Early Morning Breakup

I record Battlestar Galactica which is broadcast on BBC TWO HD at between 1am and 3am Saturday mornings.

Often there is breakup for a few minutes in most recordings.

Curiosity drives me to ask if anyone can surmise the cause?

Is the transmitter power reduced for a few minutes in the early morning?

Any ideas?
 
Record on what? If it's a T2 then, yes, I know what it is.
And no, the TX power isn't reduced in the early morning.
 
I record Battlestar Galactica on an HDR Fox T2 from BBC2 HD in these early morning slots and I've seen no problems with breakup. Receiving from Emley Moor.
 
Is that the time when dustbin emptying takes place?

Deleting old recordings is a known cause of recording glitches.
 
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Is that the time when dustbin emptying takes place?
Yes

Code:
crontabs/root
0 2 * * * /mod/sbin/anacron -s -d
anacrontab
1 6 empty_dustbin /mod/sbin/empty_dustbin -l

So empty_dustbin is scheduled to run at 2:06

You could reschedule the time anacron runs to a less disruptive time using the file editor on the diagnostics page
 
Yes

Code:
crontabs/root
0 2 * * * /mod/sbin/anacron -s -d
anacrontab
1 6 empty_dustbin /mod/sbin/empty_dustbin -l

So empty_dustbin is scheduled to run at 2:06

You could reschedule the time anacron runs to a less disruptive time using the file editor on the diagnostics page
Living up to my username, could you explain, in simple terms, what "0 2 * * *" and "1 6" mean in these snippets?

What would I need to end up with in order to run anacron at 3:45am?
 
For the crontabs/root file it's:
minute hour day month day-of-week command
and * means everything
So:
45 3 * * * /mod/sbin/anacron -s -d
would be what you want to run at 03:45 daily.
The anacrontab numbers are period (days since last run) and delay (minutes from when anacron starts).
 
Living up to my username, could you explain, in simple terms, what "0 2 * * *" and "1 6" mean in these snippets?
What Wikipedia says about it:
https://en.wikipedia.org/wiki/Cron said:
The software utility cron also known as cron job is a time-based job scheduler in Unix-like computer operating systems. Users that set up and maintain software environments use cron to schedule jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals.

The actions of cron are driven by a crontab (cron table) file, a configuration file that specifies shell commands to run periodically on a given schedule. The crontab files are stored where the lists of jobs and other instructions to the cron daemon are kept. Users can have their own individual crontab files and often there is a system-wide crontab file (usually in /etc or a subdirectory of /etc) that only system administrators can edit.

Each line of a crontab file represents a job, and looks like this:
Code:
# ┌───────────── minute (0 - 59)
# │ ┌───────────── hour (0 - 23)
# │ │ ┌───────────── day of the month (1 - 31)
# │ │ │ ┌───────────── month (1 - 12)
# │ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday;
# │ │ │ │ │                                   7 is also Sunday on some systems)
# │ │ │ │ │
# │ │ │ │ │
# * * * * * <command to execute>
The syntax of each line expects a cron expression made of five fields which represent the time to execute the command, followed by a shell command to execute.

While normally the job is executed when the time/date specification fields all match the current time and date, there is one exception: if both "day of month" (field 3) and "day of week" (field 5) are restricted (not "*"), then one or both must match the current day.

For example, the following clears the Apache error log at one minute past midnight (00:01) every day, assuming that the default shell for the cron user is Bourne shell compliant:
Code:
1 0 * * * printf "" > /var/log/apache/error_log
This example runs a shell program called export_dump.sh at 23:45 (11:45 PM) every Saturday:
Code:
45 23 * * 6 /home/oracle/scripts/export_dump.sh
Note: It is also possible to specify */n to run for every n-th interval of time. Also, specifying multiple specific time intervals can be done with commas (e.g., 1,2,3). The below would output "hello world" to the command line every 5th minute of every first, second and third hour (i.e., 01:00, 01:05, 01:10, up until 03:55):
Code:
*/5 1,2,3 * * * echo hello world
 
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Yes

Code:
crontabs/root
0 2 * * * /mod/sbin/anacron -s -d
anacrontab
1 6 empty_dustbin /mod/sbin/empty_dustbin -l

So empty_dustbin is scheduled to run at 2:06

You could reschedule the time anacron runs to a less disruptive time using the file editor on the diagnostics page
So will it help to install the advanced package 'trm' in this particular case or will it not make any difference?
 
I thought trm was used by undelete anyway, but regardless the Linux delete process is always going to be a problem.

This thread ought to be in the CF section. (Update: moved - was in Freeview section)
 
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So will it help to install the advanced package 'trm' in this particular case or will it not make any difference?
trm is installed automatically as a dependency of the webif.

When I did some experiments a few years ago it didn't remove the breakup problems - it just spread them over a longer period :(
 
I thought the dustbin in CF gradually shrank the file before deleting it as a size zero file to avoid doing large deletes?
 
That's what trm does, but it is not completely successful because of the limited processing power.
 
It would be better if the empty_dustin process could (optionally?) be made to be recording aware and defer its operation until a time when it is not recording.
 
For the crontabs/root file it's:
minute hour day month day-of-week command
and * means everything
So:
45 3 * * * /mod/sbin/anacron -s -d
would be what you want to run at 03:45 daily.
The anacrontab numbers are period (days since last run) and delay (minutes from when anacron starts).
Thank you for this.
 
It would be better if the empty_dustin process could (optionally?) be made to be recording aware and defer its operation until a time when it is not recording.
That's a good alternative. Eg check if it's doing a recording and defer (or simply abort as it'll do the same check a day later anyway).
One thing that puzzles me is why there is a need for trm. I mean why is rm resource hungry? I thought that a file delete operation in computing terms is to simply delete an index (or pointer) to a file rather than overwriting file contents.
 
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