How the #@*& does RTTY work??

Discussion in 'Working Different Modes' started by KK4JW, Jul 8, 2020.

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  1. KK4JW

    KK4JW Ham Member QRZ Page

    I'm sorry, I probably shouldn't post something like this - but I've wondered for quite some time.

    How does RTTY work??!

    I've tried messing with different RTTY programs, HRD DM780, MMTTY, etc., and while I can get the software set up and decoding (poorly), transmitting seems to be a hurdle.

    Is there some kind of frequency shift/offset for RTTY that I don't know about? I tried RTTY transmitting a few months ago, and the ONLY response I managed to decode from someone was "You don't know what you're doing, so stop!" message. Literally. Really. I've never tried RTTY again, and have went back to PSK31 and FT8.

    So can someone please break it down barney-style for me, and explain RTTY to me as if I'm 5 years old? I'd really like to play with it and try it out, but I just want to do it correctly and avoid further shame messages..
     
  2. KK5JY

    KK5JY Ham Member QRZ Page

    W4KYR, KS2G and KB0MNM like this.
  3. W7UUU

    W7UUU Principal Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Two very important questions before anyone can provide "the right answer"

    1. Are you planning on using AFSK (Audio Frequency Shift Keying) via the microphone input (or some rear panel input) and using SSB transmission?

    2. Or are you planning on using FSK (direct Frequency Shift Keying) which does NOT use audio but rather keys the offset "tones" directly much like CW? (Many modern radios do FSK - IC-7300 is a good example)

    How you approach setting everything else up hinges directly to how you answer that question.

    What is the brand and model of radio? Let's start with that....

    Dave
    W7UUU
     
    AB6RF and KB0MNM like this.
  4. KK4JW

    KK4JW Ham Member QRZ Page

    I have an Icom 7300, using the USB cable like everyone else. So I guess that would be FSK?

    Like I said, I can decode fairly well. When I was using the MMTTY software, I was able to get the little ellipse phase indicators or whatever to cross in the middle and see some decoded text. When transmitting though, I had RF output and a signal being transmitted, but that's where my knowledge ended.

    I keep trying to compare it to PSK31, which I am familiar with. Just click on the waterfall and go. Maybe that's part of the problem. I'm expecting something it isn't.
     
  5. PY2RAF

    PY2RAF XML Subscriber QRZ Page

  6. KB0MNM

    KB0MNM Ham Member QRZ Page

    KK5JY in post #2 did not specifically mention the second half of page 8, for USB users. That additional software and bit about "may allow" may be what is going to be the difference. Back in the days when PCs had no USB ports, de-9 ( RS-232) signalling was used in many interfaces to pass along transmit, receive, and push-to-talk through an associated control wire ( usually associated with DTR / DSR signalling ). With USB, we now have different signal levels and less discrete wiring for the signals. So now the USB interface in the radio ( Icom 7300 in this case ) has an input/output USB port which expects the correct signalling for push-to-talk to conform to what the computer program is sending. That add-on software "may or may not" handle what the new radio expects to see. Maybe there is another amateur radio operator who has the same radio and has the same program who is watching this thread. If so, a few menu options may be all that is needed.
     
  7. KB0MNM

    KB0MNM Ham Member QRZ Page

    In a more radio-specific manner, point your web browser to Icom as follows:
    https://www.icomamerica.com/en/products/amateur/hf/7300/options.aspx
    Instruction Manual, Advanced
    https://www.icomjapan.com/support/manual/
    IC-7300 ( Model Number )
    https://www.icomjapan.com/support/manual/?keyword=IC-7300&open=tab2&type=4#download_result
    Tips for USB port settings
    https://www.icomjapan.com/support/manual/2574/
    Tips for USB port settings ( Read PDF with Adobe Acrobat Reader )
    You are welcome.
     
  8. W5UAA

    W5UAA Ham Member QRZ Page

    Wow. Really? Well don't feel too shamed. I'm just kind of surprised someone actually sent you that. Every time I turn on my radio, I can find some one on the air I could say the same thing to.

    Since you (apparently) successfully operate PSK and FT8, I don't know what you could be doing wrong with RTTY. All three are computer generated modes. All three (audio in/audio out) are adjusted the same way. PSK and RTTY operational procedures are the same. You type and it transmits. Program some function keys to send some pre-programmed standard messages, etc.

    If anything, look into the variety of shifts and baud rates and make sure you using the most common. I believe 45 baud (or WPM.. subtle difference there) and 170 Hz shift is common on the ham bands if memory serves me correctly. And then see if you can nail down why "you're decoding poorly."

    And the next time you get a response like above, ask them for specifics. And then keep plowing ahead like most others I hear on the bands.
     
  9. AJ4WC

    AJ4WC Ham Member QRZ Page

    I’ll say this so you aren’t banging your head against the wall.

    It’s not just you...

    I found RTTY very frustrating. Since there are several ways to generate a RTTY signal, there’s always a percentage of stations you will never be able to talk to.

    I have a solid digital setup, and I’m working on 5-Band WAS, but still couldn’t get consistent results.

    Even so, I did manage to get 42 states in that mode, before JT-65 came out and killed it and PSK.

    Now I only see RTTY traffic during RTTY contests. I try to get out there and finish 50 states, but I doubt it’ll ever happen now.

    RTTY was the first digital mode, and was really cool, when that’s all there was. Now, there’s lots of options.
     
  10. WG7X

    WG7X Platinum Subscriber Platinum Subscriber QRZ Page

    RTTY is my favorite narrow band mode. Been on RTTY since the late '80's. First with an AEA PK-232, then with MMTTY and N1MM for contests and casual DX'in.

    All my radios, and there have only been a few, have all done true frequency shift keying which is a bit harder to set up than audio frequency shift keying even tho the result on the other end is the same. I really don't see why a fellow ham could not take the time to help you get set up correctly for RTTY. Lord knows, I've done it quite a few times. The most common error these days is using the wrong sideband when using AFSK. True RTTY bypasses that section of the radio's transmit section altogether, by actually physically shifting the transmit section by the required shift, normally 170hz if I remember correctly.

    Wrong sideband, wrong shift, wrong baud rate. Those are the biggest mistakes made and very easy to correct. An on-site mentor might help with getting you going on RTTY. Check out this website / .pdf : http://aa5au.com/GettingStartedOnRtty.pdf AA5AU is the RTTY guru. A good site to read.

    73 Gary
     

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