Kazuaki Anraku

Low power TAC & QVC circuits for balloon borne experiments

TAC (time-to-amplitude converter) and QVC (charge-to-voltage converter) circuits have been developed for balloon-borne experiments. The aim of the development is to reduce power consumption. The circuits were optimized by a simulation program on a workstation. The TAC measures a time interval and QVC measures an amount of charge. The time resolution of the TAC is 2 ns/count for a full scale of 8 mu s (12-b). The power consumption is 55 mW/channel. The QVC offers a resolution of 0.6 pC/count for a full scale of 1200 pC(11-b) and consumes 80 mW/channel. It is concluded that the design goals of the simulation have been achieved in the prototype TAC and QVC circuits. >

A low power flash ADC system with fast data compression ASIC for a balloon-borne experiment

A low power multichannel flash analog-to-digital converters (FADC) system with fast data compression applications specific integrated circuits (ASICs) was developed for readout of drift chambers on a balloon-borne cosmic-ray superconducting spectrometer. The FADC system consists of up to 20 FADC modules, each of which has 32 input channels, and one interface module called crate controller. Each readout channel is equipped with a 30 Ms/s 8-bit FADC and a data compression ASIC. The data compression is executed synchronously with analog-to-digital conversion (ADC), thereby compressed data is ready for event building at almost the same time as the end of digitization. Thus, both event data size and data acquisition dead-time are reduced and the data of as many events as possible can be recorded onto a limited volume storage device on the balloon-borne apparatus. The main logic circuits of the interface module consist of one field programmable gate arrays (FPGAs), with the functions able to be changed flexibly depending on demand. The system is powered by batteries, and so special care is taken to reduce power consumption.

A local network integrated into a balloon-borne apparatus

Abstract A local network is incorporated into an apparatus for a balloon-borne experiment. A balloon-borne system implemented in the apparatus is composed of subsystems interconnected through a local network, which introduces modular architecture into the system. The network decomposes the balloon-borne system into subsystems, which are similarly structured from the point of view that the systems is kept under the control of a ground station. The subsystem is functionally self-contained and electrically independent. A computer is integrated into a subsystem, keeping the subsystem under the control. An independent group of batteries, being dedicated to a subsystem, supplies the whole electricity of the subsystem. The subsystem could be turned on and off independently of the other subsystems. So communication among the subsystems needs to be based on such a protocol that could guarantee the independence of the individual subsystems. An Omninet protocol is employed to network the subsystems. A ground station sends commands to the balloon-borne system. The command is received and executed at the system, then results of the execution are returned to the ground station. Various commands are available so that the system borne on a balloon could be controlled and monitored remotely from the ground station. A subsystem responds to a specific group of commands. A command is received by a transceiver subsystem and then transferred through the network to the subsystem to which the command is addressed. Then the subsystem executes the command and returns results to the transceiver subsystem, where the results are telemetered to the ground station. The network enhances independence of the individual subsystems, which enables programs of the individual subsystems to be coded independently. Independence facilitates development and debugging of programs, improving the quality of the system borne on a balloon.

A power system of a balloon borne experiment

The article describes solid-state relays, a voltage regulator and a power management network which are employed in a balloon borne experiment. Electronics borne on a balloon experiment become more and more complicated, and the number of the batteries borne on the balloon increases accordingly. The solid-state relays are introduced to facilitate control and management of a large number of the batteries. Turn-on resistance of the solid-state relay is kept within a prescribed allowance. The solid-state relays control power supplies from the batteries. The voltage regulator features both a low dropout voltage and a large output current capacity. The low dropout voltage extends the duration while the battery supplies enough voltage for proper operation of the regulator. The solid-state relays and the voltage regulator are kept under the control of the power management network. The network is composed of relay nodes and a command node. The solid-state relays and the voltage regulator are controlled by the relay nodes. The command node receives commands sent from a ground station and makes it possible to turn on and off the electronics remotely from the ground station.<<ETX>>