I use txtempus with a Raspberry Pi Model B and an amplifier like the one described in issue #8, with an AM receiver antenna . My radio controlled watch is a Casio G-Shock GW-5500-1.
While playing with a fictitious time envelope (created by txtempus) and an Arduino, I notice that it doesn't seem mandatory to attenuate the carrier for any of the time services. One could simply switch it off as with MSF.
This configuration has some advantages :
- slight simplification of txtempus code
- simplification of external hardware (see below)
- more amplitude between high and low should improve the clarity of the signal in noisy environments (intuitive guesswork not based on actual measurements).
This change could be easily tested in txtempus : simply replace LOW by OFF in GetModulationForSecond function in dcf77-source.cc, jjy-source.cc and wwvb-source.cc.
The hardware described in issue #8 could still be used as is. GPIO17 is no longer used so R2 can be removed.
For more simplification T1 could be replaced by a N mosfet with gate directly connected to GPIO4. You'll then have this 3 components circuit :
The hairy 3 components circuit
As small mosfets like BS270 can handle up to 250 mA, you can design a more powerful emitter with two complementary mosfets as a NOT gate and a lower value resistor :
I successfully tested these circuits with JJY40 et DCF77 signals and reached a range of ten meters with JJY40 and the dual mosfet configuration.
G-Shock strong reception (L3)
I use txtempus with a Raspberry Pi Model B and an amplifier like the one described in issue #8, with an AM receiver antenna . My radio controlled watch is a Casio G-Shock GW-5500-1.
While playing with a fictitious time envelope (created by txtempus) and an Arduino, I notice that it doesn't seem mandatory to attenuate the carrier for any of the time services. One could simply switch it off as with MSF.
This configuration has some advantages :
This change could be easily tested in txtempus : simply replace LOW by OFF in
GetModulationForSecondfunction indcf77-source.cc,jjy-source.ccandwwvb-source.cc.The hardware described in issue #8 could still be used as is. GPIO17 is no longer used so R2 can be removed.
For more simplification T1 could be replaced by a N mosfet with gate directly connected to GPIO4. You'll then have this 3 components circuit :
The hairy 3 components circuit
As small mosfets like BS270 can handle up to 250 mA, you can design a more powerful emitter with two complementary mosfets as a NOT gate and a lower value resistor :
I successfully tested these circuits with JJY40 et DCF77 signals and reached a range of ten meters with JJY40 and the dual mosfet configuration.
G-Shock strong reception (L3)