The VLF transmitter DHO38 is a transmitter for VLF of the German Navy near Saterland, West-Rhauderfehn, North-Germany. It is used to transmit coded orders to diving submarines of the German Navy and of Navies of other NATO-countries. DHO38 transmits since 1982 on 23.4 kHz with a power up to 800 kilowatts. DHO38 uses an umbrella aerial, which is carried from 8 steel tube masts with a height of 352.8 metres. Each pylon stands on a huge ceramic ball, which serves as an insulator for a voltage of 300 kilovolts. DHO38-Ramsloh-map The text written above is the one you'll find if you did a search on Google for DHO38. I also wonder if everyone copies from another :-).  In the last sentence they all suffer the same spelling mistake : ... a huge 'cermacic' ball... And that's about all I could find. Searching for more information I found this : DHO38 is located in North-Germany, near the town Ramsloh. DHO38_ramsloh.jpg I have found two pictures about the antennas. The picture on the left comes from the site http://www.frequencymanager.de/ and is copyrighted by Roland Prösch. The other pictures here were found on the site http://www.wikipedia.org/ and shows the antennas from different angles. The pictures are shot by Christian Brinkmann. DHO38_masts.jpgYou could try to receive this station by using the mic/line input of the soundcard of your computer. Your soundcard must be capable of sampling at 48 kHz, if 44,1 kHz is the highest sample rate , the max receive frequency is then half of it or 22.050 kHz. Connect a long wire to it and use Spectrum Lab from DL4YHF. I monitored their signal strength from sunday 27th (Easter 2005) of march till 28th of march with SpecrumLab and plotted it out on a chart. Used my vlf loop connected to the mic input of my laptop. DHO38_plot.jpgUsing the Watch List and Plotter I made the following plot. The signal drops a bit around 19:15, increases again. Another drop just before midnight. Monday morning between 9:00 and 10:00 the station went down. Most likely for maintenance. When back on the air, the signal is a bit stronger then before. Plotting the signal strength of a vlf transmitter is what some people do detect SIDs. SID stands for Sudden Ionospheric Disturbance. I'll have to collect more info on that subject later.

One Response to “German NAVY VLF transmitter DHO38”

  1. milly carli says:

    Dear Sir,
    I teach in a school where we have a loop antenna who receives the DHO signal at 23400 Hz.
    We try to detect SID events using this signal.
    I have used your material about DHO for a lesson on electromagnetic waves in my school..thanks

    best regards

    mc