WSJT Meteors, Moonbounce, and More … FSK441 Joe Taylor, K1JT Mid-Atlantic States VHF Conference September 24, 2005

How to push the DX Limits on VHF/UHF bands Wait for a band opening Get a bigger amplifier Bigger antenna, better feedline, low-noise preamp, … – or – Use efficient coding and modulation

WSJT: What is it? A computer program Provides modulation and encoding/decoding, as in PSK31 Offers several modes FSK441 for meteor scatter JT6M for ionoscatter on 6m JT65 for EME CW for EME

Requirements for optimizing minimal QSOs Meteor scatter Speed > 100 cps Good copy at 0 dB S/N in SSB BW EME Speed ≈ 0.3 cps Good copy at –20 to –30 dB S/N

Design of FSK441 Four-tone FSK: 882, 1323, 1764, 2205 Hz Three tones or “symbols” per character Keying rate 441 baud Transmission rate 147 cps Detection bandwidth 4 × 441 Hz Short messages sent repeatedly 30s T/R sequences

Design of JT6M 44-tone FSK Sync tone every 3rd symbol Keying rate 21.5 baud Detection bandwidth 44 × 21.5 Hz Short messages sent repeatedly Message averaging 30 s T/R sequences

Design of JT65 Structured messages Sync tone plus 64 data tones Keying rate 2.7 baud Detection BW 66 × 2.7/5.4/10.8 Hz Powerful Error-Correcting Code Short messages: RO, RRR, 73 T/R sequences 60 s

FEC in JT65 Seems like magic ? Mathematically rigorous … RS(63,12) code, 6-bit symbols Corrects 25 (or even more) symbol errors “Deep search” does 4 dB better Soft-decision decoder by Koetter and Vardy (US patent #6,634,007)

Compressed and Encoded JT65 Messages Message Compressed to 72 bits (12 six-bit symbols) ---------------------------------------------------------------------- 1. G3LTF DL9KR JO40 61 37 30 28 9 27 61 58 26 3 49 16 2. G3LTE DL9KR JO40 61 37 30 28 5 27 61 58 26 3 49 16 3. G3LTF DL9KR JO41 61 37 30 28 9 27 61 58 26 3 49 17 First 21 (of 63) encoded channel symbols, including FEC: 1. 14 16 9 18 4 60 41 18 22 63 43 5 30 13 15 9 25 35 50 21 0 ... 2. 20 34 19 5 36 6 30 15 22 20 3 62 57 59 19 56 17 35 2 9 41 ... 3. 47 27 46 50 58 26 38 24 22 3 14 54 10 58 36 23 63 35 41 56 53 ...

Does it work ? Several thousand users, worldwide You can work “anyone” at 500 to 1300 miles on 6 or 2m, any time K1JT on 2m (4 x 9 el, 700 W): WAC ─ EME initials 109 DXCC 39 ─ Grids 268 WAS 42

Measured sensitivity of JT65

Measured “sync and shorthand” sensitivity

What equipment do I need? Windows computer with sound card Minimum: 400 MHz Pentium II, 64 MB RAM (you’ll be happier with more) WSJT software: free download Simple interface, serial port to PTT Audio connections, sound card to radio

Installing WSJT Free download from WSJT home page: http://pulsar.princeton.edu/~joe/K1JT Self-extracting EXE file — “click-click!” Includes a detailed manual in PDF format full description of each mode screen pictures operational hints index of controls technical appendices

VK7MO EME DXpedition Destinations: Cocos-Keeling Island (VK9C) and Christmas Island (VK9X) Bands: 144, 432 MHz Antennas: single yagi on each band Power: 300 W on 2m, 65 W on 70 cm Mode: JT65B

VK7MO DXpedition Scorecard EME QSOs on 2m: 156 EME QSOs on 70 cm: 6+ Nearly all QSOs random: no internet

… to the demos …

WSJT in FSK441 mode

Does it work? -- 231 grids on 2m

ZS5LEE works K1JT on 2m

ZS5LEE works K1JT on 2m

K1JT works RN6BN on 2m