General Instruments was one of the first to provide a digital cable standard. This used the OpenCable Harmony standard, which consisted of
- MPEG2 Video Compression
- Dolby Digital AC3 Audio
- MPEG Transport Stream Model
- ATSC System Information
- ITV-J.83 Annex B, This is also known as DVB-C Annex B
- 64QAM 256QAM Modulation support
Set Top Boxes
Motorola / General Instruments
The DCT1000 and DCT1200 was officially made available from 1997, and were the first models of digital cable units. The 1000 models supported only 64QAM broadcast, whilst the DCT1200 were capable of receiving 256QAM. The cable operator would chose the models that suited the network best, since 256QAM was capable of more bandwidth but was more prone to signal transmission errors, depending on the noise and condition of the cable network.
Cable transmissions are broadcast using the DVB-C Annex B format, also known as QAM or SCTE. For the DCT units, a variant of Digicipher is used to encrypt and scramble broadcasts. In later units this became known as MediaCipher.
These units were backwards compatible with analogue NTSC transmissions, and can descramble broadcasts designed for the previous General Instruments and Jerrold decoders/converters. This allowed for operators to transmit digital channels exclusively for digital cable customers, whilst reusing the bandwidth that was used for existing analogue customers. However this meant that existing channels that was broadcast in the analogue format did not benefit from the enhancements that MPEG2 digital had provided. Some premium channels were simulcast in both analogue and digital.
The DCT2000 was introduced in 1999 and was the replacement for the DCT1000. Initially branded under General Instrument and later Motorola, the 2000 became popular due to its customisable design with operators, where additional features could be added or removed. This allowed the 2000 to be very cost effective (aka cheap). Powered by a Motorola 68xxx with 2Mb of VRAM
There are two versions of the DCT5000, however only one was available to operators. This early version (known as the DCT5000+) was supposed to be the high end version of the DCT2000, supporting a DOCSIS cable modem for full broadband functionality (Kind of like our Pace DiTV1000 boxes of the time) however an optional IDE hard drive was also planned to be part of the design. IP telephony was also planned to be supported, allowing all three services to be delivered through one box. Triple tuners were going to be used to allow for this. A 300MIPS processor, 14Mb of combined memory and support for 3D graphics (no mention of behind the graphics chip) spec wise it would have been similar to the Dreamcast.
Unfortunately this box would become vapourware (for the original incarnation), the only thing that remains for his high end set top box would be the spec page. Despite the mention of a hard drive, DVR functionality Is not mentioned, perhaps the hard drive would be used to store applications of games?
DCT2500: An updated version of the DCT2000 models. These units have a revised internal hardware, being based on a Broadcom chipset which integrates the MPEG2 decoder, transport decoder and CPU core onto one chip, therefore reducing the complexity. IT is also smaller and consumer less power and outputs less heat.
DCT700: A reduced version of the DCT2500, designed to be used as a secondary TV box.
DCT1700/1800: Digital only cost reduced version of the DCT2500, this lacks the analogue decoding and descrambling ability of the 2500, this unit requires the cable operator to transmit all their channels in digital format.
DCT5100: Motorola’s first dedicated HD box
DCT5200: Same as the 5100, but with an internal DOCSIS modem
DCT6400/6412: Similar to the 6208 but with a 120Gb for 6412, 6400 requires an external 1394 hard drive
DCT6200/6208: HD DVR with dual tuners and 80Gb hard disk for 6208, the 6200 does not have an integrated HDD and was intended to be used with an external 1394 drive
DCT6400 Phase III/6412/6416: 6412 has a 120Gb hard drive, 6416 is 120Gb
DCT3400 Digital dual tuner video tuner, SD only
Pace started supplying cables boxes that were compatible with Motorola’s scrambling and return path protocol, Pace also supplied boxes for Scientific Atlanta networks, and European DVB networks, mainly for ntl: and Telewest.
Sony entered the digital cable TV market in 2002, and introduced their PASSAGE technology which allows multiple conditional access systems to coexist on one network. This meant an operator could deployed a next generation set top box that was PASSAGE compatible, whilst keeping their existing set top box (i.e. DCT2000) without any software changes to be made to the end set top box. PASSAGE allows a third party conditional access system (Videoguard or Nagravision, who had been trying to get into the cable TV market). Sony claim that existing TV guide middleware was compatible.
Sony cable boxes were designed to be purchased by the end user rather than the cable operator, although Sony did allow cable operators to lease their receivers. Interestingly, Sony had also released the PSX DVR, which was a PlayStation 2 with an integrated HDD with dual tuners, however this was only released in Japan and Sony may have intended to release in the US with CableCARD and PASSAGE support.
- DHG-55: STB
- DHG-55HD: HD DVR
- DHG-25: Basic set top box with a 275MIPS processor, 64Mb of RAM and 32Mb of Flash, Integrated DOCSIS modem and Memory Stick support
The early units supported STARFONE and STARLINK as their method of return path. STARFONE was essentially a dial up modem integrated into the cable box, for cable networks that were unable to carry return path or out of band data, these units required the box to dial up whenever they needed to send data back to the operator. The STARLINK units supports two way data communication, and can be thought of being similar to the DAVIC standard.
Middleware & Interactive
The Prevue guide was used as the main IPG (Interactive program Guide) software that was resident within the stb software.
Later the Pioneer Passport software was developed the DCT1000 (and later DCT2000) series for operations to deeply, which brought additional features in comparison to the Prevue software.
Microsoft also developed a TV guide, also known as Microsoft TV Foundation Edition however this was never deployed by any operator.
Various interactive middleware was developed and deployed for the DCT1000 series units. This would enable the use of interactive and on demand services, combined with the use of the return path.