Re: [time-nuts] Z3805A high value PU
Mark wrote: For the first 6 hours PU stayed at 432us, then it dropped sharply to 5.6us and then slowly climbed to 18us. Doesn't seem right to me. Nothing it does in the first 6 hours has anything to do with anything. (1) The oscillator will be swinging around wildly (comparatively speaking, relative to its stability after it has been running unmolested for months). (2) Further, 6 hours is almost certainly a shorter period than it normally uses to forecast PU, so a forecast after ANY six-hour period of data collection (even when fully warm and stable) will not be its best estimate. I do not know HP's algorithm, but it sounds like it didn't seriously try to compute PU until after 6 hours, then it started trying with (1) too little data and (2) data from an unstable oscillator, so it's no surprise it is wandering around. I'll be very surprised if it settles down near its long-term stability in less than a month of continuous, undisturbed running (continuous meaning don't turn it off, undisturbed meaning don't move it or bump it very hard -- if you do either of these, start counting from zero again). Be patient. OCXOs need time to reach stability when re-started in a new environment (particularly if they have been off for more than a few days and/or bumped around, both of which are probably true of yours). Some are better about this than others, but what I've said is pretty typical of the 10811-and-better class of OCXOs, IME. Best regards, Charles ___ 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.
Re: [time-nuts] Common-View GPS Network
Tom, On 04/17/2013 07:21 AM, Tom Van Baak wrote: Tom, you scare me some times, this is one of them... or the time actually. Magnus, I remember why I didn't measure the M12 oscillators directly -- it's a real challenge to get at the signal on the back side of the PCB and to measure it without loading the crystal. It's not like just connecting a wire to a 50R Timepod input. Here are photos of the oscillator on three different versions of the M12 board: http://leapsecond.com/pages/m12/m12-osc.htm Perhaps with some 'scope tracing you can find a buffered clock output on one of the ASIC pins. That way the same probing technique could be used on all 3 boards. OK, now you start to make sense ;-) Only #2 should be a challenge, as #1 and #3 has buffered output. Still, you want some buffering. A suitable CMOS gate should pull it off. Otherwise a FET-probe to a PSU and then into the TimePod should do the trick. Cheers, Magnus ___ 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.
Re: [time-nuts] Z3805A high value PU
Thanks Guys, you have instilled a great deal of confidence in these smartclocks for me. Anyone know where I can buy a month's supply of patience then? ;) On a more serious note, I have rack mounted both clocks with UPS power and they shall not be disturbed. http://www.vk2hmc.net/blog/?p=86 Many thanks, mark -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles P. Steinmetz Sent: Wednesday, 17 April 2013 4:03 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Z3805A high value PU Mark wrote: For the first 6 hours PU stayed at 432us, then it dropped sharply to 5.6us and then slowly climbed to 18us. Doesn't seem right to me. Nothing it does in the first 6 hours has anything to do with anything. (1) The oscillator will be swinging around wildly (comparatively speaking, relative to its stability after it has been running unmolested for months). (2) Further, 6 hours is almost certainly a shorter period than it normally uses to forecast PU, so a forecast after ANY six-hour period of data collection (even when fully warm and stable) will not be its best estimate. I do not know HP's algorithm, but it sounds like it didn't seriously try to compute PU until after 6 hours, then it started trying with (1) too little data and (2) data from an unstable oscillator, so it's no surprise it is wandering around. I'll be very surprised if it settles down near its long-term stability in less than a month of continuous, undisturbed running (continuous meaning don't turn it off, undisturbed meaning don't move it or bump it very hard -- if you do either of these, start counting from zero again). Be patient. OCXOs need time to reach stability when re-started in a new environment (particularly if they have been off for more than a few days and/or bumped around, both of which are probably true of yours). Some are better about this than others, but what I've said is pretty typical of the 10811-and-better class of OCXOs, IME. Best regards, Charles ___ 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 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] Z3805A flash dump.
I have dumped the 4 flash ROMS from my latest Z3805A but I can't make head nor tail of the contents. I am thinking the flash are interleaved. http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar I can't see any strings that make sense like the Z3801A flash. ___ 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Hi The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. Sample boards arrived yesterday, it'll be interesting to see how it does. Bob On Apr 16, 2013, at 9:51 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 4/14/2013 7:48 AM, Brian Davis wrote: Not sure if it's already been mentioned, but Linear has introduced a new part that looks interesting : LTC6957 Low Phase Noise Buffer/Driver http://www.linear.com/product/LTC6957-1 This is VERY interesting, especially the low noise PECL output. I have never seen any ECL device ever come close to that noise level. It would be interesting to see how they did that. Rick ___ 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 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
On 4/17/13 4:26 AM, Bob Camp wrote: Hi The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. I thought the whole point of fast ECL logic was that it never saturated. Of course these days, one might have very fast saturating logic that happens to have ECL logic levels and run off that ever so convenient -5.2 V power supply. ___ 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.
Re: [time-nuts] Common-View GPS Network
On 4/16/13 9:17 PM, Lachlan Gunn wrote: A few reasons: - I am interested to see what can be done with the statistics of an ensemble of oscillators---in particular, whether the additional measurements can be used to get a timescale that is more stable than just GPS and OCXO or Rb. - To produce some data that could be used for modelling other systems. - If the first point plays out, then to allow access to a more accurate timescale by amateurs who cannot justify 15k/yr for NIST's. It might be interesting to see if one could extract ionospheric data from the ensemble too. you might want to talk to Tony Mannucci at JPL.. tony.mannuc...@jpl.nasa.gov http://iono.jpl.nasa.gov/ A capability of monitoring the global distribution of ionospheric total electron content (TEC) has been developed at JPL using dual-frequency observations from a worldwide network of Global Positioning System (GPS). Using the GPS data Combined with the Kalman filter technique and an ionospheric model, global ionosphere maps (GIM) of vertical TEC can be produced with an hourly or sub-hourly resolution. http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/37457/1/05-2052.pdf http://www.atmos-meas-tech-discuss.net/4/2525/2011/amtd-4-2525-2011.pdf ___ 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
On Wed, 17 Apr 2013 07:26:46 -0400, Bob Camp li...@rtty.us wrote: On Apr 16, 2013, at 9:51 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 4/14/2013 7:48 AM, Brian Davis wrote: Not sure if it's already been mentioned, but Linear has introduced a new part that looks interesting : LTC6957 Low Phase Noise Buffer/Driver http://www.linear.com/product/LTC6957-1 This is VERY interesting, especially the low noise PECL output. I have never seen any ECL device ever come close to that noise level. It would be interesting to see how they did that. The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. What criteria do they use to distinguish the two? Application? Differential inputs and outputs? I am not surprised that it would have lower jitter than ECL if the later lacks an independent external reference. I have been looking into low jitter triggers for sampling systems recently and will probably end up using a discrete differential amplifier driving ECL logic. ___ 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
In some of my projects I like to use the MC10EL16. Does any one have an opinion on it? Bert Kehren In a message dated 4/17/2013 9:31:57 A.M. Eastern Daylight Time, davidwh...@gmail.com writes: On Wed, 17 Apr 2013 07:26:46 -0400, Bob Camp li...@rtty.us wrote: On Apr 16, 2013, at 9:51 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 4/14/2013 7:48 AM, Brian Davis wrote: Not sure if it's already been mentioned, but Linear has introduced a new part that looks interesting : LTC6957 Low Phase Noise Buffer/Driver http://www.linear.com/product/LTC6957-1 This is VERY interesting, especially the low noise PECL output. I have never seen any ECL device ever come close to that noise level. It would be interesting to see how they did that. The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. What criteria do they use to distinguish the two? Application? Differential inputs and outputs? I am not surprised that it would have lower jitter than ECL if the later lacks an independent external reference. I have been looking into low jitter triggers for sampling systems recently and will probably end up using a discrete differential amplifier driving ECL logic. ___ 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 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.
Re: [time-nuts] Z3805A flash dump.
On Wed, Apr 17, 2013 at 08:31:49AM +, Mark C. Stephens wrote:
I have dumped the 4 flash ROMS from my latest Z3805A but
I can't make head nor tail of the contents.
I am thinking the flash are interleaved.
Interleaving makes sense for performance reasons and
usually happens at bit or byte level, but I'm not (yet)
convinced that the data was dumped correctly.
http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar
Assuming that the Z3801A and Z3805A ROM contents is
somewhat similar (1x512k = 4x128k), let's take a look
at the entropy of the data:
$ cat z3801a.bin | xz --stdout | wc -c
110020
$ cat z3805-*.bin | xz --stdout | wc -c
60436
This rough estimate on the amount of non redundant
data shows that the z3801a ROM contains almost twice
as much data than the z3805 ROM dumps together.
$ for n in z3805-*.bin; do xz --stdout $n | wc -c; done
25108
30724
24712
22812
This shows that the data is almost evenly distribute
between the four dumps, so some kind of interleaving
is obviously present and none of the files are purely
random or contain just padding or similar like:
$ dd if=/dev/urandom bs=1k count=128 | xz --stdout | wc -c
131140
$ dd if=/dev/zero bs=1k count=128 | xz --stdout | wc -c
152
Now looking at the data itself, it is simple to see
that there is a positional redundancy present:
$ for n in z3805-*.bin; do xxd -g 1 $n | head -1; done
000: 6f ff 00 05 04 05 00 05 10 05 00 05 28 05 00 05 o...(...
000: 6f 10 00 05 04 fe 00 05 10 00 00 05 28 50 00 05 o...(P..
000: 6f a0 00 05 04 00 00 05 10 42 00 05 28 42 00 05 oB..(B..
000: 6f 00 00 05 04 ff 00 05 10 00 00 05 28 05 00 05 o...(...
Columns 1, 3, 4, 5, 7, 8, 9 ... are all equal, only
the columns 2, 6, 10, 14 ... contain different values
across the files, which basically means that 3 out of
4 bytes are completely identical between the 4 dumps.
(this is, where I think something might have gone
wrong with the dumps :)
Anyway, extracting the data from the columns where the
dumps actually differ gives the following data [1]:
$ xxd col.data | head -4
000: ff10 a000 05fe 00ff 0500 4200 0550 4205 ..B..PB.
010: 0510 05b4 1105 0510 05b4 0005
020: 0510 1100 05b4 0005 0510 05b4 1105
030: 1310 05b4 0005 0510 1100 05b4 0005
Comparing this with the dump from z3801a ROM:
$ xxd z3801a.bin | head -4
000: 0010 fffe 0550 0010 05b4 0010 05b4 ...P
010: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
020: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
030: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
Suggests that there is some kind of reordering required
to get the similar structure present in the hardware
vector table.
The following mapping seems to do the trick:
Pick every odd byte from the data and switch every
two resulting bytes, or as pseudocode:
for (n = 0; n 2; n++) {
for (i = 0; i dlen; i += 4) {
j = i/2;
split[n][j + 0] = data[i + n + 2];
split[n][j + 1] = data[i + n + 0];
}
}
The resulting data [2] seems to contain meaningful
strings and binary code similar to the z3801a ROM:
$ strings split.data | grep psos
@(#)$Header: psos.S,v 1.4 95/01/11 15:27:21 jacob Exp $
@(#)$Header: psos_indep.h,v 1.5 95/03/24 15:24:19 da oe uxn d
@(#)$Header: psos.S,v 1.4 95/01/11 15:27:21 jacob Exp $
@(#)$Header: psos_indep.h,v 1.5 95/03/24 15:24:19 da oe uxn d
HTH,
Herbert
[1] http://vserver.13thfloor.at/Stuff/VARIOUS/Z3805/col1.data
[2] http://vserver.13thfloor.at/Stuff/VARIOUS/Z3805/split1.data
I can't see any strings that make sense like the Z3801A flash.
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Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Very high gain front end. It's a saturating amp rather than a comparator. Wonder how it would work as a DMTD front end? Corby ___ 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.
Re: [time-nuts] Z3805A flash dump.
It is possible I didn't take the dump correctly, or there is a problem with my
burner.
I chose Binary when saving files.
Perhaps, the other possibility is those flash chips aren't the actual firmware,
just storage.
The actual firmware (program) flash chip could be located elsewhere.
However, that would seem a bit strange to me, why socket transient memory and
not the actual program itself?
How should I have taken the flash dumps?
-mark
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of Herbert Poetzl
Sent: Thursday, 18 April 2013 12:43 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Z3805A flash dump.
On Wed, Apr 17, 2013 at 08:31:49AM +, Mark C. Stephens wrote:
I have dumped the 4 flash ROMS from my latest Z3805A but I can't make
head nor tail of the contents.
I am thinking the flash are interleaved.
Interleaving makes sense for performance reasons and usually happens at bit or
byte level, but I'm not (yet) convinced that the data was dumped correctly.
http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar
Assuming that the Z3801A and Z3805A ROM contents is somewhat similar (1x512k =
4x128k), let's take a look at the entropy of the data:
$ cat z3801a.bin | xz --stdout | wc -c
110020
$ cat z3805-*.bin | xz --stdout | wc -c
60436
This rough estimate on the amount of non redundant data shows that the z3801a
ROM contains almost twice as much data than the z3805 ROM dumps together.
$ for n in z3805-*.bin; do xz --stdout $n | wc -c; done
25108
30724
24712
22812
This shows that the data is almost evenly distribute between the four dumps, so
some kind of interleaving is obviously present and none of the files are purely
random or contain just padding or similar like:
$ dd if=/dev/urandom bs=1k count=128 | xz --stdout | wc -c
131140
$ dd if=/dev/zero bs=1k count=128 | xz --stdout | wc -c
152
Now looking at the data itself, it is simple to see that there is a positional
redundancy present:
$ for n in z3805-*.bin; do xxd -g 1 $n | head -1; done
000: 6f ff 00 05 04 05 00 05 10 05 00 05 28 05 00 05 o...(...
000: 6f 10 00 05 04 fe 00 05 10 00 00 05 28 50 00 05 o...(P..
000: 6f a0 00 05 04 00 00 05 10 42 00 05 28 42 00 05 oB..(B..
000: 6f 00 00 05 04 ff 00 05 10 00 00 05 28 05 00 05 o...(...
Columns 1, 3, 4, 5, 7, 8, 9 ... are all equal, only the columns 2, 6, 10, 14
... contain different values across the files, which basically means that 3 out
of
4 bytes are completely identical between the 4 dumps.
(this is, where I think something might have gone wrong with the dumps :)
Anyway, extracting the data from the columns where the dumps actually differ
gives the following data [1]:
$ xxd col.data | head -4
000: ff10 a000 05fe 00ff 0500 4200 0550 4205 ..B..PB.
010: 0510 05b4 1105 0510 05b4 0005
020: 0510 1100 05b4 0005 0510 05b4 1105
030: 1310 05b4 0005 0510 1100 05b4 0005
Comparing this with the dump from z3801a ROM:
$ xxd z3801a.bin | head -4
000: 0010 fffe 0550 0010 05b4 0010 05b4 ...P
010: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
020: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
030: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
Suggests that there is some kind of reordering required to get the similar
structure present in the hardware vector table.
The following mapping seems to do the trick:
Pick every odd byte from the data and switch every two resulting bytes, or as
pseudocode:
for (n = 0; n 2; n++) {
for (i = 0; i dlen; i += 4) {
j = i/2;
split[n][j + 0] = data[i + n + 2];
split[n][j + 1] = data[i + n + 0];
}
}
The resulting data [2] seems to contain meaningful strings and binary code
similar to the z3801a ROM:
$ strings split.data | grep psos
@(#)$Header: psos.S,v 1.4 95/01/11 15:27:21 jacob Exp $
@(#)$Header: psos_indep.h,v 1.5 95/03/24 15:24:19 da oe uxn d
@(#)$Header: psos.S,v 1.4 95/01/11 15:27:21 jacob Exp $
@(#)$Header: psos_indep.h,v 1.5 95/03/24 15:24:19 da oe uxn d
HTH,
Herbert
[1] http://vserver.13thfloor.at/Stuff/VARIOUS/Z3805/col1.data
[2] http://vserver.13thfloor.at/Stuff/VARIOUS/Z3805/split1.data
I can't see any strings that make sense like the Z3801A flash.
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Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Am 17.04.2013 15:23, schrieb David: ... I have been looking into low jitter triggers for sampling systems recently and will probably end up using a discrete differential amplifier driving ECL logic. Why discrete? ___ 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Hi The high gain stuff was in relation to the front end that's optimized to convert sine waves to logic levels. It sounded like they are doing some sort of saturated stage and then converting it's output to ECL. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Wednesday, April 17, 2013 9:20 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver On 4/17/13 4:26 AM, Bob Camp wrote: Hi The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. I thought the whole point of fast ECL logic was that it never saturated. Of course these days, one might have very fast saturating logic that happens to have ECL logic levels and run off that ever so convenient -5.2 V power supply. ___ 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 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Hi I have no real idea how they distinguish their high gain front end from a comparator. Judging from the way it was rattled off, I suspect there's a patent application floating around somewhere. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David Sent: Wednesday, April 17, 2013 9:24 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver On Wed, 17 Apr 2013 07:26:46 -0400, Bob Camp li...@rtty.us wrote: On Apr 16, 2013, at 9:51 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 4/14/2013 7:48 AM, Brian Davis wrote: Not sure if it's already been mentioned, but Linear has introduced a new part that looks interesting : LTC6957 Low Phase Noise Buffer/Driver http://www.linear.com/product/LTC6957-1 This is VERY interesting, especially the low noise PECL output. I have never seen any ECL device ever come close to that noise level. It would be interesting to see how they did that. The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. What criteria do they use to distinguish the two? Application? Differential inputs and outputs? I am not surprised that it would have lower jitter than ECL if the later lacks an independent external reference. I have been looking into low jitter triggers for sampling systems recently and will probably end up using a discrete differential amplifier driving ECL logic. ___ 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 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Hi The EL16 is pretty much the standard go to part for a lot of ECL conversion stuff. It's commonly thought to be pretty good. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ewkeh...@aol.com Sent: Wednesday, April 17, 2013 10:20 AM To: time-nuts@febo.com Subject: Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver In some of my projects I like to use the MC10EL16. Does any one have an opinion on it? Bert Kehren In a message dated 4/17/2013 9:31:57 A.M. Eastern Daylight Time, davidwh...@gmail.com writes: On Wed, 17 Apr 2013 07:26:46 -0400, Bob Camp li...@rtty.us wrote: On Apr 16, 2013, at 9:51 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 4/14/2013 7:48 AM, Brian Davis wrote: Not sure if it's already been mentioned, but Linear has introduced a new part that looks interesting : LTC6957 Low Phase Noise Buffer/Driver http://www.linear.com/product/LTC6957-1 This is VERY interesting, especially the low noise PECL output. I have never seen any ECL device ever come close to that noise level. It would be interesting to see how they did that. The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. What criteria do they use to distinguish the two? Application? Differential inputs and outputs? I am not surprised that it would have lower jitter than ECL if the later lacks an independent external reference. I have been looking into low jitter triggers for sampling systems recently and will probably end up using a discrete differential amplifier driving ECL logic. ___ 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 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 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Hi That's sort of what I'm hoping to find out. The plan is to see how it does over the range that a TimePod will cover, and draw some conclusions. I'd be a bit surprised if it did well on *really* slow edges. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of cdel...@juno.com Sent: Wednesday, April 17, 2013 11:31 AM To: time-nuts@febo.com Subject: Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver Very high gain front end. It's a saturating amp rather than a comparator. Wonder how it would work as a DMTD front end? Corby ___ 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 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.
Re: [time-nuts] Z3805A flash dump.
I suspect your reader is not configured correctly. For example, look at the first 80 bytes of each BIN file; they should not be so identical. After you fix that, then combining low/high bytes will give you what you want. See http://leapsecond.com/museum/z3801a/eeprom.htm for an example of the result. /tvb - Original Message - From: Mark C. Stephens ma...@non-stop.com.au To: time-nuts@febo.com Sent: Wednesday, April 17, 2013 1:31 AM Subject: [time-nuts] Z3805A flash dump. I have dumped the 4 flash ROMS from my latest Z3805A but I can't make head nor tail of the contents. I am thinking the flash are interleaved. http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar I can't see any strings that make sense like the Z3801A flash. ___ 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.
Re: [time-nuts] Z3805A flash dump.
In message AA42DD206D5541258C6A474D42B3C0F1@pc52, Tom Van Baak writes: After you fix that, then combining low/high bytes will give you what you want. See http://leapsecond.com/museum/z3801a/eeprom.htm for an example of the result. /tvb If anybody feels like disassembling the code, I have started a python based reverse engineering kit called PyReveng for such jobs: https://github.com/bsdphk/PyRevEng -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
Re: [time-nuts] Z3805A flash dump.
Hi Tom: What CPU chip does the Z3805 use? When working with the PIC microcontrollers it's possible to generate pseudo source code that can be assembled to yield the actual binary image. By placing a comment at the end of each line that contains the original binary hex you can audit that no mistakes have been made. Then it's just a process of adding names to replace the hex links and after some work you have a commented source listing. But, it takes an assembler and source code generator for the CPU that's being used. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Tom Van Baak wrote: I suspect your reader is not configured correctly. For example, look at the first 80 bytes of each BIN file; they should not be so identical. After you fix that, then combining low/high bytes will give you what you want. See http://leapsecond.com/museum/z3801a/eeprom.htm for an example of the result. /tvb - Original Message - From: Mark C. Stephens ma...@non-stop.com.au To: time-nuts@febo.com Sent: Wednesday, April 17, 2013 1:31 AM Subject: [time-nuts] Z3805A flash dump. I have dumped the 4 flash ROMS from my latest Z3805A but I can't make head nor tail of the contents. I am thinking the flash are interleaved. http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar I can't see any strings that make sense like the Z3801A flash. ___ 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 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.
Re: [time-nuts] Z3805A flash dump.
On Wed, Apr 17, 2013 at 03:38:56PM +, Mark C. Stephens wrote:
It is possible I didn't take the dump correctly,
or there is a problem with my burner.
I chose Binary when saving files.
That's always a good choice :)
Perhaps, the other possibility is those flash chips
aren't the actual firmware, just storage.
The actual firmware (program) flash chip could be
located elsewhere.
Unlikely, otherwise I would not have been able to
reconstruct the (maybe?) partial data from your dumps.
(see the files I linked in the previous reply)
However, that would seem a bit strange to me, why
socket transient memory and not the actual program
itself?
How should I have taken the flash dumps?
I do not even know what ROM/Flash? chips are used
in this device, but from your reply I conclude that
they are socketed and you were able to read them
via some kind of EEPROM reader/burner?
If so, given that the 'reader' supports the chips
in question, I'd say your dumps are probably fine.
A good method is to dump each chip several times
(if possible in different ways) and compare the
results.
Assuming that everything was dumped correctly, it
might simply be that the device uses only a small
portion of the ROM/Flash for PSOS (operating system)
and the rest for data storage or checksumming.
A schematic how the chips connect to the CPU might
sched some light on the data stored/used as might
more information about the involved components.
best,
Herbert
-mark
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Herbert Poetzl
Sent: Thursday, 18 April 2013 12:43 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Z3805A flash dump.
On Wed, Apr 17, 2013 at 08:31:49AM +, Mark C. Stephens wrote:
I have dumped the 4 flash ROMS from my latest Z3805A but I can't make
head nor tail of the contents.
I am thinking the flash are interleaved.
Interleaving makes sense for performance reasons and usually
happens at bit or byte level, but I'm not (yet) convinced that
the data was dumped correctly.
http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar
Assuming that the Z3801A and Z3805A ROM contents is somewhat similar (1x512k
= 4x128k), let's take a look at the entropy of the data:
$ cat z3801a.bin | xz --stdout | wc -c
110020
$ cat z3805-*.bin | xz --stdout | wc -c
60436
This rough estimate on the amount of non redundant data shows that the z3801a
ROM contains almost twice as much data than the z3805 ROM dumps together.
$ for n in z3805-*.bin; do xz --stdout $n | wc -c; done
25108
30724
24712
22812
This shows that the data is almost evenly distribute between the four dumps,
so some kind of interleaving is obviously present and none of the files are
purely random or contain just padding or similar like:
$ dd if=/dev/urandom bs=1k count=128 | xz --stdout | wc -c
131140
$ dd if=/dev/zero bs=1k count=128 | xz --stdout | wc -c
152
Now looking at the data itself, it is simple to see that there is a
positional redundancy present:
$ for n in z3805-*.bin; do xxd -g 1 $n | head -1; done
000: 6f ff 00 05 04 05 00 05 10 05 00 05 28 05 00 05 o...(...
000: 6f 10 00 05 04 fe 00 05 10 00 00 05 28 50 00 05 o...(P..
000: 6f a0 00 05 04 00 00 05 10 42 00 05 28 42 00 05 oB..(B..
000: 6f 00 00 05 04 ff 00 05 10 00 00 05 28 05 00 05 o...(...
Columns 1, 3, 4, 5, 7, 8, 9 ... are all equal, only the columns 2, 6, 10, 14
... contain different values across the files, which basically means that 3
out of
4 bytes are completely identical between the 4 dumps.
(this is, where I think something might have gone wrong with the dumps :)
Anyway, extracting the data from the columns where the dumps actually differ
gives the following data [1]:
$ xxd col.data | head -4
000: ff10 a000 05fe 00ff 0500 4200 0550 4205 ..B..PB.
010: 0510 05b4 1105 0510 05b4 0005
020: 0510 1100 05b4 0005 0510 05b4 1105
030: 1310 05b4 0005 0510 1100 05b4 0005
Comparing this with the dump from z3801a ROM:
$ xxd z3801a.bin | head -4
000: 0010 fffe 0550 0010 05b4 0010 05b4 ...P
010: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
020: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
030: 0010 05b4 0010 05b4 0010 05b4 0010 05b4
Suggests that there is some kind of reordering required to get the similar
structure present in the hardware vector table.
The following mapping seems to do the trick:
Pick every odd byte from the data and switch every two resulting bytes, or as
pseudocode:
for (n = 0; n 2; n++) {
for (i = 0; i dlen; i += 4) {
j = i/2;
split[n][j + 0] = data[i + n + 2];
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
ewkeh...@aol.com wrote: In some of my projects I like to use the MC10EL16. Does any one have an opinion on it? Bert Kehren I have used the MC10X116 series of line receivers going back to the old MC1000 family, which went out of production 35 years ago. The MC10EL16 should have been called MC10EL116 IMHO for consistency to avoid confusion with the MC10X016 series of 4 bit counters. But I digress. These line receivers are wonderful parts that are totally bulletproof and work every time. We used to use them in frequency counters. At Zeta labs, they were often used as sine wave to logic buffers. There is just one huge drawback: the phase noise is only in the mid -140's. Over the years as faster versions of this part have come out in newer logic families, the bandwidth has increased with the predictable effect of increasing the phase noise. I haven't specifically measured the MC10EL16, but it is very likely it would continue the trend of bad (and getting worse) phase noise. Rick N6RK ___ 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Volker Esper wrote: I have been looking into low jitter triggers for sampling systems recently and will probably end up using a discrete differential amplifier driving ECL logic. Why discrete? ECL style circuits on IC's suffer from high noise in the current source. If you go discrete, you can use an inductor for a current source and get rid of this problem. I think I remember seeing an IC that was designed to use an off chip inductor to do this, but most IC designers have a different agenda than low phase noise. Rick N6RK ___ 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.
Re: [time-nuts] Z3805A flash dump.
Hi Tom, I see my 'Reader' has different options. It's a leaper 3C from Taiwan. You can download the software here: http://www.vk2hmc.net/blog/?wpfb_dl=6 and run it in the demo mode. I guess you could even load the ROM images I took and save them in different format. Under parameters, there are a number of options selectable for data set. 8 Bit, 16 bit (even and odd) and 32bit (1st, 2nd, 3rd, 4th) I was using 8 bit. Perhaps I should have been using one of the other options? mark -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Thursday, 18 April 2013 2:21 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Z3805A flash dump. I suspect your reader is not configured correctly. For example, look at the first 80 bytes of each BIN file; they should not be so identical. After you fix that, then combining low/high bytes will give you what you want. See http://leapsecond.com/museum/z3801a/eeprom.htm for an example of the result. /tvb - Original Message - From: Mark C. Stephens ma...@non-stop.com.au To: time-nuts@febo.com Sent: Wednesday, April 17, 2013 1:31 AM Subject: [time-nuts] Z3805A flash dump. I have dumped the 4 flash ROMS from my latest Z3805A but I can't make head nor tail of the contents. I am thinking the flash are interleaved. http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar I can't see any strings that make sense like the Z3801A flash. ___ 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 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.
Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver
Hi, A possible explanation is that they use the term high gain front end when they assume a controlled noise bandwidth while for a comparator the assume an un-controlled noise bandwidth. The comparator has of coarse also a noise bandwidth that should be controlled by the designer. Henk Op 17 apr. 2013, om 18:12 heeft Bob Camp li...@rtty.us het volgende geschreven: Hi I have no real idea how they distinguish their high gain front end from a comparator. Judging from the way it was rattled off, I suspect there's a patent application floating around somewhere. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David Sent: Wednesday, April 17, 2013 9:24 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LTC6957 Low Phase Noise Buffer/Driver On Wed, 17 Apr 2013 07:26:46 -0400, Bob Camp li...@rtty.us wrote: On Apr 16, 2013, at 9:51 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 4/14/2013 7:48 AM, Brian Davis wrote: Not sure if it's already been mentioned, but Linear has introduced a new part that looks interesting : LTC6957 Low Phase Noise Buffer/Driver http://www.linear.com/product/LTC6957-1 This is VERY interesting, especially the low noise PECL output. I have never seen any ECL device ever come close to that noise level. It would be interesting to see how they did that. The description from their tech guys is Very high gain front end. It's a saturating amp rather than a comparator. What criteria do they use to distinguish the two? Application? Differential inputs and outputs? I am not surprised that it would have lower jitter than ECL if the later lacks an independent external reference. I have been looking into low jitter triggers for sampling systems recently and will probably end up using a discrete differential amplifier driving ECL logic. ___ 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 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 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.
Re: [time-nuts] Z3805A high value PU
On Wed, 17 Apr 2013 08:26:08 +, Mark C. Stephens wrote: On a more serious note, I have rack mounted both clocks with UPS power and they shall not be disturbed. http://www.vk2hmc.net/blog/?p=86 Many thanks, Is it wise to install an unregulated fan inside the 3805 housing , so close to the OCXO ? I'd have thought the OCXO would like it Nice and warm with out thermic disturbances. But the i'm just a t'nut beginner CFO - Denmark ___ 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.
Re: [time-nuts] Z3805A high value PU
Hi CFO, I am normally pretty quiet on the group but I have been lurking and learning for the last 5 or so years. There is an amazing amount of information passed around the timenuts group to depths I often can't fathom. The knowledge gap between me and some of the people here is just plain scary! The 2 Z3805A I received have definitely been force air cooled, the way the dust built up on them suggests a constant flow of air across them. They could have been mounted vertically, the air being sucked out from the top (right on the horizontal). It would be interesting to know what the 'rack' that they came out of looked like and the cooling arrangement. I am kind of hoping the Double oven can take care of itself, and the fan will keep the PSU board nice and cool. I didn't drill holes in the chassis in case we deem it necessary to remove the fan(s) later on. The fans are proper 48v blowers running off 24V. When I removed the power switch, I took the input to the PSU board straight to the cannon connector on the back. I have some young kids that love to play with switches, something I really want to avoid with my GPSDO ;) I also took 2 more wires out of the Cannon connector (+ - 24v) to a flying lead socket to plug the fan in. I have kept all the bits safe so I can restore it to the original condition I received it in, just in case :) mark -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of cfo Sent: Thursday, 18 April 2013 4:32 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Z3805A high value PU On Wed, 17 Apr 2013 08:26:08 +, Mark C. Stephens wrote: On a more serious note, I have rack mounted both clocks with UPS power and they shall not be disturbed. http://www.vk2hmc.net/blog/?p=86 Many thanks, Is it wise to install an unregulated fan inside the 3805 housing , so close to the OCXO ? I'd have thought the OCXO would like it Nice and warm with out thermic disturbances. But the i'm just a t'nut beginner CFO - Denmark ___ 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 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.
Re: [time-nuts] antennas was Re: Common-View GPS Network
Another way to ask this question is what is the effect of a small deviation form the ideal dimensions? If we assume deviations of about 1/20th of a wavelength are OK then we can allow about 1cm of dimensional error. Almost anyone using simple hand tools can do better. With care using primitive garage equipment we can do much better. The old-school hand method for precision sheet metal work was to make a hardwood form and then bend and cut the metal around the wood form. I think if a cake pan would work is a matter of luck. You'd just have to find one within about 2cm of the correct diameter. If not then you be better off starting with flat sheet and hand shears. On Tue, Apr 16, 2013 at 10:46 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: From: Sarah White I just have to ask though... cake pans? really? I can't imagine it would even be possible to modify a cake pan with enough accuracy to get a usable antenna. -- 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.
Re: [time-nuts] antennas was Re: Common-View GPS Network
But the pan is just a ground plane. It isn't a reflector based on the type of antennas I saw in the photograph. Sent via BlackBerry from T-Mobile -Original Message- From: Chris Albertson albertson.ch...@gmail.com Sender: time-nuts-boun...@febo.com Date: Wed, 17 Apr 2013 12:18:00 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] antennas was Re: Common-View GPS Network Another way to ask this question is what is the effect of a small deviation form the ideal dimensions? If we assume deviations of about 1/20th of a wavelength are OK then we can allow about 1cm of dimensional error. Almost anyone using simple hand tools can do better. With care using primitive garage equipment we can do much better. The old-school hand method for precision sheet metal work was to make a hardwood form and then bend and cut the metal around the wood form. I think if a cake pan would work is a matter of luck. You'd just have to find one within about 2cm of the correct diameter. If not then you be better off starting with flat sheet and hand shears. On Tue, Apr 16, 2013 at 10:46 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: From: Sarah White I just have to ask though... cake pans? really? I can't imagine it would even be possible to modify a cake pan with enough accuracy to get a usable antenna. -- 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. ___ 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.
Re: [time-nuts] antennas was Re: Common-View GPS Network
On 4/17/13 12:18 PM, Chris Albertson wrote: Another way to ask this question is what is the effect of a small deviation form the ideal dimensions? If we assume deviations of about 1/20th of a wavelength are OK then we can allow about 1cm of dimensional error. Almost anyone using simple hand tools can do better. With care using primitive garage equipment we can do much better. The old-school hand method for precision sheet metal work was to make a hardwood form and then bend and cut the metal around the wood form. I think if a cake pan would work is a matter of luck. You'd just have to find one within about 2cm of the correct diameter. If not then you be better off starting with flat sheet and hand shears. since you can buy cake pans in even inch increments, I think the cake pan will work.. BTW, I've been looking at some choke rings with only 2 rings instead of the usual 3. Apparently, the performance isn't all that much different. When I asked why do all the other ones have 3, it boils down to the first one had 3 and everyone just copied it. Javad has a bunch of choke ring theory.. http://www.javad.com/jns/index.html?/jns/technology/Single-Depth%20Low-Multipath%20Choke%20Ring.html http://www.javad.com/jns/index.html?/jns/technology/Choke%20Ring%20Theory.html Their conclusion is you want the depth of the ring to be slightly more than 1/4 lambda. lambda/4 for L1 is 1.87 so a 2 cake pan is just about the right size. ___ 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] pin-wheel antenna
There's a very nice picture of a pinwheel from Novatel on the back cover of the March issue of GPS world.. ___ 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.
Re: [time-nuts] antennas was Re: Common-View GPS Network
From: li...@lazygranch.com But the pan is just a ground plane. It isn't a reflector based on the type of antennas I saw in the photograph. = If you are referring to my antenna farm photo, that's correct. It is also magnetic, so it holds the pucks in place. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
