[Elecraft] P3 beta firmware 01.29

[Alan Bloom]

This version is a slight modification of 01.28, which added the noise 
blanker.  The only changes are to the cursors in DATA A mode and another 
minor bug fix involving the FN1 label.  It can be uploaded from the P3 
beta web site:

ftp://ftp.elecraft.com/P3/firmware/beta/p3m0129.zip

Un-zip the file into the directory that P3 Utility uses for firmware.  
Make sure you have the most recent version of P3 Utility (1.13.1.23).  
The p3fwnotes.rtf file lists the new features and bug fixes since the 
last official release.

Below is some text I will be submitting for the P3 Owner's Manual to 
explain the new noise blanker feature.

Alan N1AL

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Noise Blanker

The noise blanker in the P3 reduces the effect of impulse-type noise on 
the display.  It has little or no effect on other types of noise such as 
thermal noise and static crashes but can dramatically reduce impulse 
noise from sources such as the AC power line and the ignition systems of 
motor vehicles.

The noise blanker is turned on or off using the menu entry "NB En" which 
can be assigned to a function key for easy access.  You can adjust the 
aggressiveness of the noise blanker algorithm with the menu entry "NB 
Level".  The higher the setting the more completely it blanks the noise 
but also the more likely it will cause distortion of desired signals. 
Use the lowest setting that effectively blanks the noise.  A value of 
about 10 or 11  is a good starting point for experimentation.  Note that 
the REF LVL and SCALE settings have no effect on the noise blanker.

If there are one or more very strong signals within the P3 displayed 
frequency range, the noise blanker has a hard time detecting the 
difference between the unwanted pulses and the wanted signals.  The 
solution is to narrow the span and/or offset the center frequency 
(perhaps using fixed-tune mode) to place the strong signals well outside 
the P3's display range.

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