JT65 software which DOESN'T lie?

Discussion in 'Working Different Modes' started by VE3GZB, Jan 4, 2016.

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  1. VE3GZB

    VE3GZB Ham Member QRZ Page

    I've been toying around now for a month or two with FLDIGI, connected to the FTdx3000 via a USB cable and I've had some success with it with RTTY, PSK31 and Olivia 16-500. I like the Olivia format very well, it's amazing how it can get a signal buried in the QRM!

    I've been hearing other signals, slow moving multifrequency tones which I've finally been able to identify as JT65. FLDIGI doesn't understand those signals.

    I downloaded two pieces of software so far in hopes to try to decode and even QSO with someone in JT65 mode. WSJT v10 and JT65-HF.

    Neither one works properly.

    The WSJT v10 software gives every good imitation of seeming to function. The waterfall display moves and it appears to be "monitoring", yet even when I hear clear signals through the speaker there is no text content being decoded. The contents of the waterfall display coincides with activity discerned in the loudspeaker. Yet no text is displayed.

    JT65-HF doesn't even know there is a radio connected to my computer (Winblows 7 on Lenovo Thinkcentre M-series).

    Rebooting after installing makes no difference with either software, they still fail to do what they claim to do.

    So is there any written-for-hams free software which does what it claims to do for JT65 decoding/encoding and will talk to a USB-equipped Yaesu rig and does not lie when you go to use it?

    73s VE3GZB
  2. N8MSA

    N8MSA Ham Member QRZ Page

    WSJT-X, currently at version 1.6.


    This is used successfully by thousands in the JT-mode community, and is by far the best option of the few applications available.

    There is also a WSJT-X mailing list that is monitored by the developers:


    And please feel free to reach out to me at the email address in my QRZ profile if you need any assistance.
    K2NCC likes this.
  3. KV6O

    KV6O Ham Member QRZ Page


    It sounds like you don't have the software configured properly, have you read the instructions? You need your PC's clock synchronized within about a second of so, neither program will work if your clock is off more than a few seconds. It's that critical.

    If you're looking for a "QSO", you might be disappointed with JT-65/JT-9 - they are pretty minimalistic. I enjoy them. :D

  4. N8MSA

    N8MSA Ham Member QRZ Page

    You bring up a couple of great points, and it's helpful that the WSJT-X documentation is amongst the best in the hobby:

  5. K3XR

    K3XR Ham Member QRZ Page

    It's been mentioned before but bears repeating clock sync a must for a mode like JT-65 had a similar problem when first trying the software. Will likely see it come up in the future as newcomers give it a try.
  6. VE3GZB

    VE3GZB Ham Member QRZ Page

    I don't know what correct configuration should accompany the software, this you would hope be accomplished by the installer process which should seek the computing environment and probe the USB ports to determine which radio if any are attached to the computer.

    FLDIGI doesn't do this but there exists Rig description files in Excel format which FLDIGI can refer to.
  7. VE3GZB

    VE3GZB Ham Member QRZ Page

  8. KV6O

    KV6O Ham Member QRZ Page


    Second paragraph:

  9. VE3GZB

    VE3GZB Ham Member QRZ Page

    As I type this I'm having a QSO with someone on Olivia. Olivia requires no such exacting time base. Why should JT65 require this when Olivia does not?
  10. WJ4U

    WJ4U Subscriber QRZ Page

    Short answer: because it does.

    Long answer, from the link above:
    JT65 requires tight synchronization of time and frequency between transmitting and receiving stations. Each transmission is divided into 126 contiguous time intervals or symbols, each of length 4096/11025 = 0.372 seconds. Within each interval the waveform is a constant-amplitude sinusoid at one of 65 pre-defined frequencies. Frequency steps between intervals are accomplished in a phase-continuous manner. Half of the channel symbols are devoted to a pseudo-random synchronizing vector interleaved with the encoded information symbols. The sync vector allows calibration of time and frequency offsets between transmitter and receiver. A transmission nominally begins at t = 1 s after the start of a UTC minute and finishes at t = 47.8 seconds.
    KI5WW likes this.

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