WWVB receiver modules - unavailible for years, are now carried by a couple of vendors (see below)
WWVB RECEIVER - DECODER - DISPLAY
"Receives U.S. Govt 60 KHz WWVB digital radio time standard broadcast from Ft Collins, CO"
This project combines the venerable PIC 16F628A micro, one 60 KHz WWVB time receiver and a LCD display to make a very accurate clock.
The program was written in Microchip assembly language and is open source for non commercial use.
Support for a 16x2 LCD with graphic signal quality and lock indication.
New features include internal PIC oscillator to simplify construction and a LED that follows the 60KHz data.
60KHz WWVB data is inverted format and receive enable low. PIC port A:0 is data, A:1 is enable.
The top photos provided by Steve Pocock KC0NGU showcase his clean build of this design.
Universal Solder, complete with a loopstick antenna for about $11. Univeral Solder Ebay
Another source is a UK vendor PV Electronics.
|The signal is a low frequency (60 KHz) AM, 1 baud digital transmission broadcast from Ft Collins, CO.
The carrier is modulated at two distinct amplitudes, one 10db lower in power. The high and low level pulse width ratios correspond to one of three bits: zero (0), one (1) and a frame marker. Each new 60 bit packet begins with two consecutive frame marker bits. This sequence only occurs at the beginning of the packet and is used as a synchronizer. Afterwards, a frame marker occurs every 10 seconds for the next 50 seconds before the sequence repeats.
Once synchronized, the program compares the incoming data to a valid structure pattern. If any of the frame markers are missing or out of sequence, the whole packet is rejected.
Next, the non data bits are stripped to form six bytes, each 8 bits wide, which contain all of the data to be extracted. Then the recovered data is stored in named variables that can be read and displayed to the LCD.
For more information about low frequency radio - Wiki Low Freq
Graphic screen indication of bit reception.
A LED that mirrors the receiver data output for signal optimization.
Clock timing tweak to maximize accuracy when not syncronized to the WWVB signal.
This is displayed in the lower right corner and defaults to 127 at power on.
FILE PACK (ZIPPED) contains firmware, schematic and instructions.
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This page was updated 10-17-2016