100Hz need to be measured, the “Minimum cycles” value (1) will ensure that a longer
measurement period is used, to measure one cycle.
Discard samples
1
This parameter specifies the number of audio cycles (zero crossings) which are ignored, when
audio is first detected. The reason for this parameter is that in conjunction with the “Rise threshold”
parameter, it can be seen that the first audio cycle after the threshold is passed, is not a complete
cycle. The following zero crossing therefore needs to be discarded because its period
measurement will be too short. The default value of 1 should be fine for all purposes.
IQ mode
DISABLE
When IQ mode is enabled, the raw I and Q channels from the ADC are fed to the USB soundcard
directly, without any demodulation. This is suitable for people wishing to experiment with using
QMX as an SDR front end, with PC SDR software to demodulate I and Q channels.
IQ Mode is not suitable for use with WSJT-X and other Digi mode programs.
TX shift thrshld
0
Specifies the number of milliHz that the detected audio signal during transmit must change before
the Si5351A is reconfigured to transmit the new value. It can normally be left at zero. For modes
like FT8 it doesn’t make any difference. For modes such as FST4W with very slow transmit cycles
and very narrow tone spacing, this parameter should be lower or zero if possible.
5.14 Beacon menu
The beacon function is an added bonus feature of this QRP Labs transceiver kit! We already have
extensive experience for several years, developing the Ultimate-series QRSS/WSPR transmitter
kits (current incarnation, the Utimate3S). These have a huge array of functionality and modes
including CW, QRSS, DFCW, FSKCW, Hellscreiber (full speed and slow FSK), WSPR, JT9, JT65,
ISCAT, Opera and PI4. The vast majority of people use the Ultimate3S kit for WSPR operation.
Since it costs nothing (no extra hardware, at least) to add this functionality to the QMX transceiver,
why not! Let’s do it!
The CW transceiver beacon function therefore contains a simplified WSPR implementation which
can transmit standard WSPR messages. It also has a GPS interface for discipline of time,
QMX operang manual; rmware 1_00_012 29
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