Updated SDR Digital Modes Guide (markdown)

SDR-Digital-Modes-Guide.md

@@ -9,7 +9,16 @@ Most of the transceivers supported by RadioLib use 2-FSK modulation for their de
 There are two way to get around this issue. The first one is to let RadioLib transmit digital modes in 2-FSK. Keeping the Bell 202 example, RadioLib will transmit RF frequency at Fc + 1200 Hz for mark and Fc + 2200 Hz for space (Fc being the RF carrier frequency). To decode this transmission using usual decoding software, the transmission **must be demodulated as LSB** (lower single-sideband). This will turn the offset in RF frequency into offset in audio frequency and get you the desired Bell 202 tones. An SDR setup might look like this:
 
 ```
-SDR dongle (e.g. RTL-SDR) -> SDR program (e.g. SDR#) set up for LSB demodulation -> virtual audio cable -> decoder (e.g. fldigi)
+SDR dongle (e.g. RTL-SDR)
+       |
+       V
+SDR program (e.g. SDR#) set up for LSB demodulation
+       |
+       V
+virtual audio cable
+       |
+       V
+decoder (e.g. fldigi or soundmodem)
 ```
 
 The other way is to force the module to transmit frequency-modulated audio in the first place. In RadioLib, this is achieved by the AFSKClient class. Unfortunately, not all modules which can transmit 2-FSK digital modes can also transmit AFSK. See the [AFSK Tone](https://github.com/jgromes/RadioLib/blob/master/examples/AFSK/AFSK_Tone/AFSK_Tone.ino) for a complete list. When using AFSK, the transmission can be demodulated as a simple FM broadcast. This mode should also be compatible with most ham radio equipment.