On Mon, 23 Jan 2006, John S. wrote:

Are you looking to decode the data transmissions or listen to the voice
signals. If the former it may take something more sophisticated because
you will have to feed a decoder.

I'm interested in both. From the radio perspective, I'll certainly be
happy (but not satisfied) when I am able to hear the station's audio.
However, I was thinking this would be a good project in part because it
leads to the logical extension of decoding the time signals. My plan of
attack is to first try to get the audio, then try inputting it to the
audio input of a PC and writing a program to decode the time signal, and
finally implementing some kind of microprocessor-based decoder.

Tobin Fricke
--
http://web.pas.rochester.edu/~tobin/

On Tue, 24 Jan 2006, Tim Shoppa wrote:

In principle that's a great idea, but the gotcha is that very near WWV's
10MHz frequency there are a lot of powerhouse SW broadcasters. Here on
the East Coast in the evenings, there are at least 10 SW broadcasters
each of which are 10x more powerful all within +/- 100kHz of 10MHz,
several of them within 10kHz of 10MHz.

What are these high-power shortwave stations on the east coast? I often
wonder what is "out there" these days to tune in.

Tobin

On Tue, 24 Jan 2006 17:20:35 GMT, "Michael A. Terrell"
wrote:

Joel Kolstad wrote:

"xpyttl" wrote in message
...
However, depending on where you are, you can typically only hear WWVB for a
small part of the day.

Does a bigger antenna help? Or is there just so much more background noise
than signal that it's a lost cause?

Hmm... isn't the data rate something like 1bps? Maybe they could do some
direct sequence spreading at 100Hz or so and improve the link margin a handful
of dB... :-)

If the problem is more or less random noise, what is the point of
spreading the transmit signal, since the same noise density would
appear in a specific bandwidth after despreading.

And lose the ability to be used as a frequency standard?

The GPS signal is DSSS and it can be used as a time and/or frequency
standard.

Paul

Paul Keinanen wrote:

The GPS signal is DSSS and it can be used as a time and/or frequency
standard.

So, you want everyone still using WWVB for a frequency standard to
spend wads of cash to convert?

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

From: (Mark Zenier) on Tues, Jan 24 2006 7:13 pm

xpyttl wrote:
"John S." wrote in message

Are you looking to decode the data transmissions or listen to the voice
signals. If the former it may take something more sophisticated
because you will have to feed a decoder.

Well, the 60 kHz WWVB transmissions were designed to be decoded, and there
are a fair number of projects out there to do just that. However, depending
on where you are, you can typically only hear WWVB for a small part of the
day.

For information on the WWV, WWVH, WWVB time codes and signal
strength, go to: http://tf.nist.gov/timefreq/index.html

From the coverage diagrams (every 2 hours), most of the
contiguous states of the USA get sufficient signal from
WWVB in any 24-hour period. That has been observed here
(Los Angeles County) using a 2 1/2 foot diameter loop;
distance to Ft. Collins is roughly 800 miles (?).

By actual test, my LaCrosse radio wris****ch was able to
sync on WWVB on an auto trip to Wisconsin and back over
September to October. Typically such radio watches only
begin checking/syncing after midnight local time. The
internal quartz timing oscillator remains stable (for
time indication) within one second in 24 hours.

Radio clocks are consumer electronics items that typically
cost $20 to $30 (depending on display size and extras such
as local temperator). If all that is wanted is automatic
time setting, it may not be a good return on time
investment to build one's own automatic-setting clock.
Those radio clocks aren't much good for zero-beating a
local frequency standard except: If the local standard
is counted down to 1-second pulses for comparison with
the radio clock (arduous process to check).

The same time code is in the WWV HF signals as a 100 Hz, One Baud, pulse
duration modulated subcarrier tone. If you've only got a communications
grade speaker in your receiver, you may not notice it.

There was once a KIT for a WWV time code receiver (Heathkit?).
As memory serves, it cost about $400 just for the kit! That
was in much older days before 25-cent 74LS00 chips.

The original requestor wanted a WWV receiver, presumably to
zero-beat a local crystal standard. ANY HF receiver will do
for that, but preferrably one whose S-Meter can show very
slow beats (well below 100 Hz). As another suggested, a
cheapo import SWL receiver can do that, adding only a
metering connection to the internal AGC line (for the slow
zero beat). Bandwidth of the IF is not of great importance
since the time-frequency bands are wider than the usual
cheapo receiver IF bandwidth.

In the northern Los Angeles area, I've never had a problem
picking up either WWV or WWVH on 5, 10, or 15 MHz, even with
a few feet of hook-up wire as an antenna. That's over a 42
year residence in this same house here. The time ticks are
good for checking progressive aging of local frequency
standards which are counted down to 1 second output...that
compared with the time tick in delay...and delay change (to
indicate very slow changes in the local frequency standard).

The time tick method was once the ONLY precise way to check
out local L.A. frequency standards when WWV was located
back east. That preciseness was to better than 1 part per
million.

A simple TRF arrangement tuned to 5 MHz will do the trick
for a receiver used solely for zero-beating and hearing the
voice announcements and time ticks. The interstage tuning
will be stable enough to pick up WWV or WWVH. To get 10
or 15 MHz carriers, add a mixer to the antenna input with
a local oscillator of 5 and 10 MHz. A local frequency
standard can supply that; no extra LO crystals required.
Four stages tuned to 5 MHz with Q = 100 will result in an
overall TRF/IF bandwidth of about 20 KHz, quite adequate
for WWV/WWVH.

"Tobin Fricke" wrote in message
F.Berkeley.EDU
As a project to learn more about building radio receivers, I'd like to
build a WWV receiver (or maybe a receiver for the Canadian station
CHU, since it's nearby and the format sounds easier to decode). I'm
looking for suggestions for how to design such a radio, reading
material, etc.

I was thinking it might be easier to design a fixed-frequency receiver
(rather than a tunable one) because I could just select the L and C
in the resonant circuit to give the right frequency. Or, since WWV
is at such "round number" frequencies, maybe I could somehow use a
crystal oscillator?

thank you,
Tobin

You might try and find a user manual for the old Heathkit GC-1000 Most
Accurate Clock.
It synchonizes the clock and local oscillator to the WWV transmissions
at 5, 10 or 15 MHz. The kit came with a preassembled and prealigned RF
board but you still had to assemble the data recovery and other parts of
the unit. The manual includes full schematics (including RF board) and
a good theory of operation section. The only thing missing are
instructions on aligning the RF board. The silly thing works pretty but
I had to build an antenna and install it in by attic to get it to
sychronize reliably.

--
James T. White

CHU Time Station : Western Canada Coverage Proposal

The CHU time station is Canada's domestic shortwave time signal station.
CHU existed long before the Internet and sattilite navigation systems like
(GPS, GLONASS, Gallaeo).
CHU provides most of the functionality of the US WWV & WWVB (Bolder,
Colorado) and WWVH (Kauai, Hawaii).

Problems with CHU's configuation that this proposal addresses

The 3.3µs per km of path that makes CHU's signals problamatic for users in
Western Canada. Even the NRC realizes this: "for all distant users of CHU,
the dominant source of time error comes from the radio wave path reflecting
off the ionosphere as the radio signal travels from the transmitter".
The poor quality of CHU reception in Western Canada and the Artic, North of
55º Latitude.
It is suggested that the 7335 kHz frequecny be reused, but it may be
advisable to find alternate frequences.
The CHU signal fomat may need to be tweaked so as to take into consideration
2 transmitter sites.
A new set of atomic clocks will be needed, as well as equipement to sync
them to NRC's atomic clocks. It may be possible to obtain secondhand atomic
clocks from UBC (Vancouver) or other universities in Western Canada.
This proposal could be replicated in Newfoundland using another existing CHU
frequency, as Eastern Canada has CHU coverage problems as well.
Universally upgrading CHU's Ottawa transmitters to 10 kw may not fix CHU
coverage problems in Western or Eastern Canada.
[...]

http://cbc.am/CHU.htm


As a project to learn more about building radio receivers, I'd like to
build a WWV receiver (or maybe a receiver for the Canadian station CHU,
since it's nearby and the format sounds easier to decode). I'm looking
for suggestions for how to design such a radio, reading material, etc.

I was thinking it might be easier to design a fixed-frequency receiver
(rather than a tunable one) because I could just select the L and C in the
resonant circuit to give the right frequency. Or, since WWV is at such
"round number" frequencies, maybe I could somehow use a crystal
oscillator?
--
http://web.pas.rochester.edu/~tobin/

you HAVE to use a crystal oscillator. due to the nature of the tuned
resonant circuits, mistuning can change the propagation delay of the
signal through the receiver by incredible amounts. soooo, you have to
be on frequency. i think I still have some where a schematic of such a
receiver from Popular Elactronics but it may take a while for me to
find it.
Saandy 4Z5KS


Tobin Fricke wrote:
As a project to learn more about building radio receivers, I'd like to
build a WWV receiver (or maybe a receiver for the Canadian station CHU,
since it's nearby and the format sounds easier to decode). I'm looking
for suggestions for how to design such a radio, reading material, etc.

I was thinking it might be easier to design a fixed-frequency receiver
(rather than a tunable one) because I could just select the L and C in the
resonant circuit to give the right frequency. Or, since WWV is at such
"round number" frequencies, maybe I could somehow use a crystal
oscillator?

thank you,
Tobin
--
http://web.pas.rochester.edu/~tobin/

Tobin Fricke wrote:

As a project to learn more about building radio receivers, I'd like to
build a WWV receiver (or maybe a receiver for the Canadian station CHU,
since it's nearby and the format sounds easier to decode). I'm looking
for suggestions for how to design such a radio, reading material, etc.

I was thinking it might be easier to design a fixed-frequency receiver
(rather than a tunable one) because I could just select the L and C in the
resonant circuit to give the right frequency. Or, since WWV is at such
"round number" frequencies, maybe I could somehow use a crystal
oscillator?

Tobin-

A couple other ideas:

1. Try your hand at building a crystal set! Just an antenna, a tuned
circuit, a diode and earphones. There could be more sophistication such
as using an amplified speaker and higher-Q tuned circuits.

2. Try a direct-conversion receiver. It may be just a more sophisticated
crystal set with RF preamplifier and on-frequency crystal filter. A
product detector could be included to convert to audio, but a diode
detector should work and wouldn't change the audio tone frequencies.

I considered using this direct-conversion approach to obtain an accurate
10 MHz signal. I wanted to use it to synchronize my oscilloscope so I
could adjust a counter's timebase (or vice-versa). However, I never built
it after finding a Rubidium controlled oscillator on eBay.

Fred

Fred McKenzie wrote:

Tobin Fricke wrote:

As a project to learn more about building radio receivers, I'd like to
build a WWV receiver (or maybe a receiver for the Canadian station CHU,
since it's nearby and the format sounds easier to decode). I'm looking
for suggestions for how to design such a radio, reading material, etc.

I was thinking it might be easier to design a fixed-frequency receiver
(rather than a tunable one) because I could just select the L and C in the
resonant circuit to give the right frequency. Or, since WWV is at such
"round number" frequencies, maybe I could somehow use a crystal
oscillator?

Tobin-

A couple other ideas:

1. Try your hand at building a crystal set! Just an antenna, a tuned
circuit, a diode and earphones. There could be more sophistication such
as using an amplified speaker and higher-Q tuned circuits.

2. Try a direct-conversion receiver. It may be just a more sophisticated
crystal set with RF preamplifier and on-frequency crystal filter. A
product detector could be included to convert to audio, but a diode
detector should work and wouldn't change the audio tone frequencies.

I considered using this direct-conversion approach to obtain an accurate
10 MHz signal. I wanted to use it to synchronize my oscilloscope so I
could adjust a counter's timebase (or vice-versa). However, I never built
it after finding a Rubidium controlled oscillator on eBay.

Fred

I know that there are several plans on the internet for building a radio
controlled clock. These involve building a fixed frequency rx and then
hooking it up to a clock. How feasible would it be to hook the same
circuit up to an amp and speaker instead of a clock? I suspect that the
clock radios listen in on 60khz, but it should be simple to insert a
crystal or change it to get 10Mhz. Also, you could build a radio with
three frequencies-5Mhz, 10Mhz, and 15Mhz in order to take advantage of
day vs night propagation.