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Flex 6K time stamp?

MikeBurns Member ✭✭
edited June 2020 in New Ideas
I'm using a 5000 now but the 6700 looks really sweet. My main requirement before I get a pair of 6700s is to be able to get GPS time stamped information on an IQ data stream (I want to do propagation and interferometer studies). After searching, my tentative conclusion is that this capability is not available now, based on the 2014 video at DCC by Steve when he said there is currently no vita-49 IF/data context stream, though he indicated it was easy to add and they were waiting for customer requests.

So I'd like to verify that this GPS time stamping is currently not available, ask if there are any concrete plans for it in the future, and if not request the feature.

Mike Burns, AB1LD


  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited March 2017
    It is not available.  I have converted your post into an Idea topic so other can comment on how they would use it.  The more use cases we have the greater the probability of adding the feature.
  • Martin AA6E
    Martin AA6E Member ✭✭✭
    edited January 2020
    I think precise time tagging would add a bunch of potential scientific applications to the 6000 series, so here's an up-vote.

    Does the GPS option, as now available, do "time" at all?  It offers a 10 MHz output with stability of 1 part in 10**12 over 24 hours (by memory), which says little about time precision, especially over shorter times.  People have suggested providing at least an NTPD service, to provide network time sync for the station.  That should be possible, with msec accuracy at least.  The request here suggests more precise tagging.  It may be possible with current hardware, but I suppose it would require FRS development and testing.
  • Ken - NM9P
    Ken - NM9P Member ✭✭✭
    edited June 2020
    Though I don't own a 6700, I would imagine that the time stamping would be handy in making my 6500 available at times for research and diversity applications.  Or perhaps later, allowing me to take advantage of other remote receivers and combine them with my 6500 to do some interesting diversity that is not possible with the 6500 alone.

    Add me to a theoretical 'Yes' list.....as a "someday" project.
  • MikeBurns
    MikeBurns Member ✭✭
    edited January 2017
    To expand on some of the possibilities in more detail.

    WSPR could be run without the difficulties of setting up the PC time sync which usually seems to be the most difficult part of getting it to work.

    New JT type modes (including WSPR) would become possible with exact time synchronization. Just as extra sensitivity can be gained with precise frequencies, so can more sensitivity be had with accurately synchronized times. Simplifying a bit, WSPR now uses about 1 second accuracy, with GPS synch should be able to get a microsecond or better accuracy, which gives six orders of magnitude increase that could be used for quite a few more dB sensitivity.

    Timing received signals from a known time source (such as WWV or Flex transmitters with the suggested enhancement) allows the measurement of propagation time. If time sync is within 0.1 microsecond that would mean measuring distances to about 100 feet. If station locations are known to typical GPS accuracy, this means the path through the ionosphere can begin to be reconstructed in some detail.

    With N stations equipped with the Flex synchronization the number of pairs of stations - and hence different propagation paths - scales like N squared. With not too many stations we could begin to sound the ionosphere at increasing resolution in space and time. Thirty stations would mean sampling almost 1000 areas of the ionosphere. I could imagine making images of the ionosphere from this data.

    With the synchronized timing, DFing becomes much easier. By comparing delays three stations can now locate a signal without the necessity of local directional antennas, and with much greater accuracy. With some signal processing coherent beam forming becomes possible, not just with local antennas but also geographically dispersed ones.  We might choose not just a direction to be sensitive to, but an actual geographic location.

    Much of this coherent signal processing requires a data connection (internet) between the stations, but since we are hams and can also transmit, the potential exists that we could do that over a link we set up ourselves. Or with some ingenuity it should be possible to design a mode that would incorporate the needed information within the digital protocol itself.

    All of this is made particularly attractive by the open source access now available with the Flex radio. WSPR evidently has already been implemented inside the radio(?) - that code could presumably be easily modified to take advantage of the time information. And with some more effort it could be expanded to take full advantage of the additional gain possible with accurate sync.

    All in all lots of possible experimenting to be done with the added potential for new and interesting digital modes.

    Mike Burns, AB1LD

  • K3SF
    K3SF Member ✭✭✭
    edited March 2020
    i concur that accurate time stamping wold add a range of possibilities to add new capability. One is indeed shared diversity reception across multiple receivers. Another would be a Dynamic Propagation Indicator.   so yes, yes  and yes...good idea...
    paul K3SF

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