default timeouts are to tight for channel scan with a HDHR3-4DC on DVB-C

[Karl Egly]

Raise the timeouts, I get not a single transport/service with the defaults.

[jendrek@…]

I have the same observation. Should this be a "minor" problem? For me, the severity is worse than medium, as no channels can be found at all (on HDHomeRun Dual). The signal is strong, my HDHomeRunView works fine (and the config-gui), as does EyeTV. From the experience with EyeTV, it may take quite a long time to detect the channels. How about making the timeout a configurable item?

[jendrek@…]

I found that there is a settable option (Signal Timeout) in Capture Card Setup under Recording Options, but evidently it is not used when discovering channels.

[Klaas de Waal]

This problem is possibly not a question of a timeout value.

The mythtv-setup code sees all the HDHomerun devices that support DVB-T, DVB-C or both, as DVB-T devices. It can work with DVB-C devices such as the HDHR3-4DC because mythtv-setup generates an "auto" tuning command that is the same for both DVB-T and DVB-C devices.
For example, for the 474MHz frequency the command is "auto:474000000".

The HDHR3-4DC tries all the modulation values in parameter /sys/dvbc_modulation and if one of these is correct for the signal then tuning succeeds in one second or so. But if the modulation values are not correct or not present then tuning will never succeed.

The modulation values can be read and written with the hdhomerun_config utility which can be downloaded from the Silicon Dust website.
For example, this are the values for my test system:

[klaas@modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
a8qam64-6875 a8qam256-6900 
[klaas@modu ~]$ hdhomerun_config 1410F45C set /sys/dvbc_modulation ""
[klaas@modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation

[klaas@modu ~]$ hdhomerun_config 1410F45C set /sys/dvbc_modulation "a8qam64-6875"
[klaas@modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
a8qam64-6875 
[klaas@modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
a8qam64-6875 
[klaas@modu ~]$ hdhomerun_config 1410F45C set /sys/dvbc_modulation "a8qam64-6875 a8qam256-6900"
[klaas@modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
a8qam64-6875 a8qam256-6900 
[klaas@modu ~]$ 

The modulation value is built as follows:

a       is always present
8       bandwidth in MHz
qam256  modulation
6900    symbol rate

Of course, the parameters have to be chosen for the local DVB-C signal.

It would be better if the MythTV did not depend on a configuration item; if the MythTV code would be changed to have explicit tuning commands, e.g. "a8qam64-6875:474000000", then the HDHR3-4DC would always work independent of the /sys/dvbc_modulation parameter configuration.

[Klaas de Waal]

Created ticket #13371 "HDHomeRun DVB-C device seen as DVB-T".

[Klaas de Waal]

The default timeout values for the HDHR3-4DC are 1000 ms for the "Signal timeout" and 3000 ms for the "Tuning timeout". With these timeout values scanning is correct on the local DVB-C signal with today's pre-v31 master.

It is possible that the tuning problem described in this ticket is solved by the resolution of ticket #13371 which makes this ticket a duplicate.

Note that if the timeout values are too low for certain cable networks then the values can be changed in the mythtv-setup Capture Card configuration.

This ticket is now closed. If there is still a problem with scanning then please re-open this ticket or create a new ticket.