NDBfinder

NDBfinder is the best accessory you can have for DXing NDBs after a good receiver and a good antenna.

NDBfinder allows you to use your PC and soundcard to receive, detect, identify and log NDBs (Non Directional Beacons used for maritime and aeronautical navigation), that would otherwise be too distant or faint to detect. NDBfinder exploits the fact that almost all navigation beacons send their idents are precisely regular intervals. Using a unique combination of two Fourier Transforms and a Boxcar Integrator, NDBfinder is able to superimpose many successive indents and in doing so it can retrieve signals that are buried in the noise. This makes it possible for NDB DXers to detect beacons far beyond the normal reception range.

NDBfinder Features

NDBfinder detects NDB transmissions using the sound card in your PC. You need a suitable LF/MF band radio receiver tuned to an appropriate frequency in the navigational beacon band. The program processes the audio signal from the receiver and shows you signals that are hidden in the noise.

Signal View - displays the raw audio signals on your PC screen in a diagnostic display which helps you to set up the connection and the soundcard.
Spectrum View - displays a scrolling spectrum of the received audio signal frequencies on your PC screen. You see an immediate display of the mose code identification if the beacon is received with good strength. By default the display covers 0-3kHz but other audio frequency ranges can be specified by the user.
Spectral Density display - shows the overall Spectral Density of the accumulated data. On this display, you can discover morse code identifications that are too weak to be seen on the Spectrum View.
Periodicity display - shows an analysis of any periodicities in the pattern in the chosen audio frequency. If there is a morse code identification buried in the noise at the selected audio frequency, its periodicity will be betrayed by a spike in this display.
Integrated display - shows the result of a boxcar integration of the signal at the chosen frequency and with the specified period. If the signal is processed for several minutes, huge improvements in the signal-to-noise ratio can be acheived. This can make the difference between a signal being undetectable and being easy to identify.
Beacon Identification - The program can decode and display the three-letter identification of the signal that you have detected.
Log file - The program can automatically save the identification, the audio heterodyne, and the ident period to a log file.
Playback - The program can play back the audio resulting from addition of multiple idents so that the signal can be identified aurally.
Script - The program can execute a command script to allow fully automated monitoring and surveying including control of receiver tuning.
Automatic search - The program can automatically search for significant periodicities in the analysis of signals. This considerably alleviates the burden of processing large volmes of data collected in an automated survey. Combined with receiver tuning and the script feature, this menas that fully automated data collection and analysis becomes possible.
Loran-C - As well as studying regular NDBs, NDBfinder can also detect Loran-C transmissions on 100kHz. Using synchronous integration at the unique GRI for each Loran-C chain, it is possible to detect weak, distant transmissions in the presence of stronger local signals.

Requirements to run NDBfinder

Pentium level PC running Windows with compatible sound card
An LF/MF receiver with USB, LSB or CW modes.
The receiver audio output must be connected to the Line-In connector on your PC.
For automated tuning, the receiver must be controllable via a serial com port.

Download NDBfinder

NDBfinder can be downloaded freely and comes in a self-extracting ZIP file which automatically installs itself. The file size is a modest 1.2Mb.

Download NDBfinder (version 2.9.5) Now.

Registration of NDBfinder

NDBfinder can be freely downloaded and used for 21 days. After that time it must be registered. Registration can be done swiftly and securely on-line and costs only Euro €25 (plus VAT for EU residents) for personal use. We strongly recommend that you ensure that NDBfinder performs to your satisfaction before registering.

Register NDBfinder Now.

Disclaimer

There are considerable variations in the legislation concerning radio reception in the different administrations around the world. It is your responsibility to determine whether or not your local administration permits the reception of navigational beacon signals. It is specifically forbidden to use NDBfinder for any illegal purpose whatsoever. The existence and the availability of NDBfinder is not to be construed as an incitement to commit any unlawful act. It is for use only in those states and regions where such use is permitted.

The technique that NDBfinder uses to decode the identifcation of very weak beacons assumes that the beacon transmission has a well defined period. Some beacon’s idents are not precisely repeatable, perhaps generated by mechanical means, which means that long period integration may not give the expected improvement in signal-to-noise ratio. Even in such cases, a modest number of cycles integration will significantly improve the detectability of the beacon signal. The most spectacular results are obtained on stable beacons by collecting data over several minutes. Success also assumes good frequency stability of the transmission and of the receiver so that the audio heterodyne remains constant throughout the data collection period.