Main Microprocessor - Spectral Display; Main Microprocessor - User Settings; Main Microprocessor - General; Main Microprocessor - Auto Functions - Ametek 7280 Instruction Manual

3.3.18 Main Microprocessor - Spectral Display

In some cases it can be useful to determine the spectral power distribution of the
input signal. The model 7280 can do this, since when the Spectral Display menu is
selected, the output processor performs a discrete Fourier transform on the digitized
input signal and displays the resulting spectrum.

3.3.19 Main Microprocessor - User Settings

The non-volatile memory associated with the main microprocessor is used to store up
to eight complete instrument settings, which may be recalled or changed as required.
This makes it much easier for an instrument to be quickly configured for different
experiments.

3.3.20 Main Microprocessor - General

All functions of the instrument are under the control of a microprocessor which in
addition drives the front-panel display, processes front-panel key operations and
supports the RS232 and GPIB (IEEE-488) computer interfaces. This processor also
drives the instrument's 8-bit digital (TTL) programmable input/output port, which
may be used for controlling auxiliary apparatus or reading the status of external logic
lines.
The microprocessor has access to a 32,768 point memory which can be used for
storage of selected instrument outputs as curves, prior to their transfer to a computer
via the computer interfaces. In addition to using this function for the normal outputs,
such as the X channel and Y channel output signals, it may also be used with two of
the auxiliary ADC inputs to allow the instrument to operate as a transient recorder.
The internal oscillator frequency and amplitude sweep functions are also controlled
by the microprocessor.
A particularly useful feature of the design is that only part of the controlling firmware
program code, which the microprocessor runs, is permanently resident in the
instrument. The remainder is held in a flash EEPROM and can be updated via the
RS232 computer interface. It is therefore possible to change the functionality of the
instrument, perhaps to include a new feature or update the computer command set,
simply by connecting it to a computer and running an update program.

3.3.21 Main Microprocessor - Auto Functions

The microprocessor also controls the instrument's auto functions, which are control
operations executed by means of a single command or two key-presses. These
functions allow easier, faster operation in most applications, although direct manual
operation or special purpose control programs may give better results in certain
circumstances. During application of several of the auto functions, decisions are
made on the basis of output readings made at a particular moment. Where this is the
case, it is important for the output time constant set by the user to be long enough to
reduce the output noise to a sufficiently low level so that valid decisions can be made
and that sufficient time is allowed for the output to settle.
The following sections contain brief descriptions of the auto functions.
Chapter 3, TECHNICAL DESCRIPTION
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