SIGNAL CONDITIONING & DATA ACQUISITION SYSTEM FOR SLEEP DEPRIVATION STUDIES

AT型微型计算机具有常驻16通道、12位A/D板， 用于测量和存储小直径(0.5 mm)的信号。X 3毫米长)， 快速(20毫秒)玻璃封装热敏电阻。校准值 每个热敏电阻都存储在单独的校准文件中， 在程序启动时加载到程序中。热敏电阻电桥 额定热敏电阻的电路容差为+/-20% 电阻，覆盖范围为25摄氏度至45摄氏度，0.01 摄氏度分辨率。自定义软件控制样品采集 信号的速率、滤波线性化、校准和存储。 A/D卡以“后台”模式运行30秒， 将数据直接传输到指定的内存位置。此模式 关闭操作可释放CPU来处理前一个间隔的数据 并且允许不间断或连续的数据采集。后 第一个周期切换存储单元，另一个周期 开始了。然后，该程序从 以前的存储位置，并确定每个热敏电阻的电阻 从电压读数来看。从这个电阻和校准 值时，计算每个热敏电阻的温度。这个 “后台”操作还允许更新或更改校准 数值(新热敏电阻)或重新定位热敏电阻(通道更改) 而不会中断数据采集。

An AT-type microcomputer with a resident 16-channel, 12-bit A/D board is used to measure and store signals from small (0.5 mm dia. x 3 mm long), fast (20 msec), glass-encapsulated thermistors. The calibration values for each thermistor are stored in a separate calibration file and are loaded into the program when the program is started. A thermistor bridge circuit accommodates a tolerance of +/-20% in the nominal thermistor resistance, and covers a range of 25 degrees to 45 degrees C with 0.01 degrees C resolution. Custom software controls the sample acquisition rate, filtering linearization, calibration, and storage of the signals. The A/D card runs in a "background" mode for 30-second intervals, with the data transferred directly to a specified memory location. This mode of operation frees the CPU for processing the previous interval's data and allows uninterrupted, or continuous, data acquisition. After the first cycle, the memory location is switched and another cycle is started. The program then downloads the 16-channel data from the previous memory location and determines the resistance of each thermistor from the voltage readings. From this resistance and the calibration values, the temperature of each thermistor is calculated. The "background" operation also allows updating or changing the calibration values (new thermistor) or relocating the thermistor (channel change) without interrupting the data acquisition.