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Working the World with WSJT-X (JT-65 & JT-9). What are the WSJT modes of JT65 & JT9. Both are digital modes optimized for extremely weak signal communications. JT65 uses a series of 64 tones for data plus a sync tone. JT9 uses a series of 8 tones for data plus a sync tone (modulation 9-FSK)
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What are the WSJT modes of JT65 & JT9 • Both are digital modes optimized for extremely weak signal communications. • JT65 uses a series of 64 tones for data plus a sync tone. • JT9 uses a series of 8 tones for data plus a sync tone (modulation 9-FSK) • Hardware requirements are a computer, computer to radio interface, and a SSB transceiver that will operate on your frequency of choice. Note: If you are set up to run the digital modes like FLDIGI & MMSSTV, you most likely have everything that you need.
Weak Signal by Joe Taylor (WSJT) In July, I had the privilege of meeting Joe at the Symposium of Amateur Radio Astronomers held at the National Radio Astronomy Observatory in Green Bank, West Virginia. Joe Taylor discovered the first Pulsar in a binary star system. He has used this to make high-precision tests of general relativity and in 1993, received a Nobel Prize in Physics for this discovery Joe Taylor, K1JT created the set of weak signal protocols used in the WSJT system for EME. This has enabled stations using a single Yagi & 50 watts to work larger stations off the moon. He then created the WSPR application used by thousands of amateurs world wide as a realtime propagation indicator on HF. His most recent accomplishment is WSJT-X, a system that enables stations running low power and compromise antennas to make world wide contacts. All of this is FREE!
Quotes from forums on the Web We've all heard the old saying, oft repeated in these review pages (usually about antennas), "if you can’t hear …them you can’t work them". Well...welcome to the new world of WSJT, I can't hear them but I work them anyway. WB0FDJ Joe is adding 3dB of gain every month. SP9TTG WSJT, and the modes contained therein (JT65/WSPR/JT2/JT4/PSK441), are with little doubt, the most cutting edge weak signal modes afforded to us as Amateurs. JT65 makes it possible to work DX that I never thought was possible with a compromise antenna and a QRP-only rig (FT-817ND) as my main/only radio. KB2HSH Although Joe provides the software free of charge, it does not come without cost. His program is so addictive that you will find yourself spending hours in the shack exploring the fascinating world of weak signals. WB4ECR JT65, and JT9 that followed, enabled me to make WAS in a month on the air, and DXCC within a couple of months, all while running 5 watts QRP to a horrible end-fed antenna stapled to trees. WB4SON
What is the attraction of the Weak Signal Modes such as JT-65, JT-9 and others? • Large antennas are NOT required (a short whip on back of rig works) • High power is not needed ( 2 to 5 watts will make lots of contacts) • Narrow bandwidth (JT-65 is 200 Hz, JT-9 < 30 Hz) • So just how does JT-65 & JT-9 stack up against the other modes … *** Levels required to obtain an intelligible output
Where does JT65 & JT9 take place? Static crash Noise RTTY Scanner Wall Wart Ionospheric Pinger HDGC SSB voice WSJT CW PSK31
Why is JT65 so efficient at delving deep intothe noise floor? • 65 tone Frequency Shift Keying- Much more efficient then on/off keying as in CW • Narrow bandwidth- 200 Hz for JT65 <30 Hz for JT9 • JT65 message much more compact then a CW message In CW – “W3SMF WA3USG FN10” takes 170 bits (bit=key down dot interval) In JT65- 71 bits • Data is sent with an redundancy ratio of 5.25 to 1 and is repeated throughout the message using a mathematical algorithm developed based on probability (Reed Solomon Codes). • A sync pulse starts each transmit cycle as a definitive reference. • Data tones are on line long enough for the receiving computer to perform quasi long term integration in order to detect them below the noise floor. • Transmit and receive cycle are both automatic and dependent upon computers at each end being in sync within 2 seconds of each other.
WSJT Modes – Structure of a QSO Both JT65 & JT9 consist of the minimum information needed to complete a valid QSO The typical QSO takes about 6 minutes Consists of a minimum of 6 T/R exchanges, each taking 1 (one) minute. This is broken down into 50 seconds to send the data and 10 seconds for the other station to decide on how he or she is going to respond. 1. Station 1 Calling CQ along with a location (eg: CQ WA3USG FN10 2. Station 2 answering along with a location (eg: WA3USG W3SMF FM19) 3. Station 1 responding with a signal report (eg: W3SMF WA3USG -07 4. Station 2 responding with a signal report (eg: WA3USG W3SMF -04) 5. Station 1 acknowledging reception of signal report (eg: W3SMF WA3USG RRR) 6. Station 2 acknowledging receipt & closing down QSO with a 73 • (eg: W3SMF WA3USG 73)
In Summary • Both Modes of WSJT (JT65 & JT9) are FUN! • Performance is amazing. • JT9 is a lot narrower then JT65 and goes a bit deeper into the noise … use it! You can fit a lot more QSO’s into the 3 KHz allocated space! • Receive & Transmit stability is required. • There seems to always be activity on the WSJT recommended frequencies (even when the band is “dead”). • It takes a bit of time & effort to set the software up and master it but anyone here can do it. The effort is part of the challenge and adds to the satisfaction of working great DX with just a few watts!
