diff --git a/README.md b/README.md
index f5ed450..0961108 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,49 @@ pip install -r requirements.txt
 ```
 
 
+# SatNOGS-client
+HOWTO connect to the Libre Space Foundation's
+SatNOGS network? Not sure.
+
+
+The Green Heron RT-21 driver that has been in Hamlib for a decade
+only supports one USB port. Th Green Heron RT-21 Az/El has one
+USB port for azimuth and one USB port for elevation. This makes
+the Hamlib driver that has been in Hamlib for 10+ years unsuitable
+for use with an Az/El antenna setup. In sum, the hardware isn't
+plug & play with `satnogs-client`.
+
+
+There is a driver under a libre license available upstream here:
+
+* https://github.com/mct/greenctld
+
+The `greenctld` in that repo was written for Python 2.
+The present `spacecruft` repo ports it to Python 3.
+This is mostly done.
+The `greenctld` daemon listens on port 4533 similar
+to `rotctld`. It is unclear to me how to get the
+`satnogs-client` to use this port instead of wanting
+to start it's own `rotctld`.
+
+
+In July of 2021, a commit was made to the main Hamlib
+repo that added dual USB control for the Green Heron
+RT-21 Az/El. This commit is not in the Hamlib version
+that is in the latest `satnogs-client` release, however.
+The new version adds a second controller command line
+option:
+
+```
+  -r, --rot-file=DEVICE         set device of the rotator to operate on
+  -R, --rot-file2=DEVICE        set device of the 2nd rotator controller to operate on
+```
+
+One option would be to adapt `satnogs-client` to use this new version.
+Another option would be to port these patches back to the version
+`satnogs-client` is running.
+
+
 # Upstream
 Port from Python2 to Python3 of mct's greenctld.
 
@@ -24,7 +67,7 @@ Copyright (c) 2017, Astro Digital, Inc.
 
 
 # License / Copyright
-Same as upstream, permissive license
+Same as upstream, permissive license, see `LICENSE`.
 
 Source: