Application note CME8000 Receiver IC Background Just as sunflowers turn their heads to catch every sunbeam, so too have a lot of countries implemented a system to get more from our sun. This system is in most countries termed Daylight Saving Time (). Governments in around 70 countries around the world have learnt to save energy and enjoy sunny summer evenings by switching our clocks an hour forward in the summer. Countries around the world Today approximately 70 countries utilize Daylight Saving Time in at least a portion of the country. While European nations have been taking advantage of the change for decades, in 1996 the European Union (EU) standardized an EU-wide "summer period." The EU version of Daylight Saving Time runs from the last Sunday in March through the last Sunday in October. implementation in other countries around the world is listed as follows: Continent Country Beginning and ending days Africa Egypt Start: Last Friday in April End: Last Thursday in September Namibia Start: First Sunday in September End: First Sunday in April Asia Most states of the former USSR. Start: Last Sunday in March End: Last Sunday in October Iraq Start: April 1 End: October 1 Israel (Estimate, Israel decides the dates every year) Start: First Friday in April End: First Friday in September Lebanon, Kirgizstan Start: Last Sunday in March End: Last Sunday in October Mongolia Stopped in 2002 Palestine (Estimate) Start: First Friday on or 15 April End: First Friday on or 15 October Syria Start: April 1 End: October 1 Iran Start: the first day of Farvardin End: the first day of Mehr Australasia Australia - South Australia, Victoria, Australian Capital Territory, New South Wales, Lord Howe Island Start: Last Sunday in October End: Last Sunday in March 1 of 3
Europe North America Australia - Tasmania Start: First Sunday in October End: Last Sunday in March Fiji Stopped in 2000 New Zealand, Chatham Tonga European Union UK Russia United s, Canada, Mexico St. Johns, Bahamas, Turks and Caicos Start: First Sunday in October End: Third Sunday in March Start: First Sunday in November End: Last Sunday in January Start: Last Sunday in March at 1 am UTC End: Last Sunday in October at 1 am UTC Start: Last Sunday in March at 2 am local End: Last Sunday in October at 2 am local Start: First Sunday in April End: Last Sunday in October Cuba Start: April 1 End: Last Sunday in October Greenland Same as EU South America Brazil (rules vary quite a bit from year to year). Also, equatorial Brazil does not observe. Chile Start: First Sunday in November End: Third Sunday in February Start: Second Saturday of October - at midnight End: Second Saturday of March - at midnight Falklands Start: First Sunday on or 8 September End: First Sunday on or 6 April Paraguay Start: First Sunday in September End: First Sunday in April Irregularities The state of Indiana in the is one of three U.S. states which do not switch from "standard" to "daylight saving" or change from daylight to standard six months later. Arizona and Hawaii are the others. By Law, most of Indiana is on Eastern Standard Time (EST) all year long. There are also other countries around the world that do not observe the system. For example, China does not following switchover in any part of the country at all. 2 of 8
and radio controlled signal Radio controlled signal is now officially provided in 5 countries of the world, namely:, Germany, Switzerland, Great Britain and Japan. Radio controlled signals provide data (including hour, minute, date, day of the week, year) accurate to the millionth of a second, as well as -related information including changeover, leap seconds and UTC correction. All these data are being transmitted every minute in 60 binary bits of information. Amongst the 5 countries that provide radio controlled signal, Japan is the only country that do not have implemented in the radio control protocol and in the country as a whole. All other protocols have bits to inform when the changeover, both from summer to winter and from winter to summer, will be implemented. An example of switchover between & is shown in the following table: Signal Year Season Date & Time XOR MASK DCF Bit 16 Bit 17 Bit 18 March 28, 00:59 0 0 1 March 28, 01:00-01:59 1 0 1 March 28, 03:00 - October 31, 01:59 0 1 0 -> October 31, 02:00-02:59 1 1 0 - October 31, 02:00 - March 27, 00:59 0 0 1 March 27, 01:00-01:59 1 0 1 March 27, 03:00 - October 30, 01:59 0 1 0 -> October 30, 02:00-02:59 1 1 0 Bit 53 Bit 58 MSF March 27, 23:58 0 0 March 27, 23:59 - March 28, 00:59 1 0 March 28, 02:00 - October 31, 00:58 0 1 -> October 31, 00:59-01:59 1 1 - October 31, 01:00 - March 26, 23:58 0 0 March 26, 23:59 - March 27, 00:59 1 0 March 27, 02:00 - October 30, 00:58 0 1 -> October 30, 00:59-01:59 1 1 Bit 57 Bit 58 WWVB April 3, 23:59 0 0 (UTC) April 4, 00:00-23:59 1 0 April 5, 00:00 - October 30, 23:59 1 1 -> October 31, 00:00-23:59 0 1 - November 1, 00:00 - April 2, 23:59 0 0 April 3, 00:00-23:59 1 0 April 4, 00:00 - October 29, 23:59 1 1 -> October 30, 00:00-23:59 0 1 3 of 8
HBG Bit 16 Bit 17 Bit 18 March 27, 13:59 0 0 1 March 27, 14:00 - March 28, 01:59 1 0 1 March 28, 03:00 - October 30, 14:59 0 1 0 -> October 30, 15:00 - October 31, 02:59 1 1 0 - October 31, 02:00 - March 26, 13:59 0 0 1 March 26, 14:00 - March 27, 01:59 1 0 1 March 27, 03:00 - October 29, 14:59 0 1 0 -> October 29, 15:00 - October 30, 02:59 1 1 0 Europe and Great Britain transmits local. This means that these two transmitters (the DCF and MSF) transmits hour information with included. transmits UTC or Greenwich Mean Time. This means in the US, the user has the manually adjust to the local zone when required. Japan transmits local, but no information is implemented up to the of writing this document. Plans were being raised in the past but no schedule are officially confirmed. and CME8000 as universal radio controlled solution As observed in above tables, change is not uniform across the world. Some countries go into summer earlier that others. And apart from the norm, some areas that do receive radio controlled signal that transmits bits in fact does not follow system at all. A good example is the state of Indiana in the. CME8000 is a real universal radio control IC which switches between 3 frequencies and four country radio controlled protocols upon the program s wish. In allowing this switch in such an easy manner, the CPU gets information from the, Great Britain, Europe, and Japan even for the most active traveler. However, with such flexibility, the programmer of the piece application must also then be able to allow the user to get correct in terms of daylight saving is concern. A combination of user s and behind the scene calculation is being used in some applications to try and achieve the best. This includes, zone mechanism, mechanism, protocol recognition in CME8000. 4 of 8
Solution 1 : data reset to whenever switch zone signal and signal in Manual by user Great Britain AUTO Switch (Central AUTO Switch Japan in Effect Effect adjustment manual before by -1 hour (MSF) by -1 hour by -1 hour (JJY) Remark: Wrong hour will appear before new whenever 1. there is no change in status from one country to another country Solution 2 : data reset to whenever switch between area (Japan, (P+M+C+E), Europe(DCF+MSF)) signal and signal in Manual by user Great Britain AUTO Switch (Central AUTO Switch Japan in (MSF) (JJY) adjustment Effect manual before by +1h by +1h Effect Remark: Wrong hour will appear before new whenever 1. there is no change in status from one area to another area (that is when both Europe and are in or both in ) 5 of 8
Solution 3 : data unchanged when switch zone signal and signal in Manual by user Great Britain AUTO Switch (Central AUTO Switch Japan in (MSF) (JJY) Effect manual adjustment before by +1h Effect by +1 hour Remark: Wrong hour will appear before new whenever 1. there is change in status from one country to another country (that is is still summer when Europe is winter or vice versa) 2. Travelling in and out of Japan Solution 4: Same as solution 3 but set to instead of AUTO in Japan signal and signal in Manual by user Great Britain AUTO Switch (Central AUTO Switch Japan in adjustment Effect manual before by +1h Effect (MSF) (JJY) Remark: Wrong hour will appear before new whenever 6 of 8
1. there is change in status from one country to another country (that is is still summer when Europe is winter or vice versa) On top of all solutions above we add the following mechanism: Note: New signal means before = WWVB, new = MSF/DCF and vice versa before = JJY, new = WWVB and vice versa before = JJY, new = MSF/DCF and vice versa received signal bits in watch by user original signal received Hour made New signal bits received in watch received Hour AUTO Switch to No AUTO No AUTO Switch to No No AUTO -1 hour AUTO No Switch to +1 hour AUTO No AUTO No Switch to + 1 hour No AUTO -1 hour AUTO Switch to -1 hour No AUTO Switch to -1 hour No No AUTO No Switch to No No AUTO No Switch to No No No AUTO Unchanged AUTO No AUTO Unchanged No AUTO AUTO No Unchanged No AUTO AUTO No AUTO No This will take care of special cases like : AUTO No No AUTO -1 hour AUTO +1 hour No AUTO No 1. Indiana in the where you have to switch off data from the signal in the entire year. 2. When user travels from Australia in summer (with on) and goes back to Europe (which is winter at the same with off). 7 of 8
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