1. 2. 3. How to Use the FlexRadio Firewire Driver DPC Latency ...

How to Use the FlexRadio Firewire Driver DPC Latency Checker to Determine OperatingModeHow to Use the FlexRadio Firewire Driver DPC Latency Checker to Determine OperatingModeSystem DependenciesMinimum PowerSDR Version:Applicable Hardware:N/AAny hardware usingthe FRS Firewire driverContent provided by: FlexRadio Systems EngineeringVersion 3.2.0 and above of the FlexRadio Systems' Firewire hardware device driver has a veryaccurate DPC (deferred procedure call) analysis tool that will automatically estimate the properWDM operating mode for the Firewire driver.In order for the DPC Latency Checker to provide an accurate assessment of the recommendedoperation mode, you must check your system with all of the applications you would normally beusing at the same time with your FlexRadio transceiver. So if you use a logging program,digital mode programs, e-mail clients, web browsers and PowerSDR specific third-party utilitiessuch as the VoiceKeyer and DDUtil (just to mention a few) at the same time with PowerSDR theseprograms must be loaded and fully operational (not just sitting idle) along with PowerSDRrunning.Also, you need to run the DPC Latency Checker for at least 5 minutes to get a sufficientsampling duration for the results to be accurate as possible. A test duration period longer than 5minutes is even better.Even though the DPC checker may indicate that you can use the Normal operation mode, is stillhighly recommended that you use Safe Mode 1 as the Operation Mode. DPCs are only onecomponent that can adversely effect the performance of a real-time audio processing applicationsuch as PowerSDR. Normal mode operation is only recommended if the PC and all of theprograms running on it do not induce long duration DPC, such as when you use a dedicated PCenvironment to run PowerSDR. If you do receive audio drop outs and program freezes whenoperating with the normal mode, immediately revert to the recommended Safe Mode 1 setting.To determine your preferred operating mode, double left click on the FlexRadio Firewire ControlPanel icon to open the Control panel.1. In the Global Settings area, click on the DPC tab on the right hand side2. Left click on the radio button labeled "Enable DPC Latency Checker"3. You will see the DPC latency values displayed in the box below the linear time scale and theRecommended WDM Operation Mode box will be populated with the suggested operating

mode. In the example below the Max Latency is 97 microseconds (us) and the recommendedWDM Operation Mode is Normal Mode.4.5.The Operation mode will automatically be set to the recommended value.To reset the DPC test, click on the Reset button. You may want to run several tests withdifferent third-party applications running to determine which ones are more likely to result inlong duration DPCs. Microsoft Outlook is one program known to be very bad for initiating longduration DPCs.You can always over-ride the suggested Operation mode and select a mode that is more forgivingof longer duration DPCs and can provide a more stable operating environment for the FlexRadiotransceiver. If you experience audio "freeze ups" or slight glitching of the received audio, changethe Operation mode to one of the Safe Mode values.This KB article may reference additional files that are available on the FlexRadio Systems web siteDownloads page. Please use the URL(s) below to download the referenced materials.An Adobe Acrobat Reader may be required to open the file. You can download Adobe Acrobatfrom here.KB Source Document(s):None ReferencedLast Modified By: Administrator, Tuesday, January 06, 2009http://kc.flex-radio.com/KnowledgebaseArticle50328.aspxMonday, March 09, 2009