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Quarterly Bulletin
Rail operator SJ improves infotainment in the new X55 train

October first, 2010 the Swedish railway traffic took yet another step towards full deregulation. The goal is to give travellers the freedom of choice. The Swedish Transportation Agency allows access to the railway infrastructure to a number of additional operators for domestic routes also on weekdays. SJ, the number one operator, is positive towards competition and improves the competitive edge, among other things, through information and entertainment in the new X55 train.

October first, 2010 the Swedish railway traffic took yet another step towards full deregulation. The goal is to give travellers the freedom of choice. The Swedish Transportation Agency allows access to the railway infrastructure to a number of additional operators for domestic routes also on weekdays.
SJ, the number one operator, is positive towards competition and improves the competitive edge, among other things, through information and entertainment in the new X55 train. Willy Stjernudde, Project Manager Infotainment infrastructure at SJ leads the way onboard one of the first X55 vehicles. We sit down in a couple of aisle seats in the car.
- You are one of the first outsiders to see the X55 in real life, he says.
We are at Bombardier in the outskirts of Västerås, Sweden. The two first X55 are equipped with state of the art information technology in a large hangar. The goal is superior service levels for customers, the passengers. SJ is developing a brand new onboard Infotainment service.
- We are continuously improving the passenger travel experience throughout the whole journey, says Willy Stjernudde.
The X55 train - Facts and Figures

Speed - Operation:

107 meters
246 seats

274 tons
200 km/h, upgradable to 250 km/h when the infrastructure allows
12 engines delivering 285 HP each, totally 3360 HP

One of the challenges has been to offer FM radio onboard the train. Radio signals are reduced by 60-70 dB by metallic walls and shielded windows and doors. The radio channels switch frequency over and over again when the train travels at 200 km/h. X2000 and X40 trains use onboard radio receivers connected to sockets at each seat but maintenance is costly.


- Cost reduction was one of the driving forces to our discussions about an alternative solution. We investigated the possibility to use a system that would allow us to perform maintenance in every car rather than at every seat.


Retransmitting FM radio onboard

The new concept includes FM radio receivers with antennas mounted on the train exterior. The RF signal is transmitted via interior antennas to the customer's FM-receiver or via MP3 streaming on the onboard web platform. Radio channels are transmitted on fixed frequencies. RDS is used to keep track of radio transmitters near the train, select and switch to the one with the stronger signal to offer an uninterrupted listening experience throughout the journey. Five channels are retransmitted. It's mostly Swedish public radio, for a particular reason.


- We based the selection on a single aspect, reasonably nation-wide coverage, says Willy Stjernudde.


RF interference must be avoided. The Swedish Post and Telecom Agency's regulations apply to the transmitters of the system. The equipment is treated similar to the tiny FM transmitters used to listen to, for instance, an MP3 player through the audio equipment in a car. The typical power transmitted from such a device is measured in nW. In comparison the FM transceiver onboard X55 transmit 0,25 mW.

Willy Stjernudde, SJ by FM Transceiver in train car
The FM Transceiver developed by Hectronic and Generic is mounted under the ceiling in the cars of the X55 train. Replacement needs to take no more than 30 minutes since the train needs to be maintained during the halt at the end station.


- I believe that the amount of time required from boarding to leaving the train when replacing a unit is some fifteen minutes says Willy Stjernudde, Project Manager at SJ.

FM Transceiver
The FM Transceiver had to fit a 19 inch 2U predefined rack to be mounted in the train even though it turned out that the hardware allowed the size to be significantly smaller.
There was an initial idea to interrupt onboard FM radio for traffic information. Licensing issues in relations with broadcasting companies made that impossible in practice. Signed agreements today implies uninterrupted radio programs onboard. It makes the license issues not more complicated than when passengers are listening to the driver's radio on public buses.


The environmental conditions are challenging to any onboard electronics.


- There are a lot of vibrations onboard a train travelling at 200 km/h, sometimes from rails in poor condition. There are environmental factors such as temperature fluctuations and humidity from the four distinct seasons in Sweden, says Willy Stjernudde. And then there is the challenge to power the hardware.


Complying with the EN 50155 standard

Massive electrical engines and sliding contacts for main power supply to the train induces electromagnetic disturbance. The applicable standard for so-called rolling stock is EN 50155 which requires the power supply to filter and stabilize power for immunity to disturbances. To complay to the EN 50155 standard all electronic components are glued and the board is coated.


The FM transceiver was developed in cooperation between Hectronic and Generic, a technical consultant based in Stockholm, Sweden. Power supply modules that met the standard were available but costly. Hectronic took on the task to develop a power supply integrated on the carrier board. The X55 has an onboard DC/DC module offering a 12 V voltage which already is significantly filtered and stabilized. The challenge still remains however. It is to develop a system compliant to EN 50155.


- We ended up developing the power supply ourselves, says Daniel Skaborn, Project Manager at Hectronic. The design was based on a cheaper, partly integrated board level module, but still we saved time.

FM Transceiver - Hardware

Click to enlarge


The system hardware is a semi-custom design including a carrier board with audio circuits and an FPGA, an FM Radio RTX Module developed by Generic and the Hectronic H6049 Qseven Module with Intel® Atom™.

The balance between realizing functionality based on components and modules versus engineering was a key to success, according to Daniel Skaborn. Audio is a great example to support that conclusion. The initial idea was to implement audio codec in the FPGA of the carrier board and use serial I2S bus for digital audio output, the same bus used by the FM Radio RTX Module.


- At an early stage in the project we became aware of the difficulties with this strategy, concerning the drivers especially.


Instead the choice fell upon discrete audio circuits. The ones available didn't use I2S, so I2S/SPDIF blocks were implemented in the FPGA.


Some of the decisions to go for components or modules existing on the market instead of designing the project increased the cost of bill of material, for sure. But the engineering time saved made up for the loss, and more.


- One must realize that this isn't a product developed for large volume production, says Daniel Skaborn.

FM Transceiver - Block diagram

Click to enlarge


Brief system specification
• Retransmission of 5 FM radio channels
• The 6th FM RX/TX channel monitors RF signal quality
• Streaming of audio over LAN
• Two analogue stereo inputs

FM Transceiver - Functionality in FPGA

Click to enlarge


Core functionality realized in FPGA are I2S to SPDIF and SPDIF to I2S converter blocks and a patch bay. The patch bay is configured to connect each output channel independently to any of the input channels.

The project started in November, 2009. Now, a year later, a hundred units have been delivered. Twenty X55 trains will be equipped with four units, one in each car of a train. There is an option for an additional couple of hundred units for a possible update of the X2000 fleet. Willy Stjernudde´s expectations are exceeded.


 - From the point when we've put the FM Transceivers in operation they have worked flawlessly. There haven't even been any minor issues.


Work and responsibilities were split between Hectronic and Generic according to the specialties of the companies. Hectronic has, among other things, developed the carrier board and the mechanics. Generic has taken on the responsibility for the design of the FM Radio RTX Module and the application software. The FM Transceiver is based on the Hectronic H6049, a COM module in the Qseven form factor, equipped with an Intel® Atom™ processor.


- I believe that the people involved in the project have had the right qualifications, says Willy Stjernudde answering the question about why the project has been successful.


The future

The FM Transceiver is included in the investments in onboard infotainment at SJ. Infotainment is an area with future prospects, according to Willy Stjernudde. He believes that the range of entertainment offered onboard will increase over the years to come. There will be targeting and adaptation towards specific audiences such as children or adults with an interest in railway.


- There are a lot of adults who are fascinated by trains, says Willy Stjernudde, and one has a feeling that he is one of them.


X55 will be in operation for the first time in Sweden during 2011. Maybe you will be one of the passengers switching on the radio to listen to FM radio distributed by hardware developed by Hectronic. In that case we wish you a pleasant journey.


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