Tag Archives: Interference

Ham Radio: Intruder Watch, State of the Art. Oder: Bandwacht nach dem Stand der Technik.

IntruderWatch_Workflow1

HF spectrum is precious. Each user has to obey specific rule – of ITU and his own country. For best communications, there have been assigned exclusive band for different user groups. The amateur radio bands for hams are among them.

“Intruder Watch” is to look out for stations which do have no legitimation to transmit on the frequencies they use. These signals can originate from broadcasters, bad transmitters with their fundamental on a legitimate frequency, broadcast, military (OTHR RADAR!), diplomatic …

Amateur radio with it’s relatively small transmitters and antennas is especially prone to be disturbed by intruders. SDRs, software and a specific workflow (see illustration on top of this page) offer an as easy as complete monitoring of such bands on a 24/7 base at low costs.

This paper shows how that can be done: monitoring and analyzing on a professional level.

Professionelles Monitoring spürt zuverlässig sämtliche Bandeindringlinge in Frequenzbereichen auf, wo diese nicht hingehören. Das ist, sogar auf 24/7-Basis, auch mit Amateurmitteln möglich. Das Werkzeug sind ein SDR, Software und ein spezifischer Arbeitsprozess.

Hier kannst Du das Paper auch auf Deutsch lesen, wie alles funktioniert – Schritt für Schritt.

Active Antennas, Interference by Power Supplies: A Test

PS_Original_Farnell_Straton_30MHz

If you don’t have much place, an active antenna is a fine alternative. You have to concentrate just on the signal-to-noise ratio, not so much on the S-Meter.

A recent test of some pre-production and (semi-)professional active antennas did not only had stunning results, but also draw my attention to noise coming from the switching power supplies of SDRs.

I did some investigations on both the performance of two active antenna vs. a quad loop of 20 m circumference and the noise coming from switched power supplies vs. two linear regulated power supplies. Read more