A METHOD AND APPARATUS FOR INCREASING THE SPEED OF ELECTROMAGNETIC SCANNING OF ELECTRONIC DEVICES

METHODE ET DISPOSITIF AMELIORANT LA VITESSE DE BALAYAGE ELECTROMAGNETIQUE DE DISPOSITIFS ELECTRONIQUE

English Abstract

Disclosed is a method and apparatus for increasing the speed of
electromagnetic emission
scanning of an electronic device under test. Included is an array of
electromagnetic emission
detection probes, decoder and driver circuits to address a selected number of
probes in the probe
array in a predetermined manner, a micro-controller to instruct and supervise
the decoder and
driver circuits, an analogue to digital converter, a memory circuit, a system
controller and a
display. The device under test is energized and located adjacent to the array
of probes. The
micro-controller instructs the decoder and driver circuits to address,
individually and successively
a specific group or list of probes during a first scanning period. The
emission level from each of
the addressed probes is measured, digitized and stored in memory circuits as a
first data set. The
system controller integrates, scales, maps and displays the first data set on
the display for
interpretation by an operator concomitant with the next data set being
collected by the
micro-controller. Collected data sets are passed to the system controller for
processing and the
sampling steps are repeated until the operator receives the desired level of
electromagnetic
characterization and terminates the scan.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for electromagnetic emission scanning of electronic devices,
comprising:
a. a grid array of probes for detecting electromagnetic emissions from an
electronic
device adjacent thereto;
b. decoder and driver circuits connected to the grid array of probes for
activating and
deactivating an individual probe or list of probes thereon;
c. a micro-controller connected to the decoder and driver circuits for
controlling said
circuits;
d. a receiver connected to the grid array of probes for receiving analogue
signals
therefrom;
e. an analogue to digital converter connected to the receiver for digitizing
the signals;
f. a digital memory device connected to the micro-controller for storing
digital data as
data sets;
g. a system controller for processing the data sets into signals suitable for
mapping,
scaling, archiving and displaying; and,
h. a visual display for displaying the processed data sets as visual images to
an operator.
2. An apparatus as claimed in claim 1 wherein said receiver is a spectrum
analyzer.
3. An apparatus as claimed in claim 2 wherein said system controller includes
a programmable
computer, operating software and a memory device.
4. An apparatus as claimed in claim 3 wherein said operating software is
WINDOWS R.

5. An apparatus for electromagnetic emission scanning of electronic devices,
comprising: a grid
array of probes for detecting electromagnetic emissions from an electronic
device adjacent
thereto; decoder and driver circuits connected to the grid array of probes for
activating and
deactivating an individual probe or list of probes thereon; a micro-controller
connected to the
decoder and driver circuits for controlling said circuits; a spectrum analyzer
connected to the
grid array of probes for receiving analogue signals therefrom; an analogue to
digital
converter connected to the receiver for digitizing the signals; a digital
memory device
connected to the micro-controller for storing digital data as data sets; a
system controller,
comprising, a data processor, a memory and WINDOWS R operating software, for
receiving
and processing the data sets into signals suitable for mapping, scaling,
archiving and display;
and, a visual display for displaying the processed data sets as visual images
to an operator.
6. A method scanning an active electronic device for electromagnetic emissions
therefrom
comprising the steps of:
a. energizing an electronic device under test;
b. placing the active device under test in a predetermined position
immediately adjacent
to a plurality of electromagnetic emission monitoring probes;
c. in a first sampling period successively activating a selected group of
probes in a
pre-determined sequence;

d. converting the analogue signals received from the selected group of probes
into a first
digital data set;
e. storing the first digital data set in the memory;
at the end of the first sampling period downloading the stored first data set
to the
system controller;
g. processing the first data set by the system controller for scaling,
mapping, displaying
and archiving;
h. concomitant with the system controller processing the data, sampling the
selected list
of probes a second time to generate a second data set;
i. repeating steps c to h above to acquire a plurality of sequential data sets
each
representing electromagnetic emissions at the time when the selected set of
probes
was sampled to form a real-time image of the electromagnetic characteristics
of the
device under test;
j. archiving the aggregated data in the system controller; and,
k. terminating the process when the desired level of characterization has been
achieved.
7. In an apparatus for electromagnetic emission scanning of electronic
devices, comprising: a
grid array of probes for detecting electromagnetic emissions from an active
electronic device

adjacent thereto; decoder and driver circuits for activating and deactivating
an individual
probe or group of probes; a receiver for receiving analogue signals from said
probes; a
programmable system controller; and a display means, wherein the improvement
comprises:
a. a micro-controller connected to said decoder and driver circuits for
directly
controlling the decoder and driver circuits; said micro-controller sampling a
probe or
list of probes in a predetermined manner thereby defining a sampling period;
said
micro-controller controlled by said programmable system controller;
b. an analogue to digital converter connected between said receiver and said
micro-controller for receiving analogue signals directly from said receiver
and converting
them to digital signals;
c. a memory device connected to said micro-controller for storing aggregated
digital
signals converted by said analogue to digital converter during a sampling
period as a
data set.
8. An apparatus as claimed in claim 7 wherein the analogue to digital
converter, the
micro-controller and the memory device act cooperatively to collect analogue
signals from a
selected list of probes representing measurements of electromagnetic radiation
from the
device under test; convert the analogue signals to digital signals; aggregate
the signals in the
memory as a first data set; and download the first data set to the system
controller for
processing and; repeating the data set generation and processing steps until
the
electromagnetic characteristics of the device under test are satisfactorily
characterized.

9. In an apparatus for electromagnetic emission scanning of electronic
devices, comprising: a
grid array of probes for detecting electromagnetic emissions from an
electronic device
adjacent thereto; decoder and driver circuits connected to the grid array of
probes for
activating and deactivating an individual probe or group of probes thereon; a
micro-controller
connected to the decoder and driver circuits for controlling said circuits; a
receiver
connected to the grid array of probes for receiving analogue signals
therefrom; an analogue
to digital converter connected to the receiver for converting the signals to
digital signals; a
digital memory device connected to the micro-controller for storing digital
data as data sets;
a system controller for receiving and processing the data sets into signals
suitable for
mapping, scaling, archiving and display; and, a visual display for displaying
the data sets as
visual images to an operator, a method of scanning an active electronic device
for
electromagnetic emissions therefrom comprising the steps of:
a. energizing the device under test
b. placing the active device under test in a predetermined position
immediately adjacent
to a plurality of electromagnetic emission monitoring probes;
c. in a first sampling period successively activating a selected group of
probes in a
predetermined sequence;
d. converting the analogue signals received from the selected group of probes
into a first
digital data set;
e. storing the first digital data set in the memory;
f. at the end of the first sampling period downloading the stored first data
set to the
system controller;
g. processing the first data set by system controller for mapping, scaling,
displaying and
archiving;

h. concomitant with the system controller processing the data, sampling the
selected
group of probes a second time to generate a second data set;
i. repeating steps c to h to acquire a plurality of sequential data sets each
representing
electromagnetic emissions at the time when the list of selected probes was
sampled to
form a real-time visual representation of the electromagnetic characteristics
of the
device under test;
j. archiving the aggregated data in the system controller; and
k. terminating the process when the desired level of characterization has been
achieved.
10. In an apparatus for electromagnetic emission scanning of electronic
devices, comprising: a
grid array of probes for detecting electromagnetic emissions from an active
electronic device
adjacent thereto; decoder and driver circuits for activating and deactivating
an individual
probe or group of probes; a receiver for receiving analogue signals from said
probes; a
programmable system controller; and a display means, wherein the improvement
comprises
a micro-controller connected to said decoder and driver circuits for directly
controlling the
decoder and driver circuits; said micro-controller sampling a probe or list of
probes in a
predetermined manner thereby defining a sampling period; said micro-controller
controlled
by said programmable system controller; an analogue to digital converter
connected between
said receiver and said micro-controller for receiving analogue signals
directly from said
receiver and converting them to digital signals; a memory device connected to
said
micro-controller for storing aggregated digital signals converted by said
analogue to digital
converter during a sampling period as a data set; and wherein the analogue to
digital
converter, the micro-controller and the memory device act cooperatively to
collect analogue
signals from a selected list of probes representing measurements of
electromagnetic radiation
from the device under test; convert the analogue signals to digital signals;
aggregate the

signals in the memory as a first data set; and download the first data set to
the system
controller for processing and; repeating the data set generation and
processing steps until the
electromagnetic characteristics of the device under test are satisfactorily
characterized, a
method comprising the steps of:
a. energizing the device under test
b. placing the active device under test in a predetermined position
immediately adjacent to a
plurality of electromagnetic emission monitoring probes;
c. in a first sampling period successively activating a selected group of
probes in a
predetermined sequence;
d. converting the analogue signals received from the selected group of probes
into a first
digital data set;
e. storing the first digital data set in the memory;
f. at the end of the first sampling period downloading the stored first data
set to the system
controller;
g. processing the first data set by system controller for mapping, scaling,
displaying and
archiving;
h. concomitant with the system controller processing the data, sampling the
selected group
of probes a second time to generate a second data set;
i. repeating steps c to h to acquire a plurality of sequential data sets each
representing
electromagnetic emissions at the time when the list of selected probes was
sampled to
form a real-time visual representation of the electromagnetic characteristics
of the device
under test;
j. archiving the aggregated data in the system controller; and
k. terminating the process when the desired level of characterization has been
achieved.

Description

CA 02264328 1999-03-O1
A METHOD AND APPARATUS FOR INCREASING THE SPEED OF
ELECTROMAGNETIC SCANNING OF ELECTRONIC DEVICES
Field of the Invention
The present invention relates to a method and apparatus for detecting and
measuring the
magnitude and location of electromagnetic emissions from electronic devices.
It is particularly
concerned with an improved method and apparatus for testing printed circuit
boards and similar
devices.
Background of the Invention
An important tool in the design of printed circuit boards is the ability to
accurately locate
and measure electromagnetic emissions from an operating printed circuit board.
The prior art
electronic emission monitors are represented by Canadian Letters Patent
1,286,724, issued to
Goulette et al. on July 23, 1991 entitled "Method and Apparatus for Monitoring
Electromagnetic
Emission Levels". This patent describes a method and apparatus for monitoring
electromagnetic
emission levels from electronic circuit boards.
The prior art describes the use of probes to scan a device under test for
electromagnetic
emissions. Each probe of interest is addressed one at a time. When a probe is
selected,
electromagnetic emissions adjacent to the probe will induce a signal therein.
The signal is
received by a measuring receiver and processed by a system controller. The
controller is used to
control the apparatus and to display the data to the operator. The controller
will not begin to

CA 02264328 1999-03-O1
display the data received from the probe array until all of the probes of
interest have been
addressed and all of the data has been collected and stored. This takes a
significant amount of
time. The time required to address a single probe and obtain the measurement
of electromagnetic
radiation coming from the adjacent device under test is in the order of 20
milliseconds. A scan
may require the addressing of an array of probes that may have over 1000
individual probes.
Therefore the time taken to measure the electromagnetic emissions from a
device under test can
be measured in tens of seconds. The controller then requires additional time
to process and
display the data.
1o Real-time scanning of an active printed circuit board, particularly when
the operating
cycle of the board under test is synchronized to the scanning apparatus
requires a rapid
succession of multiple scans to obtain an accurate electromagnetic emission
profile. Therefore
the disadvantages and limitations associated with the prior art relate to the
fact that the device
under test must be scanned as fast as possible in order to obtain an accurate
display of
electromagnetic performance synchronized to circuit board operation in real-
time. An additional
limitation in the prior art relates to use of the scanning apparatus in
production line testing. To be
effective in such an application an improved method and apparatus for
gathering data from the
printed circuit board under test in much less time is required.
2o Summary of the Invention
An object of the present invention is to provide an improved method and
apparatus for
monitoring electromagnetic emission levels from electronic devices under test
that results in a
faster scan of the device under test.
2

CA 02264328 1999-03-O1
In accordance with one aspect of the present invention there is provided an
apparatus for
electromagnetic emission scanning of electronic devices, comprising: a grid
array of probes for
detecting electromagnetic emissions from an electronic device adjacent
thereto; decoder and
driver circuits connected to the grid array of probes for activating and
deactivating an individual
probe or group of probes thereon; a micro-controller for controlling the
decoder and driver
circuits; a receiver to receive output signals from the grid array of probes;
an analogue to digital
converter for receiving analogue signals from the receiver and digitizing
them; a memory device
for storing the digital signals as data sets; a programmable system controller
for processing the
1o data sets into signals suitable for mapping, scaling, archiving and visual
displaying; and a visual
display for displaying the processed data sets as visual images to an
operator.
In another embodiment of the present invention the receiver is a spectrum
analyzer.
15 In accordance with one aspect of the present invention the system
controller comprises a
computer, operating software and a memory for controlling the overall
operation of the apparatus.
The operating software may be WINDOWS.°
One embodiment of the present invention provides a method for the improved
scanning of
2o an electronic device for electromagnetic emissions comprising the following
steps: the device
under test is energized; the energized device under test is placed in
proximity to the
electromagnetic probes; a list of probes is sampled; the data is collected,
digitized and stored as a
data set in the memory. The collected data set is downloaded to the system
controller and

CA 02264328 1999-03-O1
subsequently displayed to the operator. The process is repeated until the
operator terminates the
operation.
By adding a micro-controller, analogue to digital converter and memory
circuits between
the decoder and driver circuits and the system controller and by addressing
the probes of interest
as a list of probes concomitant with the system controller processing and
displaying the previous
data set, the present invention seeks to overcome the disadvantages found in
the prior art.
Scanning speeds one order of magnitude faster than the prior art scanning
apparatus are obtained
by processing the data from the grid array of probes as data sets from lists
of probes rather than as
1o data from the entire grid array. The increased scanning speeds allows the
creation of a more
accurate real time scan.
The present invention also facilitates the testing of the performance of
electronic devices
on the manufacturing line in real time.
Brief Description of the Drawings
The present invention will be further understood from the following
description with
references to the drawings in which:
Fig 1 illustrates, in a block diagram, an improved scanning apparatus in
accordance with
an embodiment of the present invention.

CA 02264328 1999-03-O1
Detailed Description
Refernng to Figure 1, a block diagram of an embodiment of the present
invention is
shown. Planar grid array of probes (10) comprising row and column conductors
(11) is provided.
Decoder and driver circuit (12) is connected to and controls the grid array of
probes column
conductors. Decoder and driver circuit (14) is connected to and controls the
grid array of probes
row conductors. Decoder and drive circuits (12 & 14) are instructed and
supervised by micro-
controller (18) connected thereto. Analogue to digital converter (20) is
connected to the output of
1o a receiver or spectrum analyzer (21). The receiver is connected to the grid
array of probes (10)
and receives the analogue signals generated in the probes stimulated by
electromagnetic radiation
emanating from electronic device under test (16). The analogue signals are
converted into digital
signals to form a data set. The data set is relayed to memory (22) connected
to micro-controller
(18) and stored. At the completion of the sampling period, micro-controller
(18) downloads the
15 data set to system controller (26). System controller (26) will scale, map,
archive and display the
information received on display device (28). The system controller (26) is
programmable and
directs the operation of the entire system.
In operation, the device under test (16) is positioned adjacent to scanning
array (10) so
2o that electromagnetic radiation emanating from the device under test induces
a current in those
selected probes that are adjacent to the device under test. Micro-controller
(18) instructs decoder
and driver circuits (12 & 14) to address, sequentially, a selected list of
probes of interest.
Analogue signals derived from the induced currents in the selected list of
probes are transmitted
to A/D converter (20) through receiver (21). A/D converter (20) converts the
analogue signals to

CA 02264328 1999-03-O1
digital signals. The micro-controller (26) then transmits them to memory (22)
as a data set. At
the end of the first sampling period, that is, when all of the probes in the
list of probes have been
sampled, micro-controller (18) downloads the first data set to system
controller (26). System
controller (26) scales and converts the data into a visual image of
electromagnetic radiation as a
function of position on the electronic device under test. This data is then
displayed on visual
display unit (28) and archived in the system controller's memory.
Concomitant with systems controller (26) processing and displaying the first
data set,
micro-controller (18) instructs decoder and driver circuits (12 & 14) to
sample the selected list of
1o probes again. Data collected during the second sampling period is converted
to a digital format
by A/D converter (20) and stored in memory (22) as a second data set. Upon
completion of the
second sampling period, micro-controller (18) downloads the second data set to
system controller
(26) for processing. This sampling method is repeated until the operator stops
the process. In this
way, the system controller does not have to wait until the all of the data
from the grid array is
15 collected prior to displaying it. The system controller can work on
processing and displaying a
data set while the micro-controller is collecting the next data set. This
provides for an order of
magnitude improvement in the sampling speed.
The steps of the sampling process are summarized in the following chart:

CA 02264328 1999-03-O1
CHART A
SAMPLING PROCESS
STEP ACTIVITY
1 Energizing an electronic device under test
(16).
2 Placing the active device under test in a predetermined
position
immediately adjacent to a plurality of electromagnetic
emission
monitoring probes. (10).
3 In a first sampling period successively activating
a selected group
of probes in a predetermined sequence.
4 Converting the analogue signals received from
the selected group
of probes into a first digital data set.
Storing the first digital data set in the memory.
6 At the end of the first sampling period downloading
the stored
first data set to the system controller.
7 Processing the first data set by the system
controller for scaling,
mapping, displaying and digital storage.
8 Concomitant with the system controller processing
the data,
sampling the selected list of probes a second
time to generate a
second data set.
9 Repeating steps 3 to 8 to acquire a plurality
of sequential data sets
each representing electromagnetic emissions
at the time the
selected set of probes was sampled to form
a real-time image of '~

CA 02264328 1999-03-O1
STEP ~ ACTIVITY
the electromagnetic characteristics of the device
under test.
Archiving the aggregated data in the system
controller
I 1 Terminating the process when the desired level
of characterization
has been achieved.
Numerous modifications, variations and adaptations may be made to the
particular
embodiments of the invention described above without departing from the scope
of the invention,
which is defined in the claims.

Representative Drawing