The Input Device group allows the input device to be selected. There are currently two
options in the dropdown: most users will choose
Sound Card for the input device but the FUNcube Dongle Pro+ can also be used.
The Input tab, showing the 2 current choices
Whichever device is used the Sample Rate will show the available rates and should be set to the required
maximum span. The viewed span
can easily be set later to anything down to 1kHz .
Swap IQ swaps around the I and Q input channels. The unwritten convention is for I to the Left channel, Q to the Right but this checkbox can
save resoldering a connector.
In the Sound Card group choose the Driver - for most users an MME driver is often favourite for sharing
with other software, like CW
Skimmer or a logger. ASIO is a good low-latency driver but listening to the NaP3 output on the computer speakers will need a right click on
the Console RX gain controls. Now choose your Input, which should correspond with the card (or Dongle) being fed your I/Q signals. With
MME the Output can be left as the Microsoft Sound Mapper to hear the NaP3 receiver audio on the computer (Main to left, Sub to right if
the Sub receiver is on, otherwise Main through both).
Add Latency is an important setting to avoid choppy or stuttering sound; it needs to be of the order
of 10ms for ASIO and 25ms for MME
but will vary from card to card and driver to driver. Latency is the time taken by the NaP3 DSP to process the signal, heard as a delay. A DC
Block option allows some reduction of any sound card centre spike but the results will vary with different cards. Sample Offset is needed for
a few seriously cheap cards which do not interleave the sound samples properly.
Set Gain opens a level control, described in the next section, to adjust the display calibration with the card set externally for optimum
performance. This ensures that the incoming signals do not exceed the NaP3 headroom.