diff --git a/README.md b/README.md
index ea9e309..cf4c668 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 <img alt="GitHub last commit" src="https://img.shields.io/github/last-commit/eleccoder/raspi-pico-aprs-tnc">
 
 # raspi-pico-aprs-tnc
-A TX-only [TNC](https://en.wikipedia.org/wiki/Terminal_node_controller) (Terminal Node Controller) to generate the [AFSK](https://en.wikipedia.org/wiki/Frequency-shift_keying#Audio_FSK) (Audio Frequency-Shift Keying) audio tones for [APRS](https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System) (Automatic Packet Reporting System) messages using a [RP2040](https://en.wikipedia.org/wiki/RP2040) microcontroller on a [Raspberry Pi Pico](https://en.wikipedia.org/wiki/Raspberry_Pi) board.
+A TX-only [TNC](https://en.wikipedia.org/wiki/Terminal_node_controller) (Terminal Node Controller) to generate the [AFSK](https://en.wikipedia.org/wiki/Frequency-shift_keying#Audio_FSK) (Audio Frequency-Shift Keying) audio tones for [APRS](https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System) (Automatic Packet Reporting System) messages using a [RP2040](https://en.wikipedia.org/wiki/RP2040) microcontroller on a [Raspberry Pi Pico](https://en.wikipedia.org/wiki/Raspberry_Pi#Raspberry_Pi_Pico) board.
 
 ![Signal Flow](https://github.com/eleccoder/raspi-pico-aprs-tnc/blob/main/doc/img/signal_flow.png)
 
diff --git a/doc/img/signal_flow.png b/doc/img/signal_flow.png
index 1f47957..7a1e98e 100644
Binary files a/doc/img/signal_flow.png and b/doc/img/signal_flow.png differ
diff --git a/doc/signal_flow.odg b/doc/signal_flow.odg
index fc35fe0..8444db3 100644
Binary files a/doc/signal_flow.odg and b/doc/signal_flow.odg differ
diff --git a/doc/simulation_LTSpice/Bandpass_AFSK_1200.asc b/doc/simulation_LTSpice/Bandpass_AFSK_1200.asc
index cb570ca..d11eeba 100644
--- a/doc/simulation_LTSpice/Bandpass_AFSK_1200.asc
+++ b/doc/simulation_LTSpice/Bandpass_AFSK_1200.asc
@@ -1,11 +1,11 @@
 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 400 112 336 112
+WIRE 544 112 400 112
 WIRE -32 176 -32 112
 WIRE 160 176 160 112
 WIRE 544 176 544 112
@@ -19,6 +19,7 @@ WIRE 544 320 544 256
 WIRE 544 320 336 320
 WIRE 160 352 160 320
 FLAG 160 352 0
+FLAG 400 112 out
 SYMBOL res 144 160 R0
 SYMATTR InstName R1
 SYMATTR Value 4.7k
@@ -26,11 +27,12 @@ SYMBOL cap 320 192 R0
 SYMATTR InstName C1
 SYMATTR Value 4.7n
 SYMBOL voltage -32 160 R0
-WINDOW 123 24 44 Left 2
+WINDOW 123 -92 54 Left 2
 WINDOW 39 0 0 Left 2
-WINDOW 3 24 72 Left 1
+WINDOW 3 -90 90 Left 1
+WINDOW 0 -79 22 Left 2
 SYMATTR Value2 AC 1
-SYMATTR Value SINE(0 1 1000)
+SYMATTR Value SINE()
 SYMATTR InstName V1
 SYMBOL res 192 128 R270
 WINDOW 0 32 56 VTop 2
@@ -46,3 +48,5 @@ SYMBOL res 528 160 R0
 SYMATTR InstName R3
 SYMATTR Value 10k
 TEXT 32 392 Left 2 !.ac dec 1000 1 100000
+TEXT 568 104 Left 2 ;Load
+RECTANGLE Normal 640 352 464 80 2
diff --git a/doc/simulation_LTSpice/Bandpass_AFSK_1200.plt b/doc/simulation_LTSpice/Bandpass_AFSK_1200.plt
index 7308ff8..ee61354 100644
Binary files a/doc/simulation_LTSpice/Bandpass_AFSK_1200.plt and b/doc/simulation_LTSpice/Bandpass_AFSK_1200.plt differ