Saturday, September 30, 2017

Tips for Operating the FT8 Digital Mode








The FT8 mode is taking ham radio by storm, and for good reason. Just as we were becoming despondent about entering the doldrums of the sunspot cycle, here comes a mode that can dig signals out of the noise and copy them Q5. The high bands, particularly 15, 12, 10, and 6 meters are suddenly capable of producing DX QSO's with regularity. It's miraculous.

I have been using the mode with great success to work new band countries for the DXCC Challenge award. In the process I have learned a few lessons. While the mode is actually pretty easy to master, there are a few things to pay attention to.

1. Maintain Accurate Timing. The shack computer cannot be more than a few seconds off official UTC, or this mode simply won't work. Its weak signal performance depends on perfectly timed transmission and reception sequences. My Windows 10 computer was set by default to automatically sync the time every week and that turned out not to be good enough. I have now got it syncing frequently, which solved my problem. To check your computer's accuracy bring up the clock in the lower right corner of the screen and watch it while listening to WWV. The long beep from WWV should occur exactly on the minute. Another way to check is to bring up the https://time.is web page, which will automatically display your time discrepancy.  See below for instructions on how to force your windows computer to time sync. The solution I recommend is called meinberg ntp.

2. Don't use a narrow filter. If you can control the filter bandwidth, open it up to 2.8 KHz or greater (except 60m, which is a special case). Also, if you are using SSB mode, make sure you don't have an equalizer turned on. My K3 has a digital mode that bypasses the equalizer and has its own mic input level setting. Check you manual to see if you have a similar setup to use instead of using the SSB mode.

3. Make sure your computer mic is off and gain is set correctly. I occasionally hear folks transmitting an FT8 and their mic is also on. That can be embarrassing! Watch your ALC and keep it below the threshold which is typically one bar (note that the Elecraft threshold is five bars) and by all means make sure you don't over drive the input and trash the frequency. Keep the power level down, too, to ensure a clean signal and a cool running final. Half of rated power, max, is a good rule of thumb. Remember, FT8 is a weak signal mode. There's no need to dominate the frequency with high power.

4. Read the excellent manual and watch some YouTube videos before you try to make contacts.Work a few stations before you try calling CQ. Here's a link to an excellent operating guide -- FT8 Operating Tips

5 If you need a USB interface to connect the computer audio out/in to the transceiver audio in/out, consider a Tigertronics SignalLink, MFJ 1204 or the RigBlaster plug and play control interface. I have also had success just using a Griffin USB sound card dongle with a line input (most sound card dongles just have a mic input which is easily overloaded by the line level audio output of the rig). Just plug the dongle into a usb port, change your computer sound settings to default to the dongle, plug rig audio out into the dongle line input and plug the dongle output into the rig input. Adjust the settings to prevent over loading these circuits, and go.

6. If you are a DXer like me, learn to operate split using the waterfall display. FT8 doesn't handle simplex pileups better than any other mode. Uncheck the TX=RX box. Double click on the DX station callsign you want to work, then shift click on an open frequency on the waterfall display. Practice this technique when answering ordinary CQ's.

7. For more tips and shortcuts, go to the FT8 main screen and press F3 or F5.  Download WSJT-X here:  Clicky

8. While FT8 is semi-automatic, you can send messages manually by  un-checking the auto sequence box and clicking the TX numbered boxes. You can also double click TX1 to prevent it from automatically sending and put and contest exchange in TX5.

That's about it. This mode is easy and fun to use, especially for quick DX QSO's and weak signal work. It's fast, too. QSO's only take about a minute. It is bound to make its way into the SOTA world as soon as a light weight external processor or phone app is developed.

Time Sync instructions

Meinberg NTP is the best solution I have found for time syncing in Windows. It is a free binary app without a windows interface that runs in the background as a "low overhead" service and calibrates my computer time as frequently as necessary to keep it exact. I have had it running for quite a while now and it has worked perfectly. Download here Meinberg NTP. If you want to customize monitor, or control Meinberg NTP learn more here MeinbergMonGuide.pdf

There are several other reasonably good options. Here are the instructions for setting up your windows computer for hourly time sync. The is also an app available called Dimension 4 if you aren't comfortable following these instructions or prefer a windows interface.

Make Windows synchronize time more often  Time Sync Instructions
https://www.pretentiousname.com/timesync/index.html
Make Windows synchronize time more often This page explains how to make the Windows network time (NTP) client synchronize its time more often than the default once per week. This was tested on Windows 7 but should work with Windows XP and above. Why is this important? I don't know about your machines but both my desktop and my HTPC have terrible clocks. They seem to drift by about five minutes each week and that messes up things like scheduled TV recordings or stating that it is 13:37 o'clock o...






2 comments:

  1. What we really need is a TNC modem iPhone app that allows us to operate FT8, JT65, & JT9 without any internet connection. Would be great for SOTA.

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  2. Well, I see there is something for JT65 called JT65android. It's here https://play.google.com/store/apps/details?id=org.jt65android&hl=en

    Haven't seen anything for ft-8 yet.

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