FT8 Split Mode - how to?

Discussion in 'Working Different Modes' started by KD2NOM, Sep 16, 2017.

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  1. DO8WA

    DO8WA Premium Subscriber QRZ Page

    By using Split you are occupieing 2 frequecies for one QSO, why would you do that? And you will most probably send over somebody elses transmission. And you are transmitting outside my 200hz narrow filter and get a bad report, when you get one anyway.
    To sum it up, the Split function is nonsense , maybe helpful for cheap rigs not able to perform right at the edges.

    I find it really, really inpolite to answer my CQ on a different frequency!
    (i guess 80% dont even know what exact freq they are transmitting on )

    73, DO8WA, Alexander
     
  2. W5DXP

    W5DXP Ham Member QRZ Page

    Quite often the split frequency function is useful for transmiting on the same frequency as receive but with a different combination of base frequency plus tone frequency in order to keep the signal within the passband of the filters. If I am receiving a signal on 7074 kHz plus 3000 Hz, my split frequency XCVR may transmit on 7075.5 Khz plus 1500 Hz. Receive frequency is 7074 + 3.000 = 7077 kHz and the transmit frequency is 7075.5 + 1.500 = 7077 kHz. The end result is the same whether split frequency operation or "fake it" operation is selected.
     
  3. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Manner are not involved. There is no reason you should take personal offense!
     
  4. AA4PB

    AA4PB Ham Member QRZ Page

    Why would someone do that? Because if you are DX and there are a dozen stations all calling you on your frequency at the same time then you are not likely to copy any of them. If they spread out then you can copy all of them and choose which one to answer. If you operate CW or SSB, the calling stations spread out (for DX) - FT8 is no different. It is always the calling station's responsibility to ensure that the frequency he selects for his Tx is clear before calling you. If you are not DX and there are not likely to be many stations answering your CQ then it makes more sense for stations to call you on your frequency (and be sure to relinquish the frequency back to you after the contact is complete!).

    Why would you operate FT8 with a 200Hz narrow filter selected? FT8 is designed to decode the whole 2800Hz (or so) bandwidth and display all of the signals for you. If you use a 200Hz filter then you are going to be missing many potential callers.

    Note that "SPLIT" in this discussion referrers to separate Tx and Rx goal post frequency settings on the waterfall and NOT the radio configuration settings in the setup menu.
     
    W2VW and KP4SX like this.
  5. KP4SX

    KP4SX Premium Subscriber QRZ Page

    First time I've heard of anyone doing this. First time for everything, I guess.
     
  6. VK4AQJ

    VK4AQJ XML Subscriber QRZ Page

    Well. it seems that the authors of the program have some very good reasons for recommending to operate split.

    As is often the case, reading the instructions can prove to be very beneficial. Pay particular attention to Section 9.3 onwards.

    https://www.physics.princeton.edu/pulsar/K1JT/FT8_Operating_Tips.pdf

    In summary if you are not operating split when answering a call, you are probably causing qrm and slowing down every QSO that you answer on the same frequency.
     
    Last edited: Aug 11, 2019
  7. VK4AQJ

    VK4AQJ XML Subscriber QRZ Page

    You are operating on 2 different frequencies but also two different time slots. for receive and transmit. It's counter intuitive, but it is more effective. Read my previous post. I struggle to see why you would use a 200Hz filter unless you have unticked "Flatten" in the waterfall section. I guess you also have a lot more activity in your part of the world.

    Personally I find it impolite _not_ to read the manual and to operate in an ad hoc manner that causes QRM.
     
    Last edited: Aug 11, 2019

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