Apache Labs ANDROMEDA ANAN-7000DLE MKII, User Manual

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PureSignal update for PowerSDR mRX PS
SIGNAL PROCESSING
In the 'Advanced' controls section, the 'Calibration Information' panel is visible, and, there are four new controls
that were not in PureSignal 1.0. These new controls represent new functionality that has been added and they
should normally be left at their default settings. The controls are:
** '
PIN ': Applies
a priori knowledge of the required amplifier gain and phase correction in situations where the
collected samples are insufficient for optimal calibration. This need can arise when the radio is not being
properly driven to allow sample collection over the entire operating range, or due to some other fault or
incorrect operation. This is very useful when there is a significant voltage regulation problem in an amplifier
and, therefore, the gain and phase of the amplifier appear somewhat "unstable" as PureSignal collects feedback
for calibration.
** '
MAP ': Changes the sample-collection requirements to allow easier calibration in situations where the
amplifier is detected to be in heavy gain compression. This is done by mapping the collection intervals to a
different set of intervals based upon the level of compression. Note that this relaxation in sample-collection
requirements MIGHT cause some degradation in high-order IMD. This is adaptive; the extent of the remapping
depends upon the level of compression. If there is no compression, this function has no effect.
** '
STBL ': Substantially separates the "static non-linearity" of the amplifier from the memory effects before
computing the correction. This is a step toward further work on memory effects in a future release. When this
is enabled, the "blue" and "yellow" displays on AmpView will show the extracted static non-linearity.
** '
TINT ': A largely experimental feature allowing selection of the size of the upper interval within which
samples are required to be collected. The dB value reflects the reduction from full-scale. For example, 2.5dB
means ~75% of full-scale voltage or ~56% of full-scale power. This should normally be left at the default
setting of 0.5dB (~94% of full-scale voltage and ~88% of full-scale power). This feature can be useful in
situations where an external processing system, for example a Digital Audio Workstation, is used to precisely
control the audio drive amplitude. Note, however, that Auto-Attenuate should probably be disabled when not
driving to full-scale as there may not be enough information to accurately calculate its setting which can result
in instability in the attenuator value.
NOTE ON AMPLIFIER GAIN COMPRESSION AND TUNING . For modes requiring linear amplification, it is
NOT recommended to drive amplifiers into heavy gain compression or "flat-topping." Doing so will increase IMD
significantly when PureSignal is NOT active and may increase it slightly when PureSignal is active, due to heavy
reliance on the MAP function. Driving into heavy compression will not increase your peak output power by any
meaningful amount and, when using PureSignal, it will not increase your average power at all since PureSignal
will remove the compression in the output signal to restore linearity. For vacuum-tube amplifiers with 'Tune'
and 'Load' controls, if your amplifier has excess power capability compared to your desired output level, you can
generally avoid heavy gain compression by tuning the amplifier for a higher power level than your desired
output and then backing down the drive level to achieve the desired output. The down-side of this tuning
approach may be a slight reduction in amplifier efficiency. It should be noted that there are "proper" ways to
increase your average transmit power; those include the use of the Compressor and the CESSB Overshoot
Control algorithm.
Copyright Apache Labs © page 43 26 February 2019