Doppler DF Instruments began in 1999, mostly as a "hobby" website, dealing with the topic of radio direction finding, mostly for the amateur radio community. In particular, the website described the technical principles of Doppler DFs, and also provided a complete design for such a unit. All the technical information required to allow independent construction was provided on the website, so that skilled "technical" people could make their own DF units. PC boards were also offered on the website, ( bare or assembled / tested ) for those who decided not to make their own boards "from scratch".

As the design progressed over the next few years, optional features were added to enhance its value and sophistication, and the DF eventually reached a level resembling a commercial product, more than a "hobby project". The creation of an IBM computer interface with a very popular ( and free ) display program did much to enhance its popularity and reputation. The inclusion of PDA display devices further enhanced its popularity, as well as software compatibility with pre-existing "DF network" software.

The design became fairly popular, especially in Europe where most "technical" people still develop and use their skills to build their own equipment, rather than simply buying it. At this time, dozens of DFs using the original website design are running on 5 continents out of 7. No-one in Antarctica has yet inquired. Australia almost made the list ( once ) but the sale was declined when it was determined that the DF really would not serve their desired purpose.

The "evolutionary" nature of the original design yielded a unique and powerful DF, but also one that was difficult and time-consuming to assemble. It consisted of several PC boards interconnected with hand-wired, point-to-point wiring. It was never anticipated that the original design would reach its present level of sophistication. This lack of foresight led to "afterthought engineering", and all the difficulties associated with it. By mid 2002, it was obvious that a new design was needed.

In 2003, that "second generation" design was completed, and this website presents it as a ( borderline ) "commercial" product. Dubbed with the name PicoDopp ( due to its simplicity and economy ) it still requires assembly skills by the user, and it is still intended for "technical" people, but it is a vast improvement over the original DF design. The use of a microcomputer to achieve almost all of the internal features yields a powerful yet economical design with very sophisticated features.

At this time, ( early 2011 ) more than a hundred PicoDopp DFs have been sold throughout the world, to users on all 7 continents. Most of them have been sold in North America, Europe, the Mediterranean, and Australia.

Most DF technology that is readily available consists of crude, hand-carved "hobby" DF equipment that can be constructed in a garage, or very expensive and professional DF equipment that can cost thousands of Dollars for a single unit…. there isn’t much available between these two extremes, but the PicoDopp attempts to fill that gap. It is sophisticated enough to be meaningful and useful in a world filled with computers, yet economical enough to be purchased by students, companies and government agencies that wish to investigate and "experiment" with DF technology, before committing significant resources to more ambitious DF goals.

That ( essentially ) was one of the primary goals of the PicoDopp design… to provide an economical and sophisticated DF "tool" for technical people who are not really familiar with DF technology.

It became apparent that the PicoDopp was more than a passing curiosity around 2005, and additional features were eventually added ( as optional PC boards ) to the website, to support it. The lineup of featured products was expanded to include conventional "signal strength" DFs with the introduction of the PicoPlot DF, along with the WinPlot display program for its use. An APRS transmitter ( MicroBeacon ) and an RS232 - controlled VHF reciever ( URX-1 ) were also added to the product lineup, to provide a fairly comprehensive selection of DF technologies. ( although user - assembly is still required for all of them ) Furthermore, small transmitters specifically designed for amateur radio T-hunts were added, ( MicroHunt and SquawkBox ) which have proven very popular.

In 2009, some discoveries regarding the capabilities of the ( free ) public GoogleEarth satellite - image viewing program prompted the development of a new display program for the PicoDopp DF, which plotted DF bearings on a high-quality map display, for use by mobile hunters. This was soon followed by a similar program ( DoppSite ) for base station DF sites, which allowed realtime remote viewing of ( unmanned / automatic ) DF base stations via the internet. At last, practical ( and convenient ) DF "networks" could be created by people with reasonable technical skills and means.

Almost all of the technical information about the PicoDopp is posted on various web pages, on this website. If you can’t find the information ( or don’t want to try... the website has become very large ) then general e-mail inquiries and technical questions about the PicoDopp DF can be directed to Bob Simmons. International inquiries are welcome, my e-mail address is : pelican2@silcom.com ( please note the odd spelling... )

If you would prefer to speak to me by phone, I currently ( 2018 ) have a voice mailbox where you can leave a callback number and a message, I'll call you back within a day or two. Sending an e-mail to me will accelerate that, I check e-mails far more often than I check my voice mail. ( usually every 2 hours when I'm here, which is most fo the time ) My ( U.S. ) phone number is 805-994-0618.

If you are considering a purchase, please indicate your type of DF application, and the level of your technical skills... I don’t want disappointed customers, and may actually decline a sale if I feel this DF is not suitable for your needs. If you want to proceed directly to a purchase, please click HERE.