Service Manuals, User Guides, Schematic Diagrams or docs for : Stanford Research Systems www.thinksrs.com-SR620_details
<< Back | HomeMost service manuals and schematics are PDF files, so You will need Adobre Acrobat Reader to view : Acrobat Download Some of the files are DjVu format. Readers and resources available here : DjVu Resources
For the compressed files, most common are zip and rar. Please, extract files with Your favorite compression software ( WinZip, WinRAR ... ) before viewing. If a document has multiple parts, You should download all, before extracting.
Good luck. Repair on Your own risk. Make sure You know what You are doing.
Image preview - the first page of the document
>> Download www.thinksrs.com-SR620_details documenatation <<
Text preview - extract from the document
www.thinkSRS.com
Measurements with the SR620
Application Note #2
In order to realize the full potential of the SR620 Universal Pulse Width Measurement
Time Interval and Frequency Counter, a brief look at its
several modes of operation and some of their applications is Magnetic and optical memory disk data is stored using
appropriate. It is also important for a user to understand the different modulation schemes to minimize disk real-estate and
performance specifications of the SR620, in order to draw maximize signal-to-noise ratio. For example, compact disk
reasonable conclusions from experimental data. How accurate players use 3-11 modulation to obtain very high disk density.
is a particular measurement? What errors can be expected? This scheme produces data patterns with nine different pulse
This application note defines, in detail, the performance widths (corresponding to 3, 4, 5, ...11 consecutive 0's). The
specifications and terminology for each mode of operation. SR620 can be used to measure these pulse widths and their
This information will enable the user to fully understand the variations, and display them graphically in histogram form on
capabilities and limitations of the instrument. an X-Y oscilloscope.
The first section of this application note describes the type of Rise and Fall Time Measurement
measurements that the SR620 can perform and gives some
application examples. It will give the reader an appreciation When analyzing the transition time required for a
for the wide range of applications in which the SR620 least-significant-bit change in a DAC (digital to analog
Universal Time Interval and Frequency Counter can be used. converter), the 10 % to 90 % rise time of that transition is of
importance. Once the rise time has been established, the
The second section (SR620 Specification Guide) explores the small-signal frequency response of the DAC can be calculated
specifications of the SR620 in detail. A precise definition of (bandwidth=0.35/rise time). The SR620 allows the user to set
measurement accuracy (resolution and error), along with the start and stop voltage thresholds, in rise and fall time
explanations of technical terminology, is given for each mode measurements, so that any part of a transition may be
of operation. analyzed.
Applications of the SR620 Frequency and Period Measurement
The SR620 Universal Time Interval and Frequency Counter When measuring the quality of a reference frequency source,
has been used to measure everything from the propagation the jitter (standard deviation or Allan variance) is often of
delays of integrated circuits, to the distance to the moon. Its significance. The SR620 will analyze the source over a set
versatility and affordable price have made the SR620 an gate time, and then display a distribution curve of the data
instant success in the engineering and scientific marketplaces. showing the mean frequency, minimum and maximum
The SR620 can be used to measure time interval, frequency, frequencies, and the jitter, revealing the quality of the source.
period, pulse width, phase, rise and fall time, and will also do Frequency is measured as N/(t) and Period is measured as
event counting. Statistical calculations including mean, (t)/N, where N is the number of cycles, and t is the elapsed
standard deviation, Allan variance, minimum and maximum, time to complete N cycles.
are performed on up to one million samples in all modes of
operation. In addition to displaying the statistical data on the Phase Measurement
16-digit LED display, distribution graphs of the data, in
histogram and strip chart format, can be displayed on an X-Y When characterizing operational amplifiers, it is useful to
oscilloscope. Application examples of the SR620 are know the phase verses frequency relationship. The SR620 can
discussed below. measure the difference in phase between the input and output
at different frequencies so that a Bode plot can be constructed.
Time Measurement
Event Counting
The SR620 measures the time interval between two
independent signals, A and B. An example using this mode of Used in conjunction with a discriminator, the SR620 can
operation is measuring the electrical length of a cable. The function as a photon counter that counts electrical pulses from
cable can be configured as end-to-end or single-ended, with a PMT (photomultiplier tube). It can count at a rate of up to
the remote end shorted to ground or left open. Using the built- 200 MHz. In another application, the SR620 has proven to be
in 1 kHz reference signal as a stimulus, the propagation delay a cost effective way to count canned goods traveling on a
from one end of the cable to the other, or between the incident conveyer belt as they pass a check point.
and reflected rising edge of the pulse, can be measured.
Knowing that electricity travels at approximately one foot per These examples represent only a few of many possible
1.5 nanoseconds, the cable length can easily be calculated. applications of the SR620. A full description of how to
perform these, and other types of measurements, is given in
Another time interval application is the measurement of the SR620's operation and service manual.
propagation delays of integrated circuits. Again, the 1 kHz
reference source can be used to excite the experiment, and the
time delay from the input to the output of the integrated circuit
can be measured.
Stanford Research Systems phone: (408)744-9040
www.thinkSRS.com
Measurements with the SR620
SR620 Specification Guide of the parameter being measured is important. Error consists
of the random factors mentioned above, and systematic
This section provides an explanation of the specifications of uncertainties in the measurement. Systematic uncertainties
the SR620 and their effect on the accuracy and resolution of a include timebase aging, trigger level error, insertion delay, etc.
measurement. Systematic errors may always be measured and subtracted
from subsequent measurements to reduce the error. The
Statistical Functions SR620's absolute error is typically less than 0.5 ns for time
interval measurements less than 1 ms.
The SR620 can display statistical information about the
measurement of N samples. The SR620 computes and reports Differential Non-Linearity
the mean, standard deviation or root Allan variance,
minimum, and maximum values seen during the Absolute error is of interest in determining how far a value is
measurement. The equation for the statistical functions are from the actual value. Often only the relative accuracy (the
given by: difference between two measurements) is important.
Differential non-linearity is a measurement of the relative
accuracy of a measurement, and is specified as the maximum
1 n
mean = xi
n i=1
time error for any given relative measurement. The SR620's
differential non-linearity is typically ◦ Jabse Service Manual Search 2024 ◦ Jabse Pravopis ◦ onTap.bg ◦ Other service manual resources online : Fixya ◦ eServiceinfo