Modern radios

Discussion in 'Amplitude Modulation' started by N2DTS, Nov 21, 2019.

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  1. K5UJ

    K5UJ Ham Member QRZ Page

    So what. A modern conventional radio is just a SDR in a box with a front panel.
    Assuming that's true, it has nothing to do with ham radio.
    I'm not arguing about anything, but your statement is a non sequitur. Since you seem to admit that a SDR rig can't be repaired at home, you are actually justifying my claim that older analog rigs with discreet parts are superior when it comes to maintainability.
    I don't believe broadcasters are yet running SDR transmitters.
     
    AC0OB likes this.
  2. KF5LJW

    KF5LJW Ham Member QRZ Page

    Fair question and the answer is pretty straight forward. More bits at greater sampling speed for less dollars. It is not a mature technology like superhets and CRT's. Never enough of either. Number of bits or resolution is where the dynamic range lies at roughly 6 db/bit. What I would call the toy SDR radios like Airspy and SDR Play are 12 to 14 bits. Correct me if I am wrong but I think FLEX uses 20 bits @ 245 Msps. That gives it roughly 116 db dynamic range.

    Just like Processors, RF A/D Converters will continue to improve. It is still a new tech with lots of room for improvement. It is just in the past few years that SDR radio receivers have surpassed conventional radio performance. It still has a long way to go. One heck of a market for it.
     
    KA0HCP likes this.
  3. N2DTS

    N2DTS Ham Member QRZ Page

    The China made G20 uses a 24 bit A/D converter, but its not a direct sampling radio.

    The problem is the chips get expensive as you go up.
    12, 14 and 16 bits are used in cell phones and other things so made in bulk, above that its the military that uses that sort of thing I hear.
     
  4. AC0OB

    AC0OB Subscriber QRZ Page

    Okay, I see what you're getting at.

    Personally, I would like see a super-duper version of the MAX10X series flash converter and or an improved pipeline architecture with more N-bit capability.


    Pheel
     
  5. AC0OB

    AC0OB Subscriber QRZ Page

    Modern Commercial Broadcast transmitters don't need to have an SDR architecture since they are not required to be frequency agile over many bands.

    However, A/D, D/A converters, FPGA's, and DSP processors are used widely in the Broadcash industry.

    Try desoldering one of these 144 pin puppies (it can be done but not without difficulties)::(

    FPGA XC3S502-pinout.jpg


    Pheel
     
  6. K4KYV

    K4KYV Subscriber QRZ Page

    K0OKS likes this.
  7. N2DTS

    N2DTS Ham Member QRZ Page

    Well Don, you would not want to let some sidebander get at it!

     
  8. N2DTS

    N2DTS Ham Member QRZ Page

    At that point, I would trash the board and get a new board.
    Many radios do hot have everything on one board, which helps.
    In work, we do not repair boards, we replace them.
    Many are repaired if its not too difficult and parts are available.

    In the telco world, things go obsolete in 5 to 10 years, manufacturers go bankrupt and stop supporting stuff and so on.



     
  9. AC0OB

    AC0OB Subscriber QRZ Page

    And again you just proved K5UJ's hypothesis.

    That is not only a problem in the Telco world but Globally.

    As in vacuum tubes, and since many patents have expired, some of the old IC masks are copied and sent to offshore foundary's.


    Pheel
     
  10. KM1H

    KM1H Ham Member QRZ Page

    The TS-950SD and SDX could be modded to TX thru the AM RX 6 kHz filter or even thru the 12 kHZ FM filter.

    The digital audio as built could go 200-3100 Hz with dip switch settings, higher with a mod Ive been told. I run mine wide open as built on AM AND even on SSB.
    A TS-940 with extra filters installed for CW and SSB is next to it with its own Alpha 76PA amp.

    Carl
     

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