Time signal intruder

Discussion in 'Ham Radio Discussions' started by KA2FIR, May 27, 2018.

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  1. VE3GTC

    VE3GTC Ham Member QRZ Page

    Blake,

    Well done.

    I was doing exactly the same thing last night and my results match yours. As well, my experience level with KiwiSDR is pretty much the same as yours. Practice makes perfect.

    This KiwiSDR TDoA extension is pretty slick. Used with care I can see that it will become a very useful tool.

    If I had the extra $$ in my radio fund I would put another receiver on line but that is not going happen for a while.

    cheers, Graham ve3gtc near Ottawa Canada
     
    K5URU likes this.
  2. W0PV

    W0PV Ham Member QRZ Page

    It's great that two similar methods yet using different tech approaches have converged on and confirmed a similar area of origin, first Graham and his gang on HF Underground and now Blake with KiwiSDR.

    Now if only someone in metro Chicago could organize a LAN of HF listeners to get a possible closer fix to the neighborhood and then go moe-bile to do the "last mile" tracking :D

    If I fly up there later this year the FT817 and Hamsticks mag-mount will come along just to do that.

    Who ever finds its antenna lat-lon / address ought to be declared a Master Fox Hunter.
     
  3. KK5JY

    KK5JY Ham Member QRZ Page

    Regardless of who is doing this, what do people have to gain from sending WWV-style ticks on random HF frequencies?

    The only thing I can think of is that perhaps they are sending short pulses to be able to measure the propagation delay at other locations. The short pulses might allow them to capture the different returns from multipath.

    Moving the "carrier" around lets them measure the same effects on different bands.

    I'm still trying to figure out how HF radio channels allow market speculators to execute trades faster than they can get by dropping fiber or copper...?
     
  4. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Read the rest of the thread. The purpose is probably digital communications for high-frequency financial trading. Not proven yet, but there is a likely location identified (Chicago area), an experimental FCC license identified, and company identified.
     
  5. KK5JY

    KK5JY Ham Member QRZ Page

    Except that doesn't make sense in light of the other question I asked. A noisy, fadey, skywave signal can't compete with copper or fiber in terms of speed, bandwidth, and propagation delay. The only reason to attempt it would be to communicate at a significant distance, which just compounds those issues. So using HF to facilitate high-speed trading just doesn't fly.
     
  6. K3DCW

    K3DCW QRZ Lifetime Member #212 Life Member Platinum Subscriber QRZ Page

    Except, that it can POSSIBLY compete. A radio wave travels at the speed of light. Let's presume that the computer communications do also. Both leave point "A" at the same time and arrive at point "B" at the same time. Except, there are delays on the computer circuits. You have switches that take the signal and bundle in into and out of other signals, or convert it from copper to fiber and back, move it from one carrier to another, and even simply route it around the internet. Each of these conversions takes a bit of time: microseconds, no doubt, but time nonetheless. That's why they are experimenting. They may learn and decide that the multiple skywave hops make the system perform with the same (or even worse) lag as that of terrestrial communications, or they may find that microsecond edge they're looking for enabling them to make millions.

    We're talking about an industry where the difference in making $$$ is measured in micro and nanoseconds, where a location on one side of the street is preferred over the other side of the street because of the nanosecond advantange in propagation delay over fiber, where they purposefully locate as close as possible to the highest speed direct connections to the exchanges, and where computers make decisions to buy and sell thousands of times each second. In this kind of world any edge matters and spending a few millions to experiment is chump change.
     
  7. KK5JY

    KK5JY Ham Member QRZ Page

    The problem is you are comparing Internet circuits, rather than dedicated fiber. People with this kind of cash aren't just dropping a DSL line for comparison. They can get uninterrupted glass for long distances, and that essentially eliminates a lot of the switching "stuff" that the rest of us would encounter when making Internet connections.

    Also, the HF path isn't point-to-point. It's point to ionosphere to point, possibly multiple times, and there's some serious distance that gets added to the path by doing so, even for NVIS.

    HF transmission and reception equipment also involves propagation delay. Anything that can be sent through the air can be sent through fiber faster.

    I also noticed that the license linked earlier lists PSK QAM as the only emission designator on the frequencies we're talking about. They list D7D as the designator, with bandwidths varying between 3kHz and 13.5kHz. I haven't seen any evidence that these little "ticks" contain any thing but dead carrier.

    So if the experimental license linked earlier is in fact representative of the experimenters being documented here, they are not complying with the terms of their license. Not even close.
     
  8. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Radio is faster. The propagation velocity is always slower in another medium such as fiber or cable. And then there is the delay through any amplifiers, switches, etc.
     
  9. K3DCW

    K3DCW QRZ Lifetime Member #212 Life Member Platinum Subscriber QRZ Page

    They aren't interested in using HF for connecting Kane County to Cook County IL, they're talking about connecting US to Europe, and beyond. Try to go transoceanic on your own fiber: you can't -- at least not yet. You have to go through the big carriers and that means loading on and off of their networks.


    As I said and addressed with my "multihop" skywave comments.


    If all you're trying to do is measure propagation delays to do a basic comparision of terrestrial and skywave paths, all you would need is a "tick" time-sync'd to start each pulse (radio and computer) at the precise same time. First one to be received on the far end wins! Of course, you don't do it once, you do it tens of thousands of times, in all seasons, day and night, and in all kinds of propagation conditions. Still all you need is a "tick".


    I don't disagree.


    In the end, it is experimental and it is their money to burn. The POSSIBILITY that it might work is what is apparently funding these experiements. However, I agree with you overall and believe that they'll find that it isn't worth it: better the known and consistent and manageable delays in international circuits rather than the possibilities of lost data packets or even blackouts due to ionospheric activity.
     
  10. KK5JY

    KK5JY Ham Member QRZ Page

    I have no doubt that the tick is just probing the ionosphere, but if that's what is happening, it isn't the people in the experimental license linked to the thread earlier, because A1 emissions aren't permitted under that license on any of the licensed frequency ranges.
    That makes the assumption that the "tick" signal is coming from the station described and photographed earlier, and I haven't seen anything yet showing that to be the case.
    That's the speculation in the articles. One of the articles had the good sense to admit that they were speculating about both the identity of the participants, and their motivations.

    All I'm saying is that the conjecture doesn't match the details we see/hear. There's more going on here than just some rich day-traders playing with their radios to shave microseconds from trading times.
     
    Last edited: Jul 13, 2018

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