W3EEE - DCF-39

DCF-39 Monitoring

The Data:

The Station

This is an attempt to provide data for the unravelling of the mysteries of transatlantic propagation at and about the amateur radio allocation at 136kHz. Fortunately (or unfortunately, if one lives close to one) there are high-power transmitters in Germany used for the control of aspects of their national power distribution network; one of these is centred on 139kHz (hence the '39' in DCF-39), conveniently adjacent to the international 136kHz amateur band. Also known, according to some sources, as DBF-39, DCF-39 uses a wide-spaced FSK format of 340Hz. The 'mark' frequency is 139.170kHz, whilst the 'space' is at 138.830kHz. Data is sent in short bursts of about a second or less in length every few seconds The 'space' frequency is therefore on essentially continuously, the data bursts seeming to be brief interruptions; they can be heard at the 'mark' as short 'chirrups'. At an estimated ERP of some 40kW, DCF-39 is regularly audible on the US east coast by skywave, and almost always visible late afternoon / evening / nighttime, on occasion during the day, using FFT-based analysers such as the excellent 'Argo', 'Spectran' or 'SpecLab' programs. As such it is a nearly ideal signal source for detection here in the wilds of Pennsylvania to characterize transatlantic propagation. An excellent reference for this station is available at DK8KW's website.

Method:

A 100ft. circumference screened, untuned, differentially current-sensed loop orientated on Europe feeeds a TS-140S transceiver (which is a better LF receiver than most HF radios), the audio output of which feeds DL4YHF's excellent 'SpecLab' program; peak amplitude data of DCF-39's 'space' frequency is recorded every minute. To allow for possible frequency drift, the measurement is taken over a bandwidth of 0.4Hz (an unwarrantedly large and conservative figure, incidentally), as are the peak amplitudes of the 'noiz' in 0.4Hz slices of spectrum spaced 7Hz above and below. The purpose of these is to lend a measure of confidence or otherwise to the 'real' data; static crashes and squirglies (unstable SMPSU radiations wandering through the passbands) are readily determined from close examination of the three data sets over a period of time.