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Doppler Systems LLC

Radio Direction Finders and Direction Finding Systems

Technical Application Notes

Radio Direction Finding Basics

Title/link Date Subject
Using Doppler Systems Radio Direction Finders to GeoLocate Transmitters 11 May 2015 Tutorial on using radio direction finders to geolocate transmitters.  Examples using single mobile and newworked fixed sites and mobiles are presented.
Site Location for Optimal Triangulation 24 Oct 1998 Error contours that result when 2 to 10 direction finders are optimally located in a square coverage area.
In-band Interference from a Nearby Transmitter 30 Jun 2018 Graphs that allow the separation to be calculated between the DF array and a nearby in-band transmitter in order avoid damage and/or desensitization.
Errors Due To Side Mounting DF Antenna on a Tower 11 Apr 2016 Graphs showing the error to be expected when side mounting the DF antenna array on a tower or mast. 

DDF700 Series Radio Direction Finder

Title/link Date Subject
Accuracy of Series 7000 (MPT) DF 11 April 2012 Measured bearing accuracy of all fixed site 7000 series antennas
RF Sensitivity of Series 7000 (MPT) DF 8 July 2011 Bearing stability, and probabilities of detection and false alarms for 7000 series DFs.
Wind Loading and Stresses on the Series 7000 (MPT) Antenna Arrays.pdf 21 Nov 2011 Wind loading and stress for single and stacked 7000 series antenna with and without ice loading.
Using the DDF7001 with an CalAmp Integra Radio Modem 06 November 2014 Instructions on how to set up the Integra radio modem, the DDF7001 direction finder, and the TargetTrack software in order to network the direction finders using a radio modem network.  Instructions are given for networking the direction finder with or without computers at the slave sites.
Streaming DF Audio over an Internet Connection 17 September 2013 Instructions on how to set up your router and the direction finder software to gather bearing data and receive streaming audio from the direction finder over the Internet
A Simple Homing Direction Finder Using a DDF7001 and an Android Device 7 August 2013 Instructions on how to set up and operate a DDF7001 mobile direction finder using our new Android app available from the Google Play Store
Using the AOR AR8600 Receiver with Doppler Direction Finders 13 June 2013 Settings required to use the AOR AR8600 with our direction finders
Splitters and Preamps for Driving Multiple Receivers in Series 7000 DFs 8 June 2013 When using a single antenna and multiple DF processors to simultaneously direction find on mulitiple frequencies, in general, you are better off not to use a preamp.
Guide to Lightning Protection of Series 7000 DF Antennas 27 Mar 2013 Lightning rod placement around fixed site 7000 series antennas
Back Pressurization of DF Antennas 13 Jun 2009 How to connect a low pressure dry nitrogen supply to the DF antennas for protection in extreme environments.

DDF6000 Series Radio Direction Finder

Title/link Date Subject
Sensitivity of Series 6000-6100 Direction Finders   8 Apr 2003 Discusses the difference in the algorithms used in firmware versions 4.18 and earlier and the latest version 4.19, and it provides test data showing the sensitivity for both continuous and pulsed signals. 
Using the Digi One SP to Network Doppler Systems DDF6001s using an Ethernet   6 Feb 2004 How to use a Digi One at remote sites. This solution provides very economical remote internet connectivity for the DDF6001 fixed site direction finders.
Using a Barix Instreamer to Remotely Connect a Direction Finder via a Network Connection.pdf 18 Jan 2008 How to set up and operate a remote connection using the Barix Instreamer to provide both data and audio from remote sites.
Stress Analysis of Fixed Site Series 6000 Antennas 12 Apr 2002 Stress calculations and safety factors for our fixed site antennas and antenna stacks subject to wind and ice loading.
Remote Display for Series 6000 Direction Finder 30 May 2004 How to modify a Series 6000 direction finder to connect the 5921 remote display at J2.
Wind Loading on Fixed Site Series 6000 Antennas   4 Dec 2001 Calculates the wind loading on all of our fixed site antennas and antenna stacks.

Older Models

Title/link Date Subject
A Covert Tracking System Using the DDF5931 25 Apr 2004 Construction, calibration and operation of a tracking system based on the use of the Series 5900 Direction Finding System.
Changing Baud Rate on the DDF4003 or DDF5003   1 Oct 1995 Circuit board modification needed to make this change.
Product Identification and Compatibility of Obsolete Models 24 Nov 2011 Identify older models and compatibility of summers to processors

General Interest

Title/link Date Subject
AOR AR8600MKII RSSI Connection .pdf 10 Nov 2008 How to modify this receiver for an RSSI connection on the Accessory connector.
ICOM R10 Receiver Modification to Provide S-Meter Output.pdf 21 Apr 2001 Directions for adding RSSI output to this receiver for use with any of the Doppler direction finders. 
Assigning COM Port Numbers to the Serial Ports of a USB-to-Serial Adapter.pdf  6 May 2008 Step by step method to configure multiple com ports assigned using a USB to serial adapter.