Secrets of how TV works! (Part 2) - the "heart" of a TV station
"Previously, we heard about the transmitter that delivers radio waves from the broadcasting tower to the TV sets in our homes. In the second part, we will take a look at the inside of the TV station.
When we watch TV, there is no interruption of the broadcast whether it is a TV program or commercial. Japanese TV stations use a very precise system, called the TV master APS transmission system, to make sure the footage and sound of every program and commercial are broadcast on schedule. If this system fails, broadcasting will stop. It is one of the most important systems in a TV station.
Among the many pieces of equipment used in a TV station, this system is said to play a very critical role. What it is like actually? NEC has a share of about 60 percent of the domestic market of the TV master APS transmission system. So today, like before, I am visiting the Broadcast and Video Equipment Division of NEC to learn about the system!"
Member of the Broadcast and Video Equipment Division of NEC who oversees all studio-related broadcast video systems. An expert on TV master APS transmission systems, who was also involved in the transition of analog broadcasting to digital broadcasting that took place in 2003 through 2011.
- MitaHello, Mr. Haga. Thank you for your time. First of all, could you tell us about the role the TV master APS transmission system plays in TV broadcasting?
- HagaYes. You have heard about the digital terrestrial TV transmitter in the last installment of the program, right?
- MitaYes. We heard that it converts broadcasting signals received from the TV station into radio waves at a broadcasting tower or some other facility and delivers those radio waves to the TVs in our homes.
- HagaThe TV master APS transmission system, which I'm responsible for overseeing, relates to a preceding step to the transmitter step.
- MitaPreceding step?
- HagaYes. It plays a part in sending broadcasting signals from a TV station to a broadcasting tower or some other facility. To be more specific, the system automatically switches the video and audio data of various TV programs that the TV station has collected and sends the data to the transmitter according to a preset program.
- MitaI see. Its role is to send video and sound to the transmitter according to the TV program listing.
- HagaYou're right in a broad sense, but not correct in a narrow sense.
- MitaWhat? Doesn't it send data according to the TV program listing?
- HagaThe system sends data according to the TV program listing, but it does so in more detail. I mean the TV offers not only TV programs but commercials as well. Besides these, various kinds of signals, from time and weather forecasts to data broadcasts, are brought together for broadcasting. Therefore, the program schedule is minutely programmed in a time unit less than a second, specifying when this program starts, when this commercial airs, whether to display the time and weather forecast during the break and so on. What the system does is send all the signals precisely in a predetermined order.
- MitaSo it's a difficult detail-oriented task. A time unit less than a second sounds very precise.
- HagaThat's right. In some foreign countries, for example, you may experience a situation where a TV program does not start on time or you see a blank screen for a split second between programs. In Japan, however, due to exacting standards such incidents are regarded as "broadcast accidents." An interruption of footage of even 0.1 seconds is considered a broadcast accident. So the TV master APS transmission system needs to be very precise. All the TV stations use this system. If the system fails, broadcasting will stop. That's why they call it the "heart" of the TV station.
- MitaWow, I didn't know that the system is that important! But I've never seen a room with a plate saying "TV master APS transmission system" while walking around in the TV station. I don't think the direction board in the elevator mentions such a room, either. No one has told me, perhaps because I'm a new recruit. Is that so?