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Flex 6400M noise floor

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Answers

  • Rex K0KP
    Rex K0KP Member ✭✭
    edited January 2019
    It appears that the following phenomenon is evident.  The design of the Flex makes for an S Meter that is incapable of displaying, on the meter that is, a signal below S 4 in strength.  This is because the receiver is displaying, on the S meter, noise generated internally within the filter via FFT bins.  Is this correct?

    Also, what is the matter with having the option to click in a relative reading S meter?   I think a whole lot of Flex customers would appreciate that ability.  We use all kinds of methodologies to measure things, peak, quasi peak, peak to peak, RMS, weighted average, PEP, bandwidth limited, relative indications and so forth in electronics all the time.  

    This is ham radio folks, not the National Institute of Standards Laboratory.

    Successful business models value their customers opinions and desires.  I'm sure Flex could conjure up an algorithm or two to simulate a relative analog S meter indication as an OPTION to click in if desired. 
  • Rex K0KP
    Rex K0KP Member ✭✭
    edited July 2018
    Well done Elliott.  Exemplary. 
  • Martin S. W7RU
    edited July 2018
    I am starting to understand why FT8 might become a way to establish a contact better than CW ;-)
  • N8SDR
    N8SDR Member ✭✭
    edited July 2018
    You want to see a signal below S4 or S5 simple, narrow up your receiver bandwidth! 
  • Bill -VA3WTB
    Bill -VA3WTB Member ✭✭✭
    edited July 2018
    You first comment is almost correct. What you are seeing as you pointed out the FFT bins are being sampled, this is not internal noise as such,,but the sampling we can  see in the pass band.
    If you narrow the pass band down to nothing you see the S meter read around 1 or 0.
    so what we see is the bins in the pass band sampling.
  • ua3lm
    ua3lm Member ✭✭
    edited November 2018
  • Burt Fisher
    Burt Fisher Member ✭✭
    edited November 2018
    His may be better but I don't understand Russian
    https://youtu.be/B6B89jvjto8
  • STEVE_KW5TX
    STEVE_KW5TX Member ✭✭
    It reminds of Joe Biden explaining how the economy is actually GREAT! and we should be thankful! - lol

    S5 here on the dummy load... even with the ATT on. Amazing how sensitive this thing is even without an antenna WOW...  hihi
    :#
    
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    @STEVE_KW5TX

    We could fake it as all other HF radios do, but we chose to do it accurately. Our engineers are very particular when it comes to doing math correctly.


  • ua3lm
    ua3lm Member ✭✭
    It would be great if FLEXRADIO instead of a useless ATU would make a preselector to the input of the receiver. Like yaesu ftdx101. Maybe then the ADC will stop overloading at night at 7 MHz and during the day at HF ​​bands!
    Our Chinese broadcast stations are overloading flex
    


  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited January 23

    @ua3lm

    Don't confuse a Radio Antenna Matching Unit with an external antenna tuner with a much broader tuning range. The AMU in the Radio actually exceeds its published operational range.

    The Chinese radios aren't exactly clean. I own one and have had it on the spectrum analyzer. It's IMD is terrible.

  • STEVE_KW5TX
    STEVE_KW5TX Member ✭✭

    @Mike-VA3MW

    So the standard used on my Yaesu and Icom and Elecraft was done by "fake" engineers? ok! got it!

    smh

    who knew lol

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    No, not at all. (assuming we are talking about S meters)

    When SuperHet was created over 100 years ago in 1918, that was the best they could do.

    So, next it was assumed that when your antenna was not connected, then that had to be S0. That was wrong, but simple to do and calibrate.

    But, if you design and sell a radio, you get to build it the way you wish. There is no law or requirement it has to be what it is.

    Maybe instead of an S meter, we use Banana's. You could have 10 Banana signal today! (I like the sound of it).

  • John KB4DU
    John KB4DU Member ✭✭✭✭

    Art Collins defined a standard for S-meters long ago. His standard included measuring the signal strength at the antenna terminals, 6 dB change per s unit and the other parameters Flex uses. My Icom radios don’t use any of this. Typically 3dB per s-unit but it’s not consistent, and surely not measured at the antenna terminals.

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