Attempting sub nanosecond timing with an actual 1Mohm source is an exercise in
futility. There are very few cases where one would want to attempt precision
timing measurements with such a high impedance source. The 1M pulldown on the
TICC input is merely intended to maintain a valid logic input
Also for interest the 53131a schematic is available at
http://bee.mif.pg.gda.pl/ciasteczkowypotwor/HP/53131.pdf
HP used a low input bias current bjt opamp, the Lt1008 to bias/dc servo a
custom JFET buffer driving an AD96687 comparator.
On Fri, Mar 31, 2017 at 10:34 PM Scott Stobbe
wrote:
> Fwiw
Mark wrote:
I thought about using the clamp diodes as protection but was a bit worried
about power supply noise leaking through the diodes and adding some jitter to
the input signals...
It is a definite worry even with a low-noise, 50 ohm input, and a
potential disaster with a 1Mohm input.
Fwiw, for a precision comparator you'll probably want a bipolar front end
for a lower flicker corner and better offset stability over cmos. For
high-speeds the diffpair is going to be biased fairly rich for bandwidth.
So you will more than likey have input bias currents of 100's of nA to uA
on your
FJH1100
Ultra Low Leakage Diode
Alex
On 3/31/2017 6:00 PM, Charles Steinmetz wrote:
Mark wrote:
I thought about using the clamp diodes as protection but was a bit
worried about power supply noise leaking through the diodes and
adding some jitter to the input signals...
It is a definite wo
Hi
There are a lot of GPS chips that do an I/Q mix down to a low IF. It’s then
(re) sampled from there. The “LO” in this case would down convert to the low IF
….
Bob
> On Mar 31, 2017, at 6:08 PM, Magnus Danielson
> wrote:
>
> God natt Attila,
>
> On 03/31/2017 11:29 PM, Attila Kinali wro
God natt Attila,
On 03/31/2017 11:29 PM, Attila Kinali wrote:
God kväll Magnus,
On Fri, 31 Mar 2017 21:19:00 +0200
Magnus Danielson wrote:
Still fills the function of LO, as the sample and hold operates as a
mixer and the fold-down can be seen as an overtone mix followed by a
sampling of the
God kväll Magnus,
On Fri, 31 Mar 2017 21:19:00 +0200
Magnus Danielson wrote:
> Still fills the function of LO, as the sample and hold operates as a
> mixer and the fold-down can be seen as an overtone mix followed by a
> sampling of the mix product, so well, it's about the same thing.
"Harmon
I'm happy to run a group buy for just the 8736.My last quote from the
vendor was just a bit under $27 each, and that does not come with the board
connector. I picked these boards for compatibility with Motorola
footprint, but also because it doesn't insist on goofy 3.0 volt power and
logic lev
I've just uploaded a pdf version of the HP 5090A Ops and Service manual to
Didier's site at.
http://www.ko4bb.com
For now at least it's also available at
https://www.mediafire.com/?u0bf1eips89uo3h
The 5090A was an HP product designed in the UK in the early 1960s and was
an off a
Hi Jim,
On 03/31/2017 01:07 AM, jimlux wrote:
BTW a lot of GPS receivers don't have a "first LO".. they are more like
a Tuned RF receiver - an input BPF for L1, L2, or L5, then direct
sampling at around 30-40 MHz - something that makes the GPS signals
alias down somewhere convenient (and always
Hi
The 8736 is a very nice part. I think some sort of group buy would be a good
idea.
Bob
Sent from my iPhone
> On Mar 31, 2017, at 12:14 PM, Bob Darlington wrote:
>
> I guess it's time for me to finish up that NTP cape for the BeagleBone.
> I'm using a Furuno GT-8736 ( http://www.furuno.co
Hi,
On 03/30/2017 03:46 PM, paul swed wrote:
I am curious if the first local oscillator on a GPS receiver must actually
be locked or coherent to the reference oscillator in the GPS receiver
typically running at some 10 MHz approximately. Or as long as the first LO
is quite stable it doesn't matt
I thought about using the clamp diodes as protection but was a bit worried
about power supply noise leaking through the diodes and adding some jitter to
the input signals... I'm probably just being paranoid. The TICC doesn't have
the resolution for it to matter or justify a HP5370 or better qu
links [2] and [3] give 404 errors
Dave
-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali
Sent: 31 March 2017 12:35
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPS first LO need to be locked?
[2] "A Pro
I guess it's time for me to finish up that NTP cape for the BeagleBone.
I'm using a Furuno GT-8736 ( http://www.furuno.com/en/
products/gnss-module/GT-8736 )
I built up a prototype about two years ago but... got married very shortly
after that and haven't played with it since.
Is there any intere
On 3/31/17 4:35 AM, Attila Kinali wrote:
On Thu, 30 Mar 2017 20:00:31 -0700
Peter Monta wrote:
BTW a lot of GPS receivers don't have a "first LO".. they are more like a
Tuned RF receiver - an input BPF for L1, L2, or L5, then direct sampling at
around 30-40 MHz - something that makes the GPS
On Thu, 30 Mar 2017 19:56:31 -0400
Bob kb8tq wrote:
> > Doppler is pretty big when the spacecraft is coming or going at the
> > horizon, about 5 kHz (out of 1.5 GHz, so 4-5 ppm).
> > Relatively speaking, GPS satellites are moving slowly (a few km/s)
> >
>
> So somewhere in the baseband process
On Thu, 30 Mar 2017 20:00:31 -0700
Peter Monta wrote:
> > BTW a lot of GPS receivers don't have a "first LO".. they are more like a
> >> Tuned RF receiver - an input BPF for L1, L2, or L5, then direct sampling at
> >> around 30-40 MHz - something that makes the GPS signals alias down
> >> somewh
(this might be a duplicate post... the last time I sent this, the message
bounced)
What did you do for input protection?
I want to build an input system for the TICC that incorporates some input
protection, switchable terminator, possibly settable threshold and edge
selects, and a switchabl
From: Hal Murray
That should work. I haven't found a GPS with PPS for the beaglebone. What
level of accuracy do you want? If you only need 100 ms or so, then a normal
junk GPS (no PPS) on USB should work.
==
This works with the BeagleBone:
https://www.adafruit.com/pr
Norm and Bob,
The M12+ GPS receivers mounted on the motherboard are indeed the timing units.
Chapter 5 of the Motorola M12+ User's Guide is here:
http://www.synergy-gps.com/images/stories/guides/m12+userguide.pdf
The binary commands and output messages, including timing related commands, are
in
As protection circuit I have used a 51ohm from the front panel input to the
TICC input than two diodes one from TICC input to gnd , other from TICC input
to +5V. A swichable 51ohm from front panel input to gnd allow to have 1M or 50
ohm as input impedance.
The front panel leds are drived
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