added text on commong Hamlib FreeDV problems

git-svn-id: https://svn.code.sf.net/p/freetel/code@3320 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/freedv-dev/USER_MANUAL.txt b/freedv-dev/USER_MANUAL.txt
index 2cc44945e536840a7f916ab4480a7b90a34c8d6f..07dd003deb5e0753c4c0fbd892cad21ce8a06c5b 100644 (file)
--- a/freedv-dev/USER_MANUAL.txt
+++ b/freedv-dev/USER_MANUAL.txt
@@ -22,7 +22,18 @@ When "Test" is pressed, the "Serial Params" field is populated and
 displayed.  This will help track down any mis-matches between Hamlib
 and your radio.
 
-Voice Keyer
+Serial PTT support is complex.  We get many reports that FreeDV Hamlib
+PTT doesn't work on a particular radio, but may work fine with other
+programs such as Fldigi.  This is always a mis-match between the
+serial parameters Hamlib is using with FreeDV and your radio. For
+example you may have changed the default serial rate on your
+radio. Carefully check the serial parameters on your radio match those
+used by FreeDV in the PTT Dialog.
+
+If you are really stuck, download Hamlib and try to rigctl program
+from the command line.
+
+Voice Keyer 
 -----------
 
 Voice Keyer Button on Front Page