[time-nuts] Paper about DCF77 performance

Daniel Engeler engeler at alumni.ethz.ch
Wed Jun 13 19:46:56 UTC 2012


This is my first post to this mailing list. I wrote a paper about the
German longwave time transmitter DCF77 which you may find interesting.
Here is the link, unfortunately I am not allowed to post the full PDF:


"Performance Analysis and Receiver Architectures of DCF77
Radio-Controlled Clocks", by Daniel Engeler
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
(May 2012)

DCF77 is a longwave radio transmitter located in Germany. Atomic
clocks generate a 77.5-kHz carrier which is amplitude- and
phase-modulated to broadcast the official time. The signal is used by
industrial and consumer radio-controlled clocks. DCF77 faces
competition from the Global Positioning System (GPS) which provides
higher accuracy time. Still, DCF77 and other longwave time services
worldwide remain popular because they allow indoor reception at lower
cost, lower power, and sufficient accuracy. Indoor longwave reception
is challenged by signal attenuation and electromagnetic interference
from an increasing number of devices, particularly switched-mode power
supplies. This paper introduces new receiver architectures and
compares them with existing detectors and time decoders. Simulations
and analytical calculations characterize the performance in terms of
bit error rate and decoding probability, depending on input noise and
narrowband interference. The most promising detector with
maximum-likelihood time decoder displays the time in less than 60 s
after powerup and at a noise level of Eb/N0 = 2.7 dB, an improvement
of 20 dB over previous receivers. A field-programmable gate
array-based demonstration receiver built for the purposes of this
paper confirms the capabilities of these new algorithms. The findings
of this paper enable future high-performance DCF77 receivers and
further study of indoor longwave reception.

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