Update
Have received the 5.9904 MHz xtals and when put into a circuit can easily
be tuned to 5.99000 Mhz div by 100 = 59.900 Khz and creates the 100 Hz
output. I need to figure out the correct injection setting for the SA612
mixer and in general the correct and reasonable system settings.
But it
Hi
Actually stability isn’t the main problem with the progamables. The issue is
usually phase noise ad spurs. Often they use odd multi modulo divides rather
than a PLL. That gives them a low cost chip, but the output spectrum is pretty
poor. Figuring out if you have a “bad one” or not is tough
Wow. What 8 hours can do for responses.
Great comments and appreciated. A piece of the puzzle appears to have
gotten lost from the start of the process.
This down converter system. Only detects phase change. It is not intended
to be a phase locked oscillator system that replicates what the old
coding, it's only good to watch the pretty blinken lights.
Burt, K6OQK
From: Charles Steinmetz csteinm...@yandex.com
Subject: Re: [time-nuts] WWVB d-psk-r down conversion method
Paul wrote:
The goal is to remove the psk so the old phase tracking receivers can work.
Yes, I understand
The whole point of the d-psk-r is to remove the random phase shifts
caused by the new psk modulation scheme and create a signal that the
phase locking receivers could use for frequency standard purposes.
-Chuck Harris
Burt I. Weiner wrote:
Charles,
If I recall correctly, the original point of
there is an interesting side effect with that phase modulation: in case
the crystal filter is narrow enough --to use for the old AM format--
the phase change creates an additional AM modulation, if you take in
consideration that effect by the decoding the modulation, you could
recover the time
OK
Goal of teh d-psk-r is to correct the phase shift so any of the radios will
work without modification. Be it time or frequency.
However for those with just a need for time like the spectracoms, the
remodulator circuit does that job very well and has been in use for over
1.5 years.
Darn simple.
it could be that the intention was good , but there is no reliable
atomic clock and the company which promised the chip still no t
delivered any usable, as I learned from two of my clients which are in
the were business of making atomic clocks
73
Alex
On 9/23/2014 11:06 AM, Charles
Alex wrote:
The old AM format was happy with cca 200Hz bandwidth to recover the
time information, which was utilized in many professional receivers,
which used a crystal filter for 60kHz, for the PSK format the
required bandwidth is at least five times wider, so crystal filter
would be
Paul wrote:
This down converter system. Only detects phase change.
* * *
Its output flips a signal path to invert or not invert the incoming wwvb
signal that feeds the old radios.
Ahhh, you are just building a phase detector to trigger an
inverter. That's where I hadn't followed you.
Hi Alex:
Sometime in the future there will be chips that will decode the new signals (note the s on the end of that last
word). There are a number of frame times the longest one of which takes 17 minutes and is transmitted only once per
day. This format offers 23 dB modulation gain compared
Hi Brooke,
I hope that you are right with that chip, and despite the name change of
the company -- now Xtendwave -- and recovering they will deliver
something some times. I can see that with correlation and averaging
schemes the signal to noise ratio of data, perhaps constant frequency
Hi Alex:
There's not a requirement that Xtgendwave make the chip. The modulation format is published by NIST and anyone can make
a receiver.
I would hope there's some Time Nuts that would be interested in doing this rather than trying to remove the phase
modulation.
It's my understanding
OK this is shifting to an Xtendwave discussion and the magical chips.
Been trying to get some for a long time. They had some bare dies earlier
this year.
But thats a bit small for me to work on.
I don't really have any intent to use the Xtendwave chip for this project.
Maybe one day. I can see how
According to the NIST documentation there were a couple of motivations...
1. BPSK is easier to receive in high noise environments so they say.
2. The new format supports sending additional information in addition to
the time of day. The other messages are interleaved into each minute and
they
Hi
If the idea is to decode in software in order to “de-psk” with a switch, then
things are indeed easier.
My *guess* is that the loops in most WWVB systems are tolerant of noise bursts
already. If not, they would have a hard time with the normal RX environment.
There are a number of ways to
On 9/23/14, 10:11 AM, Alexander Pummer wrote:
there is an interesting side effect with that phase modulation: in case
the crystal filter is narrow enough --to use for the old AM format--
the phase change creates an additional AM modulation, if you take in
consideration that effect by the
One of the methods suggested for working with the wwvb psk is down
converting to a lower frequency. When experimenting with NAA I had built a
24 Khz receiver that down converted that signal to a 100 Hz base band.
It was a minor effort to shift it to 60 Khz by changing the LO. I liked
what I saw.
Hi
Is it really that much harder to process a 1 KHz note out of a direct
conversion receiver than it is to process a 100 Hz note?
Put another way - you already have a crystal filter in the front end of the
“radio” right? It will do a better job knocking down an “adjacent channel” 2
KHz away
Bob
You missed nothing really. 100 Hz because thats what the NAA radio used
with the tracor doubler. So when I moved it to wwvb that was the baseband
signal.
Now that said I liked the 1 second phase flips at 100 Hz delay. Dog slow
and perfectly OK to resolve the phase flip and I can use my favored
Paul wrote:
One of the methods suggested for working with the wwvb psk is down
converting to a lower frequency. When experimenting with NAA I had built a
24 Khz receiver that down converted that signal to a 100 Hz base band.
It was a minor effort to shift it to 60 Khz by changing the LO.
*
Charles
The goal is to remove the psk so the old phase tracking receivers can work.
Whats good about this as I just typed to Bob the signal is slow and easy to
work on.
From what I have seen the phase tracking receivers have a fairly long time
constant. So the fact that the phase detect and flip
Hi
Ok, well then, here’s a thought - 10 MHz divided by 164 is 60.975. Hz. 165,
166, 167 and 168 are also “close enough” to give you a reasonable tone out of
the converter. That assumes you are after a 10 MHz standard at the end of all
this. The fact that the tone frequency is something
yes Charles you are right, but you could use a trick as you derive the
LO from the high stabile oscillator which is locked to the
down-converted carrier the IF, and the loop is locked only if the IF and
the LO frequencies having the correct value, but that loop change the
feedback polarity
paulsw...@gmail.com said:
Did try lots of frequencies and divider math to come up with a simple LO
scheme for 61 or 59 KHz. Messy.
There are companies that will make a crystal or oscillator at any frequency
you want at a not silly price. Delivery is not overnight.
Beware: There are several
Paul wrote:
The goal is to remove the psk so the old phase tracking receivers can work.
Yes, I understand that. But you want them to work like they
originally did, with the disciplined oscillator in the phase tracking
receiver phase-locked to the WWVB carrier (or else you may as well
just
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