News

Partnership Change

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.

Mobile Direction Finder Configurations

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 Read more…

In-band Interference from a Nearby Transmitter

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 Read more…

Importing Placemarks in TargetTrack

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

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 Read more…

Using Doppler Direction Finders with AOR DV1 Receiver

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 possible, 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.  Read more…

Direction Finder Sensitivity

In our specifications we call out a sensitivity specification of -123 dBm.  A detailed explanation of how we define sensitivity is given in our technical application note entitled RF Sensitivity of Series 7000 (MPT) DF but I thought I would hit the high points of the application note as a way of providing an overview of what we mean by sensitivity.  Our direction finding processor allows the user to set a sensitivity threshold.  The higher Read more…

Doppler Product Design and Manufacturing

Occasionally we are asked about how we build and test our products. So, I thought I’d share a little about our design and manufacturing process. We design all our products locally using in house engineers and some outside consultants.  This includes all the schematic design, printed wiring board design and mechanical drawings of our antennas.  Additionally we develop our own firmware and our software.  During the design process we work with our vendors to insure Read more…