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The VME64x standard includes a double data rate block transfer cycle known as 2eSST. In order to achieve the maximum bandwidth, 64-bit words are exchanged in bursts across the backplane without handshake between master and slave. Data is clocked by both the falling and rising edges of a single strobe line driven by the data producer. Transfer rates up to 320 Mbyte/s are presently supported: the standard also foresees even faster speed grades, to be released in the future. In this paper we present our tests on 2eSST beyond the actual limit set by the protocol. Bit Error Rate (BER), data timing jitter and eye-diagrams have been measured for selected bus layouts and data patterns. Performance achieved with and without the Bus-Invert encoding of the transmitted payloads are compared. Our results show that on a 21 slot VME64x backplane reliable transfers can be sustained with selected loads up to 800 MByte/s with a [10.sup.-12] BER. Index Terms--Bit error rate, bus-invert coding, data acquisition, jitter, signal integrity, VMEbus, 2eSST.

Some physics researchers retrieve EAST experiment data using the Transmission Control Protocol (TCP) in a wireless local area network (WLAN). TCP is the most commonly used transport control protocol. It assumes that every packet loss is caused by network congestion and invokes congestion control and avoidance. TCP's blind congestion control results in degraded performance in lossy wireless networks. In a wireless network, mobile hosts have first-hand knowledge of the lossy wireless links; therefore, mobile stations can make better transmission control based on the known status of wireless link. In this paper, we proposed a new mobile-host-centric transport protocol (MCP) that integrates the characteristics of sender-centric and receiver-centric transport control schemes. MCP shifts most control policies to the mobile host side. The general behavior of MCP is similar to the TCP, but by utilizing the local information collecting from the mobile node in WLAN, MCP allows for better congestion control and loss recovery. Specifically, we designed a cross-layer implementation of MCP and ran it on NS-2 network simulator. With valuable Medium Access Control (MAC) layer feedback information, MCP is able to distinguish packet loss caused by wireless random errors from network congestion more clearly and can perform a more accurate congestion control. We did extensive simulations of MCP on various WLAN scenarios, and the results show that the throughput of MCP with cross-layer feedback is higher than that of TCP Reno and Westwood. Index Terms--Information rates, Traffic control, Transport protocols, Wireless LAN.

A radiation-hard optical link is under development for readout and control of the tracking detector in the future CMS experiment at the CERN Large Hadron Collider. We present the optical system architecture based on edge-emitting InGaAsP laser-diode transmitters operating at a wavelength of 1.3[[micro]meter], single mode fiber ribbons, multi-way connectors and InGaAs Pin photodiode receivers. We report on radiation hardness tests of lasers, photodiodes, fibers and connectors. Increases of laser threshold and pin leakage currents with hadron fluence have been observed together with decreases in laser slope-efficiency and photodiode responsivity. Short lengths of single-mode optical fiber and multi-way connectors have been found to be little affected by radiation damage. We analyze the analog and digital performance of prototype optical links transmitting data generated at a 40MSamples/s rate. Distortion, settling time, bandwidth, noise, dynamic range and bit-error-rate results are discussed.

FASTCAMAC [1] is a high speed block transfer protocol with data rates up to twenty times faster than normal CAMAC [2,3]. FASTCAMAC is compatible with the CAMAC data acquisition standard. The new protocol is presented as a short tutorial for the data acquisition user. Emphasis is on FASTCAMAC as an extension to CAMAC with discussion of compatibility, performance and system aspects

A knowledge of the distribution of the attenuation coefficient is generally required for a successful correction of attenuation in nonhomogeneous regions. This can be accomplished by performing transmission measurement with either parallel or fan-bean collimation. The Monte Carlo method makes it possible to fully evaluate the results of such a correction. This study shows results from such simulations for both parallel and fan-beam transmission imaging. Also, examples of the effect of down-scatter from an emission 99mTc radionuclide into the energy window for a transmission 153Gd radionuclide are shown.

We have developed a TDC+Transputer-based acquisition system to study the X-ray imaging capabilities of a silicon [micro]strip detector with 100 and 200 [[micro]meter] read-out pitch. This system allows real-time image acquisition and display. We present images obtained with an X-ray mammography tube using sub-millimeter high contrast test objects on a 16*16 channels prototype.

The Data Acquisition System (DAQ) at the Collider Detector at Fermilab is currently being upgraded to handle a minimum of 100 events/sec for an aggregate bandwidth which is at least 25 Mbytes/sec. The DAQ System is based on a commercial switching network which has interfaces to VME bus. The modules that read out the front end crates (FASTBUS and RABBIT) have to deliver the data to the VME bus based host adapters of the switch. This paper describes a read out system that has the required bandwidth while keeping the experiment deadtime due to the read out to a minimum.

A modular, UNIX/X-Windows/Sun SPARC-based data acquisition and analysis system provides NASA X-Ray Timing Explorer (XTE) Proportional Counter Array (PCA) scientists with near real-time access to space flight instrument ground test data. This system processes data directly from five large-area, xenon-filled low-background collimated proportional counters at rates up to 2 MB/s in a networked, real-time environment. Science events are sent serially from the proportional counter flight electronics and multiplexed on a custom-designed data acquisition board. Each event is tagged with a time stamp of 1 [[micro]second] resolution and a detector identifier. A commercial Direct Memory Access (DMA) board interfaces directly to the data acquisition board allowing asynchronous transfer of buffered data to software residing on a high performance workstation. A windows-based interface provides an operator with acquisition command and control functions to capture data through the DMA board. Data is collected, buffered, and archived to magnetic disk. Histogramming and statistical functions are provided by the software enabling real-time pulse height spectroscopy, rate analysis, and spectral analysis.

We have developed a new data acquisition system for a [K.sup.0] decay experiment (E162) at KEK PS. The system has a unique pipeline operation scheme for front-end modules without 'flash' devices. This pipeline scheme enables the next event to be processed during data read-out, and thus dead-time can be reduced significantly.

The very high spatial resolution required by the Zeus Tracking Detectors and the 96ns periodic interaction between protons and electrons of the Hera collider require real time Analogue Signal Digitization at 104MHz controlled reliably to tight tolerances. Maximum event readout efficiency, fast monitoring of run time errors and testability of front end electronics require pipelining, speed and flexibility. Such an electronic Timing and Control System (TCS) is operational within three main inner detectors of the ZEUS detector and is presented in this paper.

A new data acquisition system based on concepts such as data switches and multiple-processors is described. The main topic is how data coming from a multicrate front-end in CAMAC, VME and FASTBUS are transported over different links to a buffer-matrix data switch and further into a farm of microprocessors. Modularity, scalability and multilevel data monitoring are important parts of the design goals that are presented. The system is intended for use in an experiment searching for rare events where high interaction rates are necessary and where a fast and selective trigger is difficult to define. Other experimental constraints, the trigger logical structure and the performance of the data acquisition are also described.

An electronic data acquisition system for pixelated, two-dimensional, amorphous silicon x-ray imaging arrays has been developed. The system was designed in a modular fashion with digital control provided by field-programmable logic devices. This approach allows sections of the design to be upgraded with little impact on other aspects of the system. Good analog noise performance was obtained by matching the preamplifier design to the characteristics of the array outputs. The design of this system is presented and its performance quantified.

The present article describes a transceiver VLSI chip for optical data transmission, at 1 Gbit/s (1.4 Gbit/s in selected production), made in GaAs technology. The transceiver makes the parallel-to-serial and serial-to-parallel conversion as well as the encoding and decoding of 32 bit data words. The circuit operates in a completely asynchronous mode, allowing the possibility of switching on-off the transmission in few nsec and of using the transceiver not only in point-to-point topologies, but also in flooding topologies (i.e. star connections) |2~, |9~, |12~. The radiation hardness and the relatively low power consumption, respect to TTL, of the GaAs, extend the use of the chip to a large number of applications in present and future high energy physics experimental apparatus.

A remote console system is developed to improve remote control over experimental apparatus borne on the balloon. The remote console system, residing at a ground station for balloon borne experiments, sends commands to the apparatus and receives transmissions from it. The system communicates by radio with microcomputers incorporated in the experimental apparatus borne on a balloon, where the microcomputers control the apparatus individually. The system includes plural personal computers and work stations which share the transmissions from the apparatus. The transmissions from the apparatus are formatted in a bit oriented protocol, which dispenses with a formatter and facilitate interface with the personal computers. The article describes the implementation of the system and the communication between the ground station and the balloon-borne apparatus.

An architecture for oil-wafer processing is proposed for central silicon-strip tracker systems as they are currently designed for high energy physics experiments at the SSC, and for heavy ion experiments at RHIC. The data compression achievable with on-wafer processing would make it possible to transmit all data generated to the outside of the detector system. A set of data which completely describes the state of the wafer for low occupancy events and which contains important statistical information for more complex events can be transmitted immediately. This information could be used in early trigger decisions. Additional data packages which complete the description of the state of the wafer vary in size and are sent through a second channel. By buffering this channel the required bandwidth can be kept far below the peak data rates which occur in rare but interesting events.