updated documentation

README.md

@@ -3,14 +3,21 @@
 <img src="pics/ptb.png" alt="logo" width="200" style="float: right">
 by Torsten Harenberg (DL1THM)
 
-## What is the PACTOR-TCP-BRIDGE (ptb)
+## What is the PACTOR-TCP-BRIDGE (ptb)?
 
-It's a tool that
+It's a tool that was written to be used with [Pat](https://getpat.io/), so that Pat can use PACTOR.  It connects via a serial line
+(USB or Bluetooth) or via TCP to a [PACTOR modems](https://scs-ptc.com/modems.html) made by [SCS](https://scs-ptc.com) using the extended WA8DED hostmode
+[(see the manual, chapter 10)](https://www.p4dragon.com/download/SCS_Manual_PTC-IIIusb_4.1.pdf) protocol these modems offer. To Pat, tho tools provides the following interfaces:
 
-- talks via a serial line (USB or Bluetooth) to [PACTOR modems](https://scs-ptc.com/modems.html) made by [SCS](https://scs-ptc.com) using the extended WA8DED hostmode [(see the manual, chapter 10)](https://www.p4dragon.com/download/SCS_Manual_PTC-IIIusb_4.1.pdf) protocol these modems offer
-- offers two TCP sockets which can be used by [Pat](https://getpat.io/) (and other tools)
+- two TCP sockets (DATA and Command) 
+- optionally: another TCP socket that either forwards NMEA data from an attached GNSS receiver or even translates that NMEA data to a gpsd compatible protocol, so it can be used by Pat directly
+- optionally: a pseudo tty (pty) for hamlib to use to steer the attached transceiver
 
-## What it is used for
+The following picture depicts all possibilities:
+
+<img src="pics/ptb_connections.png">
+
+## What it is used for?
 
 The main purpose is to build a connection between Pat and PACTOR modems. In order to establish a "listen" mode for PACTOR in Pat,
 the modem needs to be kept in the WA8DED hostmode. I found it easiest to create a separate program 
@@ -86,8 +93,9 @@ A matching Pat config using VARA for the example above would look like:
 ```
 
 Using PACTOR, the PTT is triggered through the modem, so you need to set `ptt_ctrl` to `false`! If you configure a `rig`, it
-needs to be connected in a way that `rigctl` can configure it. Configure your rig through the PACTOR modem
-is **not** supported in VARA mode.
+needs to be connected in a way that `rigctl` can configure it. That can be done though this software, if your TRX remote control interface
+is connected to the PACTOR modem (as depicted above). Or you have attached the remote control directly to your computer. In this case you'd 
+use `rigctl` normally. 
 
 ## GPS(d) mode
 
@@ -132,6 +140,10 @@ nmeapassthough: true
 Note that if you plan to use Pat, you'd need to run `gpsd` to use
 the position of the GNSS receiver.
 
+## TRX Control
+
+to be written.
+
 ## How to run
 
 As a rule of thumb, you have to start the PACTOR-TCP-bridge before you want to use