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Give us a Choice with the S Meter



  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited July 2018


    Do you really believe that when the IC-7610 Reads its Fictitious S0 at the antenna input when it is shorted then it is actually reading by IARU definition -127dBm (0.1microvolts @50 ohms @500Hz BW)?

  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited August 2018

    Here is the WOODBOX SMeter on my 6700

    Looks cute.. I already posted a link but here it is again



    it will do almost what you want like the swinging needles except give you the fictitious readings so many hams wish they had.

  • Rex K0KPRex K0KP Member
    edited July 2018

    Geez already, all readings are approximations, best guesses, estimations, and all are relative!  And yes quantum physics does work here, we are trying to measure electrons, those elusive little critters that have been proven to be able to be in more than one location at the same time - bi location.  They can also become entangled, traverse time, transfer information faster than the speed of light, and so forth.  Check out "Measurement in Science" a hard read concerning the philosophy of measurements.  The fact is our collective understanding of the universe is so lacking that we don't even know what we don't know.  We can't, except to measure something relative to something.  I posit the relative analog S Meter reading is just as valid as any other relative measurement made digitally.  But because it is relative doesn't make it not useful.  I posit that all measurements are fictitious, some might be a little closer to the truth than others.  If there even is real truth and real reality.  Do we even know what those two things are? 

  • Neal Pollack, N6YFMNeal Pollack, N6YFM Member ✭✭
    edited July 2018
    WOW, lots of passion on this thread :-)
    I never knew the idea of an S-Meter was so important to so many people.
    To me, it is far more important to be able to make the QSO, or hear the weak
    DX on SSB, than to stare at a meter all day   [which by nature of how many different
    manufacturers are doing it differently, is a "Meaningless Index of Performance" meter.]

    SO, if I go "key down" broadcasting a carrier, and 10 different people in different locations are receiving me
    with different model/brand rigs, different antennas, in different locations, each one will report a different reading.   Even if they were all lined up in the same field with their different rigs and antennas, they might
    well each read different.   So what use is that?    If they heard me at all, I am in their log book.  If not, I really
    don't care what the reading was :-)    And if they did log me, again, I really don't care what the reading was :-)

    And furthermore, as some previous poster pointed out, if you happen to work a contest, all the logged entries look like 59 to me, I have rarely seen different, since people are moving so fast to log contacts they don't seem interesting in staring at a meter long enough to analyze, should this be a 55 or a 57 or a 54???

    Are we perhaps getting all tangled up in measurebating, when it might be far more fun to make contacts?

  • James Del PrincipeJames Del Principe Member ✭✭
    edited July 2018
    Neal, my 45th anniversary RS Camaro has a cluster of gauges on the console for engine temperature, oil pressure, Transmission temperature and voltmeter. I could not possibly go for a spin or to the grocery store without that essential data.  Same for the 'S' meter.    HI HI       73, Jim
  • edited August 2018
    I find signal reports absolutely meaningless unless I'm engaged in a real ragchew and one of us want to compare signals with different antennas or amp on/amp off and in that case, it's extremely 'techy' to be able to quote -dBM figures.  For logging I usually use the default of 59/599 as it makes no difference for award purposes, and years from now I'm not going to care that I landed the KH1 at S1 or S9, once the QSL has been received.

  • Robert LonnRobert Lonn Member ✭✭
    edited August 2018
    Howard, I downloaded the software and set it up, however it does not look correct on my screen like yours, the image and check boxes are messes up and oversize??? Any ideas?? I run Windows 10.

  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited August 2018
    Robert, must be a resolution problem,,but I'm not sure how to fix that. Can you change the resolution to something then change it back,,it may correct it? Perhaps un install the meter and re installing it? it must have not installed correctly.
  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited August 2018
    Resolution or scaling issue in your windows screen setup.
  • Robert LonnRobert Lonn Member ✭✭
    edited August 2018
    SSDR software and other programs look perfect on my LG Monitor and on my Laptop,, so I dont think I need to change anything,, but might try that on my laptop... This is the first ever program that has done this in some 3 years... The S meter is neat, but not something I must have...  I may uninstall the program and try a few things... But appreciate the feedback.

  • James Del PrincipeJames Del Principe Member ✭✭
    edited August 2018
    All good points, Rick.   The meter is reasonably good for relative measurements, not so much for absolute values. Just think that even if it were 100% accurate, it would only be valid for that moment in time subject to propagation, antennas at each end, power levels, etc.     Jim
  • edited June 2019
    Similar question. I understand the bandwidth vs S meter reading, what I don't understand is why there is a discrepancy between the S meter and the Pan-adapter values.  With an extremely narrow bandwidth (~1 Hz.) the S meter reads S1 / -123 dBm and the noise level at the frequency of interest on the Pan-adapter has peaks at ~-132 and valleys at ~-136. The difference grows as the bandwidth increases.  With a nominal SSB bandwidth of 2.7 KHz the S meter reads S3 / -107 dBm while the Pan-adapter remains the same as before.

    In summary I noted that the noise floor on the Pan-adapter does not change as the band pass changes from very narrow to very wide and the difference between the two varies from ~13 to ~27 dBm.

    So my (similar?) question - Why is there a discrepancy between Pan-adapter and S meter?.
  • HCampbell  WB4IVFHCampbell WB4IVF Member ✭✭
    edited November 2018

    Good question.  Here’s an old post I bookmarked to help me remember:


    Just curious why these numbers are so far apart?

    Steve - N5AC, VP Engineering

    Official Response


    Quick analogy: Think of the signal you want to hear as a gold watch and noise as muddy water. I give you a bucket with several inches of muddy water and the gold watch in the bottom.  You can see a glimmer of the watch and know it's in there somewhere (you are zoomed out on the panadapter, the noise floor is high and you can see a signal occasionally peak out of the noise).  So you decide to see if the watch is in the bucket and you split the water between two buckets (zoom in on the panadapter).  This causes the watch to be in one of the buckets only and now you can see it better through the mud.  As you continue pouring into more buckets, 4 then 8 then 16 buckets, the water level goes down by half each time (3dB lowering of noise floor in panadapter).  Eventually, the watch is sticking out of the water and you can see exactly what it is.

    You'll notice that this behavior is consistent -- as you zoom out the noise floor rises by 3dB with each zoom-out because the bucket (called the bin) has twice the noise in it.  The net-net is the amount of noise you see is dependent on the bandwidth in which you measure it.  So in order to talk about "noise floor," hams have adopted a standard.  We talk about the noise floor in a 500Hz detection bandwidth.  To measure this "official ham noise floor level," just set the width of the filter in your slice receiver to 500Hz and then read the meter.  This is roughly equivalent to zooming all the way in on your FLEX-6000 and the zooming out 6 times (FLEX-6500 or FLEX-6300) or 8 times (FLEX-6700) and then the number read along the panadapter (In reality, the bin size at this point will be ~374Hz and so the panadapter reading will be off by about 1dB).

    The slice meter S-meter measures the total power of everything in the bandwidth of the slice filter -- noise and signal -- and provides this as a single power reading.

    Another analogy might be to look at a pail of dirt spread across your living room floor.  If you look through a paper towel tube, you might tell your wife that the dirt level is only "a tablespoon."  Your wife wife might look at the whole room and say "No!! There's an entire pail of dirt in here!"

    One final thing -- you will also hear hams say "I can see 10dB into the noise floor" or you might look at WSJT and see that it has numbers like -20dB meaning it sees a signal 20dB into the noise.  How is this possible?  You clearly cannot see a signal below the noise floor in your panadapter, right?  Well again, the noise floor is defined as the 500Hz noise floor.  What's really going on is that they are restricting the detection bandwidth (think narrow CW filter) and they they can hear the signal with less noise.  Your ears (brain) do this naturally on CW -- you can hear a single tone stick out of the noise because your brain does the equivalent of an FFT, divides it into buckets and then tells your consciousness "there's a bunch of noise but there a tone of roughly 1000Hz in there."  WSJT uses very narros bandwidth detectors and time-averaging to see "below the noise floor" but what's really happening is that it's reducing the detection bandwidth, splitting the noise into buckets and then looking for signals in the presence of less noise.


    Please remember that you cannot compare noise read on the S-meter in the slice receiver and the panadapter noise floor because of the different bandwidths of receivers used in the slice receiver (filter) and the FFT bin bandwidth (unless they are the same based on a zoom level).

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