FST-1 - A Radar Data Coordinate Data Transmitter built by Lewyt Manufacturing Company for use in the SAGE System. The FST-1 took the analog radar data, processed and digitized it and created digital target words that were transmitted to the SAGE Direction Center and/or to the radar site.
FST-1 Radar Data Coordinate Data Transmitter
From MIL-HDBK-162A 15 Dec 1965: "Coordinate Data Transmitting Set AN/FST-1 is used to transmit radar data from unmanned gap-filler radar sites to a heavy radar site. This equipment converts wide band radar video data into coded narrow band audio frequency signals that are transmitted over standard telephone lines. The equipment evaluates the radar data before transmission and distinguishes between weak radar pulses and noise, blocking the noise, but passing the weak radar signals."
In practice the FST-1 accepted radar video and triggers from either the FPS-14 or the FPS-18 gap-filler radars. The FST-1 quantized the video and stored the target hits on a barrier-grid storage tube (256 Azimuth Sectors by 64 Range Sectors). When a target builds up enough hits in a storage tube cell to pass the target threshold a target message is created and transmitted over voice grade phone lines to the operating radar site and in the SAGE System to the appropriate Sage Direction Center. The target information could be displayed at the radar site on an OA-947/FST-1 monitor and was processed by the SAGE center through video mappers to remove clutter returns. A single OA-947/FST-1 could monitor six remote gap-filler sites (switch selectable).