Like any experiment, you always learn something even if the results are poor.
The key points for me are...
1) Poor antenna..... Using an indoor Slim-Jim half wave vertical antenna in the attic doesn't cut it for weak signals on 144 MHz. It might be fine in the SE of the UK, the low countries or Germany but not here in Ireland.
2) Too far west..... I estimate the bulk of the FT8 stations on 144 MHz are at least 400 kms to the east of me. Roger had a lot more stations closer to him even from the continent.
3) Fewer planes..... With a 15 second transmission time, aircraft scatter probably plays a big part on the number of FT8 signals heard on 144 MHz. Here on the south coast of Ireland, most of the aircraft traffic is Trans-Atlantic going east-west. There would be a much higher number of planes criss-crossing over the south east of the UK with many at lower altitudes.
The results confirm what I would have kind of guessed anyway. FT8 is good but it's not that good. To operate 2m FT8 from here, I would need an external horizontal Yagi.
3 comments:
See results of UK Activity Contests the stations coming last are using vertical antennas on 2m.
The initial rush of activity on 144 MHz FT8 has passed, there are not as many active as there were, most have found out who they can work, some continue to monitor, and call CQ from time to time, if conditions look promising, or if some rare country or square.
Indoor antenna is too close to a lot of man made noise from electronic devices.
Aircraft scatter relies on high altitude aircraft at the mid point of path to get good range, Airscout software shows this in detail.
I bet you that if you put up a 6 element horizontal Yagi in the clear that you would be able to work a lot of stations and that includes GM stations. How about it?
It doesn't have to be expensive, make a Yagi to a proven modern design like G4CQM and spend the money saved over a commercial offering, on decent coax like Ultraflex 10. The Armstrong method of rotation will do, and if you get serious a rotator can be added later.
Power ranges used are from QRP to QRO, but you don't need power to listen and see what you can detect. Although FT8 was developed for 50 MHz Es where signals can have severe QSB and very rapid QSB, it has proven useful on many VHF bands, and has been used up to at least 432 MHz. Aircraft scatter actually can be a problem at 2 m and 70cm as the severe Doppler shift can make FT8 fail. I frequently see FT8 signals that have reflections from more than 1 aircraft and a direct signal.
2m FT8 is all on 144.174 MHz (dial frequency on USB). Many FT8 stations can operate in the SSB filter width, though if a local is very strong your receiver may be blocked, hence the need for having defined TX/RX periods.
Don't call CQ endlessly, it can deny others the chance to listen on the other period, and you will also have no idea if there is anything of interest happening on your TX period. So like so many modes used in amateur radio, it pays to listen most of the time, and CQ infrequently unless you are in a rare square or country on an expedition or in a contest.
The nice thing with FT8 is that PSKReporter will show where your signal is being received, even if the other Stations does not call you because they are busy or just not interested in working you or your square or country again .
Many keep their receiver running while doing other things, and some have quite sophisticated setups that monitor many bands at once.
MSK144 activity is on 144.380MHz. During a meteor shower it can get busy, so you can call CQ there with a suggested QSY frequency in the CQ message. Skeds can be arranged if that is your bag, or you can just operate random.
Unlike FT8, MSK144 is a WSJT 'fast mode', which takes much more bandwidth, a single MSK transmission takes up all of a standard SSB filter. However the nature of Meteor scatter means that you can operate on the same frequency as another local on the same period because meteor bursts heard from 1 station may not be heard another station in another location.
If you can hear the other station you are trying to work on MSK all of the time then it probably isn't meteor scatter, so FT8 would be more appropriate and sensitive. Conversely if you see short bursts of signal on FT8 it indicates meteor scatter and you would probably do much better on MSK where the software can decode the signal even with short bursts and in real time, unlike FT8 where you have hi wait until the end of the period before decode happens.
A good guide to MS using MSK is on Jim GM4FVM's blog
http://gm4fvm.blogspot.com/2017/08/after-es-why-not-try-meteor-scatter.html
The WSJT-X user guide covers all of this is as much detail as you could wish for.
73 and hope to work you on 50/70/144MHz (with a better 432MHz system planned for next season).
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David GM4JJJ
Thanks for the comment David. I think I'd be more inclined at the moment to put up a small beam and go for the armstrong method. The days of chasing squares are well behind me but I'm still curious about VHF conditions and listening for distant signals.
I guess the biggest change from the old days is the use of weak signal digital modes and waterfall displays which gives the whole VHF scene a new lease of life.
I know indoor aerials are a serious compromise but at least they survive the storms! :o)
My biggest problem that I have at the moment is that I keep getting distracted by other things! :o)) There's a lot to be said for being on one band.
John, EI7GL
Yes John, waterfall displays helped a lot. I was a single band VHF operator for many years (2m). After a 10 year hiatus I came back and got interested in 6m more seriously than before, even though I had missed the sunspots, and then started on 4m for the first time with the aid of the IC-7300 for that band, The UK Activity contests were the spur for me to put up antennas for those other bands. I was primarily interested in the new modes that were coming out, to see what was possible to work when we lacked the sunspots.
It sometimes seems that we are all just using the FT8 frequenciy, but there is still VHF activity on SSB and CW aid you look for it. FT8 is fine for racking up the country and square count, and seeing how far you can hear/be heard, but it is nice to have a QSO and a chat on the old modes.
No doubt that things have changed, but there has always change and progress. When I was licensed in the very early 1970's we were mostly still using xtal controlled AM . Then came mass market SSB with the Liner 2. Oscar satellites opened up inter continental VHF UHF contacts. CW allowed moonbounce with larger antennas.
At the other end of the bands we first of all had FM and repeaters. Now we have Digital Voice modes, APRS where previously we had AX25 packet radio and mailboxes.
WSJT again caused great changes, EME changed from CW to JT44 to JT65. MS from HSCW to FSK and MSK. FT8 is still being explored on 2m. A lot of people dusted off their radios to try it.
Wishing you all success with a new 2m antenna. I agree about having something that won't be a worry in the gales. I no longer have the CW EME 4 Yagi XPOL array for that reason. It had to be tied down all winter here. Now I restrict myself to a single Yagi on each band. In fact I have a dual band Yagi for 4m/6m to reduce the number of booms on the mast. It isn't that much of a compromise, though does mean I cannot be on 6 and 4 at the same time.
To me the biggest changes since I came back on have been WSJT modes and the IC-7300 which has popularised 4m weak signal work.
In a way I am glad I had the break and sold a lot of the old gear, as it allowed me to start again with new.
73
David GM4JJJ
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