- Table of contents
- BildTel 001
- Further Reading
The Telekom-branded BildTel 001 was likely the first commercially available ISDN video phone in Germany.
The specific unit I managed to acquire has been with the Hochschule für Telekommunikation Leipzig until its closure in 2022.
Architecture¶The system consists of the following parts:
- A TV screen with built-in BTX decoder (inherited from LOEWE_Multitel_TV10)
- A keyboard + phone-receiver combo (inherited from LOEWE_Multitel_TV10)
- A desktop-computer-like box called the Codec (containing the actual ISDN video telephony part, implemented by AEG/OLYMPIA)
- A video camera
The BTX Terminal LOEWE_Multitel_TV10 was used as the "user interface" for the device, adding the codec box to turn it into a video phone.
- 1x power supply
- 4x "mainboards" stacked on top of each other (two sandwiches of two PCBA)
- top two boards (CODER / DECODER) have a number of DIN 41612 slots for plug-in cards
- 6x CODEC ADSP boards plugged into slots of the CODER
- 3x CODEC ADSP boards plugged into slots of the DECODER
- 1x OUTDIG/OUTANA sandwich, consisting of two PCBA plugged into slots of the DECODER mainboard
- this is the TV output board, generating and digital-analog-converting analog TV signal
- 1x INDIG/INANA sandwich, consisting of two PCBA plugged into slots of the CODER mainboard
- this is the camera input board, receiving and digitizing the analog TV camera signal
AEG-OLYMPIA CODEC ADSP¶
This board exists 9 times in total (6x for CODER, 3x for DECODER). It hosts a digital signal processor, RAM and some FIFOs.
There are no visible differences between the boards; also the label on the GAL is identical.
Connector Marking: None
|ADI ADSP-2101||Digital Signal Processor|
|VX-8111 10.0000 MHz||Crystal Oscillator|
|2x IDT 7201SA25J||FIFO|
|2x IDT 7202SA25J||FIFO|
35.103-3030.2 SN. 3051
|Brooktree Bt101||Triple 8-bit VIDEODAC|
|Xilinx XC2018-100||FPGA 100 CLBs, 1000 Gates|
|S-Data SXO-300C 27.00000 MHz||Crystal Oscillator|
|3x IDT 7201SA25J||FIFO|
This is the analog input board.
This is the digital input board, containing the video ADC and support circuitry
|Brooktree Bt253KPJ||Color Video ADC|
|DOC31CC 27.000M||Crystal Oscillator|
|3x TI TLC272CP||OpAmp; likely buffers for analog R/G/B|
|0900-002/2||SPI flash for FPGA bitstream?|
|3x QSL QS8201-15JR||512x9 FIFO|
TV / BTX Unit¶
- EPROM image: bildtel001_tv10_btxdecoder_16772_074_349_27C010.bin
- connects to ISDN basic-rate S0 interface using 8P8C/RJ45 plug
- has two proprietary connectors for attaching video cameras
- has two SCART connectors (one for audio/video output to the TV)
- has a TAE jack for attaching an analog phone for the audio port (connected to the combined keyboard/receiver unit by default)
- has another TAE jack (purpose unknown)
- has a V.24 interface on a SUB-D 9 connector which connects to the built-in BTX decoder of the TV unit
- connects to the Codec unit using a proprietary high-density connector that appears to carry both video and power
- has an RF input for TV broadcast signals (PAL)
- has a SCART input for baseband audio/video from peripherals (like the Codec unit)
- has a DIN speaker output for attaching an external speaker
- has a built-in BTX decoder with
- an unused DIN port intended to connect to the DBT-03 BTX-Modem (not used in the ISDN video application)
- an unused centronics port
- an auxiliary V.24 port on a DIN connector interfacing the SUB-D 9 of the Codec unit
- has a cable with TAE connector attached (connects to codec unit)
The information below is based on a 2023 conversation between Harald Welte and Roland Gaidzik (project manager of the AEG-OlYMPIA Video Phone).
Prior to the Bildtel 001, there was a research project by Daimler-Benz in Ulm, who developed the codec and created a much larger prototype using a VME-bus computer.
The task of the AEG-Olympia (by then also already a Daimler subsidiary) was to translate that research into an actual product that can be produced and sold. The result was the Bildtel 001.
- More than 100 units (possibly multiple hundreds, but certainly less than 1000 units) were built.
- Most of them were purchased by Bundespost
- a few were given as loner/rental devices
- probably less than 10 were ever sold directly by AEG-Olympia to other custmers
- Stollmann (in Hamburg) was responsible for building all the electronics (of the video/codec unit)
- The ISDN call control and user interface handling was developed by AEG-Olympia in Konstanz
- 4 people working in Marketing for the product
- 7 people working on R&D
- Actual assembly of te final product happened at the AEG-Olympia factory in Wilhelmshaven
- Testing/approvals done at a FTZ Facility
- The Codec part (even for the final product) was still provided by the research team in Ulm
- It is expected/assumed, that the Bildtel 001 already implements the ITU-T H.320 standards, as there was strong desire for this by Bundespost
- The LOEWE MultiTel TV10 is used almost without modifications. Only very minor softare modifications were made
- It is not expected that the actual BTX/CEPT decoder is used in the product. The UI is generated by the codec unit and presented as analog RGB on the SCART to the TV
- The BTX/CEPT decoder likely simply passes through the keyboard input to the V.24 interface towards the codec unit
- The power supply was a standard industrial power supply bought on the market
- The video camera was a standard part bought on the market
As AEG-Olympia went out of business and shut down, the responsibility of the Bildtel 001 was passed on to Dornier (back then also another subsidiary of Daimler-Benz). Apparently the Bundespost was very much encouraging Daimer-Benz to keep that project alive and not let it die together with AEG-Oympia.
Use in Piazza Virtuale project of Van Gogh TV¶
In 1992 there was an interactive TV project Piazza virtuale done by Van Gogh TV, an artist and hacker collective. They pioneered interactive television and aspects of social networks more than a decade before this became possible for people on the Internet. As part of this project, they were using Bidltel 001 phones to transmit audio+video from remote studios to the main TV studio.You can find the following related documents/resources:
- a website documenting the overall project
- a document showing signed receipts for video telephony equipment, including Bildtel 001
- "a reference to both analog slow-scan TV as well as ISDN picture phones" at https://vangoghtv.hs-mainz.de/?portfolio=einsatz-von-slow-scan-tv-und-isdn-bildtelefonen
- interviews with the creators of the project
- an example TV programme whose content was apparently transmitted via Bildtel 001 from Zurich to the TV studio