The DEAPspace project is building an interaction framework for connecting pervasive devices over the wireless medium, supporting the development of new proximity-based collective distributed applications. The main components of this framework are the discovery algorithm and the service description model. DEAPspace provides devices with useful information about the other devices in their surroundings. This information can be queried in a consistent way that will tolerate evolutions, and allow legacy devices to continue to function in the fast-developing world of pervasive gadgets. The discovery is done in a power-efficient, and network-friendly way, and will adapt to a wide range of error conditions. This framework has been implemented, and allows the development of distributed applications that use ad-hoc transient networking as part of their function. The primary implementation was in Java. A subset of the code was also written in C, to allow the use of machines which do not have a JVM. In addition to simulation, the code has been tested over TCP/IP and the Ethernet interface of an 802.11 link.

The realization of a digital recording system using partial-response class-IV signaling with maximum-likelihood sequence detection (MLSD) is described. To perform MLSD at the high data rates encountered in recording systems, a simple implementation of the Viterbi detector based on a difference-metric algorithm is developed. Decision-directed schemes for gain control and timing recovery, for tracking variations of the gain and timing phase during data readback, and for fast initial adjustment from a known preamble are presented. The dynamic behavior of the control algorithms was studied by computer simulations. Coding was used to facilitate timing recovery and gain control, to limit the path memory length of the Viterbi detector, and to allow fast and reliable startup of the receiver. The design and properties of rate 8/9 constrained codes are examined. The problem of equalization is addressed, and analog and combined analog/digital filter implementations are developed. A simple adaptive equalizer capable of compensating variations of the recording channel characteristics with track radius and/or head-to-medium distance is described.>