Something else occurred to me after I posted.
A 0.15 volt glitch could come from capacitive coupling if there was an
open in the PPS output of if it was an adjacent pin.
On Sat, 24 Nov 2012 16:52:50 -0800 (PST), Mark Spencer
mspencer12...@yahoo.ca wrote:
Thanks all for the responses.
I am
Mark,
Are you terminating the 1PPS output with 50 Ohms? They expect 1M Ohms..
Bye,
Said
Sent from my iPad
On Nov 24, 2012, at 2:42 PM, Mark Spencer mspencer12...@yahoo.ca wrote:
Greetings. I recently acquired two Z3805A gpsdo's from the usual auction
site. (These units look like a
and, yes, if your 'scope has the 50ohm/1Mohm input capability, use the 1M
one.
On Sun, Nov 25, 2012 at 12:03 AM, Azelio Boriani
azelio.bori...@screen.itwrote:
Usually the PPS output from the Z-series GPSDO is a 26uS wide (from the
HP58503A datasheet) TTL pulse. To measure it you must use a
Usually the PPS output from the Z-series GPSDO is a 26uS wide (from the
HP58503A datasheet) TTL pulse. To measure it you must use a fast
oscilloscope (because of the fast pulse rise time) and an analog or digital
memory (because of the very low repetition rate). The best is to use a
digital
mspencer12...@yahoo.ca said:
Does any one know the specified output level for the 1pps signals or have a
high confidence measurement of the output voltage that they could share with
me ? (Measuring fast rise time signals is not really my forte and I don't
trust my measurements of an apparent
TTL transition times are not all that fast, about 6ns for LS TTL, and
with a 26uS pulse width, you would only need a fast oscilloscope to
characterize the pulse edges. Delay, phase, and pulse height
measurements in this case could be made even with a 20 MHz,
0.35/20Mhz=17.5ns rise and fall time,
Thanks all for the responses.
I am routing the signal via 50 ohm coax to the 1Meg ohm input of a 100 Mhz
analog scope using dc coupling. After some fiddling with the trigger settings
I am able to observe a brief pulse every second that appears to be .15 volts
above ground. I'm not
I can think of some possibilities with the caveat that I am not
familiar with the Z3805A units:
1. The PPS output could be damaged.
2. The PPS output could be an open collector/drain output which
requires a pull-up resistor since it can only sink current.
3. The PPS output might have trouble
