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PostPosted: Fri Apr 12, 2019 9:37 pm 
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Joined: Tue Mar 15, 2016 10:24 pm
Posts: 4
I picked a StarTech USB Stereo Audio Adapter to play with. (ICUSBAUDIO2D)

I got it to work at 96K for both TX and RX But I had to run the
TX and RX at 16 bit, or the RX at 24 bit and the TX at 16 bit.


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PostPosted: Sat Apr 13, 2019 7:56 am 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1123
That may be due to resource limitations on the USB controller. Running sound at 96 kSPS, 24 bits pretty much max's out a USB 2.0 controller:

96000 * 24 * 2 = 4608000 bit per second

that's with no overhead or protocol added. USB 2.0 should be able to handle this easily but if you try to put some other data intensive on the same controller you'll get resource errors.

Fortunately, most PC's have multiple USB controllers so you should be able to find a way to plug everything is so that it all works.

In theory, 16 bits should be good for 96 dB dynamic range where 24 bits would provide 144 dB, in the case of the StarTech the dynamic range is not limited by the number of bits but by the analog performance of the device. StarTech lists the dynamic range as 91 dB so in theory it shouldn't matter much whether you run 16 or 24 bits.

The PI SDR IQ+ has 192 kSPS converters with 107/112 dB dynamic range (RX/TX) and connects to the PC using 100BaseT Ethernet it runs PowerSDR with almost 200 kHz of spectrum. With the PI SDR IQ+ the limiting factor is now the RS-HFIQ which doesn't have more than 100 dB of dynamic range.

73,
Jim WA2EUJ


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PostPosted: Thu May 30, 2019 10:28 pm 
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Joined: Tue Mar 15, 2016 10:24 pm
Posts: 4
Thank you, for the information.


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