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WWVB time code signals

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Junior Member level 2
Sep 23, 2006
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Tallahassee, FL
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wwvb chip

I have been looking at using WWVB as a time stamp for data gathering. A company called C-MAX has a chip called CME8000 that receives the WWVB or the other time signals around the world and outputs a data ready, data and clock signal. This can be read by a MCU or PC. They also have a board level product the CMMC-8 which combines the CME8000, RTC and a MCU. This device uses CRC16 CCITT error codes for command and response. Why I do not know since these are not sent out by WWVB .

Is anyone interested in a project like this or has anyone already done so.

c-max wwvb is the web site of the US government ministry which is in charge of the transmitter. It contains detailed information of the modulation format and time code format.

If you only want to decode this signal, a PIC microcontroller would suit your needs.

I know that the CME8000 can be read with a PIC processor and in fact I have done a preliminary design. That isn't what I was asking. I was asking how much interest there is in such a project. Non the less, I will proceed with the design.

For anyone who wants to do a one up design the CMMC-8 could be used since it reduces the problem to a RS232 interface. I will probably use that first to see what the receiving problems are. The C-MAX has a PC program that will interface the CMMC-8 and display the time and data on the monitor. They, however, give no source code. To connect it to the PC you will need to use a MAX232A to generate the proper RS232 voltages. Also, the CMMC-8 does not come with the antenna. The C-MAX devices can be purchased from Digikey in the USA.

The CMMC-8 is a new product, will not be available until Dec, 07 and replaces the older product CME8000-BUS-LP-01. If the pricing stays the same it will be $30. has the datasheets.

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