Hi Michael and all,
I'm also intended to use sync_out or other GPIO to output square wave to
control noise source,
I measured 6V for sync_out and GPIO pin 1.5V.
After digging into ROACH2 schematics(page 25 in
roach2_rev2_schematics.pdf),
I found the differential signal is first converted
Hi,
Won't the U70 output, when divided by 2 by R450 and R452, need
to match the output signal from U71?
That suggests something like 2*(3.0 to 3.3V) =
6.0 to 6.6V at U70 pin 6.
I can readily guess the designer wanted at least a few
outputs from the Roach that would emmulate COTS 1PPS sources
i think matt is right about the sync output voltages and impedance.
the roach2 sync output should be about 0 to 6 volts with no load,
and about 0 to 3 volts when this signal is terminated in 50 ohms.
so no attenuator is needed if the sync signal is connected to a 50 ohm
load.
if the device that
hi zhu yan and michael,
to bring the roach2 sync output voltage down to 0 to 5 volts when driving
50 ohms,
you could use a connectorized 50 ohm 3 dB attenuator.
a 3 dB attenuator should lower the voltage from 0 to 7 volts, down to 0 to
5 volts.
best wishes,
dan
On Thu, May 18, 2017 at 1:31
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