SDR vs Analog; what is your preference?

Discussion in 'Ham Radio Discussions' started by N3AWS, Oct 10, 2018.

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  1. WN1MB

    WN1MB Ham Member QRZ Page

    The most complex method to transfer information isn't necessarily the fastest, most efficient, nor otherwise best.
     
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  2. WN1MB

    WN1MB Ham Member QRZ Page

    [​IMG]
     
    KA2RRK and KA4DPO like this.
  3. AF7TS

    AF7TS Ham Member QRZ Page

    The assumption that quantization error looks like random noise is one that bit the digital audio folk on the rear.

    _If_ the system is designed properly, you can ensure that quantization error is random, but if you do not take care to do so then the quantization error can be correlated to the signal, introducing harmonics and distortion.

    This does not detract from your final point, however. If the system has enough bits than the quantization error is rendered random simply by the existing analog noise of the system.

    73
    Jon
    AF7TS
     
  4. N6PAT

    N6PAT Platinum Subscriber Platinum Subscriber QRZ Page

    The only way to really compare SDR's to conventional radios is to actually operate both types of rigs for an extended period of time.

    I'm willing to bet that the vast majority of SDR operators have at one point owned a conventional radio. I'm also just as certain that the reverse is not true, for the majority of conventional radio owners have probably never operated an SDR.

    If that is the case then the only people who can truly provide a realistic comparison of SDR's to conventional radios are the SDR owners who have worked with both rig types for an extended period of time. Yes, lab testers can grind out the test results and you can go by those numbers but nothing substitutes for actual on the air day to day operation to determine which type you prefer and which works best for you.

    If you like your classic rig then stay with your rig. There's nothing wrong with that. But if you want unprecedented expansion capabilities (new bands, modes, etc) then go with an SDR.
     
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  5. KI3U

    KI3U Ham Member QRZ Page

    In post #108 KV6O wrote : ' Digital vs. Analog is a religious argument. There is no "wrong". '

    I agree there is no wrong, but I don't think it's a religious argument. So for example if I decide that for a particular radio-electronics situation I want to go with analog equipment because I want to be able to trust the results, rather than keeping my fingers crossed that umpteen billions of SDR transistors operating under bloatware length programming are not variously corrupting results, then it's not at all a religious sentiment - it's just my preference to suit a particular situation.

    Analog and digital have their respective domains. In some cases there isn't much choice but to go analog, at least at the front-end of the system, say in the most precisely obtainable measurements of certain parameters - achieved with an "analog" interferometer.

    Berj / KI3U
     
  6. W6UV

    W6UV Premium Subscriber QRZ Page

    My point is a valid one. Any really high performance superhet receiver design is going to be costly due to the high quality filters and other components needed to get that performance. The component complement on a direct sampling receiver is much reduced, plus the components are getting faster, better, and cheaper all the time. Note, too, that these components (ADCs, microprocessors, etc.) are not designed specifically for the ham market--they're used in commercial equipment like cellular base stations where there's strong economic incentives to improve the performance and reduce the cost of these parts.

    Comparing a modern direct sampling receiver to a 75A-4 may be an extreme example, but performance isn't the only criteria. A modern DS DSR receiver has capabilities unimaginable when the 75A-4 was a current product. Things like infinitely variable filter widths, vastly better filter shape factors, automatic notch filters, noise reduction, etc. My SDR rig can receive on eight ham bands simultaneously--how many can a 75A-4 handle?
     
  7. KV6O

    KV6O Ham Member QRZ Page

    How do you know an analog receiver isn't "corrupting" the results? I have radios that move anywhere from 30Mbps to 600Mps over 6GHz links, all in the digital domain. I can see any Bit Error Rates statistically, and know that with functions like FEC and adaptive QAM that data in = data out. In the analog domain this is impossible, each stage will "color" the signal in some fashion.

    I much more "trust" the results on a digital RF link than I do on an analog. Ever use an analog linked repeater system with more than a few links?
     
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  8. WN1MB

    WN1MB Ham Member QRZ Page

    One.

    Now it's my turn:

    How many of eight simultaneous communiques all on different bands are you - hopefully a human - going to be able to process real time?

    I suppose those among us who must fashion their shacks like NASA mission control must have the capability to receive on eight bands simultaneously for some reason. And therein lies The Truth.

    There's a point where multi-tasking becomes counter-productive - and ridiculous.
     
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  9. W6UV

    W6UV Premium Subscriber QRZ Page

    All of them. The rig's user interface presents each of these bands (called slices in the parlance of the UI) as a graphical spectrum/waterfall display. At a glance I can see if there's activity on a band and where it is. This is a very useful feature for monitoring bands like 6M that aren't open very frequently. Sure, listening to the audio of eight bands simultaneously isn't very useful, but audio isn't the only way to use the data from these bands. I've often had four copies of wsjt-x running at the same time on four separate bands while I watched for stations in countries/states that I needed. Find one and it's a single click to switch the transmitter to that band to make the contact. Try that with a 75A-4...

    Just because you can't imagine this kind of multitasking doesn't mean others can't or that it isn't useful.
     
  10. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    [​IMG]
     
    W1TRY, KA2FIR, W4NNF and 1 other person like this.

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