GC_ET.html
2022-08-29 01:13:35
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( web-site construction has been ongoing since 1994, for 27 years
>> AFX Advanced Filter ( read AFX basic FIRST )
>> AFX Roof-Triad Filter ( read AFX basic FIRST )
>> AFX 'V'_ _Variable f() Filter ( read AFX basic FIRST ) ( AFX 'V' is the Best-of-Class project )
( AFX 'V' is the Best-of-Class project )
>> AFX 'V'__Variable f() Filter ( read AFX basic FIRST ) ( AFX 'V' is the Best-of-Class project )
>> AFX Basic Filter is the current page --- please read through this page first !
>> then read the sub-pages for greater basic details.
About this project :
This project is our Current research in Analog I.C. Applications,
2014 thru 2021,
as applied to CW (morse code) Radio Operations
... posted at www.GeoCities.WS/glene77is
... posted at www.ResearchGate.net
Our Analog Project shows the evolution of filter design
from common Active BandPass circuits into Active Phased-Filtered circuits.
() This project has produced a Series of Analog Filters aproaching DSP quality
() which Emphasize Original Radical Designs .
() which Emphasize Phased-Filters and Parallel-Channel-Filters to generate Dual-Notch effects.
() This experimental project
() is about Analog Electronic Technology applied to Amateur Radio operations.
() is applied to Narrow Band-Pass Morse Code CW operations.
Our project's Applications could also include in-lab analog instrument filters
where the circuit is proto-boarded and no PC/computer required .
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Basic AFX circuit includes these modules:
1. Pre-Amp with Limiter
2. Roofing Parallel-Channel-Differential Filter
3. Active-Log_limiter
4. Quad-MFB audio filter
5. Differential-Phase Filter with Double-Notched Band-Passband.
6. Audio out 0.5 W class-B
****** The AFX 'basic' designs include these features :
****** BandPass 90Hz @ -3dB and 340Hz @ -60dB,
****** SideBand Spread = 5Hz per dB attenuation
****** Dual-Notch BandPass = -90 dB @ 350Hz bandpass
******* Variable-Frequency PassBand (600-700-800)
Below are the Functional Blocks of the General AFX circuit development
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( goto Schematics Page for Hi-res )
where it all started simply
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Revised details and hi-res schematics are in the section "AFX" 'V'
for the Phase-Filtered Dual-Notch Filter developments
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_____________the AFX Roofing-Triad-Differential Filter details: (GC_ET_AFX_CW_Roof.html)
_______ the AFX Active-Log-Limiter stage details : (GC_ET_AFX_CW_Limiter.html)
______________the AFX Quad-MFB Filter details (GC_ET_AFX_CW_Filter.htm)
_
Differential-Phase-Filter
& Integrating-Phase Filter
& Q20 Sharp Variable f(0) filter
(GC_ET_AFX_CW_FiltDIQ.html)
When Combined with Roof-Triad-Differential-Filters,
and the Quad-MFB-Band-Pass Filters,
the "A" stage Phase-Filter can produce Dual-Notches at -98 dB
Variance = 7 Hz sideband spread per dB attenuation
Refer to the above link for the details of the Phase-Flter stages.
"A" narrow Notch stage on left. "B" Wide stage center. "C" Q20 Sharp Band-Pass Follower Filter.
_________ AFX Audio Driver with Pulse-Signal-Shaping (GC_ET_AFX_CW_Audio.html)
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Above are the Functional Blocks of the General AFX circuit development
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*** P2S : Parallel-to-SumPFB-osc
*** P2D : Parallel-to-Differential
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Articles of Interest relating to CW Audio Filtering
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