Dual Link Image Coding for Earth Observation Satellites

Abstract

The conventional strategy to download images captured by satellites is to compress the data on board and then transmit them via the downlink. It often happens that the capacity of the downlink is too small to accommodate all the acquired data, so the images are trimmed and/or transmitted through lossy regimes. This paper introduces a coding system that increases the amount and quality of the downloaded imaging data. The main insight of this work is to use both the uplink and the downlink to code the images. The uplink is employed to send reference information to the satellite so that the on-board coding system can achieve higher efficiency. This reference information is computed on the ground, possibly employing extensive data and computational resources. The proposed system is called dual link image coding. As it is devised in this work, it is suitable for Earth observation satellites with polar orbits. Experimental results obtained for datasets acquired by the Landsat 8 satellite indicate significant coding gains with respect to conventional methods.Index Terms-Dual link image coding, satellite data transmission, JPEG2000. I. INTRODUCTIONS INCE the launch of Sputnik 1 in 1957, the number and diversity of satellites orbiting the Earth has not stopped growing. Nowadays, there are more than 2,000 satellites dedicated to communications, navigation, astronomy, weather, reconnaissance, and Earth observation (EO). These satellites provide services in our every-day lives such as TV, Internet, weather forecast, or geolocation, among others.Most satellites are situated in either a geostationary or a polar orbit (see Fig. 1). Satellites in geostationary orbits are at an altitude of approximately 22,000 miles and are located above a stationary point on the Earth's equator. Their communications rely on ground stations that have an uninterrupted line of sight to the satellite. Despite the fact that the high altitude restricts the communication to medium/low capacity channels, these satellites are in constant contact with the ground station, so they can transmit great amounts of data. They are commonly employed for communication-related tasks.

Learned Representation of Satellite Image Series for Data Compression

“…Preliminary studies on using the prior knowledge to improve the compression efficiency mainly focus on using images as references. In this work, the reference image can be an original historical image [32,33] or a synthesized image [24,26,34]. In our previous works [2], we used the current Google Map image as the historical reference.…”