Sunday, February 14, 2016

smooth plot in Matlab

This post has some useful techniques for using in Matlab, for smoothing data using

If curve-fitting toolbox is present, smooth can be used. Or we can roll our own, as mentioned in the link.

Saturday, February 13, 2016

video stabilization plugin for virtualdub

Video stabilization used to be available only in high-end video editing software. Realized now that Virtualdub has a plugin, too! And its development dates back to  2003. Used the Deshaker plugin from
for a video of an oscilloscope trace, pretty good!

Friday, February 12, 2016

multiple issues with sending bulk email

SSSIHL tied up with Benchmark for sending some 4000 emails, they wanted to make it into a newsletter every couple of months. There were multiple issues with the email sending.

  1. The first time around, the SPF record had not been updated to include benchmark servers, which resulted in spam filtering blocks for most of the mails. Along with SPF update, Benchmark also recommended whitelisting the Benchmark mail server IPs for mail servers. 
  2. Found that Google Apps allows whitelisting. Updated the SPF record.
  3. Then found that the SPF record was returning an error, too many lookups, via the test at - googling showed that having Godaddy's in the SPF record causes a very large number of lookups. Moved the sending of emails from the Godaddy server to google apps, removed that include, then the SPF validated. 
Finally most of the emails went through after the valid SPF. 

cleaning up C drive

All these years, I had relied on various tips and tricks for cleaning up C drive on Windows, and had never used the Properties -> General tab -> Disk Cleanup utility's "Compress old files" feature, because it used to take a long time to run. But yesterday I did, and it made 9 GB available on a drive which had only 600 MB free!

Add 2 GB to Google drive storage

K sent me an email telling me about "an annual ritual by Google. I did it last year too and got 2GB."

Do the security checkup and get 2GB added:

Have now added a google calendar reminder for this :)

Tuesday, February 09, 2016

Apache 403 Forbidden errors

P had a problem after he migrated data from an old hard disk to a new hard disk on our internal server. A couple of folders in the hard disk were supposed to be available via the local webserver - but after the migration, those were returning 403.

Finally, the issue turned out to be permissions for the parent directory. Gave the permissions, also had to add Indexes to the Options line in apache2.conf for one of the folders, all done.

Sunday, February 07, 2016

retuning tv set-top box

Doordarshan DTH, now called FreeDish, migrated from INSAT-4B to GSAT-15. P sir and R called me for re-tuning their set-top box. Since the satellites are nearby, there was no need to re-align the antenna.

R had managed to enter the correct values of frequency, polarization and symbol rate in TP edit mode. It only needed a scan of the correctly entered transponder values. The relevant menu item was in the Installation menu, Scan current ANT.