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Using FT8 to demonstrate Antenna Orientations

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

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  1. 2E0TWD

    2E0TWD Platinum Subscriber Platinum Subscriber QRZ Page

    There is however, as you are so far out of touch with reality you can’t even see why.
     
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  2. W1YW

    W1YW Ham Member QRZ Page

    Here's a picture of a (rotary) precision attenuator. (See post #55). New ones are expensive. Used ones are common at flea markets for $25-$60. Note this one has 1 dB steps. For RX RSSI only.

    [​IMG]
     
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  3. KM1H

    KM1H Ham Member QRZ Page


    Thats just an opinion; since 1500W is legal then use it to another ~10-20 dB more distance under the noise if that is what is wanted.
    Nobody whines about 1500W ++ on VHF/UHF EME paths.

    Carl
     
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  4. K8XG

    K8XG XML Subscriber QRZ Page

    This is my Observation of doing this on JS8Call working other stations that mostly are ~50 watts, some less. [JS8Call doesn't have the award seekers on it so more of a 100 watts and a wire, even QRP]

    For this time of year, since JS8Call has been out, this is what my PacMan generally looks like on 40m from Noon till dark. Then I get more curves on the west coast.

    My friends and I have always wondered why better to the south, as the 33 foot antenna is in the back yard vertical on the ground with the two story house is blocking the horizon of the south to it, mostly; as the house is 24feet vs the 33 feet. It does have the MFJ top loaded coil and Hat on it for 80 meters, that might be helping. It would be beyond me to figure out.

    Someone once had a whim that the overhead power wires in the neighbors yard to the north of me are reflecting the signal back to the south, that seems a bit of a stretch. They are up almost the same height and run east and west.

    Observations make great Ham talk but they are indeed just observations. For example it just may be that more hams are on JS8Call and FT8 [I did compare the PacMan Curve to it as well] in the south/southwest than the north/northwest of me. Lots of variables I will never figure out, just play radio and observe an have fun.

    upload_2021-10-9_17-16-44.png
     
    Last edited: Oct 9, 2021
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  5. W1YW

    W1YW Ham Member QRZ Page

    Joe and crew have all the callsigns on FT8 . It would be interesting to see the geographic density map for FT8 registrations.

    73
    Chip W1YW
     
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  6. K8XG

    K8XG XML Subscriber QRZ Page

    But also only if it also included some kind of percentage of participation time.
     
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  7. KY4GD

    KY4GD Ham Member QRZ Page

    For some reason, reading this thread made me think of the toast that Rick Sanchez gave at Birdperson's wedding. It begins "Listen, I'm not the nicest guy in the universe because I'm the smartest. And being nice is something stupid people do to hedge their bets."
     
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  8. W1YW

    W1YW Ham Member QRZ Page

    That's really offensive. Here's what wikipedia says about your allusion:

    "Known for his reckless, nihilistic behavior and pessimistic personality, the character has been well received. He is a sociopathic mad scientist who seems to know everything in the universe and thus finds life a traumatizing and pointless experience."

    Why do some licensees of Part 97 have to be made to feel uncomfortable for working hard to live up to the mission?

    You confuse 'smart' with 'effort'.

    Look: if you don't want to be around technical radio people, then try CB. No one is trying to show-up anyone. Just educate--when needed.

    73
    Chip W1YW
     
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  9. KY4GD

    KY4GD Ham Member QRZ Page

    Yes, it is. Rick is a scientist who knows everything, except why nobody likes him.
     
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  10. W1YW

    W1YW Ham Member QRZ Page

    Well, think again.

    I am certainly not a sociopath, nihilistic, and so on. And I am not an inked ripoff of Doc Brown either.

    Just use 'ignore' if you don't want to see my posts. Easy. In fact; I just put you in 'ignore'.
     
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  11. KY4GD

    KY4GD Ham Member 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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  12. 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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  13. 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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  14. 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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  15. K2ENF

    K2ENF Premium 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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