Revised band-pass-filter

README.md

@@ -27,7 +27,7 @@ Your host platform for cross-compilation is assumed to be LINUX.
 
 We just need a simple band-pass filter to extract the AFSK-signal from the PWM signal:
 
-![band-pass filter](https://github.com/eleccoder/raspi-pico-aprs-tnc/blob/main/doc/schematic/band_pass_filter.png)
+![band-pass filter](https://github.com/eleccoder/raspi-pico-aprs-tnc/blob/main/doc/img/band_pass_filter.png)
 
 ## Build the library and the example application
 

doc/schematic/band_pass_filter.sch

@@ -6,7 +6,7 @@
 <setting alwaysvectorfont="no"/>
 <setting verticaltext="up"/>
 </settings>
-<grid distance="0.1" unitdist="inch" unit="inch" style="lines" multiple="1" display="yes" altdistance="0.01" altunitdist="inch" altunit="inch"/>
+<grid distance="0.1" unitdist="inch" unit="inch" style="lines" multiple="1" display="no" altdistance="0.01" altunitdist="inch" altunit="inch"/>
 <layers>
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@@ -1530,10 +1530,10 @@ Source: AVX .. aphvc.pdf</description>
 </class>
 </classes>
 <parts>
-<part name="R1" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="R" device="" package3d_urn="urn:adsk.eagle:package:13300/1" value="10k"/>
-<part name="R2" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="R" device="" package3d_urn="urn:adsk.eagle:package:13300/1" value="1k"/>
-<part name="C1" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="C" device="" package3d_urn="urn:adsk.eagle:package:13265/1" value="220n"/>
-<part name="C2" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="C" device="" package3d_urn="urn:adsk.eagle:package:13265/1" value="47n"/>
+<part name="R1" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="R" device="" package3d_urn="urn:adsk.eagle:package:13300/1" value="4k7"/>
+<part name="R2" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="R" device="" package3d_urn="urn:adsk.eagle:package:13300/1" value="4k7"/>
+<part name="C1" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="C" device="" package3d_urn="urn:adsk.eagle:package:13265/1" value="100n"/>
+<part name="C2" library="eagle-ltspice" library_urn="urn:adsk.eagle:library:217" deviceset="C" device="" package3d_urn="urn:adsk.eagle:package:13265/1" value="4.7n"/>
 <part name="GND1" library="supply1" library_urn="urn:adsk.eagle:library:371" deviceset="GND" device=""/>
 <part name="GND2" library="supply1" library_urn="urn:adsk.eagle:library:371" deviceset="GND" device=""/>
 </parts>

doc/simulation_LTSpice/Bandpass_AFSK_1200.asc

@@ -0,0 +1,48 @@
+Version 4
+SHEET 1 880 680
+WIRE 48 112 -32 112
+WIRE 64 112 48 112
+WIRE 160 112 112 112
+WIRE 208 112 160 112
+WIRE 336 112 288 112
+WIRE 544 112 336 112
+WIRE -32 176 -32 112
+WIRE 160 176 160 112
+WIRE 544 176 544 112
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+WIRE -32 320 -32 256
+WIRE 160 320 160 256
+WIRE 160 320 -32 320
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+WIRE 336 320 160 320
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+WIRE 544 320 336 320
+WIRE 160 352 160 320
+FLAG 160 352 0
+SYMBOL res 144 160 R0
+SYMATTR InstName R1
+SYMATTR Value 4.7k
+SYMBOL cap 320 192 R0
+SYMATTR InstName C1
+SYMATTR Value 4.7n
+SYMBOL voltage -32 160 R0
+WINDOW 123 24 44 Left 2
+WINDOW 39 0 0 Left 2
+WINDOW 3 24 72 Left 1
+SYMATTR Value2 AC 1
+SYMATTR Value SINE(0 1 1000)
+SYMATTR InstName V1
+SYMBOL res 192 128 R270
+WINDOW 0 32 56 VTop 2
+WINDOW 3 0 56 VBottom 2
+SYMATTR InstName R2
+SYMATTR Value 4.7k
+SYMBOL cap 112 96 R90
+WINDOW 0 0 32 VBottom 2
+WINDOW 3 32 32 VTop 2
+SYMATTR InstName C2
+SYMATTR Value 100n
+SYMBOL res 528 160 R0
+SYMATTR InstName R3
+SYMATTR Value 10k
+TEXT 32 392 Left 2 !.ac dec 1000 1 100000