PSK31PSK31

andand otherother soundsound cardcard digitaldigital radioradio modesmodes

Alan J. Masson, GM3PSP / K6PSP Lothians Radio Society, 24 March 2010 SummarySummary

 PSK31PSK31 descriptiondescription  OtherOther digitaldigital soundsound --cardcard modesmodes  SoundSound clipsclips PSK31PSK31

 InventedInvented inin 19981998 byby PeterPeter Martinez,Martinez, G3PLXG3PLX (also(also responsibleresponsible forfor introductionintroduction ofof AmTorAmTor ))  RSGB RadCom December 1998.  “A New Radio -Teletype Mode - Improving on RTTY ”  WithoutWithout disadvantagesdisadvantages ofof somesome digitaldigital modes:modes:  Avoids need for error correction / latency, which he believes make some modes unsuitable for live QSOs  No need to send faster than can be typed by hand  High frequency stability of modern transceivers allows use of much narrower bandwidth  Powerful modern digital processors allow better coding  PSK31PSK31 isis nownow thethe mostmost popularpopular digitaldigital modemode PSK31PSK31 TechnicalTechnical SummarySummary

 Symbol rate 31.25 baud (~ 50 wpm) - considered a reasonable typing speed - easily derived from common 8kHz sample rate used in many DSP systems  Bandwidth 62.5 Hz  Differential 2 -PSK (BPSK) Binary Phase -Shift Keying  Average power 80%  Protocol Asynchronous unconnected chat mode (!)  Character set Varicode , ASCII user interface PSK31PSK31 UsesUses VaricodeVaricode CodingCoding VaricodeVaricode –– examplesexamples  a 1011  A 1111101  b 1011111  B 11101011  c 10111  C 10101101  d 101101  D 10110101  e 11  E 1110111  i 1101  Space: 1  o 111  t 101  CODE DEFINITIONS:  0 = PSK phase reversal  0 10110111  1 = No phase change  1 10111101  Every character starts and ends  2 11101101 with a 1  3 11111111  Shorter codes for most common characters, like Morse Code  4 101110111  At least two 0s are inserted  5 101011011 5 101011011 between characters ( “letter gap ”)  No character contains two 0s  Complete 128 -character ASCII set with 10 bits PSK31PSK31 WaveformWaveform

Raised Cosine waveform - smoothly changes from 0 to 1 like a cosine wave, avoiding square-wave switching-noise on phase- change being transmitted. This provides minimum bandwidth properties The amplitude changes are used to synchronize the receiver clock PSK31PSK31 ModulatorModulator

(DSBSC) PSK31PSK31 DemodulatorDemodulator InterfacingInterfacing TransceiverTransceiver && ComputerComputer

 FixedFixed --levellevel audioaudio outputoutput fromfrom transceivertransceiver toto soundsound cardcard LineLine inputinput  SoundSound cardcard LineLine outputoutput viavia levellevel --adjustadjust potpot toto microphonemicrophone input.input.  SerialSerial portport viavia optoopto --isolatorisolator toto micmic PTTPTT  (Use(Use ofof VOXVOX tendstends toto bebe unreliable)unreliable)  VariousVarious interfaceinterface boxesboxes areare availableavailable toto organizeorganize thesethese interinter --connectionsconnections DIGIPANDIGIPAN IsolatingIsolating InterfaceInterface forfor PSK31PSK31 InterfacingInterfacing TransceiverTransceiver && ComputerComputer forfor PSK31PSK31 andand manymany otherother digitaldigital modesmodes

SoftwareSoftware PackagePackage

Fixed-level Rx audio out

MIC in Sound Card Audio out

Level Adjust Interface Box

Opto-Isolator

PTT in COM1 Port out ““PSKPSK ThisThis WeekendWeekend ””

 QST Article, Jan 2010  Steve Ford WB8IMY  Receive -only  Audio input to computer via desk microphone

 Free Digipan software PSK31PSK31 SignalSignal onon WaterfallWaterfall DisplayDisplay SpectrumSpectrum ofof PSK31PSK31 SignalSignal ComparisonComparison ofof PSK31PSK31 andand FSKFSK OverOver --DrivenDriven PSK31PSK31 SignalSignal

Unwanted Clean A GROSSLY over-driven signal can Sidebands Signal have multiple unwanted sidebands BPSKBPSK SignalSignal LevelLevel ControlControl

• Audio signal level must be adjusted to operate in a completely linear manner • Overload of MIC pre-amp is most likely cause of non-linearity • This cannot be corrected using MIC Gain control • Transmitted signal should have IMD < -25 dB • IMD can be measured (Rx) in Digipan or using PSKMeter accessory in Tx mode FrequenciesFrequencies forfor PSK31PSK31

18381838 35803580 70357035 -- RegionsRegions 11 andand 33 70707070 -- RegionRegion 22 1013910139 1407014070 1810018100 2107021070 2492024920 2812028120 TheThe activityactivity ofof multiplemultiple stationsstations occupiesoccupies thethe bandwidthbandwidth ofof aa singlesingle SSBSSB channelchannel withwith thethe aboveabove carriercarrier frequenciesfrequencies RelatedRelated BPSKBPSK ModesModes

 PSK31PSK31 GeneralGeneral useuse (most(most common)common)  QPSK31QPSK31 LowLow --signalsignal // errorerror correctioncorrection  PSK63PSK63 HigherHigher --speedspeed  PSK125FPSK125F HigherHigher speedspeed  PSK250FPSK250F HigherHigher speedspeed  FSK31FSK31 SimilarSimilar toto PSK31PSK31 PSK31PSK31 SoftwareSoftware

 Digipan V.2 PSK31, QPSK31, PSK63, FSK31, Pactor Rx - including Multichannel receive screen  MixW PSK31, PSK63, QPSK, FSK31, RTTY, Packet, (Reg. fee) Pactor RX, AMTOR RX & FEC TX, MFSK/Graphics Color/BW, Olivia, Contestia , RTTY, Throb, MT63, Hell, FAX, SSTV  Stream PSK31, PSK63, PSK125, PSK250, MFSK16/8  Hamscope PSK31, QPSK31, CW, RTTY, MFSK16, Packet  PocketDigi PSK31, CW, RTTY – for programmable PDAs  MMVARI PSK31, RTTY, MFSK16, FSK31 - linked to N1MM contest logging software PSK31PSK31 DemoDemo -- RxRx

 KenwoodKenwood TSTS --850850 inin USBUSB modemode  FixedFixed --levellevel audioaudio intointo soundsound cardcard  DigipanDigipan Ver.2Ver.2 -- multimodemultimode  14.07014.070 MHzMHz OtherOther DigitalDigital SoundSound --CardCard ModesModes -- thatthat II havehave usedused  RTTYRTTY  MFSK16MFSK16  MT63MT63  HellschreiberHellschreiber  ThrobThrob  AnalogAnalog SSTVSSTV -- ScottieScottie 11  DigitalDigital SSTVSSTV –– DIGTRXDIGTRX  AllAll thesethese modesmodes useuse samesame basicbasic hardwarehardware ++ freefree softwaresoftware  Frequencies:Frequencies: 1010 kHzkHz aboveabove PSK31PSK31 (not(not SSTV)SSTV) PSK31PSK31 andand PSK63PSK63

 PSK31PSK31 demodemo (35(35 sec):sec):

 QPSK16QPSK16 demodemo (17(17 sec):sec):

 PSK63PSK63 demodemo (35(35 sec):sec): RTTYRTTY

 SoundSound --cardcard modesmodes useuse AFSKAFSK  Software:Software: MMTTY,MMTTY, MMVARI,MMVARI, MixWMixW etcetc  AudioAudio DemoDemo (25(25 sec):sec): MFSK16MFSK16  InventedInvented byby MurrayMurray GreenmanGreenman ,, ZL1BPUZL1BPU (1999)(1999)  DevelopedDeveloped forfor WindowsWindows -- NinoNino PorcinoPorcino IZ8BLYIZ8BLY  1616 tonestones spacedspaced atat 15.62515.625 Hz;Hz; 44 char/secchar/sec  FullFull --timetime ErrorError CorrectionCorrection (FEC)(FEC)  DesignedDesigned forfor longlong --haulhaul DxDx conversationsconversations  Software:Software: IZ8BLYIZ8BLY --Stream,Stream, HamscopeHamscope ;; MixWMixW  MFSK16MFSK16 demodemo (32(32 sec):sec):  MFSK8MFSK8 demodemo (55(55 sec):sec):  FSK441FSK441 (by(by K1JT)K1JT) forfor meteormeteor --scatterscatter 44 tonestones atat 147147 cps;cps; 14701470 wpm;wpm; b/wb/w 22052205 HzHz MT63MT63  DevelopedDeveloped byby PawelPawel JalochaJalocha ,, SP9VRC,SP9VRC, 19981998  6464 tonestones spacedspaced atat 15.62515.625 Hz;Hz; 1010 char/secchar/sec  PowerfulPowerful FECFEC  DesignedDesigned asas aa chatchat mode,mode, esp.esp. multimulti --stationstation  SoundsSounds likelike broadbroad --bandband noisenoise  Software:Software: IZ8BLYIZ8BLY --MT63,MT63, MixWMixW  SuperimposedSuperimposed CWCW ID:ID:  MT63MT63 500500 HzHz demodemo (40(40 sec):sec):  MT63MT63 10001000 HzHz demodemo (22(22 sec):sec):  MT63MT63 20002000 HzHz demodemo (12(12 sec):sec): HellschreiberHellschreiber  DerivedDerived fromfrom mechanicalmechanical systemsystem (Dr(Dr RudolfRudolf Hell,Hell, Germany,Germany, 1927)1927)  DSPDSP systemsystem developeddeveloped byby G3PLXG3PLX inin 19971997  ColumnsColumns ofof 1414 dotsdots // 55 columnscolumns perper charactercharacter  2.52.5 characterscharacters // secsec (25(25 wpm)wpm)  OnOn // OffOff keyingkeying ofof transmitter;transmitter; bandwidthbandwidth 350350 HzHz  Software:Software: IZ8BLYIZ8BLY --Hell,Hell, MixWMixW  FeldFeld HellHell demodemo (35(35 sec):sec):  FMFM HellHell 105105 baudbaud demodemo (35(35 sec):sec): THROBTHROB

 InventedInvented byby LionelLionel Sear,Sear, G3PPTG3PPT inin 20002000  MFSKMFSK system;system; 99 tonestones  1,1, 22 oror 44 tonestones // secsec  BandwidthBandwidth 100100 oror 200200 HzHz  Software:Software: Throb,Throb, MixWMixW  11 ThrobThrob // secsec demodemo (60(60 sec):sec):  22 ThrobThrob // secsec demodemo (35(35 sec):sec):  44 ThrobThrob // secsec demodemo (19(19 sec):sec): SSTVSSTV

 AnalogAnalog SSTVSSTV –– ScottieScottie --11 demodemo (30(30 sec):sec):  DigitalDigital SSTVSSTV –– DIGTRXDIGTRX demodemo (30(30 sec):sec): FurtherFurther ReadingReading

 RTTY/PSK31 for Radio Amateurs  By Roger Cook G3LDI  RSGB  Includes free CD of amateur programs FurtherFurther ReadingReading

 Digital Modes for All Occasions  By Murray Greenman , ZL1BPU  RSGB, 2002 PSK31PSK31 DXCCDXCC butbut itit sayssays ““RTTYRTTY ”” !!

PSK31PSK31

andand otherother soundsound cardcard digitaldigital radioradio modesmodes ANYANY QUESTIONS?QUESTIONS?

Alan J. Masson, GM3PSP / K6PSP Lothians Radio Society, 24 March 2010