The AMCS-USB is a four input multichannel scaler (MCS) card to be used in pulse counting, integrating, and histogramming applications. The AMCS-USB accepts four different pulse inputs that are counted simultaneously based upon a single Sync input signal. In addition, there are two generic pulse outputs and a third accumulation delay pulse indicating the start of an integration cycle. The AMCS-USB card is highly integrated in that all storage memory and multichannel scaler functions are contained within a single chip. Parameters such as time resolution per bin, number of bins, accumulation delay, number of accumulations, and pulse polarity are set by the user via software control. The AMCS-USB card transmits data to a host CPU at the end of a completed integration cycle. All data transfers (i.e. commands from the host and acquired data from the card) are made via the Universal Serial Bus (USB) 1.1 interface. The AMCS-USB card is in a form factor of approximately 4.2 inches x 4.0 inches. It can be used in any PC or Macintosh (laptop or desktop) based system with a USB port.
Multichannel scalers are used in a variety of applications. The AMCS-USB card was specifically designed to meet the needs of ground-based and airborne lidar-based photon counting programs, although the design does not preclude its use in other arenas. In an example airborne lidar application, a laser is fired down to the earth from a high flying aircraft. As the optical laser output moves downward, some of the light is reflected due to aerosols, clouds, and other particulate in the atmosphere. Photon counting detectors tuned to specific wavelengths detect the reflected light and output electrical signals indicating the presence of the reflected photons. The AMCS-USB card is used to receive these electrical signals. By using a synchronization signal input, the AMCS-USB card is aware as to when the data acquisition starts. It divides the time-of-flight of the laser into time ?bins? and records the number of reflected photons received in each bin. By repeating this process over the course of many laser shots, the signal-to-noise ratio is greatly enhanced versus the results given during a single laser shot. This allows an accurate histogram to be generated based on the data acquired by the AMCS-USB data. Once the desired number of lasers is fired, the AMCS-USB card transmits collected data to the host computer via the USB. During the data collection by the software, the AMCS-USB continues to count and accumulate photons in a double-bufferred memory such that no data is lost. The AMCS-USB card allows for many of its parameters to be configured via software, making this product attractive to multiple customers. In addition, the integration of the memory and the MCS functions in a single reprogrammable chip makes the AMCS-USB extremely flexible in the ability to readily customize the AMCS-USB functions for specific user needs.
