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Doppler Systems LLC

Radio Direction Finders and Direction Finding Systems

Doppler Radio Direction Finders and Direction Finding Equipment

Vendor Appreciation

June 04, 2019

Our success here at Doppler Systems requires a team effort.  Our vendors routinely go above and beyond all our expectations of them.  They are all based in the United States (most of them in the Phoenix area) and their contribution is key to us delivering high quality radio direction finding equipment to our many customers.  So, we'd like to acknowledge them (in no particular order)

QuikTek Assembly
For nearly 10 years QuikTek assembly has been our contract manufacturer for our printing circuit board assemblies.  Adan, Natalie, Bill, and the rest of the crew consistently provide high quality assemblies from their state-of-the-art facility. 

Phoenix Metalcraft, Inc.
Phoenix Metalcraft has been supplying parts and services to us for over 20 years.  Family owned and operated, they are our go to source for all our sheet metal work and the powder coating of our antennas. provides all of our custom built cases to hold antennas, cables, and any miscellaneous items needed for our systems.  They make a wide range of products for computers and radios.

Southwest Metal Finishing
Southwest provides the hard anodizing of our antenna components.  This finish is one of the features that enables our antennas to survive the harsh environments they are sometimes exposed to.

Thermal-Vac Technolgy
We use Thermal-Vac Technology to braze and heat treat our antenna frames and biconical antennas.  They provide consistenlty high quality and on-time delivery.

ABR Industries
ABR Industries provides all our custom coaxial cable assemblies. Great prices and excellent delivery times.

Arizona Components Company
Arizona Components manufactures all our custom control cables.  Very high quality cable assemblies.

Future Hardware Technology
Future Hardware is a contract manufacturer here in Phoenix.  All of our antenna balun assemblies are manufactured by them as well as our self-test generator and yaw rate sensor boards.  They provide excellent products and are very customer responsive.

RM Garrison Machining
RMG makes the majority of our machined parts for our fixed site antennas.  They are continually upgrading their equipment and facilites to provide a good quality product as a reasonable price.


We Now Support the ICOM R8600 Receiver

May 28, 2019

We recently added support for the ICOM R8600 receiver to the DDF7001 processor.  If you are interested in using this receiver please download the firmware upgrade (v 2.35) and the latest versions of the MPT User Interface and TargetTrack software.

Let us know if you have any problems with the new software.

If there are any additional receivers you want us to support send us an email.

Partnership Change

December 22, 2018

Our founder David Cunningham has sold his share of Doppler Systems to Brenda Holmes.  Dave will continue to provide technical support and consulting.  Doug Havenhill will be responsible for the day-to-day operations of Doppler Systems.  Brenda will be responsible for development of the next generation of Doppler Systems radio direction finders.

Doppler Welcomes Brenda Holmes to Our Team

October 08, 2018

Doppler Systems is excited to announce that Brenda Holmes has joined our team.  Brenda has a MSEE from University of Arizona specializing in RF and antenna design.  She also has 14 years of electronic circuit design experience.  She will be in charge of all our circuit and antenna design activities.

Mobile Direction Finder Configurations

August 27, 2018

We sell our mobile direction finders in two different configurations: our component configuration and our packaged configuration.  The direction finding performance is identical for both configurations so why do we offer two configurations?  The answer boils down to customer needs and preferences. 

The minimal component configuration consists of a direction finding processor, an antenna summing unit, and a set of antennas.  To this complement of equipment the customer adds a narrow band FM receiver and a laptop computer.  Additionally, if the customer wants to use our TargetTrack software a our DDF7055 GPS receiver can be added.  The customer has a choice of antennas that cover 100 - 1000 MHz in three bands.  The customer can choose one or more of the bands depending on his needs.  Customers who are looking to permanently install the direction finder in a vehicle usually opt for the component solution as well as customers that prefer to design their own custom packaging arrangement.

The packaged configuration comes packaged in two Pelican cases.  One of the cases houses a chassis containing the DF processor, a receiver, a laptop power supply, and the necessary power and signal cabling.  The other Pelican case contains the antenna summing unit, the antennas, the GPS receiver, and all the necessary external cables.  The packaged system offers a nearly turnkey experience and is preferred by customers who may need to deploy the direction finder on short notice on any of a number of different vehicles.

The table below summarizes the differences in the component and packaged configurations.  For futher information call us at 480-488-9755 or e-mail us.





DDF7001 MPT DF Processor Assy




DDF7080 MPT Summer Assy




DDF706x Antenna Assy







Required to use TargetTrack software

Narrow band FM receiver




Mobile Power Distributor




Laptop Power Supply









Customer Packaging

Transit Case

Packaged System comes in two Pelican cases

Windows laptop computer



MPT User Interface and TargetTrack software provided

1Must be purchased from Doppler Systems
2 Required for DF operation. May be purchased from Doppler Systems or furnished by the customer

In-band Interference from a Nearby Transmitter

July 03, 2018

In general it is not good practice to locate a transmitter close to a direction finding antenna.  But how close is too close?  We've updated our application note on this subject.  In the application note we calculate the separation required to insure that there is no damage to the direction finder.  We also calculate the level of desense caused by nearby tranmitters and the separation required to provide optimum direction finding performance.  If you are contemplating mounting your direction finder near a transmission source and have additional questions please contact us and we would be glad to help you.

Doppler Delivers 15 Fixed Site and 7 Mobile Radio Direction Finders

February 19, 2018

Doppler Systems recently completed a build of 15 fixed site systems and 7 mobile systems for one of our customers. We thought you'd like to see some photos we took during the manufacturing and test of these system. All of the final assembly and test is performed in our Carefree, Arizona facility.


Importing Placemarks in TargetTrack

January 26, 2018

We just released version 3.2.11 of TargetTrack. When using the Great Maps facility in TargetTrack this version allows the user to import placemarks from a .gpx file. This is a standard export format for Garmin software.  To download the latest version of TargetTrack head on over to our downloads page.  Feel free to e-mail us or call us with any questions.

Direction Finding Simultaneously on Multiple Frequencies Using One Antenna

November 13, 2017

One of the often overlooked features of the Doppler DDF7000 series direction finders is the ability to direction find on several frequencies simultaneously using a single antenna.  This is most often used in a fixed site system.  All that is required is a DF processor and receiver for each frequency to be monitored and a RF splitter.  The input of RF splitter is connected to the RF output of the antenna and the output of the splitter connects to each receiver.  One DF processor acts as the master processor.  It controls the frequency band (115-250, 250-500, 500-1000 MHz) and the antenna rotational parameters.  The other processors are daisy chain connected to the master processor.  Each processor has its own IP address so it can be directly accessed by a computer through a network or via fixed assigned static IP address.  Each receiver is tuned to a separate frequency of interest and direction finding data can be simultaneously collected on all monitored frequencies.  A simple block diagram of a two frequency system is shown here, but up to 32 frequencies are supported.

If you would like more information on how to configure a system to direction find on multiple frequencies simultaneously please contact us by phone 480-488-9755 or by e-mail.

Using Doppler Direction Finders with AOR DV1 Receiver

October 26, 2017

Recently one of our customers requested that we include the AOR DV1 as a receiver option.  We are always happy to support as many receivers as we can so we gladly agreed.  Our customer sent us a DV1 and we proceeded to add the firmware to control the frequency, squelch, and volume.  Since each receiver requires a different set of calibration constants we performed our calibration routine and entered the constants.  All appeared to be well.  However, occasionally when the receiver was powered off and then back on the bearing would shift by 180 degrees.  We traced the problem down to the fact that the phase of the DV1 audio is not constant for a given received signal.  Something in the processing of the received signal causes the phase to shift.  This issue does not make the DV1 unusable with our direction finders; however, each time the receiver is turned on the user must verify the calibration.  We have reported this issue to AOR and they have indicated to us that they are working on a fix.  When that fix becomes availalble we will release firmware that will support the DV1.

In the interim if you plan on using an AOR DV1 receiver with our direction finders, please make sure you check the calibration prior to proceeding on your direction finding journey.