Another way to scan DVB channels: w_scan

This is part of my series of articles on converting digital broadcast TV to IPTV: click here for the other articles in the series.

In previous articles, I’ve given examples of scanning for DVB channels using the scan utility in Linux. However, when I tried doing a channel scan yesterday, it refused to work:

angry-admin@dvb:~$ sudo scan ~/uk-CrystalPalace -u
scanning /home/local-admin/uk-CrystalPalace
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
initial transponder 490000000 0 3 9 1 0 0 0
initial transponder 514000000 0 2 9 3 0 0 0
initial transponder 545833330 0 2 9 3 0 0 0
initial transponder 506000000 0 3 9 1 0 0 0
initial transponder 482000000 0 3 9 1 0 0 0
initial transponder 530000000 0 3 9 1 0 0 0
>>> tune to: 490000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_3_4:FEC_AUTO:QAM_16:TRANSMISSION_MODE_2K:GUARD_INTERVAL_1_32:HIERARCHY_NONE
WARNING: >>> tuning failed!!!

I got a lot more tuning failed!!! messages after that, and no scan results. I’m not sure exactly what is causing this yet, but somebody else in the UK noticed this too, and suspects it began right after a very recent transmitter retune. Luckily, he also had a solution: use a different scanning tool.

w_scan

w_scan is an alternative DVB scanning tool that isn’t installed with the dvb-apps package, but can be installed from the default repositories on on most distros:

apt-get install w-scan

(Note that the underscore becomes a hyphen in the package name!)

Once installed, you can generate a channel listing in the exact same format as scan using the following command:

w_scan -X -c GB

substitute your own country code in place of GB; a list can be retrieved by issuing the command w_scan -c ?

Advantages

  • w_scan does not need any prior knowledge of the transmission frequencies other than the country, compared to scan which needs an input file containing the frequencies of at least one multiplex. This can be especially useful when the frequency information for your region is out-of-date or difficult to obtain.

Disadvantages

  • w_scan takes a lot longer to complete a channel scan. A full UK Freeview scan (including HD channels) took around 16 minutes, something which took only a minute or two using scan.
  • w_scan doesn’t list channels that aren’t currently broadcasting at the time of the scan, so you may need to run multiple scans at different times of the day to get a complete list.

About The Angry Technician

The Angry Technician is an experienced IT professional in the UK education sector. Normally found in various states of annoyance on his blog. All views are those of his imaginary pet dog, Howard.

2 responses to “Another way to scan DVB channels: w_scan”

  1. JhM says :

    I have w-scan working in Ubuntu 10.04. How do I add the frequency (channel) information to xawtv? I need a simple minded explanation, preferably with screen shots. (Thanks)