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(19) United States US 20070286028A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2007/0286028 A1 Meltzer et al. (43) Pub. Date: Dec. 13, 2007 (54) RADIO WATCH Publication Classi?cation (76) Inventors.. David- Meltzer, Wappmger- Falls, ( 51) Int. Cl. NY (Us); Gregory Blum, G04C 11/02 (2006.01) Lagrangeville, NY (U S) (52) US. Cl. ....................................................... .. 368/47 Correspondence Address: EPSON RESEARCH AND DEVELOPMENT INC (57) ABSTRACT INTELLECTUAL PROPERTY DEPT _ _ _ _ 2580 ORCHARD PARKWAY, SUITE 225 Apparatuses, circuits, and methods for rece1vmg at least one SAN JOSE, CA 95131 radio signal in a radio controlled timing apparatus using a single timing source. The present invention advantageously (21) App1_ NO; 11/423,101 eliminates the need to provide an additional timing source to receive at least one radio signal, and therefore reduces the ( 22 ) Filed; Jun, 8 , 2006 material cost and eliminates many eng ineerin g challeng es. 210 230 i K 212 \ {-220 g _i_— Reference ‘ - X) Crystal Timing Signal 1 Real'Time Real-Time Signal L Osclllator. ‘5 g GeneratorSignal ) 2*11*l:~- 213 221 \f 214 Timing Mechanism Frequency Synthesizer Local Carrier Signal / 2B5 280 267 Radio Receiver / Time Time Setting and/or Code Decoder Correction Signal Patent Application Publication Dec. 13, 2007 Sheet 1 0f 5 US 2007/0286028 A1 mEEc.8255022 \muoohwuoowc 06mm 628mmmEF\ J ow i OIF 5533i $220 NF 6520 55:80 Patent Application Publication Dec. 13, 2007 Sheet 2 0f 5 US 2007/0286028 A1 0:51 628mmmEF\ 680mm260 o9. o: Patent Application Publication Dec. 13, 2007 Sheet 5 0f 5 US 2007/0286028 A1 mEswwwEc.6:26 _mc9wcozowtoo LI Now INN US 2007/0286028 A1 Dec. 13, 2007 RADIO WATCH coupled to a frequency divider 20 Which generates a real time signal 21. The real-time signal 21 is used to drive a FIELD OF THE INVENTION timing mechanism 30, and typically, has a frequency of one pulse per second. A loW frequency broadcast time code [0001] The present invention generally relates to the ?eld signal 41 is received by an antenna 42 and ampli?ed by an of radio controlled clocks. More speci?cally, embodiments RF ampli?er 43 to generate a modulated time code signal 44. of the present invention pertain to apparatuses, circuits, and The RF ampli?er 43 is coupled to a second quartz crystal 51 methods for receiving at least one radio signal in a radio to produce a time code signal 55. The resonance frequency controlled clock using a single reference timing source. of the second quartz crystal 51 is determined by the location and/or country in Which the radio controlled clock is speci DISCUSSION OF THE BACKGROUND ?ed to operate. For example, a unit marketed for operation [0002] A radio controlled clock is a timepiece capable of in the United States may have a second quartz crystal 51 adjusting its time by receiving and decoding a special time With a resonance frequency of 60 kHz. The time code signal code signal. The time code signal is encoded With the current 55 is received by a radio receiver/time code decoder 60 time and date and may also contain a daylight savings time Which generates a time setting and/or correction signal 61. and/or leap year indicator. The time code signal may also The timing mechanism 30, by receiving the time setting contain parity bits for ensuring accurate reception. Typically, and/or correction signal 61, may therefore be synchronized this time code signal modulates a loW frequency carrier With the broadcast time code signal 41. signal Which is transmitted by a govemment-established [0006] More recent radio controlled clocks are marketed radio station. Several governments throughout the World for operation in multiple locations and/or countries and have established one or more radio stations to broadcast therefore are able to receive multiple broadcast time code such time code signals, including: the United States’ signals on different frequencies. FIG. 2 shoWs an example of WWVB broadcasting at 60 kHz; the United Kingdom’s hoW conventional multi-channel radio controlled clocks MSF broadcasting at 60 kHz; Germany’s DCF77 broadcast may differ from conventional single-channel radio con ing at 77.5 kHz; Japan’s JJY broadcasting at both 40 kHz trolled clocks. A loW frequency broadcast time code signal (transmitting in the Fukushima prefecture) and 60 kHz 141 is received by an antenna 142 and ampli?ed by an RF (transmitting on the border of the Saga prefecture and the ampli?er 143 Which generates a modulated time code signal Fukoka prefecture); China’s BPC broadcasting at 68.5 kHz; 144. A quartz crystal matrix 150 receives the modulated time SWitzerland’s HGB broadcasting at 75 kHz; and eastern code signal 144. The quartz crystal matrix may include Russia’s RTZ broadcasting at 50 kHz. Additionally, some quartz crystals 151, 152, 153 to convert the modulated time transmitters in the LORAN-C navigation system (Which code signal 144 into the time code signal 155. For example, broadcast at 100 kHz) transmit time code signals Which are a radio controlled clock marketed for operation in the United synchronized to Coordinated Universal Time (UTC). Each States, Japan, and Germany may have one each of quartz of these radio stations modulates the carrier in substantially crystals With resonance frequencies of 60 kHz, 40 kHz, and the same manner: reduced carrier pulse Width modulation. 77.5 kHz. The sWitching matrix 154 determines Which of the HoWever, since different radio stations generally broadcast plurality of quartz crystals 151, 152, 153 are electrically time code signals on different frequencies, a radio controlled connected and is con?gured by a selectable frequency clock marketed for operation in more than one location control signal 170. HoWever, in some implementations, and/or country needs to be designed to receive time code quartz crystals 151, 152, 153 are all electrically connected signals on multiple frequencies. and thus the sWitching matrix 154 is not necessary. In such [0003] Broadcast time code signals are generated by an implementation, the radio controlled clock Will be used in modulating a carrier signal With a time code signal. Gener locations Where only one broadcast time code signal 141 is ally, the modulation is accomplished by the folloWing: a present, and thus, a valid time code signal 155 Will be carrier signal is locked to a precise oscillator (such as a generated by only one of the quartz crystals 151, 152, 153. cesium oscillator); a 60-bit time code containing at least the Similar to the conventional single channel radio controlled current time and date is generated With reference to a clock, the time code signal 155 is received by a radio national time source (such as UTC); and the carrier poWer is receiver/time code decoder 160 to produce a time setting dropped and restored at pre-determined times, depending on and/or correction signal 161. In addition to the multiple the modulated value of a speci?c time code bit. quartz crystals used in the quartz crystal matrix, the con [0004] Many radio controlled clocks contain one quartz ventional multi-channel radio controlled clock might also crystal for time keeping purposes and at least one additional have an additional quartz crystal to generate a real-time quartz crystal for demodulating the broadcast time code signal 21 as shoWn in FIG. 1. signal. The quartz crystal used for time keeping purposes is [0007] Quartz crystals are used in conventional radio time frequently divided to create a one pulse per second signal clocks because they have very high frequency stability. The Which drives a display mechanism. The frequency of the use of quartz crystals to generate a real-time signal leads to quartz crystal used for demodulating the broadcast time code timepieces Which keep very accurate time. The inherent signal correlates to the frequency of the particular radio stability of quartz crystals also increases the likelihood of station to be received. accurate demodulation of a broadcast time code signal, [0005] FIG. 1 shoWs an example of a conventional radio since, the carrier of the broadcast time code signal is locked controlled clock marketed for operation in a single location to that of a very stable cesium oscillator. HoWever, the and/or country. A ?rst quartz crystal 11 is coupled With an inclusion of multiple quartz crystals signi?cantly increases oscillator circuit 12 to provide a reference timing signal 13. the cost and size of such radio controlled clocks. A conven Typically, this ?rst quartz crystal 11 has a resonance fre tional quartz crystal radio controlled clock may contain up quency of 32768 Hz. The oscillator circuit 12 is further to N+l quartz crystals, Where N is the number of radio US 2007/0286028 A1 Dec. 13, 2007 frequencies that the quartz crystal radio controlled clock is [0015] The present invention advantageously provides an con?gured to receive. For example, a radio controlled clock economical approach to receiving at least one radio signal in Which is marketed for use in the United States, Japan, and a radio controlled clock using a single reference timing Germany may contain up to four quartz crystals. In addition source. Further, the present invention advantageously pro to the increased product cost, there are engineering and vides a novel implementation of a radio controlled clock manufacturing difficulties as Well: multiple quartz crystals Which is capable of receiving time code signals broadcast on need to ?t Within the device. Thus, using multiple quartz a plurality of frequencies. These and other advantages of the crystals in a radio controlled clock may be disadvantageous present invention Will become readily apparent from the because of increased material costs and engineering chal detailed description of preferred embodiments beloW.
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