With a PC running Linux and a recent VGA card, you can emit a real digital TV signal in the VHF band to your DVB-T set-top box. DVB-T emitters are usually very expensive professional devices. Now with a standard PC you can broadcast real DVB-T channels! Examples to transmit PAL or SECAM analog signals directly to your TV are also presented. [via] Link.
A Low Cost Analog and Digital TV (DVB-T) Modulator