Very Accurate Delta Time RF Pulse Measurements
Hi Guys,
This is a little outside of time-nuts scope, but not by much. I'm interested in finding the time between two rising edges above a set threshold with preferably nS or high ps timing accuracy. Can this be simply done with a few programmed Microchip PICs or with a good short term OCXO clock? The issue I see is that a 10Mhz timing reference with 1 cycle difference in time yields 100ns resolution, which is far too large, so maybe a PIC can solve this.
This weekend project would be a multi-element antenna array, each with a super-fast response log peak power detector fed into several PICs for time of arrival. Whenever a nearby high energy RF pulse is detected, the time of arrival between two antenna elements and hence the direction toward the TX could be roughly computed. Some typical log peak detectors have an 8ns input pulse response time, so I'm hoping that rise times are similar between multiple detectors, negating the delayed response.
There are time of arrival/AoA systems out there with synthetic doppler, phased arrays, correlative interferometers, and phase comparators, but it would be interesting to accomplish super wideband AoA timing on two rising pulses with relatively cheap parts.
Thanks,
-Jerome
There was a pic app note on alternate uses for the cap sense block a while
back, not sure it that it will push you into the ps.
On Thursday, 28 July 2016, Jerome Blaha jblaha@polariswireless.com wrote:
Hi Guys,
This is a little outside of time-nuts scope, but not by much. I'm
interested in finding the time between two rising edges above a set
threshold with preferably nS or high ps timing accuracy. Can this be
simply done with a few programmed Microchip PICs or with a good short term
OCXO clock? The issue I see is that a 10Mhz timing reference with 1 cycle
difference in time yields 100ns resolution, which is far too large, so
maybe a PIC can solve this.
This weekend project would be a multi-element antenna array, each with a
super-fast response log peak power detector fed into several PICs for time
of arrival. Whenever a nearby high energy RF pulse is detected, the time
of arrival between two antenna elements and hence the direction toward the
TX could be roughly computed. Some typical log peak detectors have an 8ns
input pulse response time, so I'm hoping that rise times are similar
between multiple detectors, negating the delayed response.
There are time of arrival/AoA systems out there with synthetic doppler,
phased arrays, correlative interferometers, and phase comparators, but it
would be interesting to accomplish super wideband AoA timing on two rising
pulses with relatively cheap parts.
Thanks,
-Jerome
time-nuts mailing list -- time-nuts@febo.com javascript:;
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi
If you have a need to do < 1 ns with a counter approach, the counter will need to have a GHz clock in it. If you want to use an MCU counter, it will need to have a GHz level clock routed to it. You are unlikely to find an MCU that will do that. An FPGA can get you to 1.25 ns with direct counting. With gate based delay line techniques you can get down below 100 ps in an FPGA.
The other approach is to build a counter to get as fast as you practically can and then do an analog TDC to get a few more bits.
There are a lot of messy details past all that.
Bob
On Jul 28, 2016, at 7:12 PM, Jerome Blaha jblaha@polariswireless.com wrote:
Hi Guys,
This is a little outside of time-nuts scope, but not by much. I'm interested in finding the time between two rising edges above a set threshold with preferably nS or high ps timing accuracy. Can this be simply done with a few programmed Microchip PICs or with a good short term OCXO clock? The issue I see is that a 10Mhz timing reference with 1 cycle difference in time yields 100ns resolution, which is far too large, so maybe a PIC can solve this.
This weekend project would be a multi-element antenna array, each with a super-fast response log peak power detector fed into several PICs for time of arrival. Whenever a nearby high energy RF pulse is detected, the time of arrival between two antenna elements and hence the direction toward the TX could be roughly computed. Some typical log peak detectors have an 8ns input pulse response time, so I'm hoping that rise times are similar between multiple detectors, negating the delayed response.
There are time of arrival/AoA systems out there with synthetic doppler, phased arrays, correlative interferometers, and phase comparators, but it would be interesting to accomplish super wideband AoA timing on two rising pulses with relatively cheap parts.
Thanks,
-Jerome
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Taking a look for it also turned up a recent time-nuts thread
https://www.febo.com/pipermail/time-nuts/2016-May/097801.html
On Thursday, 28 July 2016, Scott Stobbe scott.j.stobbe@gmail.com wrote:
There was a pic app note on alternate uses for the cap sense block a while
back, not sure it that it will push you into the ps.
On Thursday, 28 July 2016, Jerome Blaha <jblaha@polariswireless.com
javascript:_e(%7B%7D,'cvml','jblaha@polariswireless.com');> wrote:
Hi Guys,
This is a little outside of time-nuts scope, but not by much. I'm
interested in finding the time between two rising edges above a set
threshold with preferably nS or high ps timing accuracy. Can this be
simply done with a few programmed Microchip PICs or with a good short term
OCXO clock? The issue I see is that a 10Mhz timing reference with 1 cycle
difference in time yields 100ns resolution, which is far too large, so
maybe a PIC can solve this.
This weekend project would be a multi-element antenna array, each with a
super-fast response log peak power detector fed into several PICs for time
of arrival. Whenever a nearby high energy RF pulse is detected, the time
of arrival between two antenna elements and hence the direction toward the
TX could be roughly computed. Some typical log peak detectors have an 8ns
input pulse response time, so I'm hoping that rise times are similar
between multiple detectors, negating the delayed response.
There are time of arrival/AoA systems out there with synthetic doppler,
phased arrays, correlative interferometers, and phase comparators, but it
would be interesting to accomplish super wideband AoA timing on two rising
pulses with relatively cheap parts.
Thanks,
-Jerome
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On Thu, 28 Jul 2016 23:12:54 +0000
Jerome Blaha jblaha@polariswireless.com wrote:
Hi Guys,
This is a little outside of time-nuts scope, but not by much.
I'm interested in finding the time between two rising edges above a set
threshold with preferably nS or high ps timing accuracy. Can this be simply
done with a few programmed Microchip PICs or with a good short term OCXO
clock? The issue I see is that a 10Mhz timing reference with 1 cycle
difference in time yields 100ns resolution, which is far too large, so maybe
a PIC can solve this.
I think the easiest way is to implement something like the PICTIC II [1].
That should get you into the order of 100ps with minimal effort.
With a little bit of care, you can make it go down to 20-30ps rms.
But I think, that the pulse generation itself is probably the part
that limits your precision, as the logarithmic amplifiers are usually
quite noisy.
Attila Kinali
[1] http://www.ko4bb.com/doku2015/doku.php?id=precision_timing:pictic
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
May be some more accurate alternative to AD8302 could do that. AD8302
could measure Gain/Loss and Phase up to 2.7 GHz. I using one in my
project and its doing its job right (I think).
On 2016-07-28 19:12, Jerome Blaha wrote:
Hi Guys,
This is a little outside of time-nuts scope, but not by much. I'm
interested in finding the time between two rising edges above a set
threshold with preferably nS or high ps timing accuracy. Can this be
simply done with a few programmed Microchip PICs or with a good short
term OCXO clock? The issue I see is that a 10Mhz timing reference
with 1 cycle difference in time yields 100ns resolution, which is far
too large, so maybe a PIC can solve this.
This weekend project would be a multi-element antenna array, each with
a super-fast response log peak power detector fed into several PICs
for time of arrival. Whenever a nearby high energy RF pulse is
detected, the time of arrival between two antenna elements and hence
the direction toward the TX could be roughly computed. Some typical
log peak detectors have an 8ns input pulse response time, so I'm
hoping that rise times are similar between multiple detectors,
negating the delayed response.
There are time of arrival/AoA systems out there with synthetic
doppler, phased arrays, correlative interferometers, and phase
comparators, but it would be interesting to accomplish super wideband
AoA timing on two rising pulses with relatively cheap parts.
Thanks,
-Jerome
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
WBW,
V.P.
If you have a unit in good condition, excess to your needs, kindly contact
me off list please.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
Sounds like you want to build something rather then use some
instruments you can buy. I've thought a little about this too as I
want to make a LIDAR to measure distance using a laser pulse. In my
case I want both low cost and for the device to be very small and
light and run off a battery
I think the way to do this is to have a function generator that
creates a ramp function that moves from zero to some max volts in 100
ns. Then when the pulse arrives you use that to trigger a capture of
the ramp's current voltage into a sample and hold. Then later look at
the difference in the volts in each sample and hold. If the time
difference is longer than one ramp period then you need to also sample
the counts in a normal counter for each pulse edge.
I guess you might use a PIC to implement the above but I find it is
always easier to write software on a larger computer. The aded cost
of using more expensive device is nothing if it saves hours or days of
effort (and you are only building one unit.)
You could use the uP internal counter to measure the rough time
interval and whatever drives that internal counter would also drive
the ramp function generator
This is a little outside of time-nuts scope, but not by much. I'm
interested in finding the time between two rising edges above a set
threshold with preferably nS or high ps timing accuracy. Can this be
simply done with a few programmed Microchip PICs or with a good short
term OCXO clock? The issue I see is that a 10Mhz timing reference
with 1 cycle difference in time yields 100ns resolution, which is far
too large, so maybe a PIC can solve this.
This weekend project would be a multi-element antenna array, each with
a super-fast response log peak power detector fed into several PICs
for time of arrival. Whenever a nearby high energy RF pulse is
detected, the time of arrival between two antenna elements and hence
the direction toward the TX could be roughly computed. Some typical
log peak detectors have an 8ns input pulse response time, so I'm
hoping that rise times are similar between multiple detectors,
negating the delayed response.
There are time of arrival/AoA systems out there with synthetic
doppler, phased arrays, correlative interferometers, and phase
comparators, but it would be interesting to accomplish super wideband
AoA timing on two rising pulses with relatively cheap parts.
Thanks,
-Jerome
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
WBW,
V.P.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
On Fri, 29 Jul 2016 09:23:02 -0700
Chris Albertson albertson.chris@gmail.com wrote:
Sounds like you want to build something rather then use some
instruments you can buy. I've thought a little about this too as I
want to make a LIDAR to measure distance using a laser pulse. In my
case I want both low cost and for the device to be very small and
light and run off a battery
For this kind of application I would recommend looking into
chips like the TDC1000 (there are multiple in this family, and
other manufacturers have similar chips). They are made exactly for
that kind of application, though with ultrasonic flow measurement
in mind. The timing resolution is high enough that you can build a LIDAR
with <10cm resolution that does consume very litte power.
For higher resolution, I would go for a sinusoidal modulation scheme
and measure the phase difference between the transmitted and received
signal. That should easily give you resolution in the sub-cm range,
but also consumes more power.
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
Hi Jerome:
The Vietnam era Radar Warning Systems used 4 wide band antennas (nose, tail & wing tips) and displayed the bearing,
rough distance & threat type on a CRT.
Near the antenna was a crystal video receiver using a multi channel filter driving Schottky diode detectors. The output
from each detector fed a video log amp.
http://www.prc68.com/I/RWR.shtml
http://www.prc68.com/I/ALR54.shtml
The Fenwick antenna patent based on time delay beam steering is far superior to a phased array in that it's frequency
independent.
http://www.prc68.com/I/Ant.shtml#TDBS
I think the basis of TOA.
Can you say more about the specifics of what you are trying to do?
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
-------- Original Message --------
Hi Guys,
This is a little outside of time-nuts scope, but not by much. I'm interested in finding the time between two rising edges above a set threshold with preferably nS or high ps timing accuracy. Can this be simply done with a few programmed Microchip PICs or with a good short term OCXO clock? The issue I see is that a 10Mhz timing reference with 1 cycle difference in time yields 100ns resolution, which is far too large, so maybe a PIC can solve this.
This weekend project would be a multi-element antenna array, each with a super-fast response log peak power detector fed into several PICs for time of arrival. Whenever a nearby high energy RF pulse is detected, the time of arrival between two antenna elements and hence the direction toward the TX could be roughly computed. Some typical log peak detectors have an 8ns input pulse response time, so I'm hoping that rise times are similar between multiple detectors, negating the delayed response.
There are time of arrival/AoA systems out there with synthetic doppler, phased arrays, correlative interferometers, and phase comparators, but it would be interesting to accomplish super wideband AoA timing on two rising pulses with relatively cheap parts.
Thanks,
-Jerome
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.