ATSC tuner

A digital receiver (a digital decoder or a digital receiver ) is a device for decoding and receiving digitally transmitted television services and related offers via cable, satellite or terrestrial antenna, especially in DVB format. Such a receiver can either be directly integrated into the playback device (see also tuner and IDTV ) or the existing equipment as an independent device ( set-top box).

  • 7.1 Digital Recording
  • 7.2 Analog recording

Pay Per View

During checkout, television ( pay TV) Digital Receiver also be used in conjunction with a decoder card (smart card ) to decode encoded Pay TV services. The card includes the process of addition of a unique identifying number (PIN), the key that allows the decoder to decode the encoded data stream. Known decoding procedures are, inter alia, the systems NagraVision, Seca or Betacrypt.

Radio

In addition to digital receivers for digital television, which often can be used for the reception of radio programs, as in the case of DVB -S and DVB -C, there are also those for audio transmissions. Corresponding formats are, for example Digital Audio Broadcast (DAB ), and Digital Radio Mondiale (DRM ) (see also digital radio). As with the video transmission also enables the digital distribution by compressing a higher quality or, alternatively, a larger number of stations; Furthermore, additional services are available.

Usually the cost of a digital audio receiver (also known as DAB tuner box ) are already comparable to digital radios, so that an external upgrade an old analog radio device is no longer worthwhile. Also, the operation of a radio device via an additional tuner box is quite cumbersome.

Interaction

In addition to the reception, decompression and possibly decipher the audio -video signals, digital receivers are usually also able to prepare program-related or independent data. In addition to text information services in the style of teletext (RDS the radio), which mainly comprises electronic program guide ( EPG) and increasingly interactive services ( Quiz, shopping, etc.) that require a return channel.

Storage

If a viewer wants to record one channel whilst watching any, other program at the same time, he needed a twin receiver with two separate tuners. Since the received digital data can be stored without loss and without great expense and then further processed or archived, there are digital receiver with integrated hard disk ( so-called hard disk recorders ), DVD burner, network interface (Ethernet) or USB interfaces over which one the recorded programs on can play the PC, and it can cut there and burn to DVD; and DVB reception cards (internal and external) for the PC, which, however, the media industry 's view provoked copyright infringement. Digital twin receivers are available with or without a hard disk. Hard disk recorders enable Timeshifting, in which a program that is currently being recorded can be played back simultaneously.

Background

A well-known and widespread in Germany Digital receiver for DVB is the d -box 1 and its successor, the d-box 2 D-Box was one of the first digital decoder, from the pay-TV provider and later DF1/Premiere World Premiere markets and of the Kirch company Beta research (encryption method Betacrypt, Java operating system betanova for the d -box 2 ) was developed. Due to the packaging of the program and the D-Box decoder achieved a rapid spread and had a long time in the area of the German pay-TV market supremacy.

Following the bankruptcy of the Kirch Group, the company Beta Research was sold and turned a little later a developing operation. Instead of Betacrypt entered the encryption method NagraVision in October 2003.

By -cost manufacturing processes digital receiver are dominant today ( both on pay TV sector as well as the satellite reception ) and displace their analog predecessors increasingly.

Technology

External

Despite the bewildering variety of devices on the market, the technology used in these units is quite uniform. Those with more than 50 percent market share (excluding the still widespread in Germany D-Box ) leading Omega chipsets ( STi5500, STi5518, etc.) all contain a ST20 32bit CPU and an MPEG decoder. You need to operate essentially only external Flash and SDRAM memory and as required by the respective receiver technology tuner module. The STi5518 also supports the connection of a hard disk.

Internally integrated

For purely digital receivers no digital -to-analog conversion is more necessary. The receiver requires only an appropriate tuner module. For example, the MPEG decoding the signal in the conventional tuner modules is already done. Added is usually a CI slot, SmartCard reader and a corresponding Dechiffrierelektronikbaustein. Therefore speak in the integrated case not more of a digital receiver, but only by a digital tuner.

Without active antenna control

DVB-C/DVB-H/DVB-T-Empfänger process at the antenna input is always a static pending antenna signal, this can only bring those received as a whole over a frequency band via a coaxial cable transferable programs. It is advantageous that several such receivers can be operated at an antenna socket without mutual interference. The disadvantage is an opposite of an active antenna control program reduced diversity. Some DVB -T receiver giving at the antenna connector from a power supply voltage to power an active indoor antenna.

With active antenna control

Can be DVB-S/DVB-S2-Empfänger process at the antenna input frequencies more than a coaxial cable at once transferred (frequency range 950-2200 MHz). These generate such a receiver at the antenna connector specific control signals ( 14/18 volt, 22 Khz diseqc ), by means of which he addressed to the receiving satellite frequency and so in the upstream multiswitch or LNB, LNB unicable retrieves.

When such devices are used on a single cable system ( DC power off), is thus a possible range of programs lost. It can be used but then the advantages of a passive antenna control. With modern digital technology this retrogression does not weigh so difficult; up to 20 TV channels ( average 6) can be packed into a digital transponder by compression. This will have a more positive impact with the introduction of new compression techniques such as H.264/MPEG4 on a variety of programs. An active antenna control, in the PAL - time diversity is essential to the program, so not absolutely necessary in the digital age.

Recording digital broadcasts

Digital broadcasts can be either digitally or convert Save only to an analog signal and then record as such.

Digital Recording

Increasingly the recording is performed on a digital storage medium. A digital storage medium is connected to the receiver or it is already an appropriate storage medium ( usually a disk partition) installed (hard disk recorder).

Analog recording

The digital systems DVB- T, DVB -S, DVB -S2 and DVB -C require special receiver or appropriately equipped televisions. The digital broadcast signal is converted into an analog receiver, which can be further processed by the classic analog device (tube TV or VCR ). Therefore, the receiver operates as a digital-to- analog converter.

Particular attention is that when DVB is no original VPS signal is broadcast more. Only gradually appropriate adjustments have been performed, but which are not supported by all channels and all digital receivers.

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