--- wikisrc/users/jruoho/dvb.mdwn	2011/08/30 18:35:13	1.2
+++ wikisrc/users/jruoho/dvb.mdwn	2011/08/31 06:56:54	1.3
@@ -12,21 +12,30 @@ Here is one basic way to test a [[!templ
 
 Scan a basic `channels.conf`:
 
-	$ scan -x 0 /usr/pkg/share/dvb/dvb-t/fi-Turku > \
-		~/.mplayer/channels.conf
+	$ scan -x 0 /usr/pkg/share/dvb/dvb-t/fi-Turku > ~/.mplayer/channels.conf
 
 Then you should be able to already use `mplayer`:
 
 	$ mplayer dvb://"YLE TV1"
 
-For more involved testing, one can use for instance `tzap` (or equivalently,
-`czap` or `szap`). In one terminal set the driver for recording:
+Above "YLE TV1" is a channel present in the configuration file. For more
+involved testing, one can use for instance `tzap` (or equivalently, `czap`
+or `szap`). First prepare again the configuration file:
+
+	$ mkdir ~/.tzap && cd ~/.tzap
+	$ ln -s ~/.mplayer/channels.conf .
+
+Then in one terminal set the driver for recording:
 
 	$ tzap -r "YLE TV1"
 
-This gives continous information such as the signal strength. Check that the
-FE_HAS_LOCK flag is present. Then pipe in an another terminal:
+This gives continuous information about the signal strength, signal to noise
+ratio (SNR), bit error rate (BER), and the number of uncorrected blocks (UNC),
+respectively. The values typically vary across cards and are often somewhat
+unreliable. But check for the FE_HAS_LOCK flag; it indicates whether the
+card has locked onto a signal. If there is a lock, pipe in an another terminal:
 
 	$ cat /dev/dvb/adapter0/dvr0 > file.ts
 
-At some point break and try to play the output file with `mplayer`.
+At some point break the pipe. If the output file is empty, something is wrong.
+Otherwise you can try to play it with `mplayer`.