documentation for gpsd added

README.md

@@ -37,6 +37,7 @@ baudrate: 9600
 mycall: N0CALL
 server_address: 127.0.0.1:8300
 data_address: 127.0.0.1:8301
+gpsd_address: 0.0.0.0:2947
 cmdline_init: ""
 vara_mode: false
 ```
@@ -48,10 +49,23 @@ vara_mode: false
 | `mycall`          | The callsign to be used on HF                                                                                               |
 | `server_address`  | server socket address for the **commands**                                                                                  |
 | `data_address`    | server socket address for the **data**                                                                                      |
+| `gpsd_address`    | **optional** See the chapter about GPS below                                                                                |  
 | `cmdline_init`    | extra commands sent to the modem before going into hostmode, separated by semicolons, Ex: `DISP BR 1;DISP A 1;DISP DIMMOFF` |
 | `vara_mode`       | see the chapter about the VARA mode                                                                                         |
 
-If you plan to you Pat with the VARA driver, data `data_address` you **must** use a port number one number higher than the `server_address`.
+
+
+## VARA mode 
+
+The VARA mode translate WA8DED commands into VARA commands and vice versa. See the VARA homepage for the "VARA TNC Commands"
+doumentation. 
+
+If enabled, software which is written to interact with the VARA software TNC to work
+with PACTOR as well. It was used by the author to use the [VARA driver for Pat](https://github.com/n8jja/Pat-Vara)
+with the PACTOR-TCP-Bridge.
+
+If you plan to you Pat with the VARA driver, your `data_address` you **must** use a port number one number higher than the `server_address`. This is a limitation of Pat's
+VARA driver.
 
 A matching Pat config using VARA for the example above would look like:
 
@@ -64,18 +78,37 @@ 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 
+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.
 
-## VARA mode 
+## GPS(d) mode
 
-The VARA mode translate WA8DED commands into VARA commands and vice versa. See the VARA homepage for the "VARA TNC Commands"
+The PTC offer the possibility to attach a NMEA compatible GNSS receiver to them. To use them with Pat, the 
-doumentation. 
+PACTOR-TCP-bridge contains a small server which provides a [gpsd](https://gpsd.gitlab.io/gpsd/) compatible server.
 
-If enabledm software which is written to interact with the VARA software TNC to work
+So your setup looks like this:
-with PACTOR as well. It was used by the author to use the [VARA driver for Pat](https://github.com/n8jja/Pat-Vara)
+
-with the PACTOR-TCP-Bridge.
+  GNSS-receiver <--serial line--> PTC  <--bluetooth or USB--> PC/tablet/phone running ptb
+
+Please note, that this builtin server does the bare minimum needed to get your position forwarded to Pat. It's
+by far no full-featured gpsd. However, it eliminates the need to run an additional process (gpsd) just
+to make your position visible to Pat (or any other gpsd client).
+
+To configure it you just need to add a line like
+
+`gpsd_address: 0.0.0.0:2947`
+
+to the config file. In Pat, a possible counterpart could look like this:
+
+```yaml
+  "gpsd": {
+  "enable_http": true,
+  "allow_forms": true,
+  "use_server_time": false,
+  "addr": "192.168.188.37:2947"
+},
+```
 
 ## How to run
 
@@ -97,7 +130,7 @@ The software supports command line options:
 Usage of ptb - the PACTOR-IP-Bridge:
   -c, --configfile string   Name of config file (default "Config.yaml")
   -d, --daemon              Daemon mode (no TUI)
-  -l, --logfile string      Path to the log file (default "/tmp/pactortcpbridge.log")
+  -l, --logfile string      Path to the log file (default "/tmp/ptb.log")
 ```
 
 which should be rather self-explaining.
@@ -113,7 +146,7 @@ A typical session (without using the daemon mode, see below) looks like this:
 
 ## "Daemon"-mode
 
-The "daemon"-mode will omit the terminal UI ("TUI") and might be useful if you have no full terminal (or to run the tool with systemd).
+The "daemon"-mode will omit the terminal UI ("TUI") and might be useful if you have no full terminal (or you want to run the tool with systemd).
 
 Instead of the UI, you will only see a message saying that you may quit with CTRL-C.