Using FT8 to demonstrate Antenna Orientations

Discussion in 'Amateur Radio News' started by KM9G, Oct 6, 2021.

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  1. KY4GD

    KY4GD XML Subscriber QRZ Page

    I had wondered if being ignored created an alert, and now I know. So thanks for finally making a useful contribution to this thread.
     
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  2. DO1FER

    DO1FER Ham Member QRZ Page

    This kind of map or data is that what I talked about in the beginning. And now it is easy to compare between the antennas, when the conditions stays nearly the same. Because when the basis stays the same and peaks in the data are deleted a comparison is possible. Good job!
     
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  3. W1YW

    W1YW Ham Member QRZ Page

    FT8 is very sensitive to detection threshholds at the lower values of its RSSI. That means there is a selection effect afoot because conditions are never 'nearly the same' over a time line that deviates from real-time. So let's say you want to compare the NVIS antenna to the inverted V on a specific link. And the inverted V is, say. -20 on a specific link (just throwing out a low number for an example). Hours go by and then you test the NVIS and get ..nothing (= no link). But you don't know, at that TIME, what the inverted V value was...it also could have been nothing, at the time you test the NVIS.

    Most FT8 contacts are at very low SINR . That's why we use FT8 in the first place: as a matched filter, it has a lower SINR threshhold for detection compared to say, CW.

    The assumption you make is that the propagation link is a very slowly varying SINR function in the hours between changing the two antennas Yet the OP shows no evidence for this. There is no data that shows that.

    Matched filter modes are like blinking Nixie tubes...you can't predict at very low SINR threshholds how they will behave as 'on' or 'off'. . Its probably a Ricean probability density function. Will detection blink on..or off at a given time? How about 10 minutes from now? Five hours from now? Typical Ricean QSB issue.

    Speaking of a Nixie tube example--enjoy the blinking cat:

    WINKING CAT NIXIE TUBE! - Bing video

    All FT8 studies of this type of a comparative nature must be done in real time.

    If you don't have a control, and don't prevent selection effects, you have no basis for any conclusions. You may 'feel' that you do-- but the brutal facts say otherwise.

    Getting mad at the messenger of these facts (and worse...implying I am a sociopath for example) is not only irrelevant and offensive, it is an embarassment for the amateur radio service. And THAT is how I 'feel'. It is a cancel-culture attempt to stop a voice of reality, just because its not what you want to hear.

    There are LOTS of great things we can do with FT8. This report is not one of them. OTOH its a great incentive to learn more and figure out what CAN be done


    73
    Chip W1YW
     
    Last edited: Oct 10, 2021
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  4. W1YW

    W1YW Ham Member QRZ Page

    I've been getting emails --ignoring the hostile ones--asking what CAN you do with FT8, science wise.

    OK, I am going to throw out an example.

    The earth gets heavier every day. This is because there is an infall of meteors, most the size of a grain of sand. We get estimates of this infall from radiosonde 'pings'. But there aren't a gazillion such radiosondes, and they don't have the threshholds of FT8. IOW, the present studies recognize that incomplete coverage and SINR issues are selection effects in the radiosonde studies. Hams and FT8 do not have these same magnitude of selection effects.

    Think about how you can use FT8 to make a more sensitive and complete 'mapping' of meteor 'pings' --not longer sporadic E--to figure out a more realistic lower limit of how the Earth grows fatter...
     
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  5. K2ENF

    K2ENF XML Subscriber QRZ Page

    Oh, yeah. And if you get the best of them, you can kick some SERIOUS belt loop.

    I had an 40m EFHW that I was using, but a tree fell on it. this caused a major issue for me, because I run a local 10m net. So,I bought a used IMAX2000 that became available....(Yes, a CB antenna!) because I needed something to run the local 10m net with that night. Yeah, I was in a hurry, so I held my nose and put it up. I was intrigued when I got reports from the locals of "Oh, wow!", For those who don't know the antenna, it's a .64 design at 10m. It's a 26ft tall unit with an advertised 3DBi or .8 DBd gain. I think this is a bit low. Experience has shown it to be a lot closer to 5DB1 at 10m

    Anyway, on the basis of the initial reports, I played a bit to see what it would do on DX. I used ft8 (and psk reporter) to dial in my antenna height and after a couple weeks of playing, I settled on on 35ft, which seems to be the best balance for the local net and the 10m DX when it comes in.

    At this point, I started to branch out a bit. I was pleased to find myself able to run 10m,12m, and 15m without a tuner. 1.1/1Dead flat across 10m, 1.7 across most of 12m and 1.4 across 15m! That would be good enough for the $30 I invested in the used antenna, but imagine my shock when I found my internal tuner (I run a 991a) works between 6 and 20m!

    On 10 and on 15, I've worked the whole of the western hemisphere with it mostly with about 65w. , with occasional hits in the both eastern and western EU, and Africa. Only places I've not gotten on the log with it yet are Australia, (Though I do see a number of reception reports from there on PSK) and the far east...(Japan, China, etc)

    The points here being, yes, use your imagination, and you'll be amazed at what you can come up with. And, that I doubt I'd have come up with the results I have without using FT8 and PSK as a rough guide on installing the thing. It accelerated 10 -fold, my dialing it in.

    By the way, I've replaced the EFHW, but that's another tale.
     
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  6. OE4KSF

    OE4KSF Platinum Subscriber Platinum Subscriber QRZ Page

    I have 2 radios and 2 antennas. One beam and my vertical. Running one radio on 10m and the other on 12m at the same time - takes a print screen from pskreporter. Then swapping the antennas on the 2 radios - and another ft8 run for 10 minutes - and comparing the view on pskreporter. Often I find that one day the vertical is doing better - another day the beam.
    Or also 1 hour later it can change. Only by using both antennas at the same time - are giving me real data to compare. The conditions are changing so fast and so often that comparing data from different hour or day do not really telling you anything. This I have learned the hard way.
    But keep up experimenting - that what a hobby like this is ment for :)
    73 - Knut
     
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  7. KM1NDY

    KM1NDY Ham Member QRZ Page

    Chip, I don't know any other way to say this. I want to try and give you a graceful out. Though I am expecting a diatribe about your faux sense of being disrespected, feelings/beliefs, ivory tower science mumbo jumbo, and bizarre pop culture references.

    Many of us do not fundamentally care how you feel about this video, our versions of radio, or the validity of the use of observations in science (i.e., otherwise considered the foundation of the scientific method). Do not interpret this to be fueled with emotion. Read what I said. I simply do not actually care about your opinions. You have, with these ongoing posts, become someone I do not have faith in when it comes to my particular learning and interest in ham radio. So what? Clearly you have supporters of your philosophies and do not need me on your team so to speak. No need to try so hard to change my mind on this, i.e., let it go. I will borrow the phrase, you do ham your way. Recognize too that I am trying to just speak for myself here, not trying to say I am taking your posts personally.

    You called us hillbillies. You made fun of our intellect. You picked on our integrity with the amateur radio service. You invalidated our carefully thought out opinions as an emotional response (which I recognize as the "logical" vs. "emotional" argument often used against certain sectors of society to discredit them). You have even gone so far as to try to make the case that we are violating FCC statutes by not listening to you. You now are accusing us of trying to cancel you.

    If I were in your shoes, I would just step away from the keyboard for a few days. Clearly you are a highly knowledgeable RF professional. I do want to highlight the word professional here. Do yourself a favor and realize that if you actually want to be seen as a guru of amateur radio, you have to earn that. You can't force it on people. You can't stand on a hill top, yelling out that you are the best and brightest and expect people to bow down to it.

    And honestly, I will add in some "feelings" here now. This thread is actually detracting from my joy of ham radio. Now, I am too old and well-established of ego to let any one person effect my happiness in life. But think of the kids, new hams, and others that you are driving away. And please realize that your posts are driving people away. I feel the need to say that you do not represent those of us in amateur radio, lest others think we are all like this and get turned off to the hobby. As someone espousing the creed to further the radio arts, you are actually doing a very poor job of it. There is a difference between art and science as any medical doctor will tell you. One is practicing with cold, hard facts, the other is doing so with finesse. Perhaps a spit shine on your delivery would earn you a bit more respect amongst your peers? It certainly would be better for the hobby overall.

    I am a very easy person to get along with and do not typically hold grudges. I suspect many of us are like that. Step away, reflect, and take a new approach, and you may get more positive results.

    Just my final 2 cents on this topic.

    Mindy
     
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  8. W1YW

    W1YW Ham Member QRZ Page

    Thanks for showing that Knut.

    73
    Chip W1YW
     
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  9. W1YW

    W1YW Ham Member QRZ Page

    Unless you thoroughly choke the coax at the feedpoint, the coax is part of your antenna system, for the other bands. This 'radiating coax' is not always a bad thing, as you are attesting. It's not optimal, but it does work.

    73
    Chip W1YW
     
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  10. DO1FER

    DO1FER Ham Member QRZ Page

    I understand your scientific intensions and your sight of view. I cant say that this is false. And your approach is maybe more elegant and unneeded precisely than other solutions. But believe in, that all roads lead to rome. That is what you have to accept.

    73,

    Cornelius DO1FER
     
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