[hpsdr] Penny FPGA Load

[Bob G Mahrenholz]

Joe,

Thanks for the explanation. It makes more sense now.

I have a fast processor on a dedicated Asus mother board with no
Internet access so I don't think its the processor. Don, W4WXE
has been helping me check out the processor and its programing.

I also received a suggestion from Luke Steele about the sampling
rate and buffer size so I think I will try that next.

Thanks again,
Bob K4QQK
 

-----Original Message-----
>From: Joe Martin K5SO <k5so at valornet.com>
>Sent: Jul 14, 2011 7:12 PM
>To: hpsdr at lists.openhpsdr.org
>Subject: Re: [hpsdr] Penny FPGA Load
>
>***** High Performance Software Defined Radio Discussion List *****
>
>Bob,
>
>Changing the sampling rate changes the bandwidth of the IQ stream  
>passed to the PC;  192,000 yields 192 KHz bandwidth, 96,000 yields 96  
>KHz bandwidth, and 48,000 yields 48 KHz bandwidth.  The amount of  
>bandwidth displayed by the panadapter is user controllable, up to the  
>maximum bandwidth set by the sampling rate.
>
>Changing the buffer size does not affect the bandwidth or the  
>display.  Neither sampling rate nor buffer size affect the update  
>rate.  The display update rate is also user selectable in the menu  
>settings.  Changing the buffer size simply reduces the amount of IQ  
>data that the PC loads before needing to go back for more data.  The  
>reason that lowering this value sometimes helps audio drop outs is  
>that on some machines the process of loading the buffer takes too long  
>to keep up with the audio output stream rate, thus there is a period  
>of no audio (a drop out).   This is especially true with USB  
>interconnection between the PC and the HPSDR board set, not so much  
>with Ethernet connection.
>
>Audio drop outs are especially prevalent with slower computers and  
>with computers that are running many processes simultaneously so it is  
>a good idea to stop all unnecessary processes that may be running on  
>your machine if you are experiencing drop outs.
>
>Hope that helps.
>
>73,  Joe K5SO
>
>On Jul 14, 2011, at 5:49 PM, Bob G Mahrenholz wrote:
>
>> Joe,
>> Does changing the buffer size and/or sampling rate change the  
>> bandwidth
>> of the panoramic display, its update rate or what?
>> Bob
>
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