Retronetworking

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h1. BildTel 001

The Telekom-branded *BildTel 001* was likely the first commercially available ISDN video phone in Germany.

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(Only digital marketing picture I could find online, courtesy of Picture Allianze / Matthias Hiekel)

The specific unit I managed to acquire has been with the "Hochschule für Telekommunikation Leipzig (HfTL)":https://de.wikipedia.org/wiki/Hochschule_f%C3%BCr_Telekommunikation_Leipzig until its closure in 2022.

h2. Architecture

The system consists of the following parts:

* A TV screen with built-in [[BTX__Prestel__Videotex__Minitel|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.

h3. Codec unit

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The Codec unit ("Bildeinheit") consists of a variety of different circuit boards:

* 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

h4. 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.

PCB Marking: @1601914L11T@

Connector Marking: None

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|ADI ADSP-2101|Digital Signal Processor|

|VX-8111 10.0000 MHz|Crystal Oscillator|

|GAL20V8A (4012-001/2)|GAL|

|2x IDT 7201SA25J|FIFO|

|2x IDT 7202SA25J|FIFO|

|3xCY7C199-45VC|RAM|

* GAL image: attachment:bildtel001-aeg_olympia_codec_adsp_4012-001_2_GAL20V8A.jed

h4. AEG-OLYMPIA OUTDIG

PCB Marking: @2401913L1T@

Connector Marking: @35.103-3030.2 SN. 3051@

top PCBA:

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|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|

h4. AEG-OLYOMPIA OUTANA

TBD

h4. AEG-OLYMPIA INANA

This is the analog input board.

PCB Marking: @0202914L1T@

Connector Marking: @35.103-3023.8/01@

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h4. AEG-OLYMPIA INDIG

This is the digital input board, containing the video ADC and support circuitry

PCB Marking: @0202915L1T@

Connector Marking: @35.103-3020.2/01@

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|Brooktree Bt253KPJ|Color Video ADC|

|Xilinx XC3030-70|FPGA|

|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|

h3. TV Camera

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h3. TV / BTX Unit

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h4. BTX decoder 

* EPROM image: attachment:bildtel001_tv10_btxdecoder_16772_074_349_27C010.bin

h3. Keyboard/receiver unit

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Actual Cherry keyboard PCBA after full disassembly, ultrasonic cleaning of all keycaps and lots of isopropanol on the PCB, removing what might be decades old coke residue:

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* EPROM image: attachment:bildtel001_keyboard_74E84.251U22g_1.0.0_010389_M2764A.bin

h2. Connections

h3. Codec unit

* 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

h3. TV Camera

* connects to the Codec unit using a proprietary high-density connector that appears to carry both video and power

h3. TV unit

* 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

h3. Keyboard/receiver unit

* has a cable with TAE connector attached (connects to codec unit)

h2. History

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.

h3. 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":https://vangoghtv.hs-mainz.de/

* "a document showing signed receipts for video telephony equipment, including Bildtel 001":https://vangoghtv.hs-mainz.de/wp-content/uploads/2021/04/picture-phone-reciepts.pdf

* "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":https://vangoghtv.hs-mainz.de/?page_id=86921

* "an example TV programme whose content was apparently transmitted via Bildtel 001 from Zurich to the TV studio":https://www.youtube.com/watch?v=bZ0WwvG_Pt8&list=PLDUukqMXwk2wJJZM9JhEGoDmx9PX2VTOk&index=24

h2. Further Reading

* "Thread on the fediverse covering the BildTel 001":https://chaos.social/@LaF0rge/111317641831468838