Changes between Initial Version and Version 1 of UserManual

Timestamp:

Nov 9, 2010, 11:56:18 AM (14 years ago)

Author:

demin

Comment:

--

UserManual

@@ +1 @@
+== Introduction ==
+
+The input to the Paella card is the pulse shaping amplifier output. The Paella
+card digitizes the input, applies real-time digital processing to the
+signal, detects the peak amplitude (digitally), and bins this value in its
+histogramming memory, generating an energy spectrum. The spectrum is then
+transmitted over the USB interface to the user's computer.
+
+The main blocks of the Paella card are:
+ - Digitazing block, based on the 20 MSPS, 12-bit ADC, AD9228;
+ - Signal processing block, implemented in a Cyclone III EP3C25 FPGA from Altera;
+ - USB interface, based on the EZ-USB FX2LP controller from Cypress.
+
+The ADC output is processed continuously using a pipeline architecture. There
+are two parallel signal processing paths: the "fast" and "slow" channels,
+optimized to obtain different data about the incoming pulse train. The "slow"
+channel is optimized to obtain accurate pulse heights. The "fast" channel is
+optimized to obtain timing information: detecting pulses which overlap in the
+slow channel, measuring the incoming count rate, measuring pulse risetimes, etc.
+
+The pulse selection logic rejects pulses for which an accurate measurement
+cannot be made. It includes pile-up rejection, risetime discrimination logic,
+etc.
+
+The histogramming memory operates as in a traditional MCA. When a pulse occurs
+with a particular peak value, a counter in a corresponding memory location is
+incremented. The result is a histogram, an array containing, in each cell, the
+number of events with the corresponding peak value. This is the energy spectrum
+and is the primary output of the Paella card.
+
+The unit also includes several counters, counting the total number of selected
+pulses but also counting input pulses, rejected events, etc.
+
+The Paella card includes hardware and software to interface between these
+various functions and the user's computer. A primary function of the interface
+is to transmit the spectrum to the user. The interface also controls data
+acquisition, by starting and stopping the processing and by clearing the
+histogram memory.