Houston Radar PD420 User manual

PD420
FMCW Radar User Manual and Installation
Guide
K-Band FMCW Ranging Radar
Built Types: PD420
Rev 1.4.2a DRAFT, September 11 2017
Houston Radar LLC
12818 Century Drive, Stafford, TX 77477
Http://www.Houston-Radar.com
Email: [email protected]
Contact: 1-888-602-3111
Open Frame
PD420

This device complies with part 15 of the FCC Rules. Operation is subject to the following
two conditions: (1) this device may not cause harmful interference, and (2) this device
must accept any interference received, including interference that may cause undesired
operation.
Changes or modifications not expressly approved by the party responsible for compliance
could void the user's authority to operate the equipment.
Any modification or use other than specified in this manual will strictly void the
certification to operate the device.
This device carries FCC modular approval and as such is labeled with FCC ID
TIAPD420. If this label is not visible when the module is installed inside another device,
then the outside of the device into which the module is installed must also display a label
referring to the enclosed module. This exterior label can use wording such as the
following: “Contains Transmitter Module FCC ID: TIAPD420” or “Contains FCC ID:
TIAPD420.” Any similar wording that expresses the same meaning may be used.
This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide
reasonable protection against harmful interference in a residential installation. This
equipment generates, uses and can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or
television reception, which can be determined by turning the equipment off and on, the
user is encouraged to try to correct the interference by one or more of the following
measures: I) Reorient or relocate the receiving antenna. II) Increase the separation
between the equipment and receiver. III) Connect the equipment into an outlet on a
circuit different from that to which the receiver is connected. IV) Consult the dealer or an
experienced radio/TV technician for help.
This equipment complies with FCC and Industry Canada radiation exposure limits set
forth for an uncontrolled environment. This equipment should be installed and operated
with minimum distance of 20cm between the radiator and your body. This transmitter
must not be co-located or operating in conjunction with any other antenna or transmitter
not described under this FCC ID, except in accordance with FCC and Industry Canada
multi-transmitter product procedures.

Warning: PD420 radar is supplied in an open frame format with exposed antenna and
electronics and thus is a static sensitive device. Please use static precautions when
handling. Warrantydoes not cover damage caused by inadequate ESD procedures and
practices.
Note: Specifications may change without notice.
Note: Not liable for typographical errors or omissions.

Table Of Contents
INTRODUCTION............................................................................................................. 6
PRINCIPLE OF OPERATION....................................................................................... 7
FMCW RADAR................................................................................................................ 7
RADAR DETECTION ZONE................................................................................................ 7
RADAR POINTING............................................................................................................. 9
BACKGROUND CLUTTER.................................................................................................. 9
Clutter Map................................................................................................................. 9
Clutter Map Time Constant ........................................................................................ 9
Choosing a CTC value.............................................................................................. 10
OPERATING MODES ....................................................................................................... 11
Highway mode (side firing only)............................................................................... 11
Intersection mode (side or front firing) .................................................................... 11
Highway mode (front firing only)............................................................................. 11
USER CONFIGURABLE DETECTION LANES ..................................................................... 12
Lane Definition ......................................................................................................... 12
Trigger Pulse Extension............................................................................................ 12
Lane Status over RS232............................................................................................ 12
Lane Setup................................................................................................................. 12
Historical Lane Counts............................................................................................. 13
CO-LOCATED RADARS ................................................................................................... 13
RADAR RANGE RESOLUTION ......................................................................................... 13
RADAR CONFIGURATION AND DATA VARIABLES........................................................... 14
INTERNAL CLOCK .......................................................................................................... 15
INSTALLATION............................................................................................................ 15
RADAR MOUNTING ........................................................................................................ 18
Beam pattern and enclosure ..................................................................................... 18
Side firing installations............................................................................................. 18
Front firing installations........................................................................................... 18
Mounting the PD420 (38x45 deg beam angle)......................................................... 18
Mounting the PD420 (20x60deg beam angle).............Error! Bookmark not defined.
Mounting Bracket...................................................................................................... 19
Location .................................................................................................................... 19
Setback and Mounting Height................................................................................... 19
HOOKUP......................................................................................................................... 20
Power Input: ............................................................................................................. 20
Serial Connection...................................................................................................... 20
Connector Pinout...................................................................................................... 21
INITIAL SETUP................................................................................................................ 23

Selecting an Operating Mode ................................................................................... 24
Selecting Clutter Time Constant and Performing Clutter Initialization................... 24
Defining Lanes.......................................................................................................... 24
Optimal Performance Checklist................................................................................ 25
SYNCHRONIZING MULTIPLE RADARS............................................................................. 26
USING WINDOWS CONFIGURATION UTILITY .................................................. 27
PD420 Basic Application Setup................................................................................ 28
PD420 Target Verification and Lane Setup.............................................................. 29
In-Radar Lane-By-Lane Counts................................................................................ 34
Reading Historical Counts Out Of The Radar: ........................................................ 35
Real Time Occupancy Indicators (experimental) ..................................................... 15
PD420 SPECIFICATIONS............................................................................................ 36
GENERAL ....................................................................................................................... 36
APPROVALS ................................................................................................................... 36
DATA INTERFACES......................................................................................................... 36
MECHANICAL................................................................................................................. 36
APPENDIX A: USING TRIGGER OUTPUTS........................................................... 37
APPENDIX B: OPTIONAL BREAKOUT BOARD ................................................... 39
Non-Isolated Mosfet version with PWM Brightness Control. May be used with
PD420 or SS300 radars. Light Sensor and brightness control is applicable only to
the SS300 radar......................................................................................................... 39
Isolated Solid-State Relay version, AC or DC capable. May be used with PD420 or
SS300 radars............................................................................................................. 40
APPENDIX C: KEEPING TIME WITH AN EXTERNAL CLOCK BACKUP
BATTERY....................................................................................................................... 41
APPENDIX D: RECOMMENDED ENCLOSURE FOR OPEN FRAME RADARS
........................................................................................................................................... 43

Introduction
Congratulations on your purchase of the Houston Radar Ranging PD420 radar. This state
of the art 24GHz K-band microwave frequency modulated continuous wave (FMCW)
radar is specifically designed for the license free battery and solar operated presence
detection market. Unlike regular Doppler radars, FMCW radars are capable of measuring
range and detecting stationary targets.
Typical applications include multi-lane traffic counters, ground loop replacement, mid-
block detectors, vehicle activated signals and intrusion detectors.
Utilizing high performance, ultra-low power DSP (Digital Signal Processing) technology
and microwave components based on a planar patch array antenna with integrated low
power PHEMT oscillator, you will find that this high quality product meets your exacting
standards for performance and reliability.
Some of the highlights of this product include:
World’s smallest and lowest power usage ranging FMCW radar. At 0.35 Watts PD420 requires 10 to 20
times less power than competing products. Well suited for solar and battery powered installations.
Up to 250ft detection range
Simultaneously detects, tracks and reports up to six individual targets.
Six user-configurable lanes allow assignment of targets to specific lanes.
Six hardware trigger outputs can be mapped to any combination of lanes.
Unmatched range resolution down to 0.25 inch (0.63cm)
1
.
Highway and intersection optimized modes allow wide variety of applications.
Companion Windows application provides intuitive GUI to set all configuration parameters and display
real time plots of the targets, lane by lane counts and accumulated count histograms.
Firmware “boot loader” allows for field upgrading of the firmware.
100% built-in self-test for high confidence.
IO break-out board available for quick evaluation.
Built-in statistics storage memory for stand-alone lane-by-lane count gathering.
Software Development Kit (SDK) with code examples for custom application development.
Full industrial temperature range. Potted for high reliability.
FCC pre-approved with CE mark.
The PD420 is not just a “front end”, rather it is a complete radar with on-board
signal processing to determine range to multiple targets and application
algorithms to enable lane-by-lane counting and storage, presence detection,
occupancy measurement and other functionality as described below.
1
For a strong, well defined target.

Principle of Operation
FMCW Radar
PD420 FMCW radars modulate the frequency of the transmit signal in a linear fashion.
The difference between the frequencies of the local oscillator and the signal returned
from the target is proportional to the time delay between these signals and thus is
proportional to the distance to target. In case of a moving target we also take into account
Doppler shift of the return signal. PD420 utilizes double linear ramp modulation, first
increasing and then decreasing the frequency of the signal. Additional information
derived from two ramps allows the radar to measure both range to target and target
velocity.
The PD420 employs advanced target tracking technique based on a proprietary algorithm
that allows it to detect, measure and track multiple targets simultaneously. It also features
advanced “application filters” pre-configured to optimize performance for a variety of
applications. The PD420 radar may be deployed as a complete product without any
further requirements for signal processing.
For a more detailed theoretical description of the principles of FMCW radar operation
please see this article on the Internet.
Radar Detection Zone
The radar detection zone has an oval shape and is defined by the beam cone (38ºx45º for
PD420, 20ºx60º for PD420) and incident angle to the road surface. Note that the beam
does not cutoff abruptly at the boundary of the detection zone but rather gradually tapers
off. Thus weak targets near the boundaries may be missed while strong targets outside
may still get detected. The strength of the target is determined by its radar cross-section
(RCS) and depends on the target material, area, shape and incident angle of the radar
beam. Large flat metallic surfaces positioned at exactly 90 degrees to the incident radar
beam make the best targets. Examples are vehicle sides, front and rear ends. Flat metal
surfaces at angles other than perpendicular to the beam tend to reflect the radar signal
away and reduce the signal strength. Two or three metal surfaces joined at 90 degree
angle, for example a corner of a pickup truck bed create perfect reflector and usually
result in a very strong return signal.
As the radar beam diverges with distance the detection zone gets wider. This can be used
to a great advantage if you need to increase the detection area. In this case, move the
radar away from the target location. This may involve, for example, mounting the radar
on the opposite side of the road or increasing setback and/or height. This kind of a setup
is often used in a loop-replacement application for intersections.

Also note that the radar beam is wider in one direction and the fundamental operation of
the radar is not affected by the mounting orientation. This fact may be used to either
widen or narrow the detection zone in the direction that matters.
For a wider horizontal detection zone, mount the radar with the wider beam in the
horizontal direction. For a narrower horizontal detection zone, mount the radar with the
narrower beam in the horizontal direction. Please consult the installation section later in
this document to determine beam width based on mounting orientation.
Important things to remember about radar detection zone:
1. The radar beam does not end abruptly at the specified angle. Per convention, we
specify “half-power” beam angles where the power falls off to half the value from
the center of the beam. Thus it is possible for the radar to detect strong targets
outside of the oval derived from a trigonometric calculation based on the beam
angle.
2. Every target has different microwave reflective characteristics. This is
characterized by the RCS and affects how much microwave energy the target
returns back to the radar. This is one of the most important factors in reliable
detection. Simple rules of thumb are:
a. Vehicle side typically has larger cross section than vehicle front
b. Vehicle rear typically has larger cross section than vehicle front
c. Larger target is likely to have larger RCS, thus a truck will provide a
stronger return signal then a passenger car or a motorcycle.
d. Metal targets have larger cross section than non-metallic targets (like
humans, animals, plastics etc.)
e. Metal surfaces joined at a 90-degree angle create perfect reflector.
f. Perfectly flat metal surface at an angle other then 90 degrees may reflect
the radar beam away and result in a weak target.
3. In a side firing configuration as the vehicle passes in front of the radar, an incident
angle momentarily becomes 90º and results in a strong return signal. This effect
manifests in a somewhat narrower detection zone compared to what may be
expected from the beam geometry.
4. Unlike in a Doppler radar, with FMCW radar there is always a fixed internal
design limit to the maximum detection range. No matter how strong the target is,
it will not be detected beyond this limit. The maximum detection range may be
found in the specification and is different for various modes of operation.

Radar Pointing
The radar beam may be pointed across the traffic at 90º to the road or in line with traffic
into incoming or outgoing traffic. Pointing the radar at an angle substantially
different from 90º or 0º is not recommended because the signal strength is severely
reduced. The industry refers to pointing the radar at 90º as a side firing installation while
pointing the radar in line with traffic is known as a front firing installation. Consult
Operating Mode section about what types of installations are supported by current
firmware.
Background Clutter
Clutter Map
Since the radar can detect stationary targets, things like fences, road curbs, lane
separators, traffic signs and other unwanted targets need to be processed and eliminated
from the output. In order to do so the radar maintains a clutter map where it stores all
these unwanted targets. The clutter map is subtracted from the signal leaving only true
targets to report.
Clutter Map Time Constant
The radar continuously adjusts the clutter map to account for changing conditions. The
rate of the adjustment is determined by clutter time constant (CTC). CTC specifies how
long does it take for an average target to fade away into the background, e.g. become part
of the clutter map and no longer be reported as a valid target. CTC is a user
programmable value and can be set from 1 second to 28 minutes. For a fast moving
traffic CTC may be set to a lower value whereas for a stopped traffic it is appropriate to
set it to a higher value. Besides automatic continuous adjustment of the clutter map, the
user can issue a command to take and store a quick snapshot of the current clutter map
and use it as a new basis the next time the radar is turned on. Typical use cases are:
1. You may issue this command during the setup when road is clear of the vehicles
so you do not have to wait for an automatic clutter map adjustment to take place.
This is especially handy in applications where a long CTC is required. A snapshot
command temporarily overrides long CTC value and speeds up clutter map
reconstruction.
2. You want the radar to start with a “mostly good” clutter map after the power cycle
in order to reduce initial adjustment time.
The clutter map adjustment rate is asymmetric. The clutter is adjusted up slowly (targets
fade away slowly) but is adjusted down fast. This facilitates improved clutter map
maintenance in situations where traffic density is high.

Choosing a CTC value
Typically you would set the CTC value to be 5 to 10 times longer than the maximum
expected presence time of real targets. Settings the CTC to too short a value may result in
real targets fading into the background thus resulting in poor detection.
Typical CTC values are 1 to 5 minutes for highway mode if vehicles are not expected to
stop in front of the radar for extended periods of time.
Typical CTC values are 10 to 30 minutes for intersection mode where vehicles may be
expected to stop in front of the radar for a few minutes at a time.
As of firmware version 127, CTC values greater than 28 minutes are not honored and are
internally limited in the radar to 28 minutes. Future versions of the radar firmware are
expected to support CTC values of up to 6 hours to allow for incident detection where
traffic may be stopped for multiple hours at a time.
You MUST issue the “Initialize Clutter” command via the provided GUI after you
have setup the radar in the intended location.
You MUST reissue this command if you change the operating mode of the radar, as
the clutter map will be considerably different.
You MUST reissue this command after you adjust the radar pointing, height or angle
on the road.
Do NOT issue “Initialize Clutter” command on a periodic basis (e.g. every hour).
First, this is not necessary. Second, the clutter map is saved to FLASH memory that
will wear out after 10000 writes.

Operating Modes
The radar can be configured to function in different operating modes that are optimized
for various applications. Current firmware supports two pre-programmed modes:
“Highway” and “Intersection”. For the best performance an appropriate mode should be
selected by the user depending on their intended application.
Highway mode (side firing only)
To take advantage of this mode the radar must be deployed in a side firing installation so
that it looks across the road and NOT directly into incoming or receding traffic.
Highway mode is used for counting, occupancy measurements and vehicle detection at
typical city and highway traffic speeds. It can easily distinguish between closely
following individual vehicles in multiple lanes. Traffic is expected to be free flowing
most of the time. If traffic does slow down and come to an occasional stop, it is
acceptable for the radar to experience brief signal dropouts as the vehicle moves across
the detection zone.
Intersection mode (side or front firing)
Intersection mode is used for presence detection of stopped or slow moving (<14mph)
vehicles. It is optimized to continuously track targets with minimal signal dropouts as the
vehicle slowly moves through the radar detection zone or comes to a complete stop for
significant length of time.
In this mode it is acceptable to miss some of the high speed targets since they appear very
different from a stopped or slow moving traffic.
Beside side-firing installation the intersection mode may also be used in a front firing
installation where the vehicle directly approaches or recedes from the radar at a slow
speed.
Highway mode (front firing only)
This mode is expected to be supported in the future via a firmware upgrade. In this mode,
the radar may be mounted such that traffic approaches or recedes from the radar at
considerable speed and both range and speed are measured.
Contact us if you have a requirement for this mode.

User Configurable Detection Lanes
Lane Definition
A lane is a user-configurable range slot within the radar’s detection zone. When a vehicle
is present within this slot, the lane gets “activated”. Lane activations are used for
presence indication whereas vehicle tracking is used for counting. For example if a
vehicle has crossed from lane to lane it will be counted once only but both lanes will be
sequentially activated. If a lane is mapped to a hardware trigger output, the radar asserts
that trigger and keeps it asserted for as long as the vehicle remains in that lane. Multiple
lanes can be mapped to the same hardware trigger output. In this case the output will be
asserted for as long as there are vehicles in any of the mapped lanes.
Trigger Pulse Extension
Trigger output duration may be extended by programming an HT variable. HT variable
represents signal extension time in milliseconds. Typical uses are:
1. Trigger pulse extension to support slow interfaces in user equipment where the
fast target that generates a very short presence pulse would otherwise be missed.
2. Lighting actuation in security systems where it is desired to have an activation
duration that is much longer than the vehicle presence time.
Lane Status over RS232
Target presence information in each lane (lane activation status) is also available in real-
time to an attached controller via the serial port. An external controller communicates
with the radar via the Houston Radar Binary protocol. The same protocol is used to
communicate to all radars (Doppler and FMCW) produced by Houston Radar. Please
contact us for an SDK (software development kit) if you wish to utilize this feature.
Additional lane information such as counts, occupancy indicators and detection events is
available through ASCII data streaming and stored data.
Lane Setup
Typically, you would configure one or more detection lanes during initial setup. Please
note that the radar measures distance along the line of view from the radar to the target
and does not correct for the mounting height. This is usually not a problem as the
supplied configuration program accumulates and displays all detected targets as a
histogram in real time regardless of lane setup and the user may simply draws the lane
boundaries around the histogram peaks. Thus no manual calculations are required.
Once lanes are configured you may map one or more of them to a hardware output. When
the radar detects target presence within a configured lane(s), it will assert the associated
hardware output.

If you have a controller board connected to the serial port of the radar, you may also
obtain lane-by-lane target presence and other lane information in real-time.
Historical Lane Counts
As of radar firmware v124 and higher (release date May 10th 2012) the radar also counts
the number of vehicles detected in each lane during every accumulation interval.
Accumulation interval is programmed in minutes via BN variable. These counts are
stored in internal memory and may be retrieved later for analysis.
Co-located Radars
When radars are located close to each other and point in the same direction they may
interfere with each other unless their frequency sweeps are synchronized. PD420 provide
facility to synchronize two or more radars in a “single master, one or more slaves”
configuration. With this arrangement, the master initiates each sweep and slaves follow
with delayed sweeps.
As an additional benefit the sweeps will have a user defined constant time lag between
them. This fact can be put to a good use in case where an external controller is looking at
data from both radars and needs to know exact delay between measurements.
Time lag should be set to a different value in each slave. A 500 us increment from master
to slave and from slave to slave is recommended but maximum lag value should not
exceed 4000 us.
The need for synchronization should be decided on a case by case base and will depend
on radar proximity to each other and beam pointing. Please see the section Synchronizing
Multiple Radars for more information.
Radar Range Resolution
The PD420 radar features an unmatched internal range measurement resolution down to
0.25 inches (0.64cm). This is achieved by utilizing a proprietary resolution enhancement
algorithm. However, there are several factors that must be considered in order to achieve
this resolution.
1. Signal strength. Very weak targets may not be able to achieve this resolution.
Target strength of 3 ‘RSS’ bars, as shown on the GUI plot is required for the best
performance.
2. Multiple return signals from same target. A large target with a complex shape
such a vehicle has many contours and surfaces that return the radar energy back to
the radar with different signal strengths. Additionally, these contours are located
at different linear distances from the radar. All these reflections are merged
together into a single range reading for that target. As the vehicle is traveling

across the radar detection zone, these combined calculations will result in a range
reading that will vary materially more than the specified resolution of the radar.
That said, the range resolution enhancement algorithm is able to achieve
significantly better effective range measurement as compared to competing
products. In many cases as much as 5 to 10x better performance can be expected.
Radar Configuration and Data Variables
The radar firmware provides uniform access method for the configuration parameters and
generated data via internal variables. Each variable is identified by a combination of its
domain and a two letter name. Persistent variables that are preserved over reboots and
power cycles belong to domain 0 while volatile variables belong to domain 2. Each
variable stores a 16-bit value. Variables with names that begin with an upper case letter
are user settable. Variables with names that begin with a lower case letter are protected
and cannot be modified by user.
Configuration parameters are stored in persistent variables. The easiest way to configure
the radar is to use supplied Houston Radar Windows Configuration Utility. It will present
you with a set of easy to understand configuration options. Once the user makes his
selection, the Configuration Utility converts user specified options into a set of
configuration variables and stores them in the radar.
Persistent variables are written to radar FLASH memory. Do NOT update settings on a
periodic basis, e.g. every second or every minute. Only change settings when the user
needs it. The FLASH memory has a limited number of write cycles and will wear out
with excessive (>20,000) number of writes. On the other hand, setting a persistent
variable to the same value repeatedly is OK because the radar recognizes that the variable
has not changed and does not update it in FLASH.
The same mechanism as used for configuring the radar is used for retrieving some of the
measurement data. Measurement data is stored in volatile variables. For example per-lane
occupancy can be retrieved from the radar as a set of six variables.
In some case an advanced user may choose to bypass Configuration Utility and access
variables directly. Radar supports both ASCII protocol for interfacing with a human
operator and binary protocol for interfacing with a computer. ASCII command interface
can be accessed via a terminal program such as Hyperterminal and is described in
Appendix E. Binary interface requires implementation of a custom software that takes
advantage of Houston Radar binary protocol SDK. An example where this may be
desired is a situation where the radar is connected to a custom controller card that cannot
run Windows applications.

Internal Clock
The radar has a built in clock/calendar function. This is used to keep the time for time
stamping historical records saved by the Advanced In-Radar traffic statistics collection
feature.
Because the radar is potted it does not feature a built-in clock backup battery. The
power must remain on for the clock to keep time. However an external clock battery
may be connected to keep time while radar goes into low power sleep mode. See
Appendix C for more details.
Real Time Occupancy Indicators (experimental)
The radar keeps real time occupancy indicators on a lane-by-lane basis. The values are
periodically re-calculated over a user-configurable time interval specified in seconds via
the TA variable and stored in O1…O6 variables in volatile domain.
An external controller may access occupancy indicators by reading variables O1 through
O6 in the volatile domain via binary protocol (requires SDK) or ASCII protocol. You
may also configure the radar to stream this data in ASCII format on a periodic basis.
Typical application of the occupancy feature is incident detection. A sudden increase in
occupancy numbers usually indicates that the traffic is slowing down or stopping.

Streaming ASCII Data
Besides lane status streaming over binary protocol, the radar may be programed to stream
certain types of data in ASCII format on its own, without receiving any further requests
from the user. The output is produced on a periodic or event driven basis. The following
data types are supported:
Per lane counts on periodic basis. Output period in seconds is programmed by TA
configuration variable. In order to enable streaming of counts, set bit 10 in MO
variable. Clear this bit to disable count streaming.
Per lane occupancy indicators on periodic basis. Output period in seconds is
programmed by TA configuration variable. In order to enable streaming of
occupancy indicators, set bit 7 in MO variable. Clear this bit to disable occupancy
indicator streaming.
Per lane realtime detection events. Detection event is declared when the vehicle
exits from the radar’s field of view. In order to enable streaming of detection
events set bit 6 in MD variable. Clear this bit to disable detection event streaming.
Note: bits are counted from 0. Bit 7 means adding (actually OR-ing) 2^7=128 to MO
value, bit 10 means adding 2^10=1024 to MO value. For example if your current MO
value is 6, you need so set it to 6+128=134 to enable count streaming. Set it back to 6 to
disable streaming.
Make sure that you do not modify reserved bits in MO variable. They are factory
reserved and changing them may disrupt normal radar operation.
Example 1
Current MO value is 6. Let’s say we want to enable both counts and occupancy indicators
printed at 10 second intervals. Using ASCII command line interface:
1. Set TA variable to value 10
set:TA 10
OK
2. Set MO variable to value 6+2^7+2^10=1158
set:MO 1158
OK
3. Observe radar output. You will see two lines of printout every ten seconds. Line
that starts with C: contains counts per lane and line starting with O: contains
occupancy indicators per lane,.
C: 0 0 0 0 0 0
O: 0 0 0 0 0 0
Example 2
Current MD value is 0. Let’s say we want to enable detection event streaming. Using
ASCII command line interface:

1. Set MD variable to value 0+2^6=64
set:MD 64
OK
2. Observe radar output. You will see LN printouts every time the radar detects a
vehicle in lane N (N=1..6). For example, if radar first detects vehicle in lane 3 and
then another vehicle in lane 5, the printout will contain two lines and look like:
L3
L5

Radar Mounting
Beam pattern and enclosure
PD420 and PD420 radars feature asymmetric beam patterns and can be supplied in either
open frame or weatherproof version. Your intended application will determine the choice
of the case type, beam pattern and beam rotation.
Side firing installations
Typically the radars will be used in a side firing installation where the radar points across
the traffic, e.g. radar beam is at 90 degree angle to the road and covers one or more lanes.
This mode must be used to detect traffic at typical highway speeds. It may also be used
for intersection and stop bars to detect stopped or slowly moving traffic.
In this mode vehicles traveling on the road at highway speeds are detected for a short
duration of time while they are crossing the beam and their velocity is mostly tangential
(at right angle to the beam) with a negligible radial (along the beam) component.
Front firing installations
Alternatively the radar may be used in a front firing mode where it is pointed up or down
the traffic. However current versions of the radar firmware do not support front firing
modes with high speed traffic. This feature will be supported in the future via a firmware
update. Avoid installing the radar where it will see the vehicles either approaching or
receding directly at/from the radar at speeds exceeding 14 mph Targets exceeding this
limit will not be detected by the radar.
Mounting the PD420
PD420-OFD is supplied in an “open frame” format. It requires a weatherproof enclosure
before it may be used outdoors. Alternatively it may be mounted as a component in
another product that already has a weatherproof enclosure
The wider beam angle in PD420 is oriented differently from wider angle of the
PD420. Make sure the orientation of the radar matches the one specified for your
radar type. Orientation can be determined by connector location in open frame units
or “Houston Radar” text on the front face of the weatherproof units.
45

Mounting Bracket
Mounting bracket should allow for sufficient adjustment of the radar pointing angle and
height. At the very minimum some degree of adjustment for the vertical angle should be
provided. The user must perform a “boresight” check to validate that the radar beam is
pointed correctly. Adding a guide fixture to facilitate boresight check is a good idea. If
boresighting is not feasible you may choose to provide means to temporarily attach an
inexpensive USB camera for the initial setup. As a last resort you may pre-calculate the
required mounting angle and make sure that the bracket provides it.
Installation must also ensure that the radar is rigidly mounted. Support structures that are
affected by wind are not a good choice. Swaying action changes radar’s field of view and
affects the performance. Note: highway mode is less susceptible then intersection mode
due to lower sensitivity and range resolution.
Location
Places that have a lot of wall area such as tunnels and overpasses are not a good location
for the radar. Walls can bounce the radar beam and create ghost targets.
Note: when beam bounce or multi-pass propagation creates ghost targets it is sometimes
possible to adjust the radar location in such way that these ghost targets would fall
outside of the user defined lanes and thus be discarded. Supplied Windows Configuration
Utility should always be used to verify the setup.
Setback and Mounting Height
In the side fire multi-lane installation the radar must be mounted in such way that it may
see over the top of the closer vehicles. This requires it to be mounted higher than the
tallest vehicle it will encounter in a closer lane. An exception to this rule is a situation
where you are detecting only the closer lane, e.g. a turn lane. In which case the radar can
be mounted at target height and pointed horizontally.
For optimal performance, the setback must be increased with the mounting height as
suggested in the table below. Insufficient setback may result in lane misdetection for the
closer lanes.
Ln 1
Ln 2
Ln 3
Ln 4
Ln 5
Ln 6
Height
Radar pointed down between one-third
and one-half of the detection zone
Acceptable range of
pointing variation.


Hookup
Power Input:
The PD420 radar features wide operating input voltage range of 5.5V-18V. In a typical
application it may be powered from a nominal 12V DC source and will feature best in
class operational power consumption of 30mA (PD420, average). There is no other
FMCW ranging radar in the world that comes close to this ultra-low power usage.
Competing products may require up to 20 times more power.
The ultra-low operational power translates directly into a longer battery life or gives you
an option to power the unit from a smaller battery and smaller solar panel.
Note: The radar employs aggressive power saving measures that include turning off parts
of the circuit that are not being used at any particular instant. To get a measure of the true
power usage, a multimeter that has an averaging function and does not suffer from
autoranging (range hunting) during measurements must be used. Otherwise you will get
instantaneous readings that will fluctuate from 3 mA to 40 mA.
Your power supply must be capable of supplying up to 40mA of current for up to 5
seconds at startup while the radar is initializing its internal systems.
Serial Connection
The radar features a true RS232 interface that is used to output target information,
indicate lane presence, access statistics data and configure the unit. RS232
2
In intersection mode when detecting only one closest lane the setback requirement can be reduced to 4 feet (1.2 m)
PD420 with vertical angle of 45º or PD420 with vertical of 60º
Number of 12
feet (4m) lanes
Minimum Setback (ft)
Highway/Intersection
Minimum Setback (m)
Highway/Intersection
Minimum
Height (ft)
Minimum
Height (m)
12
6
1.8
4
1.2
2
10
3.0
17
5.2
3
13
4.0
17
5.2
4
15
4.6
20
6.1
5
17
5.2
21
6.4
6
20
6.1
23
7.0
Radars are equipped with a green status LED. When power is applied and
radar is taking measurements this LED is blinking to indicate normal
operation.