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Does anyone know if a hobbyist can pull the time from TV signals like you can with an RPi/GPS-hat/etc? I'd love to have a bedside clock that pulls from TV signa

Does anyone know if a hobbyist can pull the time from TV signals like you can with an RPi/GPS-hat/etc? I'd love to have a bedside clock that pulls from TV signal for no other reason than I didn't even know that existed until now.

berti 8y ago
A quick Google struggled to find much. I did find that DVB-T has a transport stream called "System_clock_descriptor" with identifier 0x0B [1]. [1] Pg. 22 https://freeviewnz.tv/media/1216/freeview_dtt_transmission_rules_3.pdf https://freeviewnz.tv/media/1216/freeview_dtt_transmission_r...
deleted 8y ago
[deleted]
ThinkingGuy 8y ago
The LinuxTV dvb-apps package has a utility called dvbdate that can do this. https://www.linuxtv.org/wiki/index.php/LinuxTV_dvb-apps https://www.linuxtv.org/wiki/index.php/LinuxTV_dvb-apps
kalleboo 8y ago
If you're in a country that still broadcasts Teletext[0] then it's available over analog or DVB-T. VCRs used to do this to set their clock automatically in Europe. Also, if you already have a time, you can keep it using the 50/60 Hz of the electric grid (which is specifically regulated to keep cheap alarm clocks in sync) or the TV refresh rate (which was also kept in sync deliberately for clocks in the analog days, dunno about now) [0] https://en.wikipedia.org/wiki/Teletext https://en.wikipedia.org/wiki/Teletext
ars 8y ago
See here: http://articles.latimes.com/2001/aug/23/business/fi-37278 http://articles.latimes.com/2001/aug/23/business/fi-37278 https://en.wikipedia.org/wiki/Extended_Data_Services https://en.wikipedia.org/wiki/Extended_Data_Services It's all old stuff, but you said your interested was "I didn't even know that existed until now".
16bytes 8y ago
Not TV, but this has existed for radio for a long time: https://en.wikipedia.org/wiki/Radio_clock https://en.wikipedia.org/wiki/Radio_clock So yeah, it's possible to have a clock you never have to set that's always correct just by having an antenna.

berti 8y ago

A quick Google struggled to find much. I did find that DVB-T has a transport stream called "System_clock_descriptor" with identifier 0x0B [1]. [1] Pg. 22 https://freeviewnz.tv/media/1216/freeview_dtt_transmission_rules_3.pdf https://freeviewnz.tv/media/1216/freeview_dtt_transmission_r...

deleted 8y ago

[deleted]

ThinkingGuy 8y ago

The LinuxTV dvb-apps package has a utility called dvbdate that can do this. https://www.linuxtv.org/wiki/index.php/LinuxTV_dvb-apps https://www.linuxtv.org/wiki/index.php/LinuxTV_dvb-apps

kalleboo 8y ago

If you're in a country that still broadcasts Teletext[0] then it's available over analog or DVB-T. VCRs used to do this to set their clock automatically in Europe. Also, if you already have a time, you can keep it using the 50/60 Hz of the electric grid (which is specifically regulated to keep cheap alarm clocks in sync) or the TV refresh rate (which was also kept in sync deliberately for clocks in the analog days, dunno about now) [0] https://en.wikipedia.org/wiki/Teletext https://en.wikipedia.org/wiki/Teletext

ars 8y ago

See here: http://articles.latimes.com/2001/aug/23/business/fi-37278 http://articles.latimes.com/2001/aug/23/business/fi-37278 https://en.wikipedia.org/wiki/Extended_Data_Services https://en.wikipedia.org/wiki/Extended_Data_Services It's all old stuff, but you said your interested was "I didn't even know that existed until now".

16bytes 8y ago

Not TV, but this has existed for radio for a long time: https://en.wikipedia.org/wiki/Radio_clock https://en.wikipedia.org/wiki/Radio_clock So yeah, it's possible to have a clock you never have to set that's always correct just by having an antenna.