Agilent Three Compelling Reasons for Deep Acquisition Memory 5991-1822EN c20140624 [9] free download

File name Three Compelling Reasons for Deep Acquisition Memory 5991-1822EN c20140624 [9].pdf

Keysight Technologies Three Compelling Reasons for Deep Acquisition Memory Application Note Introduction Oscilloscope vendors specify memory depth as a primary attribute for specific oscilloscope models. This value equals the number of samples that are stored with each acquisition. Memory depth is typically specified as a per-channel value. Some oscilloscopes have interleaved memory architectures. For example, memory may have a specific value when all channels are turned on and double the value when only half of the channels are enabled. In addition to standard acquisition memory specified, most oscilloscopes have additional memory loaded on the acquisition board with this additional depth licensed separately. While acquisition memory depth is often used as a primary purchase consideration, the associated benefits and tradeoffs of deep memory require additional thought to fully appreciate. Here are three areas where deep memory adds value. 1. Capture Longer Period of Time The most obvious benefit of deep applications that require deeper acquisition memory is the capture memory. of longer periods of time at a fixed sample rate. Deep memory helps in instances where the cause and effect may be separated by a significant time period and plays a key role in viewing events that simply take longer time to transpire. Acquisition Time Window = Memory Depth / Sample Rate. As shown in Figure 1, with 1 Mpts (mega points) per channel an oscilloscope can capture .1 ms of time with 10 GSa/s sample rate. As shown in Figure 2, if the same oscilloscope instead had 100 Mpts per channel, it could capture on 10 ms of time at the same sample rate. There are wide varieties of applications and tests that benefit Figure 1. Acquisition Time Window = Memory Depth/Sample Rate. With 1 Mpts (mega from longer time captures. Having points) per channel an oscilloscope can capture .1 ms of time with 10 GSa/s sample rate. deep memory provides more flexibility To capture longer periods of time, sample rate is decreased. for engineers when they encounter Figure 2. Time Window = Memory Depth / Sample Rate. An oscilloscope with 100 Mpts per channel can capture on 10 ms of time at 10 GSa/s. Additional depth provides more time capture at a fast sample rate. 3 All advanced oscilloscopes from major vendors include a mode that allows memory to be partitioned into smaller segments. The Keysight Technologies, Inc. oscilloscopes refer to this as segmented memory. The user specifies how many seg- ments the memory should be divided into with each segment having equal length. When the oscilloscope sees the first trigger event, it stores 12.5 Mpts to capture 3 pulses 300 Kpts to capture 3