overview •
2.1 Introduction
Digital Signal Processing (DSP) devices permit multiplication and additions to be performed extremely quickly.
This ability is particularly useful for tasks which require repetitive calculations, e.g. filtering, speech and hand-writing recognition and image processing and enhancement. There are essentially two types of DSP device, low to medium performance programmable devices and high performance devices dedicated to a specific application area. Programmable devices provide the ideal solution for modest requirements (e.g. telephone echo cancelling system). These devices cannot, however, deal with the compute intenSive properties of more demanding signal processing requirements.
2.2 The INMOS solution
INMOS is dedicated to the production of high performance devices. By targetting specific high performance applications the ratio of cost to performance is greatly improved. INMOS DSP devices can individually achieve between 68 and 480 MOPS. Programming is not required as the algorithms are hardwired into the device.
Some of the devices can further be grouped together (cascaded) to linearly increase performance. These features combine to provide an economic, compact, low power and high performance solution.
INMOS DSP applications include mobile radio base systems, satellite communication links, studio TV equip-ment, image processing, handwriting recognition and radar and sonar systems. INMOS are continually work-ing to develop new products targetted at selected signal processwork-ing applications. Current areas of interest and development are directed at such areas as video phones, where a complex image must be compressed for transmission across the telephone network, and High Definition TeleviSion (HDTV) for use in broadcasting and storage of high definition TV pictures.
INMOS DSP devices are configurable rather than programmable. While a complete system could be built solely from, for example, the A100 device (one dimensional filtering) or A11 0 devices (image processing) the design is such that multiple devices can be used in conjunction with a controlling microprocessor. This arrangement of controlling microprocessor and arrayable function/algorithm specific device maintains the flexibility of a programmable system but allows very high performance in a small number of devices.
INMOS DSP devices currently include the IMS A 100 Cascadable Signal Processor, the IMS A 110 Image and Signal Processor and The IMS A121 2-D Discrete Cosine Transform Image Processor.
2.3 The IMS MOO Cascadable Signal Processor
The IMS A 100 device is suitable for processing the high-speed data streams necessary for radio, radar, sonar and satellite communications systems. The following techniques are typical:
• Convolution/correlation mount packaging to satisfy the environmental requirements of military systems.
These features are ideal for a range of radar, sonar and ultrasonic systems. Typical applications are as follows:
• Nose cone radar
• Early warning systems
• Ultrasonic weld inspection
• Phased array sonars
• Medical ultrasonics
• Towed array sonars Communications
The IMS A100 device provides enormous filtering power. A high performance or general purpose micropro-cessor used to control one or more IMS A100 devices produces a high performance adaptive filter, capable of real time countering of signal attenuation, reflection and interference in systems. The following applications are typical:
• Digital satellite communications
• Mobile digital radio
• Megastream modem applications (for example, a 2Mbitls video conferencing system)
• Telephone exchange processing for multiple ISDN data channels.
2.4 The IMS A110 Image and Signal Processor
The IMS A 110 is ideal for solving a number of real time image processing problems. The following are typical:
• 1O/2D Convolution
The image processing requirements of machine viSion systems include noise filtering, correction of distortion and enhancement of features. The IMS A11 0 contains a 20Mhz 7x3 multiplier array and line stores, a single device can therefore provide filters such as edge detectors in real time. More demanding requirements can readily be met by arraying IMS A11 0 devices. Typical applications are as follows:
• Optical alignment
• Visual inspection for defects
• Robot Vision
• Automated pathology Image compression
The ability of the IMS A 110 device to realise data compression techniques, such as sub-band/pyramid coding and linear predictive coding in real time, makes it ideal for the following applications:
• Video conferencing
• Facsimile of high-quality pictures
• Communication of images from remote observation points (e.g. satellites)
• Image archiving (e.g. medical image databases) Contrast enhancement
Image processing systems often require contrast modification in addition to image filtering. This is supported in the IMS A11 0 by the inclusion of a sophisticated data transformation post processor unit providing support for the following applications:
• Histogram equalisation (enables adjustment to different lighting conditions)
• Image contouring (e.g. for simplifying medical images)
• Dynamic range compression or expansion
Other applications
• Postal sorting
• Traffic control
• Airport baggage X-ray inspection
• Handwriting and face recognition
• Bank cheque sorting and processing
• Conversion between TV standards
• Target acquisition and tracking
• Document processing
• Medical image processing
• TV special effects
2.5 The IMS A 121 2-D Discrete Cosine Transform Image Processor
The IMS A121 is the latest INMOS DSP device. It has been designed to provide high speed computation of an 8x8 Discrete Cosine Transform (OCT) or Inverse Discrete Cosine Transform (IDCT) at video data rates for image processing. Typical applications are as follows:
• Image data compression and decompression (e.g. video codecs)
• Image understanding (e.g. image texture analysis) Image compression
OCT based image coding is appropriate for a wide range of applications which require image data compression and decompression:
• Video conferencing and video phones
• FaCSimile of colour and greyscale images
• Compact disc based interactive video systems
• Office document processing systems utilising colour or greyscale images
(e.g. Document scanners, desktop publishing systems, page printers and image archiving systems) Image understanding
The frequency domain description of an image provided by the OCT is a powerful tool for analysing textures and patterns within an image.
ASynchronous Functions.
Variants for full MIL temperature range (-55°C to +125°C )
MIL-STD-883C processing
Full 16 bit, 32 stage, transversal filter
Fully cascadable with no speed degradation or reduction in dynamic range
Coefficients selectable as 4, 8, 12, or 16 bits wide Data throughput to 15.0 MHz
High speed microprocessor compatible interface Data input and output through dedicated ports or via the microprocessor interface
Fully static high speed CMOS implementation Single +5V ±5% or ±10% power supply variants
Speech processing using Linear Predictive Coding Image processing
Waveform synthesis
Adaptive and fixed equalizers and echo cancellers Spread spectrum communication
Beamforming and beamscanning in sonar and radar Pulse compression
High speed fixed point matrix multiplication
June 1989