The project requirement was to ensure that the train driver has a visual display of the approaching platform some 300 metres before arrival at the start of the platform. All stations are built on a curve and for safety reasons the driver must ensure that the platform edge is clear prior to arrival.
Wavesight developed a bespoke solution combining a video codec and 2.4GHz radio, based around existing Wavesight products. This product was manufactured and supplied as a module for integration into other systems.
A systems integration company, Eltronix, based in Seoul, won a contract for the Seoul Subway for CCTV systems both on and off trains. The compact nature of the integrated product was a key feature in the selection of the Wavesight solution. Following extensive trials and tests the product was adopted for use within the Seoul subway railway system. These tests included testing the propagation of the RF signal within the tunnels and the high data rate required for the CCTV transfer.
The platform CCTV camera video signals are fed to a Wavesight unit located on the platform. This then relays the video signal to two other Wavesight units; one located at the tunnel entrance and the other at the tunnel exit.
On a display screen located in the train driver cab, the driver can see the platform from a point 300metres prior to arrival, whilst stationary and for 300metres after leaving the platform. Any loss of picture (out of range) results in a black screen to avoid any worries of an old or still frame.
The network identifiers are arranged so that the approaching train can only see the relevant platform and not an adjacent one.
Wavesight spent a considerable amount of time supporting the exhaustive test procedures and extensive trials required to ensure this system worked according to the customer’s exact requirements.
Eltronix have subsequently proposed similar solutions to other railway networks.