A look behind the scenes

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I’m interested and I would like to know more about VCK!

VCK (Vereniging Campus Kabel, translated Campus Cable Association) takes care of the television signal on the campus. You may already knew this, but how do they do it? What has to be done in order to offer analogue and digital television?

The rooms

There are several rooms available to VCK.

Working in the headend

On a technical level, the room in the Vrijhof is the most important room. From a technical point of view, the headend is the most important part of distributing television. At the headend, VCK makes most of its analogue and digital (IPTV) television signal. The headend is located in the Vrijhof near the library. The headend consists of 4 server racks filled with servers, modulators, satellite receivers and lots of other equipment. Everything is placed on a raised floor. This makes cable management easier. On the roof of the Vrijhof, there are six satellite dishes.

The meeting room at the Calslaan

On a weekly bases, the board of VCK gathers in the basement of Calslaan 5. The basement is a cozy place with a television, sofas, a whiteboard for meetings and a small workplace for reparations. Furthermore, there are 4 workplaces with computers and telephones for the board to work on or to write software on.

In addition to that, there are a few technical rooms for storage and to redistribute the television signal further onto the campus. These technical rooms are situated on the Campuslaan where there are a few servers running and on the Witbreuksweg where devices are stored.

IPTV

IPTV distributes about 120 channels over the network of the campus. IPTV is also distributed from out the headend.

servers

One of the server racks

A few channels of IPTV are directly delivered via glass fiber by one of our suppliers from Hilversum, but nowadays a lot of streams are made by VCK. The channels are received by satellite dishes and digital television (DVB-C) by Ziggo. The channels are received and coded with six servers filled with satellite receivers and DVB-C cards. Every server adds multiple channels to the network of the university. All servers are professional 19″ servers of Dell and HP with multiple processors and RAID configured hard drives. The servers have to be robust and need a lot of processing power to decode multiple channels at the same time. All servers of VCK use Debian for its stability and because it’s easy to roll out our own repo and software across all of our servers.

An IPTV-server with multiple satellite cards

But there is more, because there are a few network technical issues. The full HD streams of VCK are often larger than 10 Mb/s, thus only a few IPTV-users are required to cause a system overload. This is why VCK has decided to use multicast. In a multicast system, the streams are only sent once to the switches of the campus and users can send a request to a switch to receive the stream. This way, the stream only gets sent once from one server to switches with IPTV-users. There are special IP addresses reserved for multicast, so the user only has to connect to one of the special multicast IP addresses and the switch will send the requested stream to the IPTV-user.

When a channel stops working, VCK automatically receives an email about it. The configuration of the servers and the setup of the channels of the satellite hast to be done manually with SSH. However, VCK is working on software that can do these tasks automatically, so that we can add channels via a web interface and don’t have to login onto the appropriate server.

Analoge televisie

The VCK saucers on the roof of the Vrijhof

Of course, VCK still offers analogue television. This signal also starts in the headend. Part of the signal comes from Ziggo. VCK filters a large part of Ziggo’s signal with a homemade analogue filter so that there is space for other channels as well.

Pieter en Simon bezig met hele lastige dingen :)

Pieter en Simon doing very difficult things 🙂

Satellite receivers receive channels via the dishes on the Vrijhof. The satellite receivers send the analogue signal to the modulators. The modulators put the channels on certain frequencies on the cable. This way, the analogue signal is filled with a large offer of channels. The analogue signal is sent to a glass fiber laser using a coax. The glass fiber laser distributes the signal to several places on the campus. From out these places, the signal is sent to all apartments using coax. Several amplifiers, splitters and mufflers make sure that every user receives a good signal.

Want to join VCK?

Becoming an active member of VCK doesn’t mean spending hours a week to the point your study results are affected. VCK has several technical and non-technical projects you can work on. Working on those projects can take an hour a week or on time a few weekends or more if you wish to.

I’m interested and I would like to know more about VCK!