Trade.Information

Product Name: Radar Scan Converter

Product Description

The DRS Radar Scan Converter Subsystem (RSCS) with Dual-Channel Conversion is based on proven Commercial Off-The-Shelf (COTS) scan conversion technology. The RSCS, consisting of two standard VME cards (Scan Converter card and Radar Interface card), provides a complete high-performance, dual-video display processing path for multiple raw radar images.

The RSCS's key features are reverse scan conversion for instantaneous offsets and zooms, dual-channel conversion with polar memory storage, multiple radar displays in X-Windows, high-speed conversion rate (4 million pixels per second) and a fully modular interface capability to support many different radar, IFF and graphics systems.

The RSCS's reverse scan conversion algorithm is based on a powerful coordinate transformation processor, which accurately maps the incoming Rho-Theta radar image to the Cartesian coordinates of the display framestore. A field-proven image mapping technique ensures that there are no holes or spokes in the displayed image and that target shapes are preserved at all range scales. The displayed image is updated as narrow triangles, closely following the rotation of the antenna with minimal latency. The scan conversion processor is able to update a 1600 x 1280 resolution display from a 2000 in real-time with up to a 60 RPM antenna rotation rate.

Features

- Proven COTS scan conversion technology
- Dual-Channel conversion
- Two 6U VME card set
- Modularity via mezzanine boards
- Inputs up to 16 radar and IFF videos + 2 triggers
- 0.5 -1000 Nautical miles presentation
- Variable persistence and fading
- Multiple radar windows
- Reverse scan conversion for instantaneous zooms
- Offsets and zooms without re-scanning - X-Windows compatible
- X-Windows resolutions up to 1600 x 1280 - 8 Underlay and 8 overlay planes
- Concurrent display of underlay and overlay - 4M Pixels per second conversion rate
- Dual 360 Degrees Rho-Theta polar memory store
- On-Board local framestore
- X-Windows software
- Application development environment
- Built-In test

Technical Description System Flow

The RSCS consists of two standard VME cards: a Radar Scan Converter (RSC) card and a Radar Interface (RI) card. Each accommodates an add-on personality mezzanine board. The mezzanine board on the RSC card provides the interface to different manufacturers' graphics cards. The mezzanine board on the RI card provides the unique electrical interface required by various types of radar and IFF video.

Radar video enters the RI card's signal conditioning radar interface mezzanine board. Radar video is then digitized and made available to the RSC card via a dedicated high-speed 40 MB/Sec data bus. The digitized radar video then enters the RSC card via the high-speed data bus for scan conversion and processing. Converted radar data is then made available to the RSC's graphics interface mezzanine board, where it is formatted for display. Formatted scan converted radar data is then made available to the graphics controller via a high-speed pixel bus.

Radar Input

The radar input function is performed by the RI card and its radar interface mezzanine board. The radar interface mezzanine board on the RI card receives application-specific radar and Identification Friend/Foe (IFF) video and performs analog processing, mixing and digitizing to precondition the data before it is sent to the RI board. The RI board accepts multiple radar and IFF video channels in polar form, as well as radar and IFF triggers, antenna synchro interfaces and IFF mode controls. Each radar and IFF video channel has individual gain controls.

The radar and IFF channels are summed individually to form two channels of video data. The resultant two channels of video data are synchronized with their respective triggers and digitized to 8 bits. After digitization, each channel passes through a separate 256 x 8 programmable Look Up Table (LUT). This LUT may be used for non-linear transfer functions, and radar cursor DC level and/or threshold setting.

Scan Conversion

The scan conversion function is performed by the RSC card. It accepts up to two channels of 8-bit digitized video from the RI board in polar form. This data consists of individual or combined radar and IFF video. The RSC board stores up to two channels of polar data in local polar memory. The scan conversion process converts the six most significant bits of polar data to Cartesian coordinate data (X, Y) with proper scale and orientation. The results are then stored in a local framestore located on the graphics mezzanine board. The resultant scan conversion process transforms the X and Y coordinates of each screen pixel to the nearest Rho-Theta coordinates and obtains radar data for that X-Y screen pixel. This operation is performed by a dedicated coordinate transform processor to provide the precise pixel location. Rho is then multiplied by a programmable factor to give the required range scale using a 16-bit multiplier. This is followed by subtracting the North offset from Theta and range offset from Rho to give the final pixel coordinates in the polar memory store.

The scan conversion process updates the screen image in sectors to give the appearance of a rotating update closely following the antenna rotation. For each scan line sector segment within the sector, the local control processor computes the X and Y coordinates of the first pixel in terms of screen pixels relative to position of the radar origin. The processor also calculates the corresponding framestore address for this pixel and the length of the line segment. These values are loaded into a FIFO memory and are processed in order by the scan conversion logic. The processor also loads the registers defining the range scale, North offset and current black pixel value. The transformed data is then output via the graphics interface mezzanine board over a digital video interface (graphics manufacturer specific) for presentation on a raster display device in up to two independent X-Windows. In addition, up to four zoom (or daughter) windows may be allocated to the two independent X-Windows.

Persistence

The local display framestore data may be decayed digitally to simulate phosphor decay. If no fading is required, a 6-bit intensity value is read from the radar image and is written to the display framestore. When the fade option (variable persistence from 4 seconds to 100 seconds) has been selected, the new data is compared with the old pixel data, and the higher value is rewritten back to the framestore. Fading is achieved by rotating the values in the RAMDAC Look Up Table so that older target images gradually reduce in brightness (intensity). To compensate for the changing value, the new pixel values are added to a constant, which represents the current black level for the display.

Target Spreading

Target spreading is a scan conversion processor option on the RSC card. It allows target images to be spread in azimuth direction at very short range, so that even single point targets will appear on the display. The scan conversion process results in a general enlargement of the radar image in the azimuth direction at long range and a reduction at short range.

Processor and VME I/O

The RSCS is controlled by an on-board microprocessor (Motorola MC68EC030) located on the RSC card. It runs local software held in EPROM. The processor is responsible for communicating with all other cards (RI, host, etc.) via the VME bus and for controlling local on-board logic. The RSCS is able to perform 8-, 16- or 32-bit transfers via the VME bus in both master and slave modes and incorporates the logic to act as a standard VME bus master.

Software

The DRS RSCS Software Development Environment (RSDE) provides the architecture and interfaces that support the development of software applications using radar scan conversion, video windows, map graphics and X-Windows. The DRS RSDE defines the operating layers that lie between the application program and the RSCS hardware. The RSDE provides an Application Programming Interface (API), using a Graphical User Interface (GUI) linked to "C++" functions calls to allow a radar scan conversion application to be fully linked to X-Windows.

Specifications

- Data input: 16 Video, 2 triggers and synchro
- Polar memory store: 8 MBytes
- Conversion rate: 4MBytes/second
- Persistence: 4 - 100 Seconds
- Processor type: MC68EC030
- A/D Rate: 42 Mbyte samples/second
- EPROM: 1 MByte
- VME Bus master (RSC): A32, A24; D32, D16, D8E(0)
- VME Bus Slave (RI): A32, A24; D16, D8E(0)
- VME interrupt: Priority 1-7, RORA
- Display framestore: 2 MBytes
- Resolution: 1600 x 1280
- Video Output: RS-343A on interface mezzanine
- Interface mezzanine: Various radar and IFF interface already exist
- Graphics Mezzanine: IAVI (BARCO), PCI and Other Interfaces Available
- Power Requirements: 60 Watts
- Operating Temperature: -20°C to +50°C