PSK 31 Without a PC Lyle Johnson KK

PSK 31 Without a PC Lyle Johnson – KK 7 P

PSK 31 Basics Narrow Band (~63 Hz wide) n Designed for Real-Time QSOs n No Error Correction n No “Binary” Mode n Typing Speeds n Weak Signal n n Requires Linear Transmitter Not Constant Envelope (CW, RTTY) n Use SSB Tx n Micro. HAMS Digital Conference 2008

PSK Modulation Accept Data from User n Encode to Varicode “Alphabet” n Most Common Characters are Shorter n Similar Principle to Morse Code n n Modulate onto RF Carrier Phase for Information n Amplitude to Limit Bandwidth at Phase Transition n n Why? Micro. HAMS Digital Conference 2008

PSK 31 Modulation Carrier Phase Reversal Indicates “ 0” n No Phase Reversal Indicates “ 1” n Phase Reversal of a Carrier Occupies a Lot of Bandwidth! n n (From Miller, The Shape of Bits to Come) Micro. HAMS Digital Conference 2008

PSK 31 Modulation n PSK 31 Carrier Has Envelope Modulation to Minimize Occupied Bandwidth Carrier Amplitude is Reduced to Zero at Instant of Reversal n Requires Linear Transmitter n (From AE 4 JY) n Micro. HAMS Digital Conference 2008

PSK Modulation Sending a ZERO Sending a ONE Micro. HAMS Digital Conference 2008

PSK Demodulation n Need to Lock onto Phase Information Align Bit Timing n Recover Clock n Recover Data n n Need to Lock onto Frequency n n “Zero beat” with Other Station Send Clocked Bitstream to Varicode Decoder n Decoded Characters to Display Micro. HAMS Digital Conference 2008

PSK Demodulation Point 1 n Point 2 n Micro. HAMS Digital Conference 2008

Early PSK 31 Work n G 3 PLX built on PSK work on the DSP 56001 n n SLOWPSK by SP 9 VRC First Implementations with DSP Eval Boards EVK 56001 n TI TMS 320 C 5 x n DOS User Interface Programs n Became Popular with Soundcard Freeware n n Micro. HAMS Digital Conference 2008 Requires Modern Computer

Traditional PSK 31 Operation Micro. HAMS Digital Conference 2008

Traditional PSK 31 Operation SSB Transceiver n Computer with Soundcard n n n In General, not a ‘ 386 SX Running DOS 3. 3 Computer / Radio Interface Isolated Audio n May Contain Soundcard Function n n Signa. Link USB n US Interface Navigator n Rig. Expert Standard and Plus Micro. HAMS Digital Conference 2008

Traditional PSK 31 Operation n OK for Home Stations Power n Physical Space n Lighting n n Difficult for Portable Operation Laptop Screen in Direct Sunlight n Lots of Cables and “Stuff” n Power? n No Room for Lunch on the Picnic Table… n Micro. HAMS Digital Conference 2008

Demo of Traditional PSK 31 n QRX… Micro. HAMS Digital Conference 2008

NUE-PSK 31 Modem Micro. HAMS Digital Conference 2008

NUE-PSK 31 Modem Details in March 2008 QST and QEX n Portable Operation n Low Power, Sunlight Readable Display Low Cost ~$200 Ready-to-Operate or ~$150 Kit n Open Source Hardware and Software for DIY n n Produced by Am. QRP n George Heron, N 2 APB and Milt Cram, W 8 NUE Micro. HAMS Digital Conference 2008

NUE-PSK 31 Modem Eliminate PC for Portable Operation n Straightforward User Interface n Low Power Enables Field Use n n n New Technology n n Internal Batteries ds. PIC = Microcontroller + DSP Cheap Tools n Free Counts as Cheap! Micro. HAMS Digital Conference 2008

NUE-PSK 31 Modem n Software Based on AE 4 JY PSK Core Ported from PC n Well Documented n Open Source n DSP Functions from Microchip Library n Modules from Austin QRP Project n Required Writing Graphics Driver n Micro. HAMS Digital Conference 2008

NUE-PSK 31 Modem Simple Hardware n Can Be Adopted to n RTTY n PSK 63 n Other Digital Modes n n Improvements? Isolate Radio AF n Isolate Radio PTT n Micro. HAMS Digital Conference 2008

NUE-PSK 31 Station n Prototype System Micro. HAMS Digital Conference 2008

Demo of NUE-PSK 31 n QRX… Micro. HAMS Digital Conference 2008

Elecraft K 3: PSK in a Box Complete Digital Station! n Just Add an Operator! n n OK, OK Antenna n 12 VDC Power, too! n Micro. HAMS Digital Conference 2008

Elecraft K 3: PSK in a Box During K 3 Development, Wayne and I Wanted a “Fun” Mode n My IC 746 PRO has an Internal RTTY Decoder n Fun, but Rx Only n More PSK Activity than RTTY n n Wanted PSK and RTTY Also Wanted Tx! n Minimalist, but Practical n Micro. HAMS Digital Conference 2008

Elecraft K 3: PSK in a Box n Good Performance Does Not Require Complex Algorithms or Structures n From G 3 PLX -> Micro. HAMS Digital Conference 2008

Elecraft K 3: PSK in a Box n Seven Character Alphanumeric VFOB Display Surprisingly Effective n Retain Context n n What About a Keyboard? Micro. HAMS Digital Conference 2008

Elecraft K 3: PSK in a Box n Seven Character Alphanumeric VFOB Display Surprisingly Effective n Retain Context n n What About a Keyboard? Don’t Need No Stinkin’ Keyboard! n We Are, After All, Hams! n n Universal Input Device -> Micro. HAMS Digital Conference 2008

Elecraft K 3: PSK in a Box n Suitable for Casual Digital Operation In the Field n CW, RTTY, PSK 31 Now n PSK 63, Others Real Soon Now! n Just Plain Fun! n n Several Reports of “Never Operated Digital Modes Before, But Had to Try It!” Micro. HAMS Digital Conference 2008

Demo of K 3 PSK 31 n QRX… Micro. HAMS Digital Conference 2008

PSK 31 Without a PC PSK and Other Digital Modes Can Be Operated Without a PC n Dedicated, Purpose-Built Hardware n n n NUE-PSK Modem Radios with Built-In Digital Modems n Elecraft K 3 Micro. HAMS Digital Conference 2008

References n PSK 31 http: //aintel. bi. ehu. es/psk 31. html n http: //www. psk 31. com/ n n NUE-PSK Modem n n http: //www. nue-psk. com/ K 3 n http: //www. elecraft. com/news. htm Micro. HAMS Digital Conference 2008

PSK 31 Without a PC THANK YOU! Questions? Micro. HAMS Digital Conference 2008

Micro. HAMS Digital Conference 2008