Method and apparatus for guiding a user during setup of a signal measurement system

A signal measurement system with softkey menus for guiding a user in selecting a desired test setup, including selection and connection of the device to be tested, as well as selecting calibration measurement and test measurement for the device. In response to a given softkey selection, the signal measurement system prompts the user with a set of displayed textual instructions and pictorial diagrams via a user interface to step the user through setup, calibration, and measurement processes. Preferably, a signal processing unit (or analyzer) included in the signal measurement system incorporates the user interface in firmware to guide and aid the user in connecting the device to be tested to the signal measurement system for the desired test, and leading the user through calibration and measurement processes. The analyzer preferably displays the softkey menus, instructional text displays, and pictorial block diagram displays on a cathode ray tube included in the analyzer to guide the user. The displaying of sequential user instructions and diagrams facilitates proper configuration of connections for calibration of the signal measurement system, as well as connections for measurements of the characteristics of devices to be tested.

BACKGROUND OF THE INVENTION 
This invention relates to electronic test instruments and, more 
particularly, to electronic instrumentation for signal measurement. 
Specifically, the invention is directed to aiding a user to set up 
electronic test instruments for performing various signal measurements. 
An exemplary use of the invention is i the field of optical and electrical 
measurements in connection with fiber optic systems. With higher bit rates 
and wider-band modulations becoming prevalent in fiber optic systems, the 
designers and manufacturers of these systems and associated components 
need to be able to characterize performance more thoroughly and more 
precisely than ha been the case with lower transmission bandwidths. Many 
new fiber optic systems now operate at speeds of 500 MBPS and higher, 
which are equivalent to RF and low microwave frequencies. In addition, 
even though optical fiber cable is correctly classified as a low-loss 
medium, a fiber optic system can, in fact, have significant losses that 
must be identified if they are to be minimized. Accordingly, the 
measurements performed to characterize such a system have proliferated. 
Various lightwave component test systems have been developed to meet these 
measurement needs. However, the complexities of configuring, calibrating, 
and operating these test systems for performing the desired test 
measurements have dramatically escalated. This has required periodic 
retraining of personnel, increased test setup time, and resulted in errors 
due to improper test setup, calibration, and/or operation by the user. 
SUMMARY OF THE INVENTION 
One embodiment of the present invention provides a method and apparatus for 
guiding a user during setup of a signal measurement system, such as a 
lightwave component measurement system for characterizing performance of 
fiber optic systems and associated components. System guidance of the-user 
in accordance with the invention facilitates measuring the modulation 
response of elements used in conjunction with fiber optic systems. These 
include not only the optical and electrical components, but also 
electro-optical (E/O) and opto-electrical (O/E) converters; i.e., the 
transmitters and receivers. 
The preferred embodiment of the invention provides a user of the signal 
measurement system with softkey menus for selecting a desired test setup, 
including measurement selection and connection of the device to be tested, 
as well as selecting calibration measurement and test measurement for the 
device. In response to a given softkey selection, the signal measurement 
system prompts the user with a set of displayed textual instructions and 
pictorial diagrams via a user interface to step the user through setup, 
calibration, and measurement processes. Preferably, a signal processing 
unit (or analyzer) included in the signal measurement system incorporates 
the user interface in firmware to guide and aid the user in connecting the 
device to be tested to the signal measurement system for the desired test, 
and leading the user through calibration and measurement processes. The 
analyzer preferably displays the softkey menus, instructional text 
displays, and pictorial block diagram displays to guide the user on a 
cathode ray tube included in the analyzer. The displaying of sequential 
user instructions and diagrams facilitates proper configuration of 
connections for calibration of the signal measurement system, as well as 
connections for measurements of the characteristics of devices to be 
tested.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows an exemplary signal measurement system in the form of a 
lightwave component measurement system, generally indicated by the numeral 
10. Its principal elements are a lightwave component analyzer 12, a 
lightwave source 14, and a lightwave receiver 16. All of the elements of 
the lightwave component measurement system 10, including the lightwave 
source 14 and the receiver 16, are extensively characterized to achieve 
high levels of precision in lightwave measurements. FIG. 1 also shows a 
device under test (DUT), for example, a spool of optical fiber cable, 
connected to the lightwave component measurement system 10. 
The lightwave component analyzer 12 preferably comprises essentially a 3 
GHz vector network analyzer, for example, an HP 8753 vector network 
analyzer available from Hewlett-Packard Company, Network Measurements 
Division, Santa Rosa, Calif., specifically tailored for lightwave 
measurements. It provides 300 kHz to 3 GHz test signals used to modulate 
either a single-mode or multi-mode lightwave source 14 preferably 
operating at 1300 nm. 
The electro-optical characteristics of the lightwave source 14 and the 
lightwave receiver 16 in a test setup have to be sensitive, stable, and 
repeatable. Also, their modulation bandwidths need to be wider than that 
of the DUT. 
The lightwave source 14 provides a modulation signal source which 
preferably generates a high-stability, 1 Hz-resolution synthesized signal 
that can be swept from 300 kHz to 3 GHz. The intensity-modulated light 
signal from the lightwave source 14 is then applied to the DUT. 
The lightwave receiver 16 demodulates the modulated light signal for 
processing in the lightwave component analyzer 12. The transmission and 
reflection characteristics of the DUT are then displayed, preferably on a 
cathode ray tube (CRT) 18 included in the lightwave component analyzer 12, 
either as a function of the RF modulation frequency or as a function of RF 
power or distance. 
The lightwave receiver 16 is a high-stability, high-resolution precision 
receiver with 100 dB dynamic range which allows measurements over a wide 
dynamic range and enables the lightwave component measurement system 10 to 
operate with an optical sensitivity of -40 dBm. The lightwave receiver 16 
operates with both singe-mode and multi-mode optical fiber cables. Its 
optical detector is preferably a PIN photodiode. The lightwave receiver 16 
has a modulation bandwidth that preferably extends to 3 GHz, with .+-.4 dB 
flatness to 2 GHz, rolling off to -14 dB at 3 GHz. Minimum detectable 
optical signal (for modulations up to 2 GHz) is -40 dBm, and the typical 
optical dynamic range exceeds 40 dB. The 3 GHz modulation bandwidths of 
the lightwave source 14 and the lightwave receiver 16 provide ample margin 
for typical tests. 
The lightwave component measurement system 10 is operable to perform 
various measurements. Although the present invention is not directed to 
these measurements per se, a general understanding of various types of 
measurements that can be performed will aid an understanding of the 
operation of guiding the user in accordance with the invention. 
Typical optical components are optical fiber cable, modulators, and passive 
devices, such as switches, splitters, combiners, and attenuators. The 
input and output signals for testing these devices are light, and the key 
parameters measured are attenuation versus modulation frequency, 
modulation bandwidth, delay, modal pulse dispersion, electrical length, 
and location of discontinuities. For optical components (such as optical 
fiber cables, couplers, and connectors), the lightwave component 
measurement system 10 can measure such parameters as optical insertion 
loss, optical reflections, modulation bandwidth, pulse dispersion, and 
fiber length. In addition, multiple reflections can be resolved in time 
and distance with very high resolution. 
The modulation transfer characteristics of electro-optical transmitters 
(E/O) and opto-electrical receivers (O/E) can also be measured. For 
example, the responsivity of a PIN diode or laser diode can be measured, 
not only at one modulation frequency, but also as a function of modulation 
frequency from 300 kHz to 3 GHz. Additionally, modulated input power can 
be swept up to 25 dB to characterize the sensitivity or compression point 
of a source or receiver or determine it's optimum operating condition. 
Representative E/O devices are optical modulators and sources (such as 
laser diodes and LEDs). Examples of O/E devices are PIN or avalanche 
photodiode detectors in optical receivers. The key parameters for these 
devices are the same for both types, except that the independent and 
dependent variables are reversed; e.g., for E/O devices, optical power out 
is measured as a function of electrical (RF) drive, whereas RF power out 
as a function of optical drive is measured for 0/E devices. When the 
lightwave component measurement system 10 is used to characterize an E/O 
or O/E device, the initial calibration reference is established because 
both the lightwave source 14 and the lightwave receiver 16 are known. The 
DUT then is measured when it replaces its calibrated counterpart in the 
measurement setup. Typical measurements for these devices are sensitivity 
(including the compression point and the noise threshold/floor), as well 
as responsivity versus power or modulating frequency. 
The RF (or electrical) elements of the fiber optic system under test can 
also be characterized using the lightwave component measurement system 10. 
Examples of RF devices are amplifiers, filters, and cables used in a fiber 
optic system. The RF measurements include bandwidth, insertion loss/gain, 
phase, group delay, and complex impedance. 
Electrical measurements can be performed on such RF components as 
amplifiers, filters, and optical fiber cables, or a complete fiber optic 
repeater (comprising an optical transmitter, optical fiber cable, and 
optical receiver). Typical measurements include loss/gain versus 
modulation frequency or power level, modulation bandwidth, modulation 
phase shift or phase delay, distortion (e.g., group delay or deviation 
from linear phase), complex impedance (magnitude and phase), and 
electrical length (including discontinuity location). 
In accordance with the invention, the lightwave component measurement 
system 10 incorporates guidance of the user to provide operating ease. 
Firmware resident in memory in the lightwave component measurement system 
10 generates displays to provide for guided measurement setups which allow 
even first-time users to configure the lightwave component measurement 
system for various types of tests. Displayed textual instructions and 
graphics lead the user through such measurements as transmission versus 
frequency, reflection versus frequency, and transmission versus power. 
There also are menus for formatting, scaling, and plotting measurements. 
In accordance with the invention, the signal processing unit (or lightwave 
component analyzer 12) included in the lightwave component measurement 
system 10 incorporates in firmware a set of encoded softkey menus, 
instructional text displays, and pictorial block diagram displays which 
guide and aid the user while connecting the DUT for a desired test, as 
well as during the calibration and measurement processes. Code for 
generating user selections, instructions, and diagrams is embedded as a 
portion of the instrument mainframe firmware. Hence, the invention 
provides a user interface where text and graphics are combined and 
programmed into the firmware of the lightwave component analyzer 12 to 
allow the user greater ease in setting up and executing the calibration 
and measurement processes associated with the test protocol. 
Considered in more detail, the lightwave component analyzer 12 has 
programmed into it read only memory (ROM) firmware a combination of text 
and graphics which are displayed to make the lightwave component 
measurement system 10 easy to operate and use. The text and graphics show 
the user how to set up the lightwave component measurement system 10 
states and basic measurements easily and quickly. This feature is 
hereafter referred to as "guided setup." 
Guided setup is an instrument user interface feature to assist a user in 
quickly and easily connecting the DUT for a desired test and making a 
calibration or measurement. Guided setup is implemented as a series of 
softkey menus, textual displays, and pictorial displays which guide the 
user in configuring the lightwave component measurement system 10 and 
setting basic instrument parameters in order to perform a specified test 
measurement. 
The user is guided through the guided setup procedure by depressing 
softkeys. A set of softkey labels (softkey menu) is presented on the 
display of the lightwave component analyzer 12 by the firmware for each 
step in the guided setup series. Instructions for each menu are also 
preferably presented on the display of the lightwave component analyzer 
12. Once a measurement is performed, the user is also preferably presented 
with choices for formatting and displaying the measurement, as well as 
storing the instrument state resulting from the guided setup. 
FIG. 2 illustrates various screens that are presented to the user in 
accordance with the invention. Also shown in FIG. 2 is the flow of the 
user interface which enhances the ease of use of the lightwave component 
measurement system 10. FIG. 2 actually depicts various guided measurement 
CRT displays generated by the lightwave component analyzer 12. 
As shown in FIG. 2A, the analyzer 12 displays a softkey menu when the 
analyzer is turned on. Two softkey selections are available, namely, 
"GUIDED SETUP" and "NORMAL OPERATION." The user depresses the "NORMAL 
OPERATION" softkey to have access to all of the features of the lightwave 
component measurement system 10 in any sequence desired by the user. 
Conversely, the user depresses the "GUIDED SETUP" softkey for help if he 
or she wishes to check the connections for the test setup and/or to be led 
through a series of steps for setting basic parameters for operation of 
the lightwave component measurement system 10. 
When the "GUIDED SETUP" softkey is depressed, the analyzer 12 enters a 
guided setup mode by calling guided setup routines stored in the ROM of 
the analyzer. FIG. 3 is a generalized flow diagram of the guided setup 
method in accordance with one embodiment of the invention. 
Considered in more detail, FIGS. 4-11 are flowcharts of the guided setup 
method in accordance with the invention. The following pages contain a 
copy of the firmware code. The numerals shown in FIGS. 4-11 are 
implemented by the correspondingly numbered lines of code which appear on 
the following pages. 
##SPC1## 
##SPC2## 
##SPC3## 
##SPC4## 
##SPC5## 
As shown in FIG. 3, when the "GUIDED SETUP" softkey is depressed, the 
guided setup mode begins by directing the user to select the type of 
measurement desired, as indicated by the numeral 100. The analyzer 12 
directs the user to select the type of measurement desired by calling and 
executing a select measurement type subroutine 100, as shown in more 
detail in FIG. 4. 
The select measurement type subroutine 100 causes the analyzer 12 to 
display a new softkey menu and labels the softkeys, as indicated by the 
numeral 102. These softkey labels can be "BANDWIDTH," "REFLECTION," and 
"GAIN COMPRESS'N," as shown in FIG. 2B. "CONTINUE" and "NORMAL OPERATION" 
softkeys are also preferably displayed in order to enable the user to 
proceed with the guided setup mode or exit to normal operation, 
respectively. 
Also, the analyzer 12 displays a block diagram of each of the measurement 
choices, as indicated by the numeral 104 shown in FIG. 4. Representative 
block diagrams for bandwidth, reflection, and gain compression 
measurements are shown in FIG. 2B. 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 106 shown in FIG. 4. For example, the instruction 
in connection with selecting the measurement type can be "SELECT TYPE OF 
MEASUREMENT," as shown in FIG. 2B. 
Preferably, the analyzer 12 is given a predetermined set of default 
conditions, including a measurement type default condition. Accordingly, 
when the select measurement type subroutine 100 is executed, the analyzer 
12 preferably defaults to the bandwidth measurement, and draws a box 
around the diagram of this measurement type, as indicated by the numeral 
108, to show the default measurement. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 110, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 112. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 114. 
On the other hand, if the user has depressed a softkey, as indicated by the 
step 110, the analyzer 12 determines whether or not the user has depressed 
a measurement selection softkey, as indicated by the numeral 116. If so, 
the analyzer 12 draws a box around the diagram of the selected measurement 
type, as indicated by the step 108. 
If the user has depressed a softkey other than a measurement selection 
softkey, the analyzer 12 determines whether or not to continue with the 
guided setup mode, as indicated by the numeral 118. On the one hand, if 
the user depresses the "CONTINUE" softkey, as indicated by the step 118, 
the analyzer 12 calls a select device type subroutine, as indicated by the 
numeral 120. 
On the other hand, if the user depresses the "NORMAL OPERATION" softkey, 
the analyzer 12 exits the guided setup mode and proceeds to normal 
operation, as indicated by the numeral 126. Any softkey actuation other 
than a specifically mentioned one causes the analyzer 12 to inform the 
user that an invalid key has been depressed, as indicated by the numeral 
124, and await depression of an allowed softkey. 
If the user completes the select measurement type subroutine 100 by 
depressing the "CONTINUE" softkey after selecting a measurement type, as 
indicated by the step 118 shown in FIG. 4, the analyzer 12 directs the 
user to designate the type of device under test by calling and executing 
the select device type subroutine 200, as indicated by the numeral 200 
shown in FIG. 3. The select device type subroutine 200 is shown in more 
detail in FIG. 5. 
The select device type subroutine 200 causes the analyzer 12 to display a 
new softkey menu and labels the softkeys, as indicated by the numeral 202. 
These softkey labels can be "O/O," "O/E," "E/O," "E/E," "1-PORT OPTICAL," 
and "1-PORT ELECTRICAL," as shown in FIGS. 2C and 2D. "CONTINUE" and 
"PRIOR MENU" softkeys are also preferably displayed in order to enable the 
user to proceed with the guided setup mode or return to the previous menu 
for the select measurement type subroutine 100, respectively. 
Also, the analyzer 12 displays a block diagram of each of the device type 
choices, as indicated by the numeral 204 shown in FIG. 5. Representative 
block diagrams for O/O, O/E, E/O, E/E, one-port optical, and one-port 
electrical devices are shown in FIGS. 2C and 2D. 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 206 shown in FIG. 5. For example, the instruction 
in connection with selecting the device type can be "SELECT TYPE OF DEVICE 
UNDER TEST," as shown in FIGS. 2C and 2D. 
Preferably, the analyzer 12 is given a predetermined set of default 
conditions, including a device type default condition. Accordingly, when 
the select device type subroutine 200 is executed, the analyzer 12 
preferably defaults to an O/O type device measurement, and draws a box 
around the diagram of the O/O device type, as indicated by the numeral 
208, to show the default device type. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 210, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 212. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 214. 
On the other hand, if the user has depressed a softkey, as indicated by the 
step 210, the analyzer 12 determines whether or not the user has depressed 
a device type selection softkey, as indicated by the numeral 216. If so, 
the analyzer 12 draws a box around the diagram of selected device type, as 
indicated by the step 208. 
If the user has depressed a softkey other than a device type selection 
softkey, the analyzer 12 determines whether or not to continue with the 
guided setup mode, as indicated by the numeral 218. On the one hand, if 
the user depresses the "CONTINUE" softkey, as indicated by the step 218, 
the analyzer 12 calls a display measurement configuration subroutine, as 
indicated by the numeral 220. 
On the other hand, if the user depresses the "PRIOR MENU" softkey, the 
analyzer 12 recalls the select measurement type subroutine 100, as 
indicated by the numeral 226. Any softkey actuation other than a 
specifically mentioned one causes the analyzer 12 to inform the user that 
an invalid key has been depressed, as indicated by the numeral 224, and 
await depression of an allowed softkey. 
If the user completes the select device type subroutine 200 by depressing 
the "CONTINUE" softkey after selecting a device type, as indicated by the 
step 218 shown in FIG. 5, the analyzer 12 directs the user to make various 
optical and/or electrical connections for performing the selected 
measurement on the specified DUT by calling and executing the display 
measurement configuration subroutine 300, as indicated by the numeral 300 
shown in FIG. 3. The display measurement configuration subroutine 300 is 
shown in more detail in FIG. 6. 
The display measurement configuration subroutine 300 causes the analyzer 12 
to display a new softkey menu and labels the softkeys, as indicated by the 
numeral 302. "CONTINUE" and "PRIOR MENU" softkeys are preferably displayed 
in order to enable the user to proceed with the guided setup mode or 
return to the previous menu for the select device type subroutine 200, 
respectively. 
Also, the analyzer 12 displays a block diagram of the optical and/or 
electrical connections to effect the selected measurement for the 
specified device type, as indicated by the numeral 304 shown in FIG. 6. 
Representative block diagrams for the respective selectable measurements 
for the various device types appear in FIGS. 2E-2P. 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 306 shown in FIG. 6. For example, the instruction 
in conjunction with exhibiting the connections for performing a selected 
measurement on a specified device type can be "CONFIGURE MEASUREMENT AS 
SHOWN BELOW" and "MAKE NECESSARY DC CONNECTIONS," as shown in FIGS. 2E-2P. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 308, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 310. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 312. 
On the other hand, if the user has depressed a softkey, as indicated by the 
step 308, the analyzer 12 determines whether or not the user has depressed 
the "CONTINUE" softkey, as indicated by the numeral 314. On the one hand, 
if the user depresses the "CONTINUE" softkey, as indicated by the step 
314, the analyzer 12 calls and automatically executes a preset parameters 
subroutine, as indicated by the numeral 322, and then calls a set sweep 
start and stop subroutine, as indicated by the numeral 324. 
On the other hand, if the user depresses the "PRIOR MENU" softkey, the 
analyzer 12 recalls the select device type subroutine 200, as indicated by 
the numeral 318. Any softkey actuation other than a specifically mentioned 
one causes the analyzer 12 to inform the user that an invalid key has been 
depressed, as indicated by the numeral 320, and await depression of an 
allowed softkey. 
The preset parameters subroutine called and executed at the step 322 shown 
in FIG. 6 enters various default values for the parameters associated with 
the selected measurement on the specified device type. These are the 
parametric values used by the analyzer 12 during actual testing, unless 
the user intervenes. 
When the user depresses the "CONTINUE" softkey, as indicated by the step 
314 shown in FIG. 6, the analyzer 12 calls the set sweep start and stop 
subroutine 400, as indicated by the numeral 400 shown in FIG. 3. The set 
sweep start and stop subroutine 400 is shown in more detail in FIG. 7. 
The set sweep start and stop subroutine 400 causes the analyzer 12 to 
display a new softkey menu and labels the softkeys, as indicated by the 
numeral 402. These softkey labels can be "START" and "STOP," as shown in 
FIG. 2Q for O/O, O/E, E/O, and one-port optical swept frequency type 
measurements and FIG. 2R for E/E and one-port electrical swept frequency 
type measurements, or "START POWER" and "STOP POWER," as shown in FIG. 2S 
for swept power type measurements. "CONTINUE" and "PRIOR MENU" softkeys 
are also preferably displayed in order to enable the user to proceed with 
the guided setup mode or return to the previous menu for the display 
measurement configuration subroutine 300, respectively. 
Representative screens displayed at the beginning of the set sweep start 
and stop subroutine 400 appear in FIGS. 2Q-2S. The analyzer 12 then sweeps 
and takes data using the respective default values for the sweep start and 
stop parameters, as indicated by the numeral 404 shown in FIG. 7, and 
displays the data trace and graticule, as indicated by the numeral 406. 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 408 shown in FIG. 7. For example, the instruction 
in connection with selecting the sweep start and stop parameters can be 
"SET RF MODULATION START FREQUENCY AND STOP FREQUENCY," as shown in FIG. 
2Q; "SET RF START FREQUENCY AND STOP FREQUENCY," as shown in FIG. 2R; or 
"SET START POWER AND STOP POWER" and "POWER AT R, A, B INPUTS MUST BE LESS 
THAN 0 dBm," as shown in FIG. 2S. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 410, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 412. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 414. 
On the other hand, if the user has depressed a softkey, as indicated by the 
step 410, the analyzer 12 determines whether or not the user has depressed 
the "START" or "STOP" softkey, or the "START POWER" or "STOP POWER" 
softkey, as the case may be, as indicated by the numeral 416. If so, the 
analyzer 12 enables the user to enter a substitute sweep start and/or stop 
parametric value, and displays the entered value(s), as indicated by the 
numeral 418. 
If the user has depressed a softkey other than the "START" or "STOP" 
softkey, or the "START POWER" or "STOP POWER" softkey, as the case may be, 
the analyzer 12 determines whether or not to continue with the guided 
setup mode, as indicated by the numeral 420. On the one hand, if the user 
depresses the "CONTINUE" softkey, as indicated by the step 420, the 
analyzer 12 calls a set stimulus parameters subroutine, as indicated by 
the numeral 428. 
On the other hand, if the user depresses the "PRIOR MENU" softkey, the 
analyzer 12 recalls the display measurement configuration subroutine 300, 
as indicated by the numeral 424. Any softkey actuation other than a 
specifically mentioned one causes the analyzer 12 to inform the user that 
an invalid key has been depressed, as indicated by the numeral 426, and 
await depression of an allowed softkey. 
When the user depresses the "CONTINUE" softkey, as indicated by the step 
420 shown in FIG. 7, the analyzer 12 calls the set stimulus parameters 
subroutine 500, as indicated by the numeral 500 shown in FIG. 3. The set 
stimulus parameters subroutine 500 is shown in more detail in FIG. 8. 
The set stimulus parameters subroutine 500 causes the analyzer 12 to 
display a new softkey menu and labels the softkeys, as indicated by the 
numeral 502. These softkey labels can be "SWEEP TIME," "SOURCE POWER," and 
"SWEEP TYPE," as shown in FIG. 2T for swept frequency type measurements. 
Depression of the "SWEEP TYPE" softkey provides an additional softkey 
menu, as shown in FIG. 2U, which includes "LIN FREQ" and "LOG FREQ" 
softkeys. In the case of swept power type measurements, the softkey labels 
can alternatively be "SWEEP TIME" and "CW FREQUENCY," as shown in FIG. 2V. 
"CONTINUE" and "PRIOR MENU" softkeys are also preferably displayed in 
order to enable the user to proceed with the guided setup mode or return 
to the previous menu for the set sweep start and stop subroutine 400, 
respectively. 
Representative screens displayed at the beginning of the set stimulus 
parameters subroutine appear in FIGS. 2T-2V. The analyzer 12 then sweeps 
and takes data using the respective default values for the stimulus 
parameters, as indicated by the numeral 504 shown in FIG. 8, and displays 
the data trace and graticule, as indicated by the numeral 506. 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 508 shown in FIG. 8. For example, the instruction 
in connection with selecting the sweep time can be "SET SWEEP TIME," as 
shown in FIGS. 2T and 2V. Other instructions displayed in connection with 
directing the user to set the remaining stimulus parameters appear in 
FIGS. 2T-2V. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 510, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 512. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 514. 
On the other hand, if the user has depressed a softkey, as indicated by the 
step 510, the analyzer 12 determines whether or not the user has depressed 
one of the stimulus parameter softkeys, as indicated by the numeral 516. 
If so, the analyzer 12 enables the user to enter a substitute stimulus 
parametric value, and displays the entered value(s), as indicated by the 
numeral 518. 
If the user has depressed a softkey other than one of the stimulus 
parameter softkeys, the analyzer 12 determines whether or not to continue 
with the guided setup mode, as indicated by the numeral 520. On the one 
hand, if the user depresses the "CONTINUE" softkey, as indicated by the 
step 520, the analyzer 12 calls a select calibration type and define 
standards subroutine, as indicated by the numeral 528. 
On the other hand, if the user depresses the "PRIOR MENU" softkey, the 
analyzer 12 recalls the set sweep start and stop subroutine 400, as 
indicated by the numeral 524. Any softkey actuation other than a 
specifically mentioned one causes the analyzer 12 to inform the user that 
an invalid key has been depressed, as indicated by the numeral 526, and 
await depression of an allowed softkey. 
When the user depresses the "CONTINUE" softkey, as indicated by the step 
520 shown in FIG. 8, the analyzer 12 calls the set calibration type and 
define standards subroutine 600, as indicated by the numeral 600 shown in 
FIG. 3. The set calibration type and define standards subroutine 600 is 
shown in more detail in FIG. 9. 
The set calibration type and define standards subroutine 600 causes the 
analyzer 12 to display a new softkey menu and labels the softkeys, as 
indicated by the numeral 602. In the case of O/O, E/E, one-port optical, 
and one-port electrical devices, these softkey labels can be "CAL TYPE: 
NONE," "RESPONSE," and "CAL KIT," as shown in FIG. 2W. In the case of O/E 
and E/O devices, the softkey labels can alternatively be "CAL TYPE: NONE," 
"RESPONSE," and "CAL STD," as shown in FIG. 2X. If a previous calibration 
has been performed, an additional "DONE: RESPONSE" softkey appears, as 
shown in FIG. 2X. Depression of the "CAL KIT" softkey shown in FIG. 2W, or 
the "CAL STD" softkey shown in FIG. 2X, provides an additional softkey 
menu, as shown in one of the FIGS. 2Y-2II. The particular softkey menu 
that is displayed is automatically determined by the analyzer 12 based on 
the selected type of measurement and the type of DUT. The softkey menus 
shown in FIGS. 2Y-2II enable selection and/or definition of a calibration 
standard. The softkey menu shown in FIG. 2Y enables selection of a 
calibration standard for an O/O device. The softkey menus shown in FIGS. 
2Z-2CC enable selection and definition of a calibration standard for an 
O/E device. The softkey menus shown in FIGS. 2DD-2GG enable selection and 
definition of a calibration standard for an E/O device. The softkey menu 
shown in FIG. 2HH enables selection of a calibration standard for an E/E 
device, and a similar softkey menu enables selection of a calibration 
standard for a one-port electrical device. Finally, the softkey menu shown 
in FIG. 2II enables selection and definition of a calibration standard for 
a one-port optical device. "CONTINUE" and "PRIOR MENU" softkeys are also 
preferably displayed in order to enable the user to proceed with the 
guided setup mode or return to the previous menu for the set stimulus 
parameters subroutine 500, respectively. 
Representative screens displayed at the beginning of the select calibration 
type and define standards subroutine appear in FIGS. 2W-2II. The analyzer 
12 then sweeps and takes data using no calibration, as indicated by the 
numeral 604 shown in FIG. 9, and displays the data trace and graticule, as 
indicated by the numeral 606. 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 608 shown in FIG. 9. For example, the 
instructions in connection with selecting the calibration type and 
defining standards can include "SELECT CALIBRATION TYPE," as shown in 
FIGS. 2W and 2X. Other instructions displayed in connection with directing 
the user to select and define calibration standards appear in Figs. 
2W-2II. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 610, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 612. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 614. 
On the other hand, if the user has depressed a softkey, as indicated by the 
step 610, the analyzer 12 determines whether or not the user has depressed 
one of the calibration selection or definition softkeys, as indicated by 
the numeral 616. If so, the analyzer 12 sets the calibration type or 
standard definition, as indicated by the numeral 618. 
If the user has depressed a softkey other than one of the calibration 
selection or definition softkeys, the analyzer 12 determines whether or 
not to continue with the guided setup mode, as indicated by the numeral 
620. On the one hand, if the user depresses the "DONE: RESPONSE" softkey, 
as indicated by the numeral 634, the analyzer 12 calls a measure device 
subroutine and proceeds directly to test the DUT, as indicated by the 
numeral 632. On the other hand, if the user depresses the "CONTINUE" 
softkey, as indicated by the step 620, the analyzer 12 determines whether 
or not the user has depressed the "CAL TYPE: NONE" softkey, as indicated 
by the numeral 628. On the one hand, if a specified calibration has been 
requested, as indicated by the numeral 616, the analyzer 12 calls a 
perform calibration subroutine, as indicated by the numeral 630. On the 
other hand, if no calibration has been requested, the analyzer 12 calls 
the measure device subroutine and proceeds directly to test the DUT, as 
indicated by the numeral 632. 
If, however, the user has depressed the "PRIOR MENU" softkey, as indicated 
by the numeral 622, the analyzer 12 recalls the set stimulus parameters 
subroutine 500, as indicated by the numeral 624. Any softkey actuation 
other than a specifically mentioned one causes the analyzer 12 to inform 
the user that an invalid key has been depressed, as indicated by the 
numeral 626, and await depression of an allowed softkey. 
If the user has requested that a calibration be performed, when the user 
depresses the "CONTINUE" softkey, as indicated by the step 620 shown in 
FIG. 9, the analyzer 12 calls the perform calibration subroutine 700, as 
indicated by the numeral 700 shown in FIG. 3. The perform calibration 
subroutine 700 is shown in more detail in FIG. 10. 
The perform calibration subroutine 700 causes the analyzer 12 to display a 
new softkey menu and labels the softkeys, as indicated by the numeral 702. 
In the case of a transmission type measurement, these softkey labels can 
be "THRU" plus "DONE: RESPONSE," as shown in FIG. 2JJ; "RECEIVER" plus 
"DONE: RESPONSE," as shown in FIG. 2KK; or "SOURCE" plus "DONE: RESPONSE," 
as shown in FIG. 2LL. In the case of a reflection type measurement, the 
softkey labels can be "REFLECTOR" and "FRESNEL" plus "DONE: RESPONSE," as 
shown in FIG. 2MM; or "SHORT" and "OPEN" plus "DONE: RESPONSE," as shown 
in FIG. 2NN. The softkey menu for an E/E device is similar to the one for 
the O/O device shown in FIG. 2JJ. The particular softkey menu that is 
displayed is automatically determined by the analyzer 12 based on the 
selected type of measurement, as well as the type of DUT. The softkey 
menus for a transmission type measurement and a reflection type 
measurement for each type of device, except an E/E device, are shown in 
FIGS. 2JJ-2NN, the softkey menu for an E/E device being similar to the one 
for an O/O device. A "PRIOR MENU" softkey is also preferably displayed in 
order to enable the user to return to the previous menu for the select 
calibration type and define standards subroutine 600. 
Representative screens displayed at the beginning of the perform 
calibration subroutine appear in FIGS. 2JJ-2NN. The analyzer 12 then 
sweeps and takes data using calibration values, if any, as indicated by 
the numeral 704 shown in FIG. 10, and displays the data trace and 
graticule, as indicated by the numeral 706. 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 708 shown in FIG. 10. The various instructions in 
connection with performing a calibration include "REMOVE DEVICE UNDER 
TEST," as shown in FIGS. 2JJ-2LL. Other instructions displayed in 
connection with directing the user to perform a calibration appear in 
FIGS. 2JJ-2NN. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 710, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 712. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 714. 
On the other hand, if the user has selected a calibration standard, as 
indicated by the numeral 716, the analyzer 12 measures the standard, as 
indicated by the numeral 718. If the user has not selected a calibration 
standard, as indicated by the step 716, the analyzer 12 determines whether 
or not the user has depressed the "DONE: RESPONSE" softkey, as indicated 
by the numeral 720. 
If the user has depressed the "DONE: RESPONSE" softkey, as indicated by the 
step 720, the analyzer 12 determines whether or not the calibration 
standard has been measured, as indicated by the numeral 728. If not, the 
analyzer 12 awaits measurement of the calibration standard, as indicated 
by the step 718. If the calibration standard has been measured, as 
indicated by the step 728, the analyzer accesses error correction values 
based on the measured calibration standard, as indicated by the numeral 
730, and calls a measure device subroutine, as indicated by the numeral 
732. 
On the other hand, if the user has depressed the "PRIOR MENU" softkey, as 
indicated by the numeral 722, the analyzer 12 recalls the select 
calibration type and define standards subroutine 600, as indicated by the 
numeral 724. Any softkey actuation other than a specifically mentioned one 
causes the analyzer 12 to inform the user that an invalid key has been 
depressed, as indicated by the numeral 726, and await depression of an 
allowed softkey. 
If the user has decided to directly measure the DUT, as indicated by the 
step 632 shown in FIG. 9, or after a calibration has been performed, as 
indicated by the step 718 shown in FIG. 10, the analyzer 12 calls the 
measure device subroutine 800, as indicated by the numeral 800 shown in 
FIG. 3. The measure device subroutine 800 is shown in more detail in FIG. 
11. 
The measure device subroutine 800 causes the analyzer 12 to display softkey 
menu and labels the softkeys, as indicated by the numeral 802. These 
softkey labels can be "FORMAT," "SCALE REF," "COPY," and "SAVE," as shown 
in FIGS. 200 and 2PP. Depression of the "FORMAT," "SCALE REF," "COPY," or 
"SAVE" softkey shown in FIGS. 200 and 2PP provides an additional softkey 
menu, as shown in FIGS. 2QQ-2TT. The particular softkey menu that is 
displayed is automatically determined by the analyzer Depression of the 
"FORMAT" softkey shown in FIGS. 2OO and 2PP provides an additional softkey 
menu, as shown in FIG. 2QQ, which enables the user to tailor the data 
display based on selection of a desired format. Depression of the "SCALE 
REF" softkey shown in Figs. 2OO and 2PP. provides an additional softkey 
menu, as shown in FIG. 2RR, which enables the user to tailor the data 
display based on selection of a scale setting. Depression of the "COPY" 
softkey shown in FIGS. 2OO and 2PP provides an additional softkey menu, as 
shown in FIG. 2SS, which enables the user to print and plot data. Finally, 
depression of the "SAVE" softkey shown in Figs. 2OO and 2PP provides an 
additional softkey menu, as shown in FIG. 2TT, which enables the user to 
save setup parameters in a file resident in the memory of the analyzer 12. 
"GUIDED SETUP," "NORMAL OPERATION," and "PRIOR MENU" softkeys are also 
preferably displayed in order to enable the user to recall the select 
measurement type subroutine 100, exit the guided setup mode and return to 
normal operation, or return to the previous menu for the select 
calibration type and define standards subroutine 600, respectively. 
Representative screens displayed at the beginning of the measure device 
subroutine appear in FIGS. 2OO and 2PP. The analyzer 12 then sweeps and 
takes data using calibration values, if any, as indicated by the numeral 
804 shown in FIG. 11, and displays the data trace and graticule, indicated 
by the numeral 806 
The analyzer 12 additionally displays textual instructions to the user, as 
indicated by the numeral 808 shown in FIG. 11. For example, the 
instructions in connection with measuring the DUT can be "RECONNECT TEST 
DEVICE," as shown in FIG. 2PP. Other instructions displayed in connection 
with directing the user to perform a measurement of the characteristics of 
the DUT appear in FIGS. 200 and 2PP. 
The analyzer 12 determines whether or not a softkey is depressed, as 
indicated by the numeral 810, or, alternatively, whether or not a hardkey 
is depressed, as indicated by the numeral 812. On the one hand, if the 
user has depressed a hardkey, the analyzer 12 exits the guided setup mode 
and proceeds to normal operation, as indicated by the numeral 814. 
On the other hand, if the user has depressed a formatting, scaling, 
copying, or saving softkey, as indicated by the step 816, the analyzer 12 
sets the appropriate data display factors or data handling and output 
functions, as indicated by the numeral 818. The analyzer 12 next 
determines whether or not the user has depressed the "GUIDED SETUP" 
softkey, as indicated by the numeral 820. 
If the user depresses the "GUIDED SETUP" softkey, as indicated by the step 
820, the analyzer 12 calls the select measurement type subroutine 100, as 
indicated by the numeral 828. On the other hand, if the user depresses the 
"PRIOR MENU" softkey, as indicated by the numeral 822, the analyzer 12 
recalls the select calibration type and define standards subroutine 600, 
as indicated by the numeral 824. Any softkey actuation other than a 
specifically mentioned one causes the analyzer 12 to inform the user that 
an invalid key has been depressed, as indicated by the numeral 826, and 
await depression of an allowed softkey. 
The foregoing description is offered primarily for purposes of 
illustration. It will be readily apparent to those skilled in the art that 
numerous modifications and variations not mentioned above can still be 
made without departing from the spirit and scope of the invention as 
claimed below.