Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates generally to instruments for
measurement and recording, and more particularly, to instrument
systems for measurement of events or conditions at a
surveillance site, and for recording and collection of data
based on such measurement.
This invention has general utility in the measurement
and recording at a surveillance site of data relating to events
or conditions that require counting and classifying, such as
vehicle traffic on highways, pedestrian traffic through halls
- 10 and malls, product movement on production or processing lines,
- the type and amounts of particular material or gases (CO and
- NO2) in the atmosphere and the incidence oî high noise levels
adjacent highways, airport runways or in factories. In a
preferred form, the invention is applicable specifically to the
recording and collection of vehicle traffic data, for which it
is particularly well suited.
In general, it will be recognized that measurement and
recording of data as to events and conditlons of the kind
described have been carried out heretofore with the use of both
local and central type systems. With both types of systems,
sensors or detectors are typically employed at surveillance
sites for detecting the conditions or events under surveillance
and supplying signals to apparatus at the sites. Local data -
recorder systems use apparatus of many different types. The
simplest type of such apparatus includes counters which are
- incremented by signals from the detectors and accumulate a total
- courit which is displayed on a dial. ~ore comple~ apparatus
provides for processing the signals from the detectors to derive
; other data, for example, in the case of highway vehicle
monitoring systems, velocity, vehicle type and other traffic
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data which are recorded on paper or magnetic tape To collect
the data, personnel visit the surveillance sites and read the
instrument dials or remove the records in the form of a roll
of paper tape or cassette or reel of magnetic tape on which
the data is recorded.
Central data recorder systems usually employ cables or
telephone line connections from the apparatus at the site which
is utilized to transmit the data over such cables or lines to
a central processor and recorder. In such central systems,
the apparatus at the site may be solely electrical or electronic
apparatus for processing the signals from the detectors and
converting those signals to a form suitable for line transmission
to the central processor and recorder.
Local recorder systems, in general, have a number of
advantages such as lower initial equipment cost and lower
installation cost, and greater flexibility since the individual
field recorder units may be shifted from one location to another
as the need changes for information. Central recorder syste~s,
- while more costly in initial equipment and installation, are
( -20 generally capable of obtaining and recording data of more
complex character. In addition, because the unit at each site
location of a central recorder system, serves only to process
and transmit the data to a central recorder, the transmitter
unit, in general, is of relatively simple construction and
may be totally electronic with no recorder mechanism or other
mechanical device being required as a component.
In the case o local recorder systems, the mechanical
parts of recorder devices in the recorder units raise problems
in ~yst2m operation. These problems range from reliability and
mainte~an^e problems, particularly where the recorder units are
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out-of-doors and subjected to moisture, vibration, vandalism,
temperature variations, etc., which may cause interruptions
in operation or affect data reliability; to problems in data
collection. Personnel charged with the responsibility of
collecting the data travel to each site, remove the paper
tape or magnetic tape record, replace the used record, and
inspect the units to determine whetherthey are operating
properly. Most local recorder units are desirably self-po~ered
by batteries, and such recorder mechanisms consume substantial
power and drain the batteries so that battery recharging or
replacement on a frequent basis is necessary.
Thus, both local and central data recorder methods
have their advantages and disadvantages. The disadvantages
of the local recorder system revolve mainly about the practical
problems of physically collecting the recorded data and
- maintaining the local recorder units due to their mechanical
complexity and relatively heavy power consumption to insure
consistent operation and reliable data. Furthermore, local
recorder systems as presently known are not capable of processing
detector signals to derive and classify data as to events or
conditions of widely varying types ~ithout replacing the field
units or components thereof.
It is, therefore, an object to provide a local recorder
system whlch affords certain, although not all, advantages of
central recorder systems while re~aining the advantages of local
recorder systems and eliminating their principal disadvantages.
More specifically, it is an object of the invention to
p-ovide apparatus for data collection, in the form of local
recorder units for collecting and storing data not on e~pendible
record medium as known heretofore, but in semi-conductor memory
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for subsequent readout and transfer to a recording device of
a separate and independent portable reader-recorder instrument.
A further object is to provide a local recorder unit
which is programmable such that the kinds of data recorded in
the unit may be changed, to suit changing surveillance needs,
without requiring physical replacement or change of the
components of the recorder unit.
Another object is to provide a local recorder unit
which has no moving parts and uses no expendible elements,
which have been required heretofore in local recorders, such
as magnetic tape decks or paper tape drives, printers or punches
which use expendible tapes or other recording medium, and
simplifying the construction and reducing the cost of the local
recorder units while at the same time increasing the flexibility
of the recorder units to carry out a variety o. data storage
tasks and increasing the capacity of the individual recorder
units for data storage.
~ ore particularly, it is an object of this invention
to provide a data collection system utilizing a plurality of
local recorder units, each adapted to be placed at surveillance
sites, and a single portable reader instrument which may be
coupled to any one of the individual recorder units to monitor
the operation o~ the recorder unit, check the validity of the
stored data, change the programs in the recorder unit, and read
the stored data from the recorder unit and re-record the data
in the reader instrument, so that it is recorded for
subsequent processing.
~ nother object of the invention is to provide a local
recorder unit for data collection, particularly suited for
- traffic data collection, which utilizes individual recorder
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units which -are programmable to carry out different functions,
including:
1. Recording different traffic data
simultaneously and accumulating such data
for predetermined time pexiods/ including:
a. vehicle count from up to eight
lanes Qf hi~hway txaffic,
b. yehicle type classificatiQn,
c. vehicle lengt~ çlassi~ication,
d. yehicle ~peed classification, and
e. vehicle headway.
2. Transmitting the data while it is being
recorded, to a separate readex instrument for
display;
3. Transmitting açcumulated data stored in
the recorder unit, to a separate reader
instrument for recording and other processing;
and
4. Processing accumulated data stored in the
receiver unit and converting the data to a
format readable by a computer and transmitting
the data in that ~ormat to a processing center.
~n accordance With the inVention, apparatus is pro-
vided for counting and recording the count of events at a
surveillance site such as counting vehicles moving past a
roadside location, the apparatus including a recorder unit
adapted to be set at a surveillance site and connected to
detector means providing detector signals responsive to
events, and whre the recorder unit has circuits for processing
the data and a memory for storing the data. Also provided
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is a manually portable reader instrument for readin~ the
data from the recorder memory,-and re-recording the data.
preferably the reader circuit means includes a microprocessor
operable in response to signals from the detector means
for recording the events as count data, and for transferring
the count data on a time interval basis to separate
locations in said memory means, and a terminal providing
means for interconnection between the recorder unit and
peripheral equipment such as a reader ~nstrument. The
invention also pr~vides a reader instrument which may be
connected to a recorder unit teXmina~ for readin~ data from
the recorder unit ~emory and re-recording the data on a
recorder device which is part of thç reader instrument,
preferably a cassette recorder which provides means for
reading and recording the data from a number of different
recorder units at separate sites or locations.
How the foregiong is achieved with this invention
may be understood by referring to the accompanying drawings,
wherein:
Figure 1 illustrates a recorder unit connected by
cable to a separate, portable reader instrument, in accordance
with this invention.
~ ig. 2 is an overall system diagram illustrating
different methods for using the recorder units and reader.
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instruments of the present invention, and shoY7ing that data
read by reader instrument from a plurality of local reeorder
units and re-recorded on a reeording device in _he reader
instrument, is transferrable by subsequent readout from the
reader instrument to other recording medium for subsequent
processing, such as a disk recorder, a computer, an IBM compatible
tape unit, etc. Alternatively, with an acoustical coupler from
the reader instrument, the recorded data in the recording device
of the reader instrument may be transferred over telephone lines
to a central processor. The system also illustrates direct
- transfer to telephone lines from the recorder units for
-- transmittal to a central processing unit, or other peripheral
device.
Fig. 3 is a sehematie diagram illustrating a loeal
reeorder unit eonnected to vehiele deteetors on a roadway, at
a road site and connected by a eable to a reader instrument,
the basie eireuitry of the reeorder instrument and reader
instrument being illustrated in bloek diagram form.
~ igs. 4A and 4B taken together illustrate in sehematie
form the eireuitry for a recorder unit and reader instrument
exemplifying tne present invention.
Figs. 5A and sa depict a flow diagram which the data
processing system of the reeorder unit of this invention
utilizes.
Fig. 6 depiets a general flow diagram for a reeorder
unit program for deriving and storing vehiele elaqsifieation
data.
FigO 7 illustrates deteetor relay eontaets for multiple
detector systems.
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Fig. 8 illustrates diagrammatically the relation
between detector outputs and flag control signals.
Figs. 9A-9D depict a flow diagram for a recorder unit
program, showing in more detail than in Fig. 6, a se~uence for
deriving and storing vehicle classification data.
Figs. lOA-lOB depict a flow diagram which the data
processing system of the reader instrument of this invention
utilizes.
While the invention has utility in various fiel2s
for measurement and recording of data relating to events or
conditions that require counting and classifying, such as in
the field of pollution control where it is desired to detect,
classi~y and record data as to pollutants (particulate or
~ases) in the atmosphere, or in the field of noise control
where it is desired to detect, classify and record noise levels
both inside buildings and out-of-doors, for the purpose of
setting forth a preferred embodiment, the invention is shown
in the drawings and will be described hereinafter embodied in
apparatus for vehicle traffic surveillance.
; 20 TRAFFIC SURVEILI~CE SYSTEM
Referring to Fig. 1, appaxatus constructed in
accordance with the invention is shown as comprising a recorder
unit 20 connected by a cable 22 to detectors 1, 2, 1', 2'
providing output signals to the recorder unit 25. In this
field o~ use, the detector output signals represent vehicles
passing on the roadway which are to be counted and classified.
ln ~ther fields of use, sensors or detectors will be used in
a similar manner to produce signals xepresenting the event or
c~ndition under surveillance. Included within the recorder
unit 20 is a central processor unit (CPU) and semi~conductor
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memory for program and data storage, the CPU being operated
under program control to process the signals received from the
sensors or detectors and store in the semi-conductor memory
data derived from the detector output signals. Applied in the
field of traffic surveillance, traffic data in the form of
vehicle count and classification is derived from the detector
outputs and such traffic da~a is stored within the semi-conductor
memory of the recorder unit for subsequent readout.
Also shown in Fig. 1 is a portable reader instrument 24
which, according to this invention, can be interconnected with
the recorder unit 20 by a cable 26. A plug on one end of
the connecting cable 26 is insertable into and removable from
a terminal receptacle 30 on the recorder unit casing 32, and by
! - means of this connecting cable 26 the reader instrument 24 may
be interconnected with an individual one of a number of different
recorder units, each adapted to be placed at a surveillance site,
such as a roadside location, in the case of traffic surveillance.
The reader instrument 24 has a control panel 34, as
indicated in Fig. 1, providing a keyboard 36 for manually
controlling the reader instrument, and via the connecting
~- cable 26, the recorder unit 20. Also pro~ided on the control
panel 34 of the reader instrument 24 are pushbutton switches 38,
toggle switches 40, a visual display device 42, and a tape
recording device 44. Included within the reader instrument 24 is
a central processor unit (CPU) and semi-conductor memory for
storage of programs. Programs are stored for operating the CPU
of the reader instrument 24 under program control to read data
from the memory component of the recording unit 20, under command
from the reader instrument, and re-record such data on magnetic
~ape by means of the recording device 2~. Programs are also
_ stored in the reader instrument memory for transfer and loading
into the program storage memory of the reoorder unit 20.
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Both the recorder unit 20 and reader instrument 24 are
housed in weather-proof casings, the recorder unit casing ~eing
sealed since access into the unit is not required under conditions
of normal use in the field. Access to the internal operating
components of the recorder unit is provided by way of the "modem"
and "detector" receptacles and the terminal receptacle 30 on the
,' outside of the recorder unit casing. The reader instrument casing
has a hinged cover which when closed provides a weather-proof
casing, and the reader instrument 24 is portable for carr~ing
from one site to another for collection of data stored in
recorder unit memory by persons charged with that task.
Also illustrated in Fig. 2 are other aspects of the
`~ system of this invention. Thus, the reader instrument 24 is also
provided with the capability of reading data stored on recording
medium such as magnetic tape and transmitting it to standard
receiving equipment such as a disk recorder, a computer, a tape
recorder, or other similar unit of a processor center. The
processor center may be equipped with a tape reader, and in
such event a cassette of magnetic tape may be removed from
the reader instrument recording device, and the data on the
cassette tape read in the processor center. With an acoustical
coupler, the recorded data on tape in the ~ecording device
of the reader instrument may be transferred over telephone lines
to a processor center, as shown in~Fig. 2. Direct transfer to
telephone.lines fxom the recorder units for transmittal to a
central processing unit is achieved with the recording unit of
this invention having included therein a device DAA for reading
data from the memory component of the recorder unit 20 and
converting such data into form suitable for direct telephone
line transmission to a processor center.
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Detectors
Recorder units 20 of this invention are supplied witn
signals from detectors or sensors that represent the event or
condition under surveillance. In the field of traffic
surveillance, vehicle representing signals are provided by
detectors actuated by vehicles on the roadway. Sucn detectors
may be pressure responsive devices, inductance loop type
detectors, or other devices for providing vehicle representing
signals as desired. For purposes of describing the invention,
I0 the recorder unit 20 in ~ig. 1 is shown connected by the
cable 22 to inductance loop type detectors on the highway, and
signals from the detectors provide via the cable input signals
to the recorder unit circuitry. Various arrangements of such
inductance loop type detectors may be utilized depending on the
data required. For example, to count vehicles and record count
data, the simplest case, a single inductance type loop detector
in each lane of, illustratively, a two-lane highway having north
and south ~ound lanes, will provide the requisite signals for
counting vehicles in each lane. To derive ~ore complex data,
such as vehicle velocity, two detectors are installed in a lane
at a known spacing, for example, 16 feet from the leading edge
of the ~irst detector (detector ~1) and the leading edge of the
second detector (detecfor ~2) in the direction of trav~l of the
vehicles. With two conventional inductance loop detectors in
each of lanes 1 and 2, each detector with its associated circuitry
may be connected, as shown diagrammatically in Fig. 7, to actuate
relay contacts 1~ 2 and 2-1, 2-2, and produce an output
signal representing a vehicle moving over the detector. When
the vehicle reaches the leading ed~e o~ the detector, the relay
contacts are closed, and such con~acts remain closed until tnhe
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vehicle leaves the detector. ~eferring to the diagra~matic
timing diagram Fig. 8, vehicle representing signals from the
two detectors (detectors "l and ~,2) in a lane are sho-,7n as
pulses or voltage levels established and maintained by the
detector contacts l-l, 1-2. From detector 41 (the first
detector in a lane in the direction of vehicle travel), a pulse
, is supplied for the duration a vehicle is over detector '1.From detector ~2 (the second detector in the same lane), a pulse
is supplied for the duration a vehicle is over detector ~2. As
will be explained hereafter, with the distance between the
leading edge of detector 11 and detector 12 being known, and
. the time for the vehicle to travel that distance being
represented by the time interval Tl between the leading edge of
. the first pulse and the leading edge of the second puise,
velocity ror that vehicle may be derived. Moreover, in carrying
out the invention, with the velocity having been derived for a
vehicle, and the duration of time T2 for the vehicle to move
over detector ~,1 being represented b~ the length of the first
pulse, the length of the vehicle may be derived to provide
vehicle length data.
- Recorder Unit
In accordance with the present invention, the recorder
unit 20 is constructed as shown in Fig. 3 using a central
processor unit (CPU) 46 pre~erably-directly connected
with program and data storage means (memory) ~0. -The
input/output circuitry 48 interfaces with the peripheral
devices to which the recorder unit 20 is connected, such as
vehicle detectors and a reader instrument 24. As earlier noted,
the recorder unit 20 may be connected via lines with other
peripheral devices in a processor center (see Fig. 2) such as
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a CRT terminal, a computer, disk storage unit or the like
through a modem.
In keeping with the preferred form of the invention,
the CPU 46, program and data storage means 50 and input/output
circuitry 48 are implemented with semi-conductor chips, and
for the CPU 46 it is preferred to utilize a microprocessor,
, Intersil IM 6100 having been found suitable and being preferred
for that purpose. A standard RAM memory system organized in a
plurality of memory fields is preferably employed to provide
the program and data storage means 50. It is recognized,
however, that other microprocessors, and other forms of program
and data storaye, or data processing and memory storage circuits
constructed using discrete components, may be used and the
invention is not limited to the specific components described
hereinafter. It is preferred, however, to operate a
programmable processor under program control to perform the
various functions carried out by the recorder unit, alone and
in association with the reader instrument 24 and other
peripheral devices.
It has been found that recorder units so constructed
--' and operated provide many advantages when used in the field
with the reader instrument of this invention. Where the
recorder units are utilized to derive and store traffic data,
the reader instrument may be utilized to monitor and display
the velocity and other traffic data concerning vehicles passing
on the highway without interrupting the ongoing recording process,
to calibrate the recorder units based on operator observation,
- to reprogram the recorder units to change the type of traffic
data derived and stored, as well as to read data stored in the
recorder units and re-record it in the reader instrument. The
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combination of recorder units and reader instr~lment provides a
more facile system for collecting traffic d~ta. How that is
achieved will appear from the following.
Reader Instrument
The reader instrument 24, like the recorder unit 20,
is constructed using a central processor unit (CPU) 52, data
storage means 53, with input/output circuitry 54 for interfacing
with the devices on the control panel 34 including the visual
display device 42, such as an LED or LCD display and also the
peripheral devices to which the reader instrument is connected,
principally the recorder unit 20 as shown in ~ig. 3. It will
be recalled, however, that the reader instrument 24, as shown
in Fig. 2, may be connected to other peripheral devices for
transmittal of data recorded in the recording device 56 of the
instrument. The block diagram of Fig. 2 of the circuitry of
the reader instrument will be recogni~ed, as will the block
diagram for the recorder unit circuitry, as conventional bloc~
diagrams for microprocessor based products.
The reader instrument 24 of this invention is operable
to monitor the operation of the recorder unit 20 and display
~-- to the operator on the display 42 one or more of the various
traffic conditions being recorded, as they are recorded by
and without affecting the ongoing recording process carried-
out in the recorder unit. The reader instrument 24 of this
inYention further includes means for calibrating the recorder
unit and for loading programs into the memory 50 interfaced
~ith the programmable processor of the recorder unit, the
data storage means 53 of the reader instrument being proYided
for recorder unit program storage as well as program storage
re~uired for program contxol of the functions o~ the reader
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instrument. While heretofore, local recorder units have had
a single mode of operation to record data as to
traffic conditions, means are provided in the
reader instrument to change the operating mode of the recorder
unit of this invention from a recording mode to a transmitting
or readout mode, such that the recorder unit and reader
instrument operate in combination to provide for recording
data and for reading out the data for subsequent processing,
~nalysis and use.
The data collection procedure with this invention can
be readily contrasted with that presently used. Presently,
! the person charged with data collection travels to each
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recorder unit site, opens the recorder unit case, removes the
paper tape or cassette of magnetic tape with the recorded data
from the unit, and writes information in a notebook or tag as
to the station number, data, etc. A new roll of paper tape
or fresh section of unused tape is threaded into the printed
device, or a fresh cassette is inserted into the recorder unit
and the unit is reset for ongoing recordins. The batteries
f,-~ 20 must be inspected as well as the machine overall to insure
it is operating properly. The record tape is carried to the
central recorder station where the data is then converted to
punch cards, printed records or otherwise processed.
With the system of this invention, on the other hand,
the yerson charged with data collection carries the portable
reader instrument 24 to each recorder unit site and couples
the cable 26 to a weather-proof receptacle 30 on the outside
of the case of the recorder unit tFig. 1). This automatically
connects the reader instrument 24 and the recorder unit 20
electrically. In keeping with the lnvention, the reader
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instrument keyboard 36, pushbuttons 38 and toggle s~litches 4~,
through the circuitry provided in the instrument, are
operable to transmit commands to the recorder unit over the
cable 26, and also to record on the record medium in the
recording device 44 of the reader instrument, station number,
date and other header data as a preliminary to readins data
from the recording unit. The data stored in the memory of the
recorder unit 20 may also be verified for station number, time,
date and validity, to determine whether the recorder.unit has
been operating properly. ~ro~ision is thus made for determining
whether the recorder unit 20 is malfunctioning, and if so, the
unit may be replaced in the field.
The collection procedure with checking for proper
operation of the recorder unit 20 and validity of the stored
data is a very simple and rapid procedure with the present
invention, involving only plugging in the reader instrument
cable 26 to the recorder unit 20 and performing the verification
and header procedures with the aid of the manual controls of
the reader instrument 2g.
The apparatus of this invention facilitates the data
~-i collection procedure as well as the procedure of processing
the data, by using in the reader instrument 24 a recording
device 44 having a data storage capacity which is much greater
than th~ data storage capacity of the individual local recorder
units 20. Using, as preferred, cassettes of magnetic tape as
the storage medium in the reader instrumen~ 24, data gathered
from a plurality of local recorder units 20 may be recorded on
a single cassette of tape. This not only facilitates collection
of data by reducing the number of cassettes required to be
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handled in the field, but also acilitates the prscessing of
data at the processing center and eliminates errors since the
data read from each local recorder unit 10 and recorded on the
magnetic tape is clearly identified on the tape itself.
System Operation
The recorder unit 20 is operative in a number Oc
, different modes. When connected only to the detectors of
an adjacent highway (lanes 1 and 2, detectors ~ 2), it is
operative in a recording mode involving processing under
program control signals received from the detectors to
derive traffic data, such as vehicle count, velocity
and/or length, and recording such traffic data in
~ the memory components of the recorder unit. When also
connected to the reader instrument 24, the recorder unit 20
is operative in one of several different modes under control
from the reader instrument. For example, the recorder unit
is operative to continue recording of traffic data
and also to displa~ such data on the visual display device 42
provlded by the reader instrument -- a display mode; the
recorder unit 20 is operative to read traffic data
from its memory components, which data is re-recorded in the
recording device 44 included in the reader instrument -- a read
mode; it is operative to change the programs in the program
memory component of the recording unit, such new programs
- being transferred from the reader instrument -- a
re-progr~mming mode; it is operative to be calibrated by
instructions received from the reader instrument -- a
calibration mode; it is operative to check its programs and
pr~cessing routines and sub-routines -- a diagnostic mode.
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These are exemplary of the various modes in which the recorder
unit is operative.
With regard to the reader instrument, when connected
to the recorder unit it is operative in corresponding modes
to those described for the recorder unit, i.e., a read
, re-record mode, a display mode, a recorder calibration mode,
a recorder diagnostic mode. The reader instrument is also
operable to set up or reset the recorder unit for its recording
mode of operation.
CPU and Memory Architecture
As stated above, various conventional CPU's and
memory devices may be used for the recorder unit 20 and
receiver instrument 24 to carry out, under program control,
the functions of these devicss. Intersil brochure ~OM 8/75
describes the IM 6100 microprocessor previously referred to
as a suitable and preferred CPU or both the recorder unit
and reader instrument. Briefly summarizing the description
contained in said brochure, the IM 6100 CPU is a single
address, fixed word length, parallel transfer microprocessor
~ 20 using 12-bit, two's complement arithmetic. The internal
circuitry is static and designed to operate at any speed
between DC and the maximum operating frequency. The CPU
is supplied with external crystal cloc~ signals. These
signals are utilized to establish the timing and state
signals internally by the timing and state control circuit.
The CPU is also supplied with pulses on a frequsncy related
to real time, and through the program control of the CPU
provides a time base synchronized with time of day and
permitting under program control, storage of traffic or other
data in separate memory locations of predetermined fi~ed ~ime
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intervals, such as one half hour or one hour, so that when
subsequently read out an additional item of data is provided,
namely, the time of day of traffic flow conditions.
The CPU is diagrammatically illustrated in Figs. 4A
and 4B as comprising an accumulator (AC) which is a 12-bit
register with which arithmetic and logical operations are
performed. Data words may be fetched from RAM me~ory to the
accumulator or stored from the accumulator into memory. The
accumulator also serves as an input/output register and all
programmed data transfer passes through the accumulator.
The 12-bit memory address register (MAR) contains the
address of the memory location that is currently selected for
reading or writing. The MAR is also used as an internal
register for microprogram control during data transfers to
and from memory and peripheral devices. The 12-bit progran
counter (PC) contains the address of the memory location from
which the next instruction is fetched. During an instrument
fetch, the PC contents are transferred to the memory address
register and the PC is then incremented by one. Branching-
normally takes place under program control, however, duringan input/output operation, a peripheral device may specify a
branch address. Under program control, skip instruction
increments may be achieved with the PC, and a peripheral device
can also cause the next sequential instruction to be kipped
via the PC.
The arithmetic and logical unit ~ALU) perform~ both
ar thmetic and logical operations -- two's complement binary
addition, AND, OR and complement.
The 12-bit input/output multiplexer handles data,
address and instruction transfers, into and out of, the CPU,
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from or into, the main memory and peripheral devices on a
time-multiplexed basis.
During an instruction fetch, the instruction to be
executed is loaded into the instruction register (IR). The
programmed logic array (PLA) is then used for the correct
sequencing of the CPU for the appropriate instruction. After
an instruction is completely sequenced, the major state generator
scans the internal priority network, the state of which decides
whether the machineis going to fetch the ne~t instruction in
sequence or service one of a plurality of exteranl request lines.
The memory and device control unit provides external
! control signals to communicate with peripheral devices, memory
and other regis~ers.
The instructions of a program for control of the C2U
are 12-bit words stored in memory. ~he CPU makes no distinction
~etween instructions and data which are transferred into and
out of the CPU via the multiplexer and accumulator. The
preferred I~ 6100 microprocessor has a basic addressing capacity
of 4~ 12-bit words, which may be expanded. A preferred memory
~20 system is organized in ~K word blocks called memory fields.
Each memory field is subdivided into pages numbered
se~uentially. The high order bits of a 12-bit memory address
denote the page number and the lower order ~its specify the
address of the memory location within the given page. During
an instruction fetch cycle, the contents of the program counter
are transferred to the memory address register and the program
counter is incremented by one so that it contains the address
of the ne~t seguential instruction.
The CPU utilizes a techni~ue of addressing a location
- pointed to by the contents of the PC. ~ocations on a current
.. , ., . _ . . ., . . , . , , , _ , ,, . . , , , _ _ _ _ _ . _
19
50~i
page of the memory system are directly addressed by the MAR
contents, and locations on other pages are indirectly addressed
by a pointer address in a directly addressable location on the
current page.
There are three general classes of memory instructions,
referred to as memory reference instructions (MRI), operate
instructions (OI), and input/output transfer instructions (IOT).
The memory reference instructions (MRI) operate on the contents
o a memory location or use the contents of a memory location
to operate on the accumulator or the program counter. The
operate instructions (OI) consist of groups of microinstructions
used to perform logical operations on the contents of the
accumulator, to test the contents of the accumulator or to
perform logical operations on the contents of the accumulator
and other registers.
The input/output transfer instructions (IOT) are used
to initiate the operation of peripheral devices and to transfer
data between peripheral devices and the CPU. The IM 6100
provides for three types of data transfer with peripheral
-;20 devices; programmed data transfer; interrupt transfers used in
interrupt systems to service several peripheral devices
simultaneously permitting computational operations to be
performed concurrently with data t~ransfer operations; and direct
memory access by which varible-si~e blocks of data are
transferred between peripheral devices and ~he memory with a
minimum of program control.
Af~er an instruction is completely sequenced, the major
stat~ generator scans the internal priority network, the state
o~ the priority network deciding the ne~t sequence of the
~achine. This priority network is connected to wait and
,
J
,
~39~iQ5
reset lines. If no signals appear on such lines, the C~U
~etches the next instruction pointed to by the contents of
the program counter.
While various memory systems may be utilized, a
preferred system for a recorder unit 20 constructed using an
IM 6100 CPU which has a basic addressing capacity of 4X 12-bit
words, employs integrated circuit R~'l semi-conductor chips
providing a full 32K words of memory, to provide capacity for
storing large amounts of program instructions and traffic data.
The data is represented in memory location in unsigned integer
notation in the preferred memory system.
~_ With the maximum number ranges for such a notation
being 4094, it will be noted that since the maximum vehicle
count per lane on the heaviest traveled highway does not exceed
2000 vehicles per hour, the accumulated vehicle count for two
lanes may be stored in one memory location without overflowing,
when accumulated for separate one hour periods. Optionally, with
doùble precision, the maximum number range will be about (4K)2,
and a greater vehicle count may in such case then be stored.
The memory system also provides the "registers"
referred to in connection with the programs detailed later.
Thus, the memory system provides memory locations, rather than
requiring discrete memory registers, serving the category
register functions wherein vehicle velocity and vehicle length
data, for example, are accumulated for periods of time followed
by the transfer of accumulated totals to separate memory locations.
Further details on the memory system architecture and
,
orga~ization may be obtained by referring to the previously
identified brochure for the CPU I~ 6100, 40M 8/75. Said brochure
also provides information as to how to program`this particular
. . . . . . . . . .. . . . .................. .
,
21
~9~iS05
CPU. With the use of such information, a progra~.~mer can
write the software and program this CPU to carry out desired
functions. Of course, the software will vary depending on
the particular functions to be performed. In order to
explain this invention, illustrative programs are described
hereinafter for the recorder unit and receiver instrument
CPU's when used in the field of traffic surveillance, but it
should be understood that by modifying and changing the
programs, this apparatus may be suited for measurement and
recording in the other fields mentioned hereinbefore.
. .
22
5~5
Program Control
The various functions carried out by the recorder
unit 20 and reader instrument 24 under program control may best
be understood by referring to program flow charts on Figs. 5,
6, 9 and 10. It is well within the capability of one having
ordinary skill in the art to program a microprocessor of
standard type to implement these flow charts.
A program for vehicle counting is shown on Figs. S~-SB,
and will be used as a simple example to explain various
functions of the recorder unit. While other programs may ~e
used, more complex programs are shown in Figs. 6, 9 and 10, for
controlling the recorder unit to derive and store more complex
trafic data, and for controlling the reader
instrument when connected to the recorder unit.
The recorder unit may be considered located at a roadside
site and connected to single detectors in each lane of a
two-lane road to monitor traffic in both lanes. To operate the
- recorder unit in accordance with the invention, a program ror
vehicle counting described in the flow chart of Figs. 5A-5B
~-~ 20 is stored in the recorder unit memory to operate the CPU to
derive vehicle count from vehicle representing signals from
the lane detectors, which is the desired traffic
data, and store vehicle count ~or each lane for one-hour periods
in separate locations in the memory system.
Referring again to Fig. 5A, it will ~e seen that with the
power turned on in the recorder unit and after the recorder
unit processor executec a clear routine in response to the
reset switch being actuated, the step is executed to transfer
the detector input signals appearing on the data input ports of
the CPU to the accumulator. The incoming signals from the
.. . - :
23
.
5~?5
detectors are routed by the input/output circuitry to speci~ic
processor ports which are used for transfer of data to and
from the accumulator on a time multiplexed basis, while other
ports transmit and receive control and clock signals.
In the case of the vehicle counting program flow
charted in Figs. 5A and 5B, this program provides for counting
vehicles in a multiple lane highway adjacent the site at which
the recorder unit is located and contemplates counting vehicles
in up to 12 lanes of traf~ic. The input/output circuitry thus
provides for transfer of the outputs from single detectors in
each of up to 12 lanes to separate processor ports. The
preferred CPU of the recorder unit has an accumulator (~C)
which is a 12 bit register to which up to 12 detector outputs
are transferred via 12 specified input/output ports in the form
sf a positive or a ~ero voltage level t"l" or "0") representing
the state of the detector contacts.
Referring to Fig. 5A, the program there illustrated
shows as the first step "clear read flag". In this program,
reading of vehicle count data from memory and transfer of such
~-~20 data to the read instrument on command, i9 interleaved with
measurement and recording of vehicle count, so that the ongoing
measurement and recording process proceeds without
`interruption as the read operation is carried out. Thus, with
the reader instrument connected to the recorder unit, by
operating the reader instrument keyboard to issue a read
; command, a 1ag signal is established which will result in the
transfer of vehicle count data stored in semi-conductor memory
of the recorder unit, to the reader instrument for re-recording.
As a first step in this program, however, the read flag if
- established is cleared, so that the measurement and recording
~~~ ~~ ~` ~ ~~` ~ process may proceed.
24
.~ .
.
650~
Thus, the next step is "input 12 contacts", ~hich
represents that the detector outputs for as many lanes as
are being monitored and which are connected by the
input/output circuitry to corresponding processor ports, a_e
transferred as "l's" or "0's" to the accumulator of the CPU
of the recorder unit. The program compares the contents of
the accumulator each program cycle, with the contents the
previous program cycle. A change in any bit, ~7hen caused by
a vehicle passing from the zone over the detector, is counted
as a vehicle. One practical problem arises because of detector
relay contact bouncing in the periods of transition between
,- states ~hich produce multiple changes in bits of input data.
~he next step in the program is "debounce delay", an interval
introduced to permit successive scans of the processor ports
during the same program cycle in order to determine whether any
change in voltage level is the result of detector relay con.act
bouncing, which represents a spurious change of state of the
contacts rather than an actual change of state of the detector
outputs representing a vehicle entering or leaving the zone
over a detector and thus, a vehicle which should be counted.
In the present case, a vehicle is counted when it leaves the
zone over the detector in the lane the vehicle is traveling.
That is reflected by a negative transition of the pulse produced
by the detector relay contacts, from a positive voltage level
to a æero voltage level (a "l" to a "0")~ Under program control
the CPU looks for the trailing edge of the detector contact
GUtpUt pulse in each lane, iyno::es pulse oscillations caused
by contact bouncing as spurious signals, and increments a counter
in response to each such negative transition or trailing edge
o~ a pulse to count vehicles.
.. ,, . _ .. _ .. _ . .. , . , .. _ .... . . . . . . . . . . . . .
, ' -
, ~
65~5
In some cases of traffic surveillance, it is desired
to accumulate vehicle count in groups of lanes rather than
in separate lanes. In the program shown on Fig. 5A, provision
is included for subdividing the 12 lanes of a highway into
groups of lanes as desired, using a "category counter register" to
accumulate vehicle count in such lanes. A "category counter
' register" is successively incremented each program cycle to
store the vehicle count for multiple lanes. After the count
for that group of lanes has been accumulated for a period of
time, the accumulated count is transferred to data storage.
The counter and register functions, as well as the data storage
- function, is served by locations in memory, in the preferred
foYm of the invention, rather than b~ separate discrete
components, and the locations in memory are pointed to by
pointers.
As shown in Fig. 5A, each program cycle the
12 input/output ports of the processor are successively
scanned (input 12 contacts -- input 12 contacts) after an
interval described as "debounce delay", until any oscillation
of the relay contacts has passed, and the contents of the
-- accumulator have stakilized for that program cycle. Then
the question is asked "Any new contacts?". In this step, the
contents of the accumulator are compared with the contents of
tha accumulator the previous program cycle to determine whether
any bit in the accumulator register has changed. If "yes", the
program enters a sequence to count vehicles in groups of lanes.
The first step is to "rotate contacts". The accumulator is
rota~ed, i.e., a shift operation is performed to transfer the ~`
contents of the accumulator bit-by-bit in serial order to the
link, a one-bit register, and under program control each bit
, . , . . ~ , . . . ^ , . . , , . , . , . _ ,
26
~9~j5~5
in the accumulator is compared with the correspor.ding bit in
the accumulator during the previous cycle to determine any
change; the circuitry performs the "Exclusive OR" function and
produces a "high" or "1" output responsive to any such change
which represents a vehicle to be counted. Thus, after the
step "rotate contacts", there is shown the step "increment
group counter". The group counter is utilized to keep track
of the number of lanes making up a group. Thus, if the lanes
are to be grouped into two 6-lane groups, the group counter is
incr,-mented twice as the accumulator is rotated once. If the
lanes are to be divided into four 3-lane groups, the group
( counter is incremented three times while the total 12 bits of
the accumulator are shifted through the link. Each
sub-sequence, therefore, the group counter is incremented and
the question is asked "End of group?". If "no", the question
is asked "contact hiqh?". As noted above, if any bit of the
accumulator contents when compared with the same bit the
preceding cycle shows a change representing a vehicle to be
counted, the "contact high?" question is answered "yes" and
the category counter register is incremented. If the answer
is "no", representing for that particular lane no vehicle to
be counted, the sub-sequence loops and the next bit of the
acc~mulator is looked at. At the end of each group, the
~end of group?" question is answered "yes". The category
pointer is then incremented 50 that the count for the next
subgroup o~ lanes will be stored in a new location in memory
serving the "category counter register" function. At the end
o the categories, the counter and pointer are reset and the -
program returns to the start.
--. , . .. . , , - . . -- , . . . . _ . . . .. . .. _ , , _ . .. _ _ . _ ,
27
,~
'
~¢3~5~35
It will thus be seen that in addition to ~Jehicle
count, a classification function is performed in that the
vehicle counts are, or may be, classified into groups of
lanes as desired.
As shown in Figs. SA-SB, the reading of data from
the recorder unit memory by the reader instrument, in response
to a read command from the reader instrument, is interleaved
with the registering and recording of vehicle count in the
recorder unit memory. The timing of each cycle of scanning
input~output ports of the processor, and counting vehicles
represented by a change in state of the voltage level appearing
'`~ on any one or more of the input/output ports, is established by
the internal timing circuitry of the CPU, and with a standard
- CPU s~ch as the Intersil 6100 may be set to about one
millisecond. The program gives priority to counting vehicles
o~er reading stored data and, therefore, until a check of the
detector contacts indicates no change in state of any one of
the contacts (any new contacts? -- no), the program loops;
when a check of the detector-contacts (as represented by the ~ -
~20 voltage levels in the data input/output ports) indicates "no
change", the program exits from the loop (or daes not enter
the loop) and continues to the segment shown on Fig. SB where
any read command from the reader instrument results in a
read operation.
In this program, the data stored in memory is read
in small blocks, for example, in ll-bit characters each program
cycle. It will be seen that depending on traffic flow
conditions, the gaps in ~ehicle flow may be shorter or longer.
The transfer of data takes place inll-bit characters for as
many program cycl~s as fit into a gap, and the read process
.. .. . . .. . . _ . , .... _ . . , . _ . . . . . . . _ . . ... _ . , _
28
.
.', ' ~ ,.................. ~,
~119~5
is interrupted and the program waits for the next gap before
the read process continues. In this manner, the counting and
recording process is not slowed down or interrupted for reading,
and missing a vehicle is avoided.
During heavy traffic flow conditions, the readout
process proceeds at a slow rate and may require several minutes
to fully read out all data stored in the memory of the recorder
unit, interleaved during such gaps in vehicle flow. Under
lighter traffic flow conditions, the read process will proceed
more rapidly since many more characters may be read out without
interruption during the longer gaps in vehicle flow.
~s shown in Fig. 5B, the program proceeds with the
input/output control port of the CPU being chec~ed for commands
from the reader instrument. The next step is the "clock
ready?". The program branches once each minute to increment
the clock counter. At the end of each hour (or other shorter
or longer time interval, as desired), the contents of the
category counter registers each having the accumulated vehicle
count for a group of lanes, are transferred to memory locations
via the data table pointer, the data table pointer is
incremented and the program returns to reiterate the counting
sequence.
If the answer to the "clock ready?" question is "no",
and a read flag is set by a read command received from the
reader instrument, one character composed of multiple bits of
data (for example, the ll-bit character mentioned hereinbefore)
s~ored in recorder unit msmory, is transferred to the reader
instrument.- The particular bits of data transferred are
addressed by a character pointer, which is incremented
following each character transfer to address the next set of
,, . ., . , ., . ,, _ ,. ... .. . . ........................................ .
. .
~.' . ` ' ~
- bits to b~ transferred. With the character pointer at a
terminator, representing all data transferred, the read flag
i5 cleared.
The program, as shown in Fig. SB, also contemplates
transfer from the reader instrument of other control signals
or commands besides read commands, and operation of the
recorder unit under program control in response to such other
control signals or commands. Thus, as shown in Fig. 53, with
the read flag not set, and the reader status low, the program
enters the reader instrument program on Fig. lOB as indicated
by the off-page locator "B" at the bottom of Fig. 5B. With
( the reader status high, the program returns to the counting
sequence commencing with the "input 12 contact" step of
i Fig. 5A.
" .. ,.,_ , . . . . . . . ............ .
...
6i50~;
Turning to Fig. 10B, with a ra~der instrument connectea
to the recorder unit and the cable "field mode", the program
sequence is there shown for the reader instrument to carry ou~
its ~arious functions in conjunction with a recorder unit. For
example, with the "start key" of the reader instrument not
actuated, and the "display key" of the reader instrument
actuated, the mode is entered for active count register display
from the recorder unit without interrupting the ongoing
recording mode of the unit.
With the start key actuated, the reader instrument is
operated to execute a series of steps leading to transfer of
stored data from the recorder unit memory and re-recording on
the cassette tape of the recording device of the reader
instrument. The sequence of steps, in response to successive
actuating of the start key, contemplates displaying by means
of the key~oard, identification, time and date data and
recording such data on the cassette tape, followed by the steps
of requesting data transfer and inputting and recording the
traffic data on the cassette tape as shown on ~ig. 10B. This
) 20 se~uence also contemplates altering the set-up date, after the
traffic data transfer and recording process for resetting the
recorder unit for subsequent processing and recording of
traffic data.
The illustrated programs for the reader instrument also
pro~ide for special operations as shown on Fig. 10B. Thus,
with the "start key" not actuated and the "rewind key" actuated,
the subprocess is executed of :ecording an end of tape (EOT)
code on the cassette tape in the recording device and rewinding
the cassette tape. Control keys 0-8 when actuated cause the
execution o~ different processes. For example, "control
- - 8tart" key when actuated calls for a program transfer to the
recording unit, to change the program stored in its memory and
... .
31
., ~ .
- ~96~S~S
thereby change the type of parameter data derived and stored
in the recorder unit. Operation of "control 3" ~ey calls for
direct data transfer fxom the recorder unit memo~y ~ith the
data displayed on the reader instrument display device. By
actuating "control 2" a signal is transmitted to the recorder
unit to speed up the data transfer step and immediately cause
accumulated data in the lane registers to be transferred to
memory. Actuating control keys 4-8 calls ~or operations such
as time display, diagnostic procedures, and recorder unit
adjustments.
Referring now to Fig. 6, a program for operating the
recorder unit to derive more complex traffic data, and to
`~ classify and store such data in semi-conductor memory, is sho~Jn
in this general flow chart. A more detailed flow chart of the
s~me program is shown in Figs. 9A-9B. To derive as shown in
Figs. 6, 9A-9B, vehicle velocities and length, dual detectors in
aach of two highway lanes provide vehicle representing signals
to the recoxder unit. The concept behind the program is to set
for each lane a control flag for the duration of time a vehicle
is over the first detector, and another control ~lag for the
duration of time requixed for a vehicle to travel from the
leading edge of the first detector in a lane (in the direction
of travel of the vehicle) to the leading edge of the second
detector in the same lane. The setting and clearing of such
flags is diagrammatically illustrated in Fig. 8. Utilizing such
lag signals in the course of the program, vehicle velocity and
length traffic data is derived, classified in categories, and
~tored in memory.
Another consideration in the establishment of this
program for deriving velocity and length data and classifying
and storing such data, is to process the signals representing
.. . . . .. . .
veh~cles in both lanes and store intermediate results based on
those signals, and after the vehicles have cleared the ~ones
32
., ' .
!
S3~
over the detectors, to calculate and derive the desired
traffic data (velocity, length) based on the intermediate
results. This contemplates that with all foreseeable tra'fic
flow conditions on a two-lane highway, for example, a "windGw"
will be provided during which vehicles in both lanes have
cleared the zones over the detectors and during that "window"
before following vehicles arrive over the detectors, the
vehicle velocity and length is calculated, classified and sto~ed.
Thus, referring to Fig. 5, at the start of the program, the
vehicle representing signals from the detectors in lanes 1
and 2 are routed by means of the input/output circuitry to
( input ports of the CPU. This means in the case where dual
detectors are in each of two highway lanes, a signal may be
produced by one or the other of the two detectors in each lane.
It is not contemplated that two vehicles will be actuating the
dual detectors in a lane since only 16 feet separates the
detectors.
The next step in the program, as shown in Fig. 6 and
also Fig. 9A, is the question "reader connected?". I~ "yes",
-20 the program branches to the reader instrument program on
Fig. l~B. With the reader instrument not connected, the
question is asked "new hour"O This program contemplates
accumulating classification data for one hour, and at the end
of each hour transferring data stored in registers to new
locations in memory. The next processing step, generally
indicated in Fig. 6 as "Increment ~ane Counters, etc. n,
involves incrementing lane countexs each cycle of a program
loop which is precisely timed to take a fixed period
e~tablished for vehicle classification systems, preferably on
the order of 1.34 milliseconds, which program loop is not
~, . . . . . . .. . . . ~ _ . . . . .
r ~
33
~ ;
5~5
te~minated until the vehicles in both lanes have cleared both
detectors, indicated by the decision point "All Flags Reset?"
in Fig. 9B. In this program loop, as shown on Fig. 6 and
Figs. 9A-9B, the lane counter B is incremented successively
each cycle, for the period of time the B flag is set, as
shown in Fig. 8, so that the number accumulated in the B
counter represents the duration of ti~e a vehicle is over the
first detector in lane l; lane counter A is incremented each
cycle of the program loop for the period of time the A flag
is set, so that the number accumulated in the A counter
represents the duration of time of travel for the same vehicle
f to travel between the leading edge of the first detector in
the lane to the leading edge of the second detector in the
lane. Separate A and B lane counters are provided for both
lanes. The program exits from the loop when a vehicle in one
lane has cleared the zones over the detectors, or when vehicles
are traveling past the detectors in both lanes, when both
vehicles have cleared the detectors in both lanes. Thus, after
the lane counter incrementing process, the question is asked
~ ~0 "vehicles cleared both detectors?".
In the more detailed flow chart of the same program
in Figs. 9A-9B, at the corresponding point in the program the
question asked is "All Flags ~eset?". After vehicles have
cleared both detectors in both lanes, and the program exits
from the loop, the processes are executed of calculating the
vçlocity of a vehicle in each lane, and based on the velocity
- calculation, calculating the length of the vehicle knowing the
given distance between the detectors. The velocity is
classified and separate registers for each veloci~y category
are incremented; the vehicle leng~h is classified and separate
.
"
3~
' ~ t
. .
' ' ` .
` ~9~5~5
length registers for each category are incremented. Each hour, all v~locity
and lengthcategory registers are transferred to memory as shown by the flow
chart.
Turning now to Fig. 9A, for a more detailed illustration of the
program steps, the program as there shown includes as a first step "clear all
flags" and next "input detector contacts". As noted earlier, when connected
to dual detectors in two lanes, it is expected that either one but not both
of the detectors in each lane may be actuated during any given machine cycle.
The next question is "reader connected?" and if "yes", the reader instrument
program, depicted on Fig. lOB, is entered. If "no", the question is asked
"clock ready?", and if the answer is "yes", the steps are executed, first of
incrementing the clock counter and then, if a new hour, executing the step of
transferring to different memory locations the accumulated counts in the
category registers, a data table pointer serving the functions of addressing
the desired locations in memory. The data table pointer is incremented, so
that the data table pointer has the starting address for the memory locations
where the registers are to be transferred at the end of the next hour. The
program loop exits at the step "clear lane l-B flag"
Referring to Fig. 8, the A flag is set for the duration of time of
travel of a vehicle from the leading edge of the first detector in the lane to
the leading edge of the second detector in the same lane. The B flag is set
for the duration of time for the vehicle to pass the first detector in the
lane. Referring again to Fig. 9A, the step "clear lane l-B flag" refers to
the clearing of the B flag for lane 1. Next the question is asked "lane 1
contact 1-1 set?"; this refers to the detector #1 contacts in lane 1. If the
answer is "yes"~ both A
-35-
j k/~ b
,' . .
~ 65~S
and B flags for lane 1 are set (as sho~Jn in Fig. 8) and the
question is then asked "lane 1 contact 1-2 set?", referring to
the aetector ~2 contacts in lane l. If the ans-~er is "yes",
since the detector ~2 contacts are set well after a vehicle has
left the zone of detector ~1, the step is executed to clear the
A ~lag. Thereafter, the step is executed to clear the B flag
for lane 2. The question is then asked "lane 2 contact 2-1
set?'', referring to the detector ~l contacts in lane 2. If the
answer is "yes", both the A and B flags for lane 2 are set and
then the question is asked "lane 2 contact 2-2 set?", referring
to the detector #2 contacts in lane 2. I~ those contacts are
; set, representing that a vehicle has left the ~irst detector
and has actuated the second detector, the next step is executed
~clear ~ flag, lane 2".
In summary, to this point in the program, the contacts
for the dual detectors in both lanes have been scanned. If a
vehicle is passing the first detector (detector ~1) in either
lane, resulting in the first detector contacts being closed,
the B flag for that lane is set, as indicated in Fig. 8. If
-~ 20 a vehicle has entered the zone of the second detector in either
lane, thereby closing the second detector contacts, the A flag
for that lane, which was set when the vehicle actuated the
first detector, is reset. The steps of setting and resetting
flags are iterated every sub-cycle represented by the program
loop, which is a predetermined and fixed period, preferably
1.34 milliseconds so that, as indicated in Fig. 8, the A flay
signal is maintained for the duration of time Tl whi e the
- B $1ag signal is maintained for only the duration of time T~.
The continuation cf the flow chart on Fig. 9B reveals the
successive steps of inorementing lane counters in response to
` 36
s~
set flags. Thus, the question is as~ed "Flag A, lane l set?~.
If "yes", lane l counter A is incremented. Then the question
is asked "Flag B, lane l set?". If the ans~er is "yes", the
lane l counter B is incremented. Similarly, the A and B flags
for lane 2 are tested and the lane count is incremented with
the flags set. The program loop earlier referred to is started
at the decision point "all flags reset?". If the answer is
"no" indicating ~hat for either lanes l or 2, one or the other
of the A or B flags is set, then the program returns to the
step "clear lanes l-B flag" of Fig. 9A, after a resolution
delay determined by the desired resolution of the detector
signals. Recognizing that the program loop involves a passing
through the steps on Fig. 9A each l.3~ milliseconds, it will
be seen that each lane counter is incremented each l.34
milliseconds for as long as the corresponding lane flags are
set. Thus, the A counter for each lane will be incremented
for as long as the A ~lag is set and the B counter in the same
lane will be incremented for as long as the B ~lag is set. The
number of counts accumulated in each counter will, therefore,
represent in the case of the A counter, tne time Tl, and in
the case of the B counter, the time T2. With all flags reset,
representing that vehicles have left the ~ones of the dual
detectors in both lanes, the program proceeds to the program
segment flow charted on Fig. 9C.
As there indicated, the first step involves the questio~
nlane l-A counter equals zero~ f the ~ counter for lane 1
contains no number, the next three steps are s1;ipped. If the
A counter for lane l contains a number, the program proceeds
through a calculation to derive vehicle velocity for a vehicle
in lane l, by dividing a conversion factor-by the number
_ _ . _ .. . , . _ . . , _ .
'
~19~i5(~5
accumulated in the A counter for lane 1. The conversion factsr
is based upon the known distance between the leading ~dge o~
the two detectors in lane 1 described earlier as substantially
16 feet, and thereby converts the number in the A counter
which represents accumulated time in increments of 1.34
milliseconds, to velocity in m.p.h. The next step is to find
the velocity category -- usual velocity categories are 35-45,
45-55, 55-65, over 65 and after the particular category
has been found, the category registér which fits is
incremented as the next step in the program.
The program then proceeds to a velocity derivation for
a vehicle in lane 2. Thus, the question is asked "lane 2-A
counter equals zero?". If the A counter for lane 2 contains
a number, the same process steps are followed to find the
. vehicle velocity represented by tha number in the counter, and
to increment the category register which fits. Following the
incrementing of a velocity register for lane 2, the program
reaches a decision point where the question is asked "display
mode selected?"O This is included to demonstrate that the
recorder unit functions, upon command from the reader instrument,
to enter and execute a display mode seauence without interruption
of the normal reco~ding function. Thus, if upon reader command
the answer is "yes", the accumulated count in the A registers
in both lanes 1 and 2 will be displayed, and the program will
then continue on to the length determination and classification
~teps flaw charted on Fig. 9D. Thus, as indicated on Fig. 9D,
the auestion is asked "lane l-A counter equals zero?". If
~he A counter ~or lane 1 contains a number, the step is executed
of divlding the number in the lane l-A counter by 16, tha
distance between the leading edge of detector ~1 and the leading
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~9~5~5
edge of detector #2, in order to provide a number "X"
representing velocity. The next steps involves the calculation
of dividing the number in lane l-B counter by the number X,
the result of that calculation being the length of the vehicle.
The next s-tep is to find the length category and thereafter to
increment the length category register which fits. As desired,
the length category registers may be solely for truc~s and
cars, or may include various categories for different length
trucks, etc.
~urning to Fig. 9D, a similar sequence of steps to
derive length data and classifica~ion in categories is carried
, out for lane 2. Thus, the lane 2-A counter is tested and i~
. ~ .
it contains a number, the number is divided by 16 to produce an
intermediate result "X"'. Next, the number in lane 2-B counter
is divided by X' to provide vehicle length. The length category
is ~ound and the appropriate length category register
incremented, for lane 2. Again, the program illustrates that a
display mode may be selected, on command from the reader
instrument and entered to display the accumulated total in the
length categroy registers for lanes 1 and 2. It will be
observed that with the display mode entered, there will be
visually shown on the reader instrument display, the lengths of
vehicles as they pass on the highway, without interrupting the
ongoin~ recording function of the recorder unit. A~ter the
display mode sequence is completed, the program returns to the
start point on Fig. 9A.
Ref~rring to Fig. lOA, a flow chart of certain operations
o~ the reader instrument carried out under proyram control is
there illustrated. With the power turned on in the reader
instrument, the reader instrument as well as the recorder unit
39
~3~5e~
being self-powered by means of its own battery source, the keyboard matri~ is
scanned and t-he test is made whether the cable is "field mode", i.e., connectedto a recorder unit. If "yes", as earlier noted, the recorder unit operation
to process signals from detectors and record traffic data may continue without
interruption or, as shown in Fig. 10B, with the start key of the reader instru-
ment actuated, a sub-routine may be entered for displaying and altering
identification of the recorder unit as a preliminary to transferring data from
the recorder unit memory to the cassette tape in the reader instrument followed
by data transfer and recording. As also shown in Fig. 10B, with the cable
field mode and the recorder operative, using control and special function keys
on the reader instrument, various monitoring and diagnostic steps and proceduresmay be carried out such as requesting time data from the recorder unit and
displaying it on the reader instrument display device, and other like functions.One major function involves transfer of programs from semi-conductor memory
of the reader instrument to semi-conductor memory of the recorder unit. One
of the control keys, illustratively the "control 11' key of the reader instru-
ment, as indicated in Fig. 10b, when actuated causes the reader instrument CPU
to operate under program control to so transfer program data from the reader
instrument to the recorder unit.
Referring again to Fig. 10A, with the cable of the reader instrument
"output mode", the system is conditioned for transfer of recorded data from
the reader instrument cassette tape. This is carried out, as indicated
dlaera~matically iD Fig. 2, to trtnster the recorded data previously collected
-40
jk/~
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from the recorder units and recorded on th~ cassette tape of
the reader instrument, to another cassette tape, a magr.etic
disk or magnetic tape or other storage unit at a processor
center. Thus, referring to Fig. 10A, after the cassette tape
has been rewound, and with the start key depressed, and the
cable "output mode 1", transfer of the data on the cassette
tape begins with the output heading information follo~ed by
data from the cassette tape. For this purpose, the recording
device 44 of the reader instrument 24 includes, preferably,
a tape deck provided with tape engaging heads and associated
mechanism and circuitry for both recording data on the tape
stored in cassettes and reading data from the tape. Connections
through the input/output circuitry 54 are provided from the
recording device 44 to an output terminal 56 on the reader
instrument, for transmitting data read from the tape to
peripheral devices, as shown in Fig. 3.
- As indicated, the data may be transferred from the
tape directly to peripheral devices, or, as an option, the
data on the tape may be converted to a different format. For
example, the data may be converted to a format readable ~y a
computer by means of the reader instrument CPU operating under
program control stored in the program storage means of the
reader inst~ument. The reformated data may be fed directly
to a computer or transferred to a magnetic disk or magnetic
tape storage device and re-recorded in the altered format.
Whether transferred in the format originally recorded Gn the
cassette tape or in an altered format, after transfer of the
data and the generation of the end of the tape code (EOT), tne
prscess exits from the data output mode and returns, as
indicated on Fig. 10A, to the start of the program cycle.
... . . . . . . .. . ..... . . . . .
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Other program checking and diagnostic sub-routines are
carried o~t under control of the keyboard, as indicated in
the flow chart on Figs. 10A and 10B.
Thus, the system of this invention provides a
recorder unit 20 and reader instrument 24 each having
programmable data processors 46, 52 (C~U's) which provide
' control means to carry out the functions o- the respective
units. Separate programs are stored in the recorder unit
memory 50 for operating the recorder unit control means 46
and in the reader instrument memory 5~ for operating the
reader instrument control means 52. The detector contacts l-l,
1-2, etc., shown in Fig. 7, may be mounted in a saparate
enclosure but are preferably mounted inside the recorder unit
case and connected to the I/O circuitry 48. Signals produced
by the detector contzcts in response to vehicle or "event"
signals from the detectors or sensors, illustratively
inductance loops in roadway lanes ~Figs. l and 3)f are
carried by the I/O circuitry 43 to the in?ut/output ports of
the recorder unit C~U 46.
, 20 ~eferring to FigsO 3 and 4A, the data processor
control means 46 of the recorder unit 20 includes an
arithmetic and logical means (ALU) for deriving data (such
as count data used in traffic surveillance) in response to
input signals received at the CPU inpu~/output ports, in
accordance with instructions of a program stored in the
memory means 50. The control means 46 and the memory means ~0
are connected for transferring instructions to the control
means 46 and for transferring derived count data to the memory
means 50. ~ reader receptacle 30 is also on the outside of the
~ec~rZer unit case for a connect cable 26 leading to the
..........
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42
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9~
reader instrument 24. The control means 46 includes mean~ ~-
for reading count data stored in the memory means 50 in
accordance witn the program of instructions in response to
read commands received from the reader instrument 24, and
for transferring count data so read to the reader receptacle 30.
The portable reader instrument 24 which is separate from the
recorder unit 20, as shown in Fig. 1, has a receptacle 5~ on
the outside for the connect cable 26.
The data processor control means 52 of the reacer
instrument 24 is effective under a program of instructions
from the memory means 53 to generate display, record and
read commands in response to selective activation of the keys
~ ,
of the keyboard 36, and for transmitting read commands over
the connect cable 26 to the recorder unit control means 46.
The reader instrument control means 46 also inc7udes means
actuated in response to record commands for operating the
recording device 4~ for re-recording on record medium (tape
stored in cassettes), count data received from the memory
means 50 of the recorder unit 20 in response to such read
commands. The control means 52 of the reader instrument
is also operabla to actuate the display 42 to display count
data in response t~ such display com~.ands.
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