Empathy List Archives

DK

Dan Kemppainen

Thu, Aug 11, 2011 8:10 PM

Hi All,

I could clairify things a little. My event of interest is basically a
fast frequency shift of a signal that drifts between 1800 and 2600Mhz.
There is slow drift of this signal of many hundreds of Mhz, with fast
frequency shifts of approximatley +/- 150Khz. I believe that the
150Khz shifts are nearly instantaneous, but currently have no way to
measure exactly how fast they occur. Slow drifts are corrected for by
a loop in the down converter.

Currently there is a first down conversion stage to ~900Mhz. This is
then down converted again to an arbitrary frequency band (50Mhz in
this example, but this could be moved from ~10Mhz to 200Mhz or greater).

Obviously it would be advantageous to keep the low frequency band as
high as possible, at least when trying to determine when the frequency
shifts occur with any digital detectors. Probably for any analog
detectors also.

Bob,

Obviously I'd like to get as close to the real zero crossing as
possible, but I'm sure I don't need 0.6pS. If I could tell if the
signal was within maybe +/- 15 or 20Khz, it may be acceptable. I could
always double the frequency then down convert to increase the
deviation. Basically, I have another timing device that will record
every single event within 5nS, as long as they don't exceed ~1e6
events per second. That's the unit I'll feed the signal into, and what
I need to keep happy.

I did just learn about Gilbert cell mixer that works from DC to 500Mhz
yesterday. I didn't realize they were available with that wide of a
bandwidth. With this part as an option, it may be possible to do a
quadrature detection around the several hundred Mhz range. That way
subsequent low pass filters can have fairly high bandwidth. I'm sure
the results here will probably be noisy, but maybe still acceptable???

However, I'd still like to it digitally if possible. Maybe even adding
a second VCO with high modulation bandwidth to use a PLL with to track
the input signal. Maybe then a phase detector comparing that PLL
output and the reference signal and some high speed digital processing
could prove useful. Not sure tho, still need to think about that.
Probably would end up needing some multi Ghz flip flops to make that
work...

Ultimately this may not be possible digitally, but I thought if anyone
here knew of anything it would be here...

Thanks all!
Dan

Hi All, I could clairify things a little. My event of interest is basically a fast frequency shift of a signal that drifts between 1800 and 2600Mhz. There is slow drift of this signal of many hundreds of Mhz, with fast frequency shifts of approximatley +/- 150Khz. I believe that the 150Khz shifts are nearly instantaneous, but currently have no way to measure exactly how fast they occur. Slow drifts are corrected for by a loop in the down converter. Currently there is a first down conversion stage to ~900Mhz. This is then down converted again to an arbitrary frequency band (50Mhz in this example, but this could be moved from ~10Mhz to 200Mhz or greater). Obviously it would be advantageous to keep the low frequency band as high as possible, at least when trying to determine when the frequency shifts occur with any digital detectors. Probably for any analog detectors also. Bob, Obviously I'd like to get as close to the real zero crossing as possible, but I'm sure I don't need 0.6pS. If I could tell if the signal was within maybe +/- 15 or 20Khz, it may be acceptable. I could always double the frequency then down convert to increase the deviation. Basically, I have another timing device that will record every single event within 5nS, as long as they don't exceed ~1e6 events per second. That's the unit I'll feed the signal into, and what I need to keep happy. I did just learn about Gilbert cell mixer that works from DC to 500Mhz yesterday. I didn't realize they were available with that wide of a bandwidth. With this part as an option, it may be possible to do a quadrature detection around the several hundred Mhz range. That way subsequent low pass filters can have fairly high bandwidth. I'm sure the results here will probably be noisy, but maybe still acceptable??? However, I'd still like to it digitally if possible. Maybe even adding a second VCO with high modulation bandwidth to use a PLL with to track the input signal. Maybe then a phase detector comparing that PLL output and the reference signal and some high speed digital processing could prove useful. Not sure tho, still need to think about that. Probably would end up needing some multi Ghz flip flops to make that work... Ultimately this may not be possible digitally, but I thought if anyone here knew of anything it would be here... Thanks all! Dan

CA

Chris Albertson

Thu, Aug 11, 2011 8:28 PM

Seems to me like an HP 5335A is well suited to this task. It measures
frequency in the required range and has adjustable gate times so you can get
updates at the rate you need. These sell on eBay for as low as $200 and
from other placed for $600. They have signal conditioning, and a computer
interface all in one rack mount box. Accuracy is better then you say you
need.

On Thu, Aug 11, 2011 at 1:10 PM, Dan Kemppainen dan@irtelemetrics.comwrote:

Hi All,

I could clairify things a little. My event of interest is basically a fast
frequency shift of a signal that drifts between 1800 and 2600Mhz. There is
slow drift of this signal of many hundreds of Mhz, with fast frequency
shifts of approximatley +/- 150Khz. I believe that the 150Khz shifts are
nearly instantaneous, but currently have no way to measure exactly how fast
they occur. Slow drifts are corrected for by a loop in the down converter.

Currently there is a first down conversion stage to ~900Mhz. This is then
down converted again to an arbitrary frequency band (50Mhz in this example,
but this could be moved from ~10Mhz to 200Mhz or greater).

Obviously it would be advantageous to keep the low frequency band as high
as possible, at least when trying to determine when the frequency shifts
occur with any digital detectors. Probably for any analog detectors also.

Chris Albertson
Redondo Beach, California

Seems to me like an HP 5335A is well suited to this task. It measures frequency in the required range and has adjustable gate times so you can get updates at the rate you need. These sell on eBay for as low as $200 and from other placed for $600. They have signal conditioning, and a computer interface all in one rack mount box. Accuracy is better then you say you need. On Thu, Aug 11, 2011 at 1:10 PM, Dan Kemppainen <dan@irtelemetrics.com>wrote: > Hi All, > > I could clairify things a little. My event of interest is basically a fast > frequency shift of a signal that drifts between 1800 and 2600Mhz. There is > slow drift of this signal of many hundreds of Mhz, with fast frequency > shifts of approximatley +/- 150Khz. I believe that the 150Khz shifts are > nearly instantaneous, but currently have no way to measure exactly how fast > they occur. Slow drifts are corrected for by a loop in the down converter. > > Currently there is a first down conversion stage to ~900Mhz. This is then > down converted again to an arbitrary frequency band (50Mhz in this example, > but this could be moved from ~10Mhz to 200Mhz or greater). > > Obviously it would be advantageous to keep the low frequency band as high > as possible, at least when trying to determine when the frequency shifts > occur with any digital detectors. Probably for any analog detectors also. > > > Chris Albertson Redondo Beach, California

JC

Jose Camara

Thu, Aug 11, 2011 9:07 PM

If this is not a board design situation, but just a lab setup to measure and
characterize it, the 53310A could also work, giving a plot of frequency x
time, right on the instrument. GPIB can bring data out, too. They go for
$300 to $1500 on eBay.

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Chris Albertson
Sent: Thursday, August 11, 2011 1:29 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Frequency Comparator Ideas needed

Seems to me like an HP 5335A is well suited to this task. It measures
frequency in the required range and has adjustable gate times so you can get
updates at the rate you need. These sell on eBay for as low as $200 and
from other placed for $600. They have signal conditioning, and a computer
interface all in one rack mount box. Accuracy is better then you say you
need.

On Thu, Aug 11, 2011 at 1:10 PM, Dan Kemppainen
dan@irtelemetrics.comwrote:

Hi All,

I could clairify things a little. My event of interest is basically a fast
frequency shift of a signal that drifts between 1800 and 2600Mhz. There is
slow drift of this signal of many hundreds of Mhz, with fast frequency
shifts of approximatley +/- 150Khz. I believe that the 150Khz shifts are
nearly instantaneous, but currently have no way to measure exactly how

fast

they occur. Slow drifts are corrected for by a loop in the down converter.

Currently there is a first down conversion stage to ~900Mhz. This is then
down converted again to an arbitrary frequency band (50Mhz in this

example,

but this could be moved from ~10Mhz to 200Mhz or greater).

Obviously it would be advantageous to keep the low frequency band as high
as possible, at least when trying to determine when the frequency shifts
occur with any digital detectors. Probably for any analog detectors also.

Chris Albertson
Redondo Beach, California

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.

If this is not a board design situation, but just a lab setup to measure and characterize it, the 53310A could also work, giving a plot of frequency x time, right on the instrument. GPIB can bring data out, too. They go for $300 to $1500 on eBay. -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Chris Albertson Sent: Thursday, August 11, 2011 1:29 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Frequency Comparator Ideas needed Seems to me like an HP 5335A is well suited to this task. It measures frequency in the required range and has adjustable gate times so you can get updates at the rate you need. These sell on eBay for as low as $200 and from other placed for $600. They have signal conditioning, and a computer interface all in one rack mount box. Accuracy is better then you say you need. On Thu, Aug 11, 2011 at 1:10 PM, Dan Kemppainen <dan@irtelemetrics.com>wrote: > Hi All, > > I could clairify things a little. My event of interest is basically a fast > frequency shift of a signal that drifts between 1800 and 2600Mhz. There is > slow drift of this signal of many hundreds of Mhz, with fast frequency > shifts of approximatley +/- 150Khz. I believe that the 150Khz shifts are > nearly instantaneous, but currently have no way to measure exactly how fast > they occur. Slow drifts are corrected for by a loop in the down converter. > > Currently there is a first down conversion stage to ~900Mhz. This is then > down converted again to an arbitrary frequency band (50Mhz in this example, > but this could be moved from ~10Mhz to 200Mhz or greater). > > Obviously it would be advantageous to keep the low frequency band as high > as possible, at least when trying to determine when the frequency shifts > occur with any digital detectors. Probably for any analog detectors also. > > > Chris Albertson Redondo Beach, California _______________________________________________ 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.

BC

Bob Camp

Thu, Aug 11, 2011 9:48 PM

Hi

If you need to know when the shifts occur in tens of ns, that significantly
limits what you can do. Getting > 20 million readings a second is tough. If
this is an off the air signal, it's noise is probably not good enough for
you to estimate it accurately enough in that time frame.

If this is FSK, then modulation theory gets in the way a bit. 150KHz
instantaneous shifts generate a lot of energy at the shift point. You also
need to worry about dynamic range in addition to signal to noise.

How about a simple FM discriminator with a bandwidth around 10 MHz and a
center at 50 MHz?. Feed the output into an A/D and take it from there. It's
probably as good as anything else you could do.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dan Kemppainen
Sent: Thursday, August 11, 2011 4:11 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Frequency Comparator Ideas needed

Hi All,

I could clairify things a little. My event of interest is basically a
fast frequency shift of a signal that drifts between 1800 and 2600Mhz.
There is slow drift of this signal of many hundreds of Mhz, with fast
frequency shifts of approximatley +/- 150Khz. I believe that the
150Khz shifts are nearly instantaneous, but currently have no way to
measure exactly how fast they occur. Slow drifts are corrected for by
a loop in the down converter.

Currently there is a first down conversion stage to ~900Mhz. This is
then down converted again to an arbitrary frequency band (50Mhz in
this example, but this could be moved from ~10Mhz to 200Mhz or greater).

Obviously it would be advantageous to keep the low frequency band as
high as possible, at least when trying to determine when the frequency
shifts occur with any digital detectors. Probably for any analog
detectors also.

Bob,

Obviously I'd like to get as close to the real zero crossing as
possible, but I'm sure I don't need 0.6pS. If I could tell if the
signal was within maybe +/- 15 or 20Khz, it may be acceptable. I could
always double the frequency then down convert to increase the
deviation. Basically, I have another timing device that will record
every single event within 5nS, as long as they don't exceed ~1e6
events per second. That's the unit I'll feed the signal into, and what
I need to keep happy.

I did just learn about Gilbert cell mixer that works from DC to 500Mhz
yesterday. I didn't realize they were available with that wide of a
bandwidth. With this part as an option, it may be possible to do a
quadrature detection around the several hundred Mhz range. That way
subsequent low pass filters can have fairly high bandwidth. I'm sure
the results here will probably be noisy, but maybe still acceptable???

However, I'd still like to it digitally if possible. Maybe even adding
a second VCO with high modulation bandwidth to use a PLL with to track
the input signal. Maybe then a phase detector comparing that PLL
output and the reference signal and some high speed digital processing
could prove useful. Not sure tho, still need to think about that.
Probably would end up needing some multi Ghz flip flops to make that
work...

Ultimately this may not be possible digitally, but I thought if anyone
here knew of anything it would be here...

Thanks all!
Dan

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.

Hi If you need to know when the shifts occur in tens of ns, that significantly limits what you can do. Getting > 20 million readings a second is tough. If this is an off the air signal, it's noise is probably not good enough for you to estimate it accurately enough in that time frame. If this is FSK, then modulation theory gets in the way a bit. 150KHz instantaneous shifts generate a lot of energy at the shift point. You also need to worry about dynamic range in addition to signal to noise. How about a simple FM discriminator with a bandwidth around 10 MHz and a center at 50 MHz?. Feed the output into an A/D and take it from there. It's probably as good as anything else you could do. Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Dan Kemppainen Sent: Thursday, August 11, 2011 4:11 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Frequency Comparator Ideas needed Hi All, I could clairify things a little. My event of interest is basically a fast frequency shift of a signal that drifts between 1800 and 2600Mhz. There is slow drift of this signal of many hundreds of Mhz, with fast frequency shifts of approximatley +/- 150Khz. I believe that the 150Khz shifts are nearly instantaneous, but currently have no way to measure exactly how fast they occur. Slow drifts are corrected for by a loop in the down converter. Currently there is a first down conversion stage to ~900Mhz. This is then down converted again to an arbitrary frequency band (50Mhz in this example, but this could be moved from ~10Mhz to 200Mhz or greater). Obviously it would be advantageous to keep the low frequency band as high as possible, at least when trying to determine when the frequency shifts occur with any digital detectors. Probably for any analog detectors also. Bob, Obviously I'd like to get as close to the real zero crossing as possible, but I'm sure I don't need 0.6pS. If I could tell if the signal was within maybe +/- 15 or 20Khz, it may be acceptable. I could always double the frequency then down convert to increase the deviation. Basically, I have another timing device that will record every single event within 5nS, as long as they don't exceed ~1e6 events per second. That's the unit I'll feed the signal into, and what I need to keep happy. I did just learn about Gilbert cell mixer that works from DC to 500Mhz yesterday. I didn't realize they were available with that wide of a bandwidth. With this part as an option, it may be possible to do a quadrature detection around the several hundred Mhz range. That way subsequent low pass filters can have fairly high bandwidth. I'm sure the results here will probably be noisy, but maybe still acceptable??? However, I'd still like to it digitally if possible. Maybe even adding a second VCO with high modulation bandwidth to use a PLL with to track the input signal. Maybe then a phase detector comparing that PLL output and the reference signal and some high speed digital processing could prove useful. Not sure tho, still need to think about that. Probably would end up needing some multi Ghz flip flops to make that work... Ultimately this may not be possible digitally, but I thought if anyone here knew of anything it would be here... Thanks all! Dan _______________________________________________ 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.

time-nuts@lists.febo.com

Re: [time-nuts] Frequency Comparator Ideas needed