Posts Tagged ‘ft8’
In The Loop! – First Impressions of the MFJ-1788
May 30th, 2018 | 
Author: Was feeling pretty chuffed after repairing the MFJ-1788 'Super Loop' and couldn't wait to try it out! So for a couple of evenings of experimenting I put the loop in the garden on a 5ft pole held up by a heavy drive-on stand with 20m (65ft) of RG58 running into the shack.
I chose the easy option of using FT8 to do some testing, selecting the 30m FT8 frequency initially. I tuned the loop and was met with a cacophony of signals, far louder than my usual OCFD would receive. Working with around 30 Watts had a few contacts in a brief 30 minute session, including a nice one in Greece with SV1IW.
What was striking was the lack of noise and just how tight the tuning was, indeed I had to tweak the tuning a couple of times during tests, a slight adjustment either way and the signals just disappeared. I checked out 40m and 20m as well with similar good results.
I had a few more sessions and a few days later I tried it out to receive the Shortwave Radiogram broadcast from Bulgaria on 9400kHz, this time as it was a broadcast band had to use my ear to do the tuning, adjusting till I heard a rise in 'noise' and signal.
I am very happy with the loop. Transmission wise it unsurprisingly doesn't seem a huge improvement over the OCFD on its resonant bands, it scores over the OCFD is on its 'non-resonant' bands such as 30m and 17m. But the massive improvement is in receiving, signals are stronger and noise is much lower, picking up some more distance signals even given the poor conditions.
I also have had issues trying to operate the radio remotely, I have tuned it up on an FT8 frequency in the morning and then later in the day logged in to try to make a few QSOs during a coffee-break to see the loop has drifted out of resonance. This can only be down to the loop getting warm in the summer sun.
I am still evaluating the antenna but am looking at making a better controller, over on AmateurRadio.com where this blog is syndicated, I have had a number of kind comments including one from Elwood Downey, WB0OEW who pointed me to his published design of a controller, using a similar method to what I was toying with. Thanks Elwood.
73 for now, more updates soon.
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| Temporary test setup |
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| PSKReporter showing where I was spotted |
I had a few more sessions and a few days later I tried it out to receive the Shortwave Radiogram broadcast from Bulgaria on 9400kHz, this time as it was a broadcast band had to use my ear to do the tuning, adjusting till I heard a rise in 'noise' and signal.
I have now got the loop up on a rotator and mounted slightly higher up with a shorter length of RG213 (not on the video) it is still quite low and unfortunately is slightly shielded to the south by the neighbours metal roofed building,Trying out the loop antenna, @SWRadiogram— Andrew Garratt (@nerdsville) May 19, 2018
images this afternoon from Bulgaria 9400kHz pic.twitter.com/53HRwIHUQz
I am very happy with the loop. Transmission wise it unsurprisingly doesn't seem a huge improvement over the OCFD on its resonant bands, it scores over the OCFD is on its 'non-resonant' bands such as 30m and 17m. But the massive improvement is in receiving, signals are stronger and noise is much lower, picking up some more distance signals even given the poor conditions.
The antenna cannot be said to be a pretty thing to have in the garden! The tuning is very particular, in the video I show the 'auto tuning' isn't ideal. It requires the radio to be putting out a signal into a mismatched load for what could be nearly a minute. Not good for the radio and is a source of QRM during this time, the usual technique of tuning slightly off a QSO frequency is more problematic due to the sharpness of the resonance. You can still tune off frequency and then tweak with the slow tune buttons to bring it in. I've noticed that on some of the higher bands it occasionally doesn't auto-tune because the 'dip' seems very short/sharp and the controller doesn't react in time and overshoots especially using low power settings.still evaluating the RX of the mag-loop and according to pskreporter heard 92 countries, 1182 stations on FT8 30m/40m in the last 17 hours.. pic.twitter.com/ZuWZOFFiP2— Andrew Garratt (@nerdsville) May 22, 2018
I also have had issues trying to operate the radio remotely, I have tuned it up on an FT8 frequency in the morning and then later in the day logged in to try to make a few QSOs during a coffee-break to see the loop has drifted out of resonance. This can only be down to the loop getting warm in the summer sun.
I am still evaluating the antenna but am looking at making a better controller, over on AmateurRadio.com where this blog is syndicated, I have had a number of kind comments including one from Elwood Downey, WB0OEW who pointed me to his published design of a controller, using a similar method to what I was toying with. Thanks Elwood.
73 for now, more updates soon.
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| The antenna farm |
Short Demonstration of Using Ham Radio Deluxe with WSJT-X and FT8 Digital Mode
Ham Radio Deluxe can log your WSJT-X FT8, JT65A, and JT9 QSOs, via the JT-Alert software. This is a demonstration of my use of HRD and Logbook, during an FT8 QSO,today.
As some of you know, I have had some differences of opinion regarding the selection of frequencies chosen by the FT8 creators and advocates. Regardless, I do still use the mode. Here is proof:
Go ahead and share, if you would. And, please subscribe to my YouTube channel, as I will be creating many how-to videos in the near future.
Thanks and 73 … de NW7US
The rise and rise of FT8
There is no doubt in my mind that FT8 has been phenomenal.
Every day this new digital mode seems to attract more and more people. It works with the briefest of openings and the software needed is free. It takes up about 60Hz only and works with weak signals. On a recent (rare for me) visit to 20m, DX from all over the world was spotted.
Even on 2m VHF, most days I spot signals from all over western Europe under flat conditions even with my omni antenna.
What will the Es season bring on 6m this year with this mode?
LHS Episode #204: Jump Around
In this episode, your hosts discuss the monkeyshines at the ARRL, the overwhelming popularity of a certain digital mode, Spectre and Meltdown (of course), WINE 3.0, WSJT-X, twclock, CLLOG, dxSpot and a whole lot more. Thank you for tuning in and hope your 2018 is going well.
73 de The LHS Crew
A fantastic FT8 guide!
If you have or are thinking of diving into the FT8 digi world I was made aware via a Dutch blogger Paul PA0K (his brand new call) of this amazing FT8 operating guide by Gary Hinson ZL2ifb. This guide is for the seasoned FT8 op, the beginner and those who are not sure if they really want to give it a go but would like to learn what it's all about. I won't to go on and on about the guide..... just read it and find out for yourselves, it's a great addition to anyone interested or operating FT8.
FT8 anomaly or long delayed echo?
My friend Alf, LA2NTA, has sent med these screenshots from when he has been operating FT8. The first image is when operating 10 meters and took place early in November.
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| Two of LA2NTA CQs being received by himself on 10 meter (in red) |
It shows how his own CQ comes back to him at 10.54.00 and at 11.00.00 and is decoded in his own receiver.
The second example is from 20 meters and took place just a few days ago.
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| LA2NTA CQ being received by himself on 20 meter (in red) |
For the first example he also took an image of the spectral display. It shows lots of repeated noise burst all over the FT8 band.
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| FT8 band on 10 meters showing some form of noise all over the band |
It is hard to explain this, but my hunch is that it is something local and not a propagation phenomenon, but who knows?
Best Digital Mode? … Not Really
For the past year, as interest in the digital modes began to skyrocket, I have been reading the topical discussions and questions posted in the WSJT Yahoo Group.Since the introduction of FT8, the group's daily traffic has soared and easily occupies the vast majority of inquiry.
Far and away, most questions either involve software / computer configuration problems or inquiries involving the operational use of the software itself. I am often surprised at the range of inquiry and in almost all questions involving the software itself, it just comes down to 'reading the manual' ... it seems that hams, like so many others, just don't like to read manuals and for a technically-oriented hobby, I find this peculiar. Perhaps it's because I'm just the opposite, and will usually go over instructional material, more than once, before plugging something in or installing any new software.
Not all digital modes are 'created equal' nor with the same purpose in mind and for those new to these modes or making the transition from traditional mode operations, sorting them out can often be a source of confusion. One such user broached this very topic with his recent inquiry:
I have been using JT65 and FT8 a lot, mainly on 6m DX to receive weak signals in the noise floor. QSB is acting fast there and the 15s intervals are a major advantage of FT8 to be able to complete rare contacts.
But which algorithm is better to decode weak signals in theory and practice? Do the long intervals allow the JT65 algorithm to decode weaker signals than FT8?
If both modes are equivalent is there any reason to use JT65 rather than FT8?
Bill, G4WJS, has been handling most of the technical inquiries and I thought his reply might help others that could be wondering the same thing:
... simple answer, neither wins in all situations. Each mode in WSJT-X is designed for a certain set of requirements and given those the protocol and the decoders try to optimize sensitivity and robustness.
Bill, G4WJS, has been handling most of the technical inquiries and I thought his reply might help others that could be wondering the same thing:
... simple answer, neither wins in all situations. Each mode in WSJT-X is designed for a certain set of requirements and given those the protocol and the decoders try to optimize sensitivity and robustness.
JT65 was designed initially for EME where ultimate sensitivity was necessary and one minute T/R periods with variable bandwidths between 180Hz up to 400Hz, to cope with Doppler spreading, was deemed acceptable for practical QSOs.
FT8 is not as sensitive, a few dB behind JT65A but as you point out it is particularly suitable for multi-hop 6m Es propagation where openings can be very short. This is no surprise as it was crafted for exactly that. OTOH FT8 has become *very* popular on HF, probably because most HF QSOs do not need ultimate sensitivity and the 15s T/R period makes QSOs four times as fast compared with JT65. This last attribute is surely what is driving the massive uptake on HF on the current "easy DX" propagation bands like 20m for daylight paths and 40m for darkness paths.
JT9 was designed for HF and uses about 1/10 of the bandwidth of JT65A along with even better sensitivity. Unfortunately many users use ancient software with no JT9 support or are working through JT65 goals like WAS mode specific endorsements so JT9 does not get the attention it deserves. Although JT9 works for many on 6m, the tighter frequency tolerance required is a limitation for many with older rigs.
Both FT8 and JT65A have two pass decoders that can dig out multiple overlapping signals (similar techniques could be developed for JT9 but the need has not been seen yet).
FT8 has the AP decoder which gets a couple of dB extra sensitivity for critical decodes and also helps with truncated or interrupted messages in some cases.
WSPR is a pseudo beacon mode that uses a short message and two minute T/R period that has greater sensitivity than even JT9 despite the signal being only 6Hz wide. WSPR like JT65A and FT8 uses a two pass decoder capable of decoding overlapping signals.
There is also MSK144, QRA64, JT4, the fast versions of JT9, ISCAT, FreqCal and Echo mode. Each with a specific purpose and maybe for other opportunities they were not initially designed for.
For myself, I have yet to download the latest WSJT-X release, as I presently have no need, nor see the need to use FT8. To utilize the new release, I think I'll need to delete my older (pre-FT8) version, in order to avoid file confliction problems. My older version works very well for what I do need, and that is JT9. There are a few features on the software that I also find handy, which have been removed in the newer versions ... I think.
I can however, visualize losing out on some great DX opportunities on 6m during the summer, if the huge exodus from the CW DX mode to the FT8 mode continues to escalate. I really hate the idea of this happening but if that's what it takes, I'll install the FT8 version on my small contest-logging laptop which means building a new interface to run the 756PROIII on FT8.FT8 is not as sensitive, a few dB behind JT65A but as you point out it is particularly suitable for multi-hop 6m Es propagation where openings can be very short. This is no surprise as it was crafted for exactly that. OTOH FT8 has become *very* popular on HF, probably because most HF QSOs do not need ultimate sensitivity and the 15s T/R period makes QSOs four times as fast compared with JT65. This last attribute is surely what is driving the massive uptake on HF on the current "easy DX" propagation bands like 20m for daylight paths and 40m for darkness paths.
JT9 was designed for HF and uses about 1/10 of the bandwidth of JT65A along with even better sensitivity. Unfortunately many users use ancient software with no JT9 support or are working through JT65 goals like WAS mode specific endorsements so JT9 does not get the attention it deserves. Although JT9 works for many on 6m, the tighter frequency tolerance required is a limitation for many with older rigs.
Both FT8 and JT65A have two pass decoders that can dig out multiple overlapping signals (similar techniques could be developed for JT9 but the need has not been seen yet).
FT8 has the AP decoder which gets a couple of dB extra sensitivity for critical decodes and also helps with truncated or interrupted messages in some cases.
WSPR is a pseudo beacon mode that uses a short message and two minute T/R period that has greater sensitivity than even JT9 despite the signal being only 6Hz wide. WSPR like JT65A and FT8 uses a two pass decoder capable of decoding overlapping signals.
There is also MSK144, QRA64, JT4, the fast versions of JT9, ISCAT, FreqCal and Echo mode. Each with a specific purpose and maybe for other opportunities they were not initially designed for.
For myself, I have yet to download the latest WSJT-X release, as I presently have no need, nor see the need to use FT8. To utilize the new release, I think I'll need to delete my older (pre-FT8) version, in order to avoid file confliction problems. My older version works very well for what I do need, and that is JT9. There are a few features on the software that I also find handy, which have been removed in the newer versions ... I think.
Of course there is always the possibility that the trend will reverse as many eventually find that FT8 contacts are not all that interesting. The inability to exchange anything other than minimal required QSO information is the price paid for that extra sensitivity ... fine for that once in awhile new one in the log but not very satisfying for everyday communications.
The 'reversing trend' was also addressed in a recent posting to the WSJT Yahoo Group:
In my opinion it is nice to see a steady return to JT65 & JT9.
An all round better mode.
Still a bit short on the DX stations but I am sure they will follow soon.
Pretty much what a lot of us said would happen: an initial surge to FT8 and then things would settle down. Just another tool in the toolbox that does not have to be “better” or “worse” than anything else that has a few advantages over some modes in some areas (Es, for example) and disadvantages over others. None of these modes has to be classified as “good,” “bad,” “better,” “worse,” etc just like I don’t consider a screwdriver “better” overall than a hammer but each tool does a different thing. I suppose it’s human nature to attempt to classify things that way.
I have also seen some confusion when some are describing WSPR 'QSOs'. This is disturbing since there can never be a two-way exchange of information, all via radio (a QSO) using the one-way WSPR beacon-mode. Some may be confusing 'WSPR QSO's' for the actual Weak-Signal two-way 'WSPR QSO' modes such as JT65, JT9, FT8 etc.
Since WSPR relies on an internet back-channel exchange of information (to see where you've been heard), there is no actual on-air exchange of the data needed to claim a legitimate contact. To make such a claim would be no different than two stations, each running a beacon and calling each other up on the telephone to say that they can hear each other and calling it a two-way 'QSO'!
I have been using, and will continue to use JT9 on the new 630m band where signal levels are often too marginal for CW work but easily handled with this digital QSO mode ... otherwise I'll keep pounding brass whenever I can!
