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[Discuss-gnuradio] Problem with 192KHz sampling rate on alsa source

From: Marcus D. Leech
Subject: [Discuss-gnuradio] Problem with 192KHz sampling rate on alsa source
Date: Tue, 28 Dec 2010 17:14:00 -0500
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20101103 Fedora/1.0-0.33.b2pre.fc14 Thunderbird/3.1.6

I'm running Fedora 14, with the latest Gnu Radio code.

I have an M-Audio Revolution 7.1 sound card, which can sample up to 192KHz.

I have a flow-graph that sets the card up for 192KHz sampling, and I've confirmed that the hardware apparently thinks it's sampling at 192KHz, but when I display the FFT of the resulting sample stream, the spectrum is "mirrored" about 48KHz, almost as if something, somewhere, is running at the wrong sample rate, but I can't figure out *where* that might be.

Do I have to do anything special to pulseaudio configuration to get support for the 192KHz rate? This particular card uses the Envy24HT
  (ICE1724) chipset:

Here's the hw_params file from /proc/asound  for the card in question:

format: S32_LE
subformat: STD
channels: 2
rate: 192000 (192000/1)
period_size: 1920
buffer_size: 7680

This is a 24-bit card, which means that the driver is using S32_LE -- does that confuse Gnu Radio Alsa source? Is it expecting 16-bit samples,
  and mis-interpreting the 32-bit samples it's getting?

Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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