Application: DCF77 Decoder
Reinhard
Posts: 489
In Western Europe, there are the so-called DCF77 - long-wave transmitter.
This post on 77KHz the exact time and date information.
A 10 Euro RF part and P1 are sufficient to decode this time information.
There are many applications using AVR's and PIC's,
but an application without interrupt is not known to me.
That's why I publish this demo.
Although an application without INT I still know:
http://sophisticatedcircuits.wordpress.com/2014/06/05/projekt-dcf77-empfanger/
cheers Reinhard ;-)
This post on 77KHz the exact time and date information.
A 10 Euro RF part and P1 are sufficient to decode this time information.
There are many applications using AVR's and PIC's,
but an application without interrupt is not known to me.
That's why I publish this demo.
Although an application without INT I still know:
http://sophisticatedcircuits.wordpress.com/2014/06/05/projekt-dcf77-empfanger/
cheers Reinhard ;-)
1024 x 600 - 104K
Comments
That is very cool. I really want to do that. What is the 10 Euro part and where does one get one?
A few years back I tried building a receiver just to try and detect any signal from DCF77. Never mind decode it. Never did get it to work. Helsinki is right on the edge of the useful range for DCF77. I have found however that DCF77 clocks do actually work in southern Finland.
What is the problem with interrupts? Can't WAITxxx on pin changes do what you want to do with an interrupts? I have to have a look at your code.
the modul is this:
http://www.conrad.de/ce/de/product/641138/?gclid=CNfPluqLr8ACFWTHtAodSicAag&insert_kz=VQ&hk=SEM&WT.srch=1&WT.mc_id=google_pla&s_kwcid=AL!222!3!48256877817!!!g!!&ef_id=U-uGiwAABPRfA-3Z:20140825185606:s
The interrupt with free is a joke.
Many of my colleagues can not imagine a real-time program without interrupt .
I'm always advertising for the propeller here in Germany.
Because the synchro-cog, the system synronized again and again.
so it is very stable.
Many applications sync only on the full hour.
the challenge is;:
bit 1 to bit 14 contains proprietary encrypted weather data.
I want to crack.
-Phil
Thanks. I have read that the Conrad modules are not so good at this distance but seeing as you have gone to the trouble to write the code I'm going to order one and try it. Luckily I have a south facing apartment with nothing much in between my balcony and DCF77 !
Err..yeah, sorry missed the joke. Still I notice you are not using WAITxxx on the pins but rather looping on the pin state. Not that it matters much but using WAIT could save a lot of power if you need a low power solution.
I just read that German master atomic clocks, that ultimately drive DCF77, are in Braunschweig. I was there last summer shopping for radars, wonderful city.
Be careful, Digikey has the CMMR-6P-60 which is for 60KHz not the CMMR-6P-77 that is for 77.5KHz as used by DCF77.
I guess the 60KHz is for the Yankee equivalent time signal.
-Phil
I use actualy the Propeller Demo Board and supply the RF - modul with VDD from Demo Board.
From RF - modul I use the non-inverted output, with a 470 Ohm Pullup Resistor.
P16 is blinking every second, by toggle-cog,
P23 indicate synchro bit found, by synchro-cog.
the genTestOut - cog is not necassary, I used it before I have the RF - Modul for test purpose.
Heater, thank you for the tip with lower power consumption. I try it.
Have you seen the link in my first post ?
There has one build a Decoder with (180) discrete Transistors ;-)))
(unfortunaly only in german language)
Do you know any other place I can get such a thing?
Yes I did see that discreet DCF77 receiver. Amazing work!
http://www.pollin.de/shop/dt/NTQ5OTgxOTk-/Bausaetze_Module/Module/DCF_Empfangsmodul_DCF1.html?utm_source=google&utm_medium=pvgl&utm_content=810054&gclid=CITLwI6lr8ACFfMZtAod-U4AXQ
OK Thanks. I'll try and order a couple of modules from there.
Now I have the urge to build a "geek" clock with 60 LEDS in a circle displaying the DCF77 time code as shown in the "wheel" diagram on that ebay page!
The telling time is then an exercise translate from BCD code ;-)
Install alarm as an ultra-bright LED dimmer,
so you can simulate a sunrise.
It is winter again.
Certainly going to need a sunrise simulator around here very soon.
I did actually have a cheap DCF77 controlled alarm clock a few years back. The first one I bought did not work at all. It was replaced with one that did work, for about 3 weeks before the display died. I still have the ferrite antenna rod and capacitor assembly out of it.
just 4.95 Euros + shipping
Turns out they only take PayPal on their web store but I deciphered enough German to figure out that if I sent an order in I would get their bank details for payment by bank transfer in return. It worked!
The DCF77 module is tiny, about 1cm square PCB + ferrite antenna, but it arrived in a huge box. "What on Earth?" I thought. Well they had included a copy of their printed catalogue. Lot's of good stuff in there. All in German of course. But they have a picture of everything. A good old world style catalogue.
Top marks for Pollin Electronics.
Now to see if I can actually get a signal out of that thing so far away from Germany here....
Erlend
My DCF77 project idea got overrun by a few other projects. I'll get back to it. Hopefully soon.
I'm sure a Prop could make a DCF77 transmitter. I think I'd want it to modulate an external RF oscillator so as not splat harmonics all over the place. Of course transmitting such a signal is illegal so better make sure it's not loud enough to be heard anywhere. Which probably means it's not very useful.
For reception in basements and so on I would put the DCF77 module on the roof and relay it down by Zigbee or even a wire.
http://obex.parallax.com/object/194
By: Thierry Eggen, ON5TE, created: 2013-04-04
I used locked to a GPS
Fantastic! Now it is becoming very tempting to do a nasty practical joke to my brother.... :cool:
Erlend
There are also better transmitter:
http://en.wikipedia.org/wiki/TDF_time_signal
Frequency: 162 kHz
Power: 2000 kW (1000 kW at night 00 - 06h)
It is located near the village of Allouis - France
Time signals are transmitted by phase-modulating
therefore thay are inaudible, what is important
because it's also super power regular AM transmitter.
It's emission power is 40-80 times DCF77.
DCF77 is sometimes [during day a summer] very
difficult to receive.
TDF162 would be very nice project for Propeller 1 Multicore.
If someone will be intrested I will send more details of
implementiations made using ATMEL microcontrollers.
Please write me pvt. e-mail.
Very interesting. Strangely I have never heard of it despite searching around for such things over the years. No. If it works and is generally interesting why not discuss it here or some other open forum?
The material is in pdf file, and I am not familiar enough in radiotechnics
to discuss details regard phase modulation by myself.
That was my point.
I hope this link will work, there is PDF article with very detailed description of TDF162 time signal decoding
with ATMEL ATMEGA series. Also general descussion about the TDF162 signal structure can be found there.
here is a public link:
{ see next posts, there is a newer version of this file ***ZWK***}
Very interesting, maybe my next project.
Thank you.