USES (JC06)

The USES chip is a lossless data-compression chip that can compress data at rates up to 20 Msamples/s with a maximum quantization of 15 bits/sample. USES provides 14 Rice algorithm coding options plus a low-entropy option and implements the CCSDS lossless data-compression standard.

Highlights

• Lossless compression up to 20 Msamples/s
• 14 Rice algorithm coding options plus one low-entropy option
• Up to 15 bits of quantization
• 14 bits of quantization for multispectral data
• Data may be positive or two’s complement
• Supports continuous or discontinuous data streams
• Parallel 16-bit packetized output
• Radiation-hard gate array in a 196-pin flat pack using 88 I/O pins
• Meets CCSDS lossless data-compression standard

Description

USES accepts sampled data and codes it using lossless algorithms. Input data may be two’s complement or positive and quantized within the range N = {4 … 15} bits. Maximum quantization is 15 bits/sample except in multispectral mode, in which the maximum quantization is 14 bits/sample.

The sampled data may, for example, be imagery, digital audio, data from transform bins, or data from scientific measurements. The chip operates on small blocks of data rather than an arbitrary number of data samples. The block value J must be set to 8, 10, or 16 samples per block. If a scan line does not end in an integral number of J samples, the final input block must be filled to J samples using the ValBlk input signal.

USES has two major modes of operation: compression and bypass. In compression mode, the entropy coder is used to code input data, while the preprocessor may or may not be used. Coding may occur after the data is preprocessed using prediction modes, or input data may be routed around the preprocessor so that it goes directly to the entropy coder. In bypass mode, no compression or insertion of bits is performed; the chip functions as a packetizer, forming data into 16-bit words.