This list was updated in 2018. http://www.telepostinc.com/soundcards.html <http://www.telepostinc.com/soundcards.html>
wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Oct 31, 2021, at 11:54 AM, Joe Subich, W4TV <li...@subich.com> wrote: > > >> What I haven’t quite figured out is how important is this really is >> to weak signal digital decoding. > > Low noise in a sound card is important to weak signal decoding in two > ways: > > 1) you want the inherent noise floor in the sound card to be 10 to 15 > dB *LESS* than the minimum - receiver noise + "antenna" - noise. On > VHF with a very quiet receiver the receiver noise can be quite low. > > 2) high noise level in a sound card directly subtracts from the dynamic > range (ADC clipping - noise floor). With a high noise floor, strong > signals either overflow the ADC or the receiver AGC must reduce gain > with moves the weak signals below the (higher) noise floor. > >> After testing, I settled on a Sound BlasterX G5 model SB1700 which > > tested at about -120dB noise level. > > -128 dB relative to what? A quality 16 bit sound card has a theoretical > dynamic range of 97dB - a quality 16 bit card (low noise) will produce > about 90 dB dynamic range in practice. A 24 bit sound card has 144 dB > theoretical dynamic range but a practical 24 bit sound card will produce > maybe 115 dB dynamic range but to take advantage of that dynamic range > the sound card (any audio preamps and the ADC) need to operate with a > supply voltage greater than the typical 3.3 or 5 V USB supply. A 24 bit > sound card with a 5 V (USB) supply will be lucky to achieve 100 dB > dynamic range. > > 73, > > ... Joe, W4TV > > > On 2021-10-31 10:41 AM, SteveL wrote: >> Dave, >> This interest caught my eye awhile back: >> http://members.chello.at/oe1mww/sound-card-check/ >> <http://members.chello.at/oe1mww/sound-card-check/> >> I’ve tested several of the inexpensive (<$10) nameless USB sound card >> dongles using his method and saw a wide variety of noise floors - however >> significantly higher than a name brand USB card. After testing, I settled >> on a Sound BlasterX G5 model SB1700 which tested at about -120dB noise >> level. How does this compare? My nameless sound dongles noise level tested >> -70 to -90dB - a big difference. >> What I haven’t quite figured out is how important is this really is to weak >> signal digital decoding. >> Steve >> aa8af >>> On Oct 30, 2021, at 10:49 PM, David Christ <radio...@mchsi.com> wrote: >>> >>> Yes this has been bead to death previously. Jim Brown made a number of >>> suggestions in a paper from 2014. However the market has changed. Those >>> models are all discontinued and those manufacturers' follow ons are much >>> more expensive and have features that are not needed for sound card modes. >>> Any offerings of these older models seem to be coming from overseas. The >>> $100 and under market seems to be dominated by mystery brand dongles which >>> are a gamble. >>> >>> So can any one recommend a tried and true sound card interface for use >>> between an K3 (without a sound card) and a MacBook Pro (which has no mike >>> or line in jack)? I would like to hear from people who have actually the >>> unit, not just speculation. >>> > > > ______________________________________________________________ > 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 wun...@wunderwood.org ______________________________________________________________ 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
