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.