Cellular Modem Information

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h1. Siemens GSM-R CAB Radio

Osmocom has been provided with two ancient Siemens GSM CAB Radio devices, i.e. the kind of MS installed fixed into a train engine.

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h2. Sub-Rack Hardware

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h3. Backplane

At the back of the sub-rack there's a custom back-plane to interconnect the various modules

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h3. High Voltage Power Supply Module

This is a fully encapsulated, passive cooled, DC/DC converter with

* Input voltage 65..150V

* Two output voltage rails of 12V / 4A

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h3. 12V -> 5V DC/DC converter Module

This is a circuit board that generates a 5V rail from 12V

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h3. GSM Modem Module

This is a module implementing the actual GSM-R modem. It consts of two circuit boards: One digital and one analog/RF.

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h4. Digital Board

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h4. RF Board

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h3. PC/104 embedded PC Module

This is a carrier board hosting a PC/104 embedded x86 Mainboard.

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h4. Carrier

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We can see this carrier interfacing with

* the 8-bit lower portion of the ISA bus on the PC/104 connector

* both of the UARTS of the SBC

h4. PC/104 x86 SBC

This is a swiss-made Digital-Logic MSM586SEV.

* 586 compatible processor (AMD ELAN520) @ 133 MHz

** ELAN520 data sheet: attachment:22004b.pdf

* 32 MByte SO-DIMM memory

* 16 MByte M-Systems DiskOnChip MD-2202-D16

* 4x UART / COM port

* 1x parallel port

* 1x RTC

* AT-keyboard, PS/2, Floppy, IDE interface

* PC/104 bus

Resources:

* Data sheet: attachment:Microspace_Digital_Logic_MSM586SEN_Datasheet2_201872793522.pdf

* Manual: attachment:Microspace_Digital_Logic_MSM586SEN_Manual_201872793522.pdf

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h3. I/O board

This is a board that brings signals from the backplane and frontplane and brings them to connectors towards the main connector panel.

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We can see a number of SRDA05-6 TVS diode arrays as ESD protection measure, as well as some Datatronic LM201-1 signal transformers.

h3. Audio PA + Relay board

This board appears to contain an audio Power Amplifier

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h3. Frontplane

There's a board on the front side of the unit which interconnects the I/O board and the Relay / Audio PA board.

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h2. Handset Hardware

The specific handset unit here was used for demo purposes ourside an actual train cab.  So the auto-radio-looking user interface unit plus the receiver were mounted together with a 230V AC -> 110V DC power supply in an enclosure that you can connect  to the subrack via two cables.

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h3. Internal Pictures

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h2. Connector pinout

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h3. EXT RADIO (DB-15 female)

h3. SER I/O (DB-25 male)

h3. HMI 1 (DB-25 female)

This is the connector used to interconnect with the User Interface unit. HMI most likely means _Human Machine Interface_.

h3. HMI 2 (DB-25 female)

h3. MVB OUT (DB-9 female)

This is internally wired 1:1 with the MVB IN connector.  It likely contains an interface to the _Multifunction Vehicle Bus_ of the train.

See https://en.wikipedia.org/wiki/Train_communication_network for details on MVB.

h3. MVB IN (DB-9 female)

h3. ANT (N)

This  a standdard 50-ohms N-type conector to connect to the GSM-R antenna.

h3. PMU (DB-9 male)

This connector is forwarded internally to the DB-9 connector on the front of the embedded PC. Probably serial console.

h3. TRAIN POWER AND I/O (circular connector)

|_.Pin (ext)|_.Internal Connector|_.Internal Connector Pin|_.Wire color|_.Purpose|

|H|PL6|1|rose||

|K|PL6|2|white||

|M|PL6|3|green||

|P|PL6|4|purple||

|S|PL6|5|blue||

|J|PL6|6|black||

|L|PL6|7|red||

|N|PL6|8|yellow||

|R|PL6|9|orange||

|B|PL6|10|green||

|T|PL7|1|white||

|d|PL7|2|green||

|F|PL7|4|blue||

|A|PL7|5|red||

|U|PL7|6|rose||

|e|PL7|7|blue||

|G|PL7|9|grey||

|C|PL7|10|yellow||

|V|PL8|1|white||

|D|PL8|3|purple||

|W|PL8|4|red||

|E|PL8|6|orange||

|c|PL9|1|orange||

|Z|PL9|2|rose||

|X|PL9|3|green||

|b|PL9|4|grey||

|a|PL9|5|red||

|Y|PL9|6|yellow||