Frequency utilization efficiencies of digital and analog TV Broadcasting
When analog Television Broadcasting is digitalized, it becomes possible to send a lot of information by the same bandwidth. As for digital broadcasting, the utilization efficiency of the electric wave is several times as good as that of the analog broadcasting.
The digital broadcasting purpose is effective use for the frequency.
The spread of cellular phones etc. make the frequency of the electric wave insufficient recently. The analog broadcasting has shifted to digital broadcasting to answer these demand.
When the analog broadcasting is digitalized, a lot of information can be sent by the same bandwidth. When the ground analog broadcasting is completely digitalized, about 1/3 of the present Television Broadcasting frequencies can be finally used for a new usage.
The analog broadcasting is inefficient of the channel arrangement.
One channel of the television uses the bandwidth of 6MHz. Broadcasting channel 8 and 10 was not able to be used by the analog broadcasting when there was broadcasting in channel 9.
This is because the obstruction of the next channel becomes a problem when broadcasting is in the next channel by the character of the electric wave of the analog broadcasting. Therefore, it is necessary to make it to the blank every one channel in the analog broadcasting.
The analog broadcasting uses the next channel in CATV. This is because strength of the electric wave between channels can be thoroughly done because it transmits the electric wave with the cable. The adjoining channel cannot be used because it changes when strength of the electric wave between channels receives it when the electric wave is transmitted with an antenna.
The obstruction of the next channel can be received quite unquestionably even with the channel to which the electric wave is adjacent in digital broadcasting compared with this. Twice the electric wave can be effectively used only by this.
A little obstruction depends on an analog, digital characteristic this, and is due to the characteristic that the error correction can be done even if the signal changes into not the complete influence but digital a little by the obstruction.
Effective use for electric wave by digitalization and compression technology
The terrestrial digital broadcasting can broadcast by the compression technology of digitalization and the signal with one channel of 6MHz past band for three channels of a standard image quality. (The high-definition television broadcasting uses all 6MHz because of one broadcasting.)
In a word, the electric wave can be effectively used by as much as three times by the compression technology of digitalization and the signal. The electric wave can be efficiently used by as much as six times by matching it to the efficiency improvement of the electric wave use by the use of the above-mentioned adjacent channel.
Use state of electric wave of ground analog Television Broadcasting
- VHF Low channel (1ch-3ch)
- 18MHz of 90MHz-108MHz
- VHF high channel (4ch-12ch)
- 52MHz of 170MHz-222MHz
- UHF (13ch-62ch)
- 300MHz of 470MHz-770MHz
These totals become 370MHz. They are 62 channels.
Use of electric wave of present ground digital Television Broadcasting
- UHF (13ch-62ch) For 50 channels
- 300MHz of 470MHz-770MHz
It becomes 50 channels 300MHz because all UHF allocated in the television is used now.
Use of electric wave of ground digital Television Broadcasting in the future
- UHF (13ch-52ch) For 40 channels
- 240MHz of 470MHz-710MHz
Because 60MHz of UHF allocated in the television will be diverted to another in the future, it becomes 40 channels 240MHz.