I want to create a business in the field of telecommunications technologies (digital TV), what advice can you give? What amount of start-up capital should be for the average company?
It depends on what you want to do at first because the capital question is a little tricky as it depends on various things. For example, do you want to only establish business or you want to take it all at once - all the advertising, targeting and etc? So I would strongly suggest first creating a business plan and seeing what your requirements are. After then, you will be able to evaluate the capital needed as you will already know in which region (because prices mostly depends on it) you want to start.
@Vincentas raises some valid questions to which I would add: Are you going to stock telecomm equipment to sell? If so, what products, services, etc., do you plan to offer? The type and amount of equipment that you need to stock as a distributor will have a major impact on investment, of course. Getting trained and certified in a major brand or two will be another cost, of course. Finally, will it just be you manning the business or will you need staff?
What do you mean "average company"? In my view the size of seed capital depends on what will be the scope of your business and customers, without a business plan for exact figures are impossible. You will need to rent a room, buy equipment such as http://www.infomir.eu of this, hire people to work, start advertising, etc. In this business, a lot of competition and you need to have some predominantly (innovation) for the start