FT8 Split Mode - how to?

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

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  1. KD2NOM

    KD2NOM XML Subscriber QRZ Page

    Good morning,

    I have been working FT8 for a couple of months now and have quite a few contacts. I have been stumped with one feature however - Split mode.

    I have a Yaesu FT-450D and if I run split mode 'fake it' - it seems to work for the first couple of transmits - meaning that if I tune to 7.074 and I attempt to QSO with a contact below 1600Hz, the frequency on the VFO drops to the appropriate frequency during tx, and then returns to 7.074 for rx. However after a couple of transmits, the tx frequency remains, and then each subsequent TX lowers the frequency until I am completely out of range - 'chasing' the contact down the band.

    If I set WSJT-X to 'rig' mode - I lose the 'S' in the frequency circle (although it stays green). I see the VFO briefly switch from A to B on tx, however I don't believe it is actually transmitting on the second VFO. If I select 'split' on my rig - I get the 'S' in the frequency circle until the first transmit - then it is gone.

    I've yet to determine if this is a rig issue, software issue or cable issue. I use a CAT cable to control and the WSJT-X software is set to 'FT-450' (there is not D option).

    Has anyone been able to successfully run in split mode using an FT-450D (or any other rig for that matter)? I am running RC2 version of WSJT-X.

    Best regards,

    Mark - KD2NOM
     
  2. K1WTF

    K1WTF Ham Member QRZ Page

    IC-7300 here, rig split mode works well. VFO A is set to listening frequency, VFO B is transmit frequency. Just note that depending on where you are in the 'waterfall' your rig may or may not change frequency to TX. In settings under advanced, there is a 'Receiver Bandwidth' setting that will determine when your rig uses split mode.

    The point of using split mode is so when you're at the lower or upper edges of your waterfall you still get linear TX response from your rig, so for example if my rig TX bandwidth normally starts to fall off below 300hz, if I'm transmitting down at 200hz the rig will change the VFO before transmitting. This is normally due to the TX frequency response/bandwidth (for example, TX bandwidth may be 300-2500hz)

    Fake it mode will change the main VFO between the set RX frequency and the TX frequency each time you TX. Using rig mode it will setup VFO A and B for the rx/tx frequencies, and actually puts your rig into split mode (which will RX on VFO A, TX on VFO B).

    If it turns out you can't get split mode to work, you can do a few tests to determine where your rig can TX properly. One easy way is to attach a dummy load to your rig, and set your tx frequency near 1800-2000hz, and note the power output on an external power meter. Drop down near 300hz tx freq, see how the power compares, keep dropping down another 50hz at a time until you see the power output start to decrease significantly. Then set your 'start frequency' in the water fall about where your rig power starts to drop off on the lower end. Next go to the top end of the waterfall, maybe start around 2200hz, and keep increasing TX frequency 50hz at a time until you see rig output drop again. Then adjust your waterfall window width and the 'bins/pixel' setting to around the upper frequency where your rig output drops. Now you will only see the frequencies in your waterfall that you can respond to. Just note, that the decode window may show signals that are outside your waterfall (and thus outside your TX bandwidth).

    Hope that helps provide some info about split mode. Unfortunately I don't have any info about the FT-450D specifically, maybe someone else can chime in about wsjtx and the FT-450D in their setup.
     
  3. KD2NOM

    KD2NOM XML Subscriber QRZ Page

    Thank for that excellent reply!

    I think my rig simply may not work properly. Here is what I experience:

    - with the rig set in 'fake it' mode
    - frequency VFO A set to 7.074
    - I see someone calling CQ at 500 Hz on the band
    - I double click to start the exchange
    - VFO A goes to 7.073.50 on the first exchange
    - instead of returning to 7.074, VFO A stays at 7.073.50
    - on the next exchange, VFO A goes down to 7.072 and walks off the frequency after a couple of exchanges.

    I don't recall if this happens if the station I'm calling responds - and that forces my rig back on the listening frequency - I'll have to test that out - but if I am calling CQ split (calling at 500Hz and listening at 1600Hz) it walks down the frequency (I know that is not the way it should be done - for for bug testing purposes that is how I tested).

    I'll cruise over to the WSJT-X forums and post there as well

    73, KD2NOM
     
  4. ND6M

    ND6M Ham Member QRZ Page

    the term "split" on FT 8 is a poor choice of terms

    "split" on FT8 is not like "split" for (say) DX.

    you don't really "listen 5 up", (or in this case "1.1 up")..... the software hears and decodes everything in the passband.

    Many people will talk about success in working stations by calling "split" to get around QRM. they really are maximizing their signal as K1WTF posted.
     
    KK5JY likes this.
  5. K1WTF

    K1WTF Ham Member QRZ Page

    Seems there might be an issue with the rig control itself after your TX to set the radio back to the normal RX frequency. If you're on linux, launch wsjtx from the command line, see if you get any errors after TX about rig control. Not sure if wsjtx shows info on windows if you launch from a command line.

    Another thing you could try is a different baud rate to your rig in wsjtx. Also check the rig poll rate, mine is set to 1 second.
     
  6. ZL1LC

    ZL1LC Ham Member QRZ Page

    Often I get responses from several stations to my CQ and ask them to Work Split. I'm waiting for them to reply by staying in the waterfall and am not monitoring outside of it.

    I'm expecting them to uncheck the "Lock Tx to Rx" box in their WSJT-X application and move their transmitted signal up or down the waterfall a little, even 50Hz.

    When I start, I find a clear portion of the waterfall, uncheck the above box and call CQ. When a station off my frequency comes back, the program sorts it out. If I want to stay on that frequency, but answer another station's CQ, I enter his call in the call box. If you click on his call, your TX will move to his frequency and that kills the Split.

    Hope that helps and look forward to working more stations working Split.

    73
    Jim ZL1LC
     
    K3RW likes this.
  7. VK4AQJ

    VK4AQJ XML Subscriber QRZ Page

    By operating "Split", you're also reducing congestion. Think about this. If a station puts out a call and two or more answer on exactly the same frequency, it slows down the QSO. The resolution is to call split. I've also seen strings and strings of RRR or worse RR73 because the other station was operating on exactly the same frequency (and others were trying to tail-end the QSO on exactly the same frequency. This causes more congestion. Another issue is that the station calling may not be on a clear frequency for you (too close to a local station). In that case, operating split will allow you to complete the QSO without causing QRM to the local station.

    If you can find a quiet spot and lock your transmit frequency, it is easy to work station after station that way without QRM from other stations.

    All these are good arguments for operating split. The authors of the software have designed it so that any reply within the window is highlighted make split operation advisable in most occasions.

    This concept of "your frequency" is not helpful on FT9. As far as I'm concerned, if I'm calling on even, others are free to call CQ odd on that frequency, because I don't usually answer stations on the same frequency.

    "If you click on his call, your TX will move to his frequency and that kills the Split."
    Not if you check the hold TX Frequency box.

    73 - Jim VK4AQJ
     
    Last edited: Jul 6, 2018
    N5AVF and KP4SX like this.
  8. K2CQW

    K2CQW Ham Member QRZ Page

    Split puts yer xmit in da sweet spot, dot's it. Read da manual cus all else has failed. Been spitting wit' me 450d for a year, no issues. I have not committed the settings to memory.
     
  9. W7UUU

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

    Is this a serious post? Do you really speak like this?

    FT8 split is not "RF frequency split" - it's "AF frequency split". It will not be explained in the FT-450D manual, but rather in the FT8 manual. If you do "RF frequency split" (i.e, "5 UP") you'll never make a contact. Save that for CW, SSB, RTTY, etc.

    It's a very simple concept - transmit at one audio frequency, that's "in the clear" and receive the station you've double clicked on.

    Dave
    W7UUU
     
    WU8Y, KS4W and KP4SX like this.
  10. VK4AQJ

    VK4AQJ XML Subscriber QRZ Page

    You could look at it as either an AF split or a small RF split, but I agree with your comments re 5 up. If you have a rig with CAT and two VFOs, split is easy without even using the split option in the WSJT-X software.
     

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