# MSF/DCF/RBU Time Station Receiver Implementation **URL:** \ **Category:** GNU Radio\ **Created:** [May 15, 2014, 9:26pm UTC](https://www.ruby-forum.com/t/msf-dcf-rbu-time-station-receiver-implementation/241167 "2014-05-15T21:26:47Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [May 15, 2014, 9:26pm UTC](https://www.ruby-forum.com/t/msf-dcf-rbu-time-station-receiver-implementation/241167/1 "2014-05-15T21:26:47Z")
Hi Everyone, In recent days I had the idea to plug my LF preamp and antenna into my 192k Soundcard. Even with Nyquist being his usual pain, that still gives me DC to 96kHz. Perfect for certain time stations 🙂 I lashed up a linear receiver, put it on 59kHz, and what do I hear ? “pip pip pip” from MSF. Switch to 76.5kHz, and hear DCF’s simpler 100ms and 200ms “pip pip pip”. Thought I’d get adventurous and tried 66.666k, and I hear pips again (not quite the same, more of this later) I lashed up a quick Goertzel filter at 250Hz, and re-tuned so I was 250Hz off from MSF. Hacked up some code to actually decode the output of GRC to the timecode bits for MSF. It decodes perfectly, even without parity checking! DCF, I haven’t quite got around to that bit yet, but it was detecting the 100mS and 200mS very well, despite the periodic (relatively) wide band noise that was around last night. In case anyone is interested, the flow graphs are located at [http://hal.g7iii.net/GRC/Radio\_Clocks/](http://hal.g7iii.net/GRC/Radio_Clocks/) They are in .grc format, and .png Feel free to use them, however be aware as well as device changes, you will probably have to fiddle with the threshold and squelch levels, but they might be a useful starting point for anyone wanting to do a WWV/WWVB/JJY/BPM decoder. Now, RBU, There’s a thing. It is a little more complex, as rather than just a carrier, it uses two tones. Only each 100mS is divided, and there are periods of time with an unmodulated carrier, and even no carrier at all within each 100mS period. The gory details are located at > **[RBU (radio station)](https://en.wikipedia.org/wiki/RBU_%28radio_station%29)** > > RBU is a time code radio station located in Moscow (.mw-parser-output .geo-default,.mw-parser-output .geo-dms,.mw-parser-output .geo-dec{display:inline}.mw-parser-output .geo-nondefault,.mw-parser-output .geo-multi-punct,.mw-parser-output .geo-inline-hidden{display:none}.mw-parser-output .longitude,.mw-parser-output .latitude{white-space:nowrap}56°44′00″N 37°39′48″E / 56.73333°N 37.66333°E / 56.73333; 37.66333 (RBU transmitter)). It transmits a continuous 10 kW time code on 66⅔ kHz. Thi RBU i... This is challenging. The best I have come up with is in the RBU flowgraphs at the same URL using the CTCSS Squelch block (incl with a Goertzel filter ahead of it), but I get missing 100mS “packets” [for want of a better term], and even some times when it thinks both the 100Hz and 312.5Hz tones are active at the same time! (This is most likely one squelch not closing before the other opens) Is this the approach other folks would take with trying to decode RBU ? Or are there other approaches that might work better ? Suggestions would be welcomed, and if anyone wants a recording of RBU to test their own code with, just holler. Iain ---
**Author:** ![Iain\_YoungS\_G7III](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/3da27b/32.png) [@Iain\_YoungS\_G7III](https://www.ruby-forum.com/u/Iain_YoungS_G7III)\ **Post date:** [May 15, 2014, 9:32pm UTC](https://www.ruby-forum.com/t/msf-dcf-rbu-time-station-receiver-implementation/241167/2 "2014-05-15T21:32:20Z")
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**Author:** ![Iain\_YoungS\_G7III](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/3da27b/32.png) [@Iain\_YoungS\_G7III](https://www.ruby-forum.com/u/Iain_YoungS_G7III)\ **Post date:** [May 15, 2014, 9:48pm UTC](https://www.ruby-forum.com/t/msf-dcf-rbu-time-station-receiver-implementation/241167/3 "2014-05-15T21:48:57Z")
On 15/05/14 20:30, Marcus L. wrote: > I worked on a WWVB receiver a few years back. Then realized that I’m in an > apparent “null” in the WWVB transmit pattern. Even > my commercial WWVB clocks cannot receive it. Sigh. Ah, that’s unfortunate, to say the least. And now they’ve gone and complicated it even further with the Phase Shift Keying stuff. I have a similar issue with BBC Radio 4 Longwave here, despite not being particularly far from the transmitter, it is def weak with me. Which reminds me. DCF, Radio 4, and TDF (France) also twiddle the phase of the signal for a more accurate timecode. I have the details of that twiddling, but am at a bit of a loss as to how I might use the PSK blocks and friends within GRC to decode them. (For me, it’s moving from the deep end of the pool where I’m very happy fiddling around, and the deep ocean, so if anyone has any suggestions on where to start that would also be appreciated.) My PSK knowledge is entirely from Amateur Radio, although I did manage to write a PSK receiver in GRC that would receive all the fldigi PSK modes, but even that was converted from someone else’s raw python flowgraph doing the same thing!) Iain ---
**Author:** ![Iain\_YoungS\_G7III](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/3da27b/32.png) [@Iain\_YoungS\_G7III](https://www.ruby-forum.com/u/Iain_YoungS_G7III)\ **Post date:** [May 16, 2014, 12:30am UTC](https://www.ruby-forum.com/t/msf-dcf-rbu-time-station-receiver-implementation/241167/4 "2014-05-16T00:30:00Z")
Iain Young, G7III wrote > I lashed up a quick Goertzel filter at 250Hz, and re-tuned so I was > 250Hz off from MSF. Hacked up some code to actually decode the > output of GRC to the timecode bits for MSF. It decodes perfectly, > even without parity checking! Thank you for the post. I was experimenting with WWVB reception also and will have to try this for NDB DX reception. What advantage does the Goertzel filter have as opposed to just using a narrow band FIR? I see you still have to specify the 250 Hz offset in the filter, so I assume it doesn’t help with detection if you drift off frequency. Thanks, Lou KD4HSO – View this message in context: [http://gnuradio.4.n7.nabble.com/MSF-DCF-RBU-Time-Station-Receiver-Implementation-tp48268p48271.html](http://gnuradio.4.n7.nabble.com/MSF-DCF-RBU-Time-Station-Receiver-Implementation-tp48268p48271.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Iain\_YoungS\_G7III](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/3da27b/32.png) [@Iain\_YoungS\_G7III](https://www.ruby-forum.com/u/Iain_YoungS_G7III)\ **Post date:** [May 16, 2014, 7:30pm UTC](https://www.ruby-forum.com/t/msf-dcf-rbu-time-station-receiver-implementation/241167/5 "2014-05-16T19:30:57Z")
Hi Lou, You Wrote: On 15/05/14 23:28, madengr wrote: > doesn’t help with detection if you drift off frequency. > I’m not actually sure what advantages if any the Goertzel has over a > narrow-band FIR, although there is a post in the archive from Marcus > suggesting 15% CPU. It was mainly an arbitrary decision on my part. I had been thinking about how to detect particular tones some time ago, and discovered the Goertzel filter. Some of the other reasons why I selected it this time were: a) I could be off frequency from DC when looking at complex waterfalls (I often write my flowgraphs in this way) I guess an extra Frequency Translating FIR filter could be used b) I could hear the signal more easily while developing c) RBU was going to need something like this, and it seemed easier to start with a single tone (carrier). Not that I’m getting much further with RBU at the moment… d) It also essentially decimates. Out of the Goertzel as shown is a 1kHz sample rate (48k/48). For the radio clocks that was more than sufficient, and meant less data needed to be stuffed down the pipe and processed at the other end. (see [http://permalink.gmane.org/gmane.comp.gnu.radio.general/7128](http://permalink.gmane.org/gmane.comp.gnu.radio.general/7128) for how it actually works) You are correct that the Goertzel filter doesn’t help you keep lock if you drift off frequency. It’s whole reason for being is to detect a particular tone. In being off frequency by the same amount the Goertzel, of course, it “sees” the carrier as the expected tone, and lights up. 73s Iain PS:and with that comment about detection if you drift off frequency, you now have me thinking if I could re-implement using some kind of PLL. Gagh, another project, but I need to find some simple examples first ---
**Author:** ![Iain\_YoungS\_G7III](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/3da27b/32.png) [@Iain\_YoungS\_G7III](https://www.ruby-forum.com/u/Iain_YoungS_G7III)\ **Post date:** [May 16, 2014, 7:39pm UTC](https://www.ruby-forum.com/t/msf-dcf-rbu-time-station-receiver-implementation/241167/6 "2014-05-16T19:39:33Z")
On 05/16/2014 01:29 PM, Iain Young, G7III wrote: > I’m not actually sure what advantages if any the Goertzel has over a > narrow-band FIR, although there is a post in the archive from Marcus > suggesting 15% CPU. > With the advances in VOLK, it would be useful to try the benchmarks > again to see which approach > is best. > – Marcus L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami.