[time-nuts] DSP-93 Source For WWV/H

[Hal Murray]

> I wonder if anyone has taken this source and done that already.

The NTP package that comes from
   http://support.ntp.org/bin/view/Main/SoftwareDownloads
has a driver for WWV/H
  ntpd/refclock_wwvb.c

 * Audio WWV/H demodulator/decoder
 *
 * This driver synchronizes the computer time using data encoded in
 * radio transmissions from NIST time/frequency stations WWV in Boulder,
 * CO, and WWVH in Kauai, HI. Transmissions are made continuously on
 * 2.5, 5, 10 and 15 MHz from WWV and WWVH, and 20 MHz from WWV. An
 * ordinary AM shortwave receiver can be tuned manually to one of these
 * frequencies or, in the case of ICOM receivers, the receiver can be
 * tuned automatically using this program as propagation conditions
 * change throughout the weasons, both day and night.
 *
 * The driver requires an audio codec or sound card with sampling rate 8
 * kHz and mu-law companding. This is the same standard as used by the
 * telephone industry and is supported by most hardware and operating
 * systems, including Solaris, SunOS, FreeBSD, NetBSD and Linux. In this
 * implementation, only one audio driver and codec can be supported on a
 * single machine.
 *
 * The demodulation and decoding algorithms used in this driver are
 * based on those developed for the TAPR DSP93 development board and the
 * TI 320C25 digital signal processor described in: Mills, D.L. A
 * precision radio clock for WWV transmissions. Electrical Engineering
 * Report 97-8-1, University of Delaware, August 1997, 25 pp., available
 * from www.eecis.udel.edu/~mills/reports.html. The algorithms described
 * in this report have been modified somewhat to improve performance
 * under weak signal conditions and to provide an automatic station
 * identification feature.
 *
 * The ICOM code is normally compiled in the driver. It isn't used,
 * unless the mode keyword on the server configuration command specifies
 * a nonzero ICOM ID select code. The C-IV trace is turned on if the
 * debug level is greater than one.


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