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JT9

Discussion in 'Working Different Modes' started by WH2HAO, Apr 27, 2013.

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  1. WH2HAO

    WH2HAO QRZ Moderator QRZ Page

    Hello,

    Does anyone have experience using JT9, the new digital mode. Just curious if it will become a popular mode worth using.
     
  2. K5RCD

    K5RCD XML Subscriber QRZ Page

    It's a great mode. Very similar to JT65 HF only more robust in the noise of the lower bands and much narrower bandwidth.

    JT9 has really taken off in popularity the past week or so since Laurie, VK3AMA released WSJTX Alert (JTX ALERT). It functions just like JT65 Alert and both can be downloaded at the same time from http://ham-apps.com/.

    Right now the most popular frequencies are 14.078 and 21.078 and 10.130 (or thereabouts). The JT9 GUI has the most popular frequencies already configured, so you only need to click on the band and it will change your radio frequency for you if you have your rig set up for CAT control.

    Download JT9 at http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html Scroll down to WSJTX and download the latest version.

    You're going to like it. I predict it will surpass JT65 HF in popularity quite soon, and maybe make it obsolete.

    Have fun !
     
  3. W8MRL

    W8MRL Premium Subscriber QRZ Page

    I love it. The only downside I've run into is when someone is running to much power but that isn't the program's fault as much as the someone that hasn't realized that 5 watts is about all you need. I've JT9 contacts with Ham's who are running 1 watt or less. I am going to build or I may just buy an attenuator so I can drop my power output below 5 watts

    There isn't much reason to continue to use JT-65 other than there are still many more users running JT-65 so there can be slim pickings sometimes when running JT9.

    For those interested in digital modes definately follow the link above, in Randy's post, an d/l the program.

    Rob
    W8MRL
     
  4. WH2HAO

    WH2HAO QRZ Moderator QRZ Page

    Rob, why do you say JT65 may be obsolete, I mean what specifically makes JT9 better exactly. I’m still reading up on it.

    Thanks.

    David.
     
  5. W8MRL

    W8MRL Premium Subscriber QRZ Page

    Well, I didn't say JT-65 was obsolete. It's still a popular mode.

    JT9 works very well in noisy conditions and weak signal decoding. According to the author it's about 2 dB more sensitive and uses less than 10% of the bandwidth of JT-65.

    Rob
    W8MRL
     
  6. W6UV

    W6UV Premium Subscriber QRZ Page

    Here we go again with another power argument. If JT9 is so efficient, then why are you running 5 whole watts? Shouldn't a few microwatts be enough for anyone?
     
  7. K2NCC

    K2NCC XML Subscriber QRZ Page

    It often is. I've never worked as much QRP before using the likes of JT65, JT9 and WSPR.

    Most rigs I've known natively only go down to 5 or maybe 1W.

    But 5W is hardly "all you need".
     
  8. W8MRL

    W8MRL Premium Subscriber QRZ Page

    As I said in my original post, I'm looking at an attenuator to cut my output further.

    What do you mean by "another power argument"? I only commented because I dislike an overloaded waterfall caused by someone either very close or running more than minimal power. Maybe you enjoy an overloaded waterfall, but it's not my preference. Why are you being such a curmugeon? Has this been a bad day?
     
  9. K3DCW

    K3DCW XML Subscriber QRZ Page

    Why blame power for your "overloaded waterfall" when the most common culprit is poor AGC and/or RF Input setting management? Why blame the other operator if you are unwilling to tweak the rig for the optimum balance of settings?

    Power is a relatively minor player in JT9 (and JT65) propagation. The difference between 5 and 100 watts is only 13dBm, or about 2 S-units. Propagation path variables can result in an impact that exceeds 20dBm, or in other words equivalent to the difference between 10 and 1000 watts. JT9 (and JT65) is NOT a QRP mode, it is a weak-signal mode...there is a difference.

    All of that being said, oftentimes you 5 watts (or much less) is indeed all you need. However, at least when using JT65, there have been times where 100 watts was what was NEEDED to complete the QSO over the path I attempted. That doesn't make me a bad operator as long as my signal is kept clean.


    73

    Dave
    K3DCW
     
  10. K2NCC

    K2NCC XML Subscriber QRZ Page

    So true. I could use 1W to get a -02 report from a station 8000 miles away and get a -22 report with 100W 800 miles away. Or vice versa.
     
  11. W8MRL

    W8MRL Premium Subscriber QRZ Page

    No one has called anyone a "bad operator". I listed a pro and a con, based on my opinion only, in an attempt to reply to the thread originators post.
    You must really be having a bad day. Please try to relax - it's a just a simple reply to a simple forum question. Wow.
     
  12. K5RCD

    K5RCD XML Subscriber QRZ Page

    The way to control QRP power output is by sound card adjustment. I run my rig at the normal 75 to 80 watts so the ALC will function properly, and reduce power with the PC soundcard. With careful adjustment one can get down into the 250 milliwatt range, assuming the power meter is accurate enough and designed for measuring in the QRP range. Sound card adjustment is also part of setting up the receive function to keep the waterfall at a useable level when in the presence of a strong signal.
     
  13. W6UV

    W6UV Premium Subscriber QRZ Page

    An "overloaded waterfall" is caused by your receiver's AGC reaction to a strong signal in the IF passband. As long as people insist on using filters wide enough to drive a truck through for narrow bandwidth modes such as JT9 and PSK31, this will be an issue.

    Let me ask you this: what filter are you using when running JT9? I'll bet it's either a 2.4 kHz or 3 kHz filter, right? That's roughly equivalent to using a 300 kHz filter on 20 meters when operating SSB. Would you expect good results on 20m SSB using a filter that's about as wide as the entire band? No? Why not? That's what people are expecting to do in narrow bandwidth digital modes like PSK31 and JT9.

    Let me ask you another question: how do you know that +10 JT9 signal that's overloading your waterfall is the result of someone running high power? It could very well be a 5 watt signal over an ideal propagation path. The -24 signal right next to it might very well be a 500 watt signal coming over a poor path. How can you tell? You can't.
     
  14. K2NCC

    K2NCC XML Subscriber QRZ Page

    I wonder how you would. Is there some meter I can stand outside someone's house and measure PEP or such?
     
  15. N9DSJ

    N9DSJ Subscriber QRZ Page

    A calibrated field strength meter? Might need to work out the volts per meter thing and take into consideration if the antenna is a ground mounted vertical or stacked mono-banders at 150 feet :)

    I think the much over-hashed argument is "weak signal" versus "low power". I run low power to a fairly large antenna...I am sure someone in a lobe of the antenna will get more signal from me than when I run higher power from my reference dipole. But if propagation is horrid my signal will be low on both; if propagation is good, I might have a strong enough signal in either scenario to distress someone compelled to watch on a waterfall display the equivalent to an entire SSB bandwidth. This is the case for many digital modes also..a long standing area of, errr... discussion.

    Seems endemic to waterfall watchers; seldom hear CW ops, even QRP'ers, say others need to drop their power levels to some oddly decided "standard" based on who knows what. Basically even if your waterfall is "blanked", if you ride the rf gain, kill AGC, narrow your rx filter and let the JT9/JT65 programs DSP do its thing you can decode a lot. You do not need to see it well or hear it well to decode the given transmission. I have often had the waterfall display totally blacked out with no impact on decoding.

    73,

    Bill N9DSJ
     
  16. KB2HSH

    KB2HSH Ham Member QRZ Page

    During this weekend that just passed, I had the chance to try out JT9, and so far I like what I see. However, I noticed that there is (what appears to be) an issue with the software. When WSJT-X is running, if I click on ANYTHING within the program's interface, the next time it goes to transmit out, there is no audio. This causes me to have to kill the program and restart it. Is anyone else having this problem??

    John KB2HSH
    Elma, NY
     
  17. N2ADV

    N2ADV Premium Subscriber QRZ Page

    Not that problem but I can't get the software to even key my K3 :(
     
  18. VE3FMC

    VE3FMC XML Subscriber QRZ Page

    I'd love to try this mode but I can not get the software to load on my system. When started the program comes up and then closes. I get a Runtime Error that states "This application has requested the Runtime to terminate it in an unusual way."

    I have tried uninstalling and reinstalling the software and still have no luck. I guess it doesn't like my XP setup.
     
  19. KB2HSH

    KB2HSH Ham Member QRZ Page

    Not trying to be sarcastic...what are your system specs? RAM and CPU?
     
  20. K5RCD

    K5RCD XML Subscriber QRZ Page

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