baudHighly redundant (FEC)Bandwidth of 485HzTones spaced at 10.8HzSync tone 32.3Hz below data.Allows for frequency error and EME Doppler shift with and 2.7 KHz passband.Transmission lasts about 25 s, with a gap at the beginning and end to allow for timing error and EME delay. (Like FSK441, operators use alternating 30-second periods)135 intervals (bits)69 are devoted to sending the sync toneOther 66 intervals are used to send the 22-char message three times.Tyler Griffiths - N7UWXScott Honaker- N7WLO
24 Soundcard Digital Communications JT44 – Terrestrial UseJT44 works well on troposcatter paths that are too short for MS enhancementSeveral operators have used it on 6m for borderline TE, and marginal Es openings.Microwave non-line-of-sight pathsCould be a good way of overcoming atmospheric absorption above 10GHzContest stations can make otherwise impossible contactsIt can take some time but is perfect for otherwise impossible Field Day and contest shots. There’s usually some down-time during a contest that is perfect for these contacts.TE – TransequatorialEs – Sporadic ETyler Griffiths - N7UWXScott Honaker- N7WLO
25 Soundcard Digital Communications JT44 – EME UseJT44’s ability to recover extremely weak signals makes it ideal for EMEMost activity by arranged schedule.144MHz is the most popular band.Also operation on 50 MHz, 432MHz, and 1296 MHz so far….A pair of single-yagi stations should be able to work each other, with QRO powerPortable EME operation can be a realityDXpedtions can afford to bring gearW5UN has been copied with a “Ringo-Ranger” vertical on 2m! A couple of people have copied him locally via EME for the first time in just the last couple weeks (December 2002). The stations had 13 element yagis in 2m with watts. One didn’t even have elevation control.Tyler Griffiths - N7UWXScott Honaker- N7WLO
26 Soundcard Digital Communications What Does It Take?Windows PCWindows 98 or higher recommendedPentium 150MHz or betterSoundBlaster compatible soundcardMost laptop sound systems workMore expensive cards have less noise and are more frequency stable/accurateInterface cablingRigBlaster or Rascal interfaces not necessarySome software has higher DSP requirements than others. These requirements will vary. Most packages will work with this.Interfacing can be simply the audio lines from the back of the radio into the soundcard with a simple RS-232 PTT switch. The Rascal interface adds isolation on the PTT and audio lines. The RigBlaster adds level conversions and mike switches to allow use of mike/speaker connections on radio.Tyler Griffiths - N7UWXScott Honaker- N7WLO
27 Soundcard Interfacing Soundcard Digital CommunicationsSoundcard InterfacingMost radios have audio in/out PTT on back via a Data or AUX portThese line level in/outs are bestMike/speaker levels can be used with appropriate attenuationPTT support generally via transistor or optoisolator switchPTT can be done with CAT port but requires radio-specific softwareI would recommend ALWAYS using AUX connections on the back of the radio, rather than speaker/mike if available. The audio is cleaner, no level/impedance conversion necessary, level adjustments are limited to the computer side because they never change on the radio.Virtually all packages expect PTT switch to be on the serial port. Some can use the computer control (CAT) port to tell the radio to transmit but this is software and radio specific. MixW can also do the CAT PTT switching for most radio Icom/Kenwood/Yaesu radios. The FT-817 Commander supports CAT switching for its PSK31 mode.Tyler Griffiths - N7UWXScott Honaker- N7WLO
28 Soundcard Digital Communications PTT SwitchingThis is the simplest and cheapest PTT switches available. With a little effort, it can be built into a DB-9 hood so no external box is required for an interface (unless audio isolation is desired/required).Tyler Griffiths - N7UWXScott Honaker- N7WLO
29 Soundcard Digital Communications Soundcard InterfaceThis is the Rascal interface. It has an optoisolator (4N33) for the PTT line and 1:1 audio transformers on both audio leads. It also has ferrite cores on the audio leads to eliminate RF feedback. This is one of the best designed interfaces available.Tyler Griffiths - N7UWXScott Honaker- N7WLO
30 Soundcard Digital Communications Soundcard InterfaceThis is the Rascal interface. It has an optoisolator (4N33) for the PTT line and 1:1 audio transformers on both audio leads. It also has ferrite cores on the audio leads to eliminate RF feedback. This is one of the best designed interfaces available.Tyler Griffiths - N7UWXScott Honaker- N7WLO
32 Soundcard Digital Communications Remote ControlRadio tuning, antenna rotation, transmission and reception are all computer controllableThis software is easily remote controlled via Terminal Server, Team Viewer or NetMeetingUsing Skype to talk on the radioAccess can be via LAN or InternetThere are shared radios on the InternetThe soundcard modes are ideally suited for remote control because the audio doesn’t need to be sent over the network – it’s all processed locally. There are currently radios on the Internet that allow radio tuning and reception via NetMeeting. Some even allow transmission via an application that handles PTT. This is all simply software, after this basic hardware is in place.Imagine sitting in the living room watching TV with the laptop and wireless network card. You have terminal services installed on the computer (running Windows 2000 or Windows XP) in the radio room and the Remote Desktop client on the laptop. You connect to the machine in the radio room via Remote Desktop, run HamScope and tune to look for some PSK31 activity. You make a few contacts and then tune to and look for some CW. You see a CW signal on the waterfall display, click on it and make a CW QSO. You can do all this while sitting in the chair watching TV Perhaps from your office at work or a friend’s house…Now see what a computer hooked to a radio can do? Unplug the mike and plug in the computer and no more noise about computers and the Internet killing ham radio!Tyler Griffiths - N7UWXScott Honaker- N7WLO
33 Soundcard Digital Communications ResourcesDigiPan:Fldigi:Ham Radio Deluxe:Winlink 2000:Signal link USB:West Mt. Radio:microHAMRascal:Rig ExpertAGW Packet Engine:KB3KAO Sound card TNC:Sound Card Packet:Web RadiosDigipan PSK softwareWest Mountain Radio carries the original RigBlaster interfaces atMFJ also carries RigBlaster style interfaces atTyler Griffiths - N7UWXScott Honaker- N7WLO