My mistake. I just tried this with 192K sampling rate and you are limited to the minimum recommended buffer size, which means you do have to increase the buffer up to the next highest power of 2.
My testing was with 96K and I didn't encounter this problem since I use a 1024K buffer. My bad. -Tim -----Original Message----- From: Tim Ellison Sent: Wednesday, September 03, 2008 10:56 AM To: 'Howard Grams'; FlexRadio List Subject: RE: [Flexradio] Buffer Size for use with new device driver 3.2.0.1556 "The earlier device driver reported a suggested minimum buffer size, but allowed you to use a slightly smaller one to reduce latency, with the documentation saying "The Minimum Buffer Size shown in Figure 13 is not an absolute value, but rather an estimate. It is perfectly reasonable to select a buffer size smaller than the minimum recommended if your PC has enough processing power to overcome inherent system latency." But the new device driver seems to preclude that. It seems a bit much for the driver to not allow my choice of minimum buffer size, and then set itself to a value that cannot be matched in the PowerSDR setup." This is not true. You can set the sampling rate to 1024. We just need to work through the issue you are having. Please provide information regarding your PC O/S configuration. What is the "operation mode" of the Firewire driver? -Tim -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Howard Grams Sent: Wednesday, September 03, 2008 10:39 AM To: FlexRadio List Subject: [Flexradio] Buffer Size for use with new device driver 3.2.0.1556 Hi all, I followed the instructions for upgrading in order the Firewire device driver 3.2.0.1556, the firmware 1.2.1.1556, and finally PowerSDR 1.14.0. When I go to configure the sampling rate and buffer size in the FLEX-5000 Firewire control panel, I select my favorite sample rate of 192kHz. But when I try to set the buffer size, it is set to 1152, and will not change to 1024 even if I select that value from the drop-down box. (I can set 3072 or 2048, but none of the powers-of-two less than that.) The documentation still says that "It is recommended that only values that are powers of 2 (256, 512, 1024, and 2048) be used for the Buffer Size." When I configure PowerSDR 1.14.0, I am only allowed a buffer size of 256, 512, 1024 or 2048; size 1152 to match the firewire driver is not allowed, and of course the Flex-5000 documentation says "Change the Buffer Size to the same value you entered in the FLEX-5000 Control Panel (see Figure 13 on page 27)." The earlier device driver reported a suggested minimum buffer size, but allowed you to use a slightly smaller one to reduce latency, with the documentation saying "The Minimum Buffer Size shown in Figure 13 is not an absolute value, but rather an estimate. It is perfectly reasonable to select a buffer size smaller than the minimum recommended if your PC has enough processing power to overcome inherent system latency." But the new device driver seems to preclude that. It seems a bit much for the driver to not allow my choice of minimum buffer size, and then set itself to a value that cannot be matched in the PowerSDR setup. While I'm thinking of it, would it not be possible for PowerSDR to read out the sample rate and buffer size set in the device driver and use those values instead of putting the onus on the user to configure the same matching information in two separate places and run the risk of them not matching? -- Regards, Howard _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/ _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
