H A R D W A R E I N S T A L L A T I O N
C H A P T E R 1
Table 5 below shows initial settings for the driver's Sample Rate, Buffer Size and Operation Mode. You
should start with these values and if you desire you can experiment with other settings. In some cases,
where audio drop outs are being experienced, larger buffers may need to be used. Also, see Appendix
A for more detail.
Table 5: Initial Driver Configuration Settings
Modulation
Mode
Sample
Rate (kHz)
Buffer Size
Operation
Mode
CW
48
512
96
512
Safe Mode 1
Phone
48
512
96
1024
Safe Mode 1
Note:
The sample rate will automatically follow whatever is set in PowerSDR
(see page 32).
Operation Mode
There are four
Operation Modes
1
to choose from: Normal and Safe Mode Levels 1 – 3,
where Normal
is the most aggressive and Safe Mode 3 the safest.
The default operation mode is
Safe Mode Level 1
and should be used in almost all cases. If you choose to operate with the Normal mode and your FLEX-
3000 freezes up, you should revert to Safe Mode Level 1. In very rare circumstances your PC may
have internal latencies where Safe Mode Level 1 does not work optimally with your system. In these
cases, you should select either Safe Mode 2 or Safe Mode 3 to provide a stable environment to run the
FLEX-3000.
Once you have verified that all is working well, you may fine tune the settings to best match your
system and favored modulation mode.
Note 1:
We strongly recommend you leave the Operation Mode in Safe Mode
Level 1, which offers the best trade-off between ability to recover (no
freeze-ups) and audio latency. However, if you experience regular
freeze-ups, you should increase the Safe Mode Level to either 2 or 3
Note 2:
We strongly suggest you select buffer sizes that are powers of 2 (256,
512, 1024 and 2048).
Note 3:
The minimum buffer size that can be set is a function of both the
sample rate and the Safe Mode setting. For Safe Mode 1, the
minimum buffer size at 96kHz is 1024 and at 48 kHz is 512.
1
Technically these Operation Modes control how successfully the hardware driver recovers from buffer over and under runs.
Some hardware drivers and third-party applications issue what are called delayed procedure calls (DPCs). Higher Safe Modes
allow the driver to handle longer DPC latencies at the cost of more audio latency.
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2003-2009 FlexRadio Systems