S E T U P F O R M C H A P T E R 8
buffer at 48kHz sampling rate is 2048/48000 = 42.7ms in length. Faster machines should be able to run 512
Sample buffers without issue. For best CW performance, set the audio buffer to 512 or less.
Sample Rate
The sample rate is locked to 48kHz unless your selected hardware supports higher rates (96 or 192kHz).
Using these higher sampling rates will result in a wider panadapter display. For best CW performance set
the sample rate to at least 96kHz
Line In Gain
Sets the Line In volume on the selected mixer for consumer grade cards. Note that recommended and
legacy cards have been tested and the optimal value is set by default. Selecting Unsupported Card on the
Sound Card Selection will unlock this control. This control is not used for the Delta-44 or Edirol FA-66.
Mic In Gain
Sets the Microphone volume on the selected mixer for consumer grade cards. This control should be set in
order not to overload the sound card. The front panel MIC control can add software gain if using a
professional grade card (Delta-44 or Edirol FA-66) or if your consumer card cannot provide adequate gain.
Latency
Using the manual option, the user may add additional latency (in milliseconds) to the audio buffering
system for better audio performance. When the manual setting is off, the delay is set to 0ms. Note that some
systems will have trouble with the manual setting on and values below around 15ms. We recommend using
the default automatic latency setting for best results.
Output Voltage
Figure 67:Sound Card Output Voltage
Note: The Sound Card Output Voltage is not displayed when using a
recommended or legacy card. We have found that the variance from card
to card (same model) is negligible (+/- 0.04V). For this reason, for
recommended and legacy cards we only use our measured default values.
The sound card output voltage is the measured single channel AC voltage on the sound card Line Output
when running the test. To run the test, first unplug the To Line Out cable from the SDR-1000 enclosure.
Click the Test button to begin sending the full range signal. Use an AC voltmeter to measure the voltage
between the connector tip and the connector ground. Next, record the measured value in the box. Using a
value that is higher or lower than your actual output will cause the power calibration to be inaccurate.
77 FlexRadio Systems
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