Didier Juges said the following on 10/28/2006 12:18 AM:
The clock shaper uses a commercial 10.7 MHz IF transformer, readjusted
down to 10 MHz (see schematic at
http://www.ko4bb.com/ham_radio/Manuals/2_GPS_Stuff/Clock_Shaper.jpg).
It provides light loading to the OCXO through the 390 ohm
John Ackermann N8UR wrote:
To minimize jitter and tempco, you probably ought to stay away from a
comparator if you can. I've had good success using the input circuit
from Brooks Shera's GPSDO which is a 74HC4046 PLL, but using only the
input circuit and not the PLL section itself.
John Ackermann N8UR [EMAIL PROTECTED] wrote:
Didier Juges said the following on 10/28/2006 12:18 AM:
The clock shaper uses a commercial 10.7 MHz IF transformer, readjusted
down to 10 MHz (see schematic at
http://www.ko4bb.com/ham_radio/Manuals/2_GPS_Stuff/Clock_Shaper.jpg).
It provides
Magnus Danielson wrote:
Look at the AD8561 datasheet first. The 74HC4046 is much slower than the
AD8561 and the higher output slewrate of the AD8561 is certainly good to keep
jitter down. The 74HC4046 is worse for that aspect.
What I would rather critize Didiers schematic for is the lack of
There are sudden increases in noise (bursts that last from seconds to
minutes) on the plots I posted.
I believe the sudden and drastic increase in noise at times comes from
the GPS loosing lock. At the moment, I cannot hook up the computer to
the GPS and verify, but I will do that later.
In
From: Didier Juges [EMAIL PROTECTED]
Subject: Re: [time-nuts] Allan Deviation - continuing saga...
Date: Sat, 28 Oct 2006 08:44:27 -0500
Message-ID: [EMAIL PROTECTED]
Magnus Danielson wrote:
Look at the AD8561 datasheet first. The 74HC4046 is much slower than the
AD8561 and the higher output
kd7ts wrote:
Didier Juges wrote:
There are sudden increases in noise (bursts that last from seconds to
minutes) on the plots I posted.
I believe the sudden and drastic increase in noise at times comes from
the GPS loosing lock. At the moment, I cannot hook up the computer to
the GPS
Didier Juges wrote:
Magnus Danielson wrote:
Look at the AD8561 datasheet first. The 74HC4046 is much slower than the
AD8561 and the higher output slewrate of the AD8561 is certainly good to keep
jitter down. The 74HC4046 is worse for that aspect.
What I would rather critize Didiers
kd7ts wrote:
Didier Juges wrote:
There are sudden increases in noise (bursts that last from seconds to
minutes) on the plots I posted.
I believe the sudden and drastic increase in noise at times comes from
the GPS loosing lock. At the moment, I cannot hook up the computer to
the GPS
Most timing receivers I've worked with usually mask out anything below about
10 - 15 degrees. Minimises multi-path and tropo effects.
Seem to remember having to tweak a Datum unit several years ago on an
installation due to a large metal cooling tower at 20+ degrees above our
antenna site.
Rob
My DSL-modem will buffer several hundreds of milliseconds while doing
heavy down/up-loading. Hence do NOT fill any of the pipes between you and
the ntp server. Even though you probably control only one hop and the
later routers are probably not buffering as much as my DSL-modem.
Here is a start
From: Dr Bruce Griffiths [EMAIL PROTECTED]
Subject: Re: [time-nuts] Allan Deviation - continuing saga...
Date: Sun, 29 Oct 2006 10:35:44 +1300
Message-ID: [EMAIL PROTECTED]
Good Morning Bruce!
Comparators are fine with a good layout.
As you sharpen up the rise-times, layout becomes more and
Eric Haskell wrote:
I purchased this item to ebay to play with the YIG. Can anyone help with
proper voltages to apply to this unit and which pins they go to?
Eric Haskell
KC4YOE
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Didier Juges wrote:
Dr Bruce Griffiths wrote:
Good timing antennas have built in ceramic or equivalent bandpass
filters to minimise the effect of interference.
A patch antenna is not as satisfactory as a quadrifilar helix or a choke
ring ground plane antenna for accurate timing
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Good timing antennas have built in ceramic or equivalent bandpass
filters to minimise the effect of interference.
A patch antenna is not as satisfactory as a quadrifilar helix or a choke
ring ground plane antenna for accurate timing
Greetings to all,
Yes, it is me, Bert, VE2ZAZ. I guess you know who I am by now
An amateur radio acquaintance forwarded one thread of this forum to me today. I
appreciate the constructive comments from those who understand the objectives
met by my GPS-derived standard design. I almost fell
Didier Juges wrote:
That's the impression I am getting. I do not know if any of the GPSDO
that I have seen described in recent literature take care of this properly.
It seems when the GPS goes nuts, the 1 PPS goes quite a bit out of
normal range, so it should not take too much
Dr Bruce Griffiths wrote:
Didier
Alternative GPSDO solution
Divide the 10MHz reference by 32 resync the output to 10MHz with a fast
D flipflop and then divide the D flipflop output by 4 using a 2 bit
switchtail ring (Johnson) counter.
Low pass filter the outputs of both divide by 4
I moved the GPS antenna as high as I could in the shack (instead of on a
shelf at eye level) and it seems to have significantly improved the signal.
Here is the latest plot of the HP10811 against the GPS, unlocked.
http://www.ko4bb.com/Test_Equipment/HP10811-GPS-10-29.png
(sorry the screen
Stumbled on the Rocky Horror Show, which seems to have become timeless.
The song Let's do the time warp again seems appropriate for the USA
time-change Sunday. It's just a jump to the left, put your hands on your
hips, do the pelvic thrust, let's do the time warp again. Something about
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