DCF77 reception problems - Page 1
Forum section: electronics / general

author: Zbig
author_rank: Frequent Contributor
timestamp: March 11, 2016, 08:37:07 pm
content: HiI'm a bit obsessed with having my clocks show accurate time since I was a kid (sadly, it doesn't mean I grew up to be a punctual person). That's why I have used various DCF77-synchronized clocks (wristwatch included) throughout the years whenever possible. As of recently, I'm finding getting a reliable time signal reception harder and harder. Now I live 815 km from Mainflingen, at the elevation of some 50 m, give or take, and DCF77 reception in my apartment is borderline at best. I managed to find a sweet spot on one of the walls where my weather station is able to get valid DCF77 frames most of the time. As for the other wall clocks - no such luck. It could be days or weeks for them to manage receiving the transmission or they just won't get it at all. It almost feels as if the actual transmitter power has been reduced. I'm aware of the weather conditions, time of day, year, etc. all having effect on the longwave transmission but, from memory, I could swear the success rate dropped significantly in the recent years. What are your observations? Is it only me?

author: Jeroen3
author_rank: Super Contributor
timestamp: March 11, 2016, 08:50:02 pm
content: You could just have a dodgy receiver. Or a noise source. It's easy to make noise at 77Khz with todays electronics.But I remember it working awful when I tried decoding the signal myself 4 years ago. The wall clocks at the workplace seem to keep hanging in there for a while now. But at night everything is off there.

author: bktemp
author_rank: Super Contributor
timestamp: March 11, 2016, 09:01:48 pm
content: A SMPS working near 77.5kHz can block DCF77 receiption completely, even if you are near Mainflingen.Cheap self oscillating SMPSs don't have any fixed operating frequency. Depending on the load they operate at a couple of kHz up to a few 100kHz.I had this a couple of times.

author: dave_k
author_rank: Frequent Contributor
timestamp: March 12, 2016, 05:09:12 am
content: Do any designs exist to take the output of a GPS module and convert it to DCF77 .. ? That would be a neat solution.

author: kripton2035
author_rank: Super Contributor
timestamp: March 12, 2016, 08:03:52 am
content: I've got the same problem some years ago, and so was unable to get a strong dcf77 signal in my house.I began to look into NTP servers and it works finetoday with an esp8266 module at less than $3 it's even way cheaper than a dcf77 module !!!!I agree that for existing dcf77 meteo stations this is still a problem ...may be a hack with an esp8266 module outputing a corresponding dcf77 signal and connect it to the existing dcf77 module? should give it a try...edit: already been tried .. he hehttps://www.elektormagazine.com/labs/dcf77-emulator-with-esp8266

author: German_EE
author_rank: Super Contributor
timestamp: March 12, 2016, 09:09:14 am
content: There has been no reduction in power of the DCF77 signal over the last four weeks (my DCF receiver has a signal strength meter). Some work was done weekend of 13th/14th February that meant a reduction in power and I don't remember a dip in signal strength before that.You could always try an external antenna and a signal repeater. The following project is for WWVB on 60 KHz but it can easily be modified for 77.5 KHz:http://ka7oei.blogspot.de/2013/03/getting-atomic-wwvb-clocks-to-work.html

author: Zbig
author_rank: Frequent Contributor
timestamp: March 19, 2016, 03:44:03 pm
content: Quote from: bktemp on March 11, 2016, 09:01:48 pmRight, noticed that too! My Eurochron weather station couldn't sync its clock with my Lenovo laptop's PSU plugged into the nearby socket. When we're at it, it seems silly they didn't put the DCF-77 in the external sensor you already have outside of your window. Anyway, one of the clocks on one of my walls, just doesn't seem to be able to get a proper signal no matter what, even with all the potential interference sources switched off. Oh well, I guess I'll just take it off the wall and put it on the balcony for a while after the DST transitions (that'd be next Monday). This way it'll get synced at least twice a year :-) Not quite what I was after but well, what could you do.

author: Zbig
author_rank: Frequent Contributor
timestamp: March 19, 2016, 03:46:22 pm
content: Quote from: German_EE on March 12, 2016, 09:09:14 amI might actually look into that, thank you.