I believe the Flex to be 16 bits and the Icom to be 14 bits, but if anyone has data to the the contrary, feel free to post it.
Even the most expensive 16-bit A-to-D converters, operating at RF sampling rates, can exhibit nonlinearity or even non-monotonicity in their lowest-order bits. The usual work-around is to dither (spread) the clock signal, either on the chip itself or by injecting a separate tone. This can help, but the results can be uneven. The result is that two direct-sampling radios of exactly the same model can vary considerably in IMD performance. In the K3S, the ADC is operated at much lower sampling rates (48 kHz, as required for the 15 kHz second IF). Since it is also fully protected by crystal roofing filters, an entire class of wideband sampling spurious responses is eliminated, and the much higher “NBSFDR” spec applies (narrowband spurious-free dynamic range). No dithering is required, and receiver sensitivity never has to be reduced due to out-of-band signals. That and the strong front end are why so many Field Day, multi-op contest, and DXpeditions stations use K3S’s and K3’s. 73, Wayne N6KR > On Jul 30, 2017, at 9:49 AM, Lynn W. Taylor, WB6UUT > <kx...@coldrockshotbrooms.com> wrote: > > Wayne, > > How much resolution is available (how many bits per sample) in the typical > modern A/D converter used in an IC-7300 or Flex? > > 73 -- Lynn > > On 7/30/2017 9:14 AM, Wayne Burdick wrote: >> The K3S, an SDR/superhet hybrid, includes narrowband protection of its >> A-to-D converters in the form of roofing filters (crystal filters). This is >> fundamentally different from the approach taken by direct-sampling radios, >> which have only very broadband filtering ahead of their ADCs. Typically, >> front-end band-pass filters are 0.5 to 4 MHz wide. Their ADCs will be >> impacted by all strong signals in this range, alone and in summation. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
