Call Search

New to Ham Radio?
My Profile

Friends Remembered
Survey Question

DX Cluster Spots

Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
Author Topic: HF Sky Wave Radiolocation/RDF  (Read 11841 times)

Posts: 67

« on: August 16, 2017, 12:49:25 PM »

Reading Witvleit's paper on NVIS got me interested in HF radiolocation methodologies, particularly in a military context.

Anybody with experience in radiolocation of HF sky wave transmitters who would care to comment on the ins-and-outs? My impression is that it is difficult to precisely geo locate an HF transmitter solely through the use of sky wave single site location collectors. Also, it seems that E layer propagation can add quite a bit of ambivalence.

Posts: 1492

« Reply #1 on: August 26, 2017, 07:04:19 PM »

There are a number of Direction finding algorithms that very very accurate.  They can easily  identify your transmitter location to the house in the street from a long way  away.

This direction finding method is called super resolution. They all use standard DSP algorithms thats available in the public domain. The 2 most popular are MUSIC and ESPRIT. They are technically cable of 0.1 degree resolution on the azimuth.

The most  advanced of these DSP based direction find systems can also resolve a transmitters location using a single direction finding station. This method is called Single Sight Location. Its what most regulatory agencies like the FCC uses. Its more powerful when cross referenced to a number of DF stations. Its so accurate that these days most  use a single direction finding location. Stupid hams who ham have no idea how fast and accurate these systems are. From my experience using these systems is that its easy to tell  from end of  the street a ham  is transmitter from. They are that accurate. The method is simple and the mathematics is simple. What is not so simple is the  receiver and DSP hardware. Single site location direction finding  could be done from the current generation of direct sampling receivers if someone took the time to implement the technique. All you need is access to is accurate  ionospheric height sounding data. Most DF station of a radiosonde at the DF station.

Hams  could easily run a direction finding network the could track jammers for months after they have done the jamming. The processed data can be recorded and a jammer could be  identified months later! Thats generally how many regulatory agencies work. They collect the data and process the data to identify the target offending transmitters. Even something like a whistle  or microphone click is long enough for DSP direction finding algorithms.  Companies like R&S have plenty information on their web pages  about this everyday hardware. These days super resolution is old hat!  The many stupid hams have no idea how powerful these new generation of direction finders are. If they knew they would not be causing interference!
Pages: [1]   Go Up
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!