Radio controlled clock
A radio controlled clock includes a main unit and interchangeable antenna modules. The main unit includes an operating circuit and contacts. The circuit has a CPU and decoders for decoding RF time signals having different carrier frequencies received by the modules. The decoders are connected to the contacts. Each module has a body connectable to main unit body, an operating circuit, and contacts connectable to the contacts of the main unit when a module is connected to the main unit. The circuit of the main body includes a receiver tuned to receive a RF time signal having a specific carrier frequency broadcast in a particular country and sends the signal received, via the contacts to a decoder, enabling the CPU to display the local time on a display.
1. A radio controlled clock comprising:
a main unit; and
at least two separate antenna modules selectively connectable to the main unit for co-operation with the main unit,
the main unit comprising
a main body,
a liquid crystal display (LCD) and a plurality of keys on the main body,
a main operating circuit housed within the main body, and
a plurality of main unit electrical contacts supported by the main body;
the main operating circuit comprising
a CPU control unit connected to the LCD for displaying time and to the keys for control, and
at least two decoders connected to the CPU control unit for decoding radio frequency time signals having different carrier frequencies and received by respective antenna modules, the decoders being connected to the main unit contacts;
each of the antenna modules comprising
a module body releasably connectable to the main body of the main unit,
a module operating circuit housed within the module body, and
a plurality of module electrical contacts supported by the module body for connection to the contacts of the main unit when the antenna module is connected to the main unit; and
the module operating circuitry comprising a receiver tuned to receive a radio frequency time signal of a specific carrier frequency broadcast in a particular country or region and to send the signal received, via the main unit and module contacts, to the respective decoder of the main unit for enabling the CPU control unit to display local time on the LCD according to the signal received.
2. The radio controlled clock as claimed in claim 1 , wherein the receivers of the at least two antenna modules are tuned to receive radio frequency time signals having different carrier frequencies selected from 77.5kHz, 60kHz and 40kHz for decoding by respective decoders of the main unit.
3. The radio controlled clock as claimed in claim 2 , including a third antenna module and wherein the main unit includes a third decoder for the third antenna module, the three receivers being tuned to receive radio frequency time signals having respective carrier frequencies of 77.5kHz, 60kHz, and 40kHz for decoding by respective decoders.
4. The radio controlled clock as claimed in claim 3 , wherein the CPU control unit includes a circuit connected to two of the main unit contacts for automatically identifying the antenna module connected to the main unit by detecting a high/low level signal at each of the two main unit contacts by the receiver of the antenna module connected to the main unit.
5. The radio controlled clock as claimed in claim 1 , wherein each antenna module includes a respective antenna connected to the corresponding receiver.
6. The radio controlled clock as claimed in claim 1 , wherein the CPU control unit includes a circuit connected to at least one of the main unit contacts for automatically identifying the antenna module connected by detecting a high/low level signal at least one main unit contact by the receiver of the antenna module connected to the main unit.
7. The radio controlled clock as claimed in claim 1 , wherein the receiver of one of the antenna modules is tuned to receive radio frequency time signals having the same carrier frequency but different data protocols, and the CPU control unit includes a circuit for prompting manual selection of an appropriate protocol on the LCD in response to the connection of the antenna module to the main unit.
8. The radio controlled clock as claimed in claim 1 , wherein the CPU control unit includes a self-counting clock circuit independently operating without an antenna module being connected to the main unit, whereby the main unit operates as a stand-alone clock.
9. The radio controlled clock as claimed in claim 1 , wherein the CPU control unit includes a thermal sensor for measuring and indicating temperature at the LCD.
10. The radio controlled clock as claimed in claim 1 , wherein the module body of each of the antenna modules includes a projecting plug for insertion into the main body of the main unit, thereby connecting the module body to the main unit main body.
11. The radio controlled clock as claimed in claim 10 , wherein one of the main unit and antenna modules includes a spring-loaded catch for engaging a part of the other through a snap action upon insertion of the plug into the main unit main body, thereby locking the main and module bodies together.
12. The radio controlled clock as claimed in claim 10 , wherein the main unit and antenna modules have substantially the same outer cross-section so that when the main and modular bodies are connected together, their adjacent peripheral surfaces substantially match and lie flush with each other.