Re: [time-nuts] TICC / TimeLab fun

[John Ackermann N8UR]

Hi Chris --

Two possibilities:

1.  Make sure you have TimeLab set for the correct mode (timestamp vs
time interval), for two channels, and for the right scaling factor (for
timestamps, scale by 1).  Any of those can cause 1e0-type results.

2.  If the two channels have timestamps that are within a few
nanoseconds, there can be a crossover where the channel sequence doesn't
maintain strict "ABABABABAB" order.  TimeLab expects that order and if
you get something like "ABBA" apart from bad '80s music you also get bad
readings.

The easiest way to avoid the problem is to split the TICC output stream
into the two channels and then feed them into TimeLab separately.  It is
possible to do that and still get real time readings by using the "Read
Streaming ASCII file" TimeLab acquire option, but it takes a little
finagling to do it.

[ BTW -- this is not really a "bug" in either the TICC or in TimeLab,
it's just the way things work.  I've spent much time thinking about
addressing it in the TICC code, but there's no sure-fire fix that works
across all possible operating scenarios. ]

Hope this helps.

John

On 4/29/20 1:12 PM, Chris Burford wrote:
> I'm trying to characterize a pair of GPSDO units using the TICC / TimeLab.
> The issue I'm having is when both GPSDO units are wired simultaneously to
> the TICC the resulting ADEV plot looks a little strange, beginning at
> 3.74E-1. Both GPSDO units are referenced against my PRS-10 Rb for the clock
> source.
> 
> If the GPSDO units are wired individually to chA then all seems fine and the
> plot begins with a more anticipated value of about 1.4E-8. I'm at a loss as
> to where to proceed from here to get both units characterized
> simultaneously.
> 
> Thanks for the assistance.
> 
> Chris
> 
> 
> 
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Re: [time-nuts] TICC / TimeLab fun

[John Moran, Scawby Design]

Chris

I don't have any of that kit yet but it seems to me that the two units have 
locked to each other somehow, a bit like the question I raised a while ago 
about crystals locking to each other.

Just a pure guess though.

John
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Re: [time-nuts] TICC / TimeLab fun

[Bob kb8tq]

Hi

You have three inputs to the TICC:

1) The “frequency standard” input that delivers 10 MHz to the device.

2) The (likely pps) to channel A

3) the (likely also pps) to channel B

The device runs a continuous time count based on the frequency standard input. 
Each edge it sees on channel A gets a time stamp indicating when that positive 
edge
happened. It will keep on counting time for quite a while ( = I forget how long 
 :) ). Yes, 
this *assumes* you have the TICC set to time tag. If it is set to something 
else, you will get
whatever you asked for. 

If all you have is a pair of standards, put one into the 10 MHz and the other 
into channel A
or channel B. That gives you the whole picture of what’s happening with the two 
standards.
You have two devices and thus only one difference. It will show you that 
difference. 

Unless you have a third accurate standard, that’s as far as you can go. TimeLab 
needs to understand
what it is being fed. If it does, you will get a plot of some sort. It may be 
the noise floor of the
TICC.

With a third standard, it depends a bit on just *where* you decide to feed it 
in. Does it go into
the reference input at 10 MHz? Is it one of the “likely a pps” signals? In most 
(but not all) cases
it does go into the 10 MHz input. 

First step in doing three is to do a noise floor check. Grab a piece of coax to 
offset the pps to 
channel A vs channel B. With a single source feeding both inputs (and the 
device set up properly)
the data output (chan A vs chan B)  will be the noise floor of the TICC. If 
it’s not, either the TICC
has a setup gotcha or TimeLab does not understand what it needs to do.  To keep 
everything happy
coax in the range of 20 or 30 feet should work fine. 

The same process (sort of) could be done with a device that delivers both a pps 
and 10 MHz. You
could feed it into the TICC the same way as a two standard test. The result 
would be the noise floor
of the TICC plus the noise  in the 1 pps divider chain. Is the divider in this 
or that device more or less
noisy than the TICC? Who knows …...

Bob

> On Apr 29, 2020, at 1:12 PM, Chris Burford  wrote:
> 
> I'm trying to characterize a pair of GPSDO units using the TICC / TimeLab.
> The issue I'm having is when both GPSDO units are wired simultaneously to
> the TICC the resulting ADEV plot looks a little strange, beginning at
> 3.74E-1. Both GPSDO units are referenced against my PRS-10 Rb for the clock
> source.
> 
> If the GPSDO units are wired individually to chA then all seems fine and the
> plot begins with a more anticipated value of about 1.4E-8. I'm at a loss as
> to where to proceed from here to get both units characterized
> simultaneously.
> 
> Thanks for the assistance.
> 
> Chris
> 
> 
>  Channel.png>___
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[time-nuts] GPS antenna splitter recommendation?

[Frank O'Donnell]

I'm looking for a splitter to allow three or four GPSDO's to share my 
roof-mounted Lucent PCTEL KS24019L112C 26db GPS twist antenna.


I understand from scanning past threads that inexpensive splitters by 
companies like Mini-Circuits often turn up on eBay, but I'm having 
trouble narrowing down to one that will work for my situation. Can 
anyone recommend a specific splitter that wouldn't be too expensive?


Thanks much,

Frank




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[time-nuts] TICC / TimeLab fun

[Mark Sims]

Lady Heather's TICC parser does not expect alternating ABAB readings and 
handles the ABAB vs ABBA situation properly.
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Re: [time-nuts] GPS antenna splitter recommendation?

[Bob kb8tq]

Hi

Here’s a few:


https://www.ebay.com/itm/MINI-CIRCUITS-ZN2PD2-50-S-500-5000-MHz-DC-PASS-POWER-SPLITTER-COMBINER-SMA-RF/303304610774?_trkparms=ispr%3D1&hash=item469e5d13d6:g:lnkAAOSwadda-dWk&enc=AQAEAAACcIQvEcHUrT7nmUC3yY5qbPyaBN1nJEDYW8MyypsJPgXKJXIsITcN%2FKrpKO55R9QEPxkxT2C13G%2F8Xk%2FPP292RqnkdoqMREuiokDYomKFgDYMyHK5NpBmYMrTGVRBghCM9ucW5EHQatAcaroMUERVocWILBJZr0aAL1rg0BMb2FAEC95paFI6Exo4L0NvOSnUXBhmsTofTuG4acn5hM%2B3rU21j6tKdyUwbBGWWvsvmgYGGqawn%2BZ5hoJBdodFVbrR9vuU%2FTFR3Rs1eNMgxBw3JU3QDd4YPFspcp5Q56lUVqU%2BwjyPY98srkHv4%2FmspPqCZflMtwL4%2Fl2s54WQWL0ilRctyNRd9Eklavo%2FRPLKMqaLl8YufMK6My0G6TKwQE76FVvs2rlM5FAvQki2ZpLtWHDH8jbtZ%2BrznJ00vHBvzeQD76ER991HEZ9eTDrSumgnul%2BGawZ%2BH1By24%2FZwWzGmHd%2BYkr3INeW2T3jAkDArDDNo%2F0xRvldLmRdZog%2FNYQwSP%2BAoDBym0hUbeDbsmBuKFei0be%2FyKlTSlFNfjq68PsZg%2BtiWaw4Qseki9qCJ%2FeWC93VQpx%2BdGe0jdT6RtSn1sVgWA3N68JtgQLW%2Fdu5fiik6Pilz5gvmtS8FUFUtIGPA%2FFjkfY%2FLZEPscsbNKfL3kybfuP7JA9KCJj2icZcq9lfHA3sL8wyzbn9P87JRwbiJBie3GN6hc7wb2exiQR7DOeCcxgab7MaJgRYp7BhMh%2FgInUCR9oJ4jMYbSx%2FP8tkPog1%2BIO9vbFKkx3Rss5D4FK8CFEulk0%2Fjk4b59m3O9nt7XTmXAPLAlsxNS3JIhTRZg%3D%3D&checksum=303304610774b70feddababe48ce92db06723c4bed61


https://www.ebay.com/itm/Mini-Circuits-ZFRSC-42-S-DC-4200-MHz-2-Way-0-Coaxial-Power-Splitter/362978034441?hash=item54832d4309:g:5LEAAOSwpXBeogtk
 


https://www.ebay.com/itm/Mini-Circuits-ZFSC-2-2500-S-Splitter-10-2500MHz/333575123789?hash=item4daaa0734d:g:YhUAAOSwvXRelgES
 



https://www.ebay.com/itm/Mini-Circuits-ZAPD-21-RF-Signal-Splitter-SMA-Connectors-2-WAY-50-500-2000MHz/392380225626?epid=1901750628&hash=item5b5baf185a:g:LqgAAOSwvf1dUdvN
 


https://www.ebay.com/itm/Mini-Circuits-ZN4PD1-63W-S-RF-Power-Splitter-250-6000MHz-Qty-Available-GOOD/133387795141?hash=item1f0e883ac5:g:tdoAAOSwAbxel2o~
 


https://www.ebay.com/itm/NEW-Mini-Circuits-ZAPD-21-S-DC-Pass-Power-Splitter-Combiner-500-2000MHz/164076236933?hash=item2633b4b085:g:uaIAAOSwR-9eQaf1
 


https://www.ebay.com/itm/New-Mini-Circuits-ZB6PD-2-S-800-2000-MHz-Power-Splitter/114155096838?hash=item1a942c8b06:g:jNIAAOSwedNedT92
 


Now, these are simply pulled out of the first dozen or so hits on an eBay 
search for “Mini Circuits power splitter” on eBay. Anything that covers 1.5 GHz 
will do the job.

Bob


On Apr 29, 2020, at 8:18 PM, Frank O'Donnell  wrote:
> 
> I'm looking for a splitter to allow three or four GPSDO's to share my 
> roof-mounted Lucent PCTEL KS24019L112C 26db GPS twist antenna.
> 
> I understand from scanning past threads that inexpensive splitters by 
> companies like Mini-Circuits often turn up on eBay, but I'm having trouble 
> narrowing down to one that will work for my situation. Can anyone recommend a 
> specific splitter that wouldn't be too expensive?
> 
> Thanks much,
> 
> Frank
> 
> 
> 
> 
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Re: [time-nuts] GPS antenna splitter recommendation?

[Frank O'Donnell]

On 4/29/20 6:01 PM, Bob kb8tq wrote:

Here’s a few:


Bob, thanks very much for the suggestions.

Five of the seven splitters in your list appear to offer a total of two 
output ports. What I'm looking for is one that will accommodate 
(specifically) three or four ports.


Of the remaining two on the list, this one:


https://www.ebay.com/itm/Mini-Circuits-ZN4PD1-63W-S-RF-Power-Splitter-250-6000MHz-Qty-Available-GOOD/133387795141?hash=item1f0e883ac5:g:tdoAAOSwAbxel2o~
 



has five outputs and costs $50. Probably usable, though I was wondering 
if going with additional output ports could increase possible loss? And 
also, the price isn't a show-stopper but is a little high for what I was 
hoping for.


The other one:


https://www.ebay.com/itm/New-Mini-Circuits-ZB6PD-2-S-800-2000-MHz-Power-Splitter/114155096838?hash=item1a942c8b06:g:jNIAAOSwedNedT92
 



isn't entirely clear to me. The text says it's a three-port, but I count 
four visible connectors that look like output ports, and two more that 
might be hiding under caps. This one goes for $19.90.


Given all of that, do either of these two seem like the optimal way to 
go if I want to plug in three or four GPSDO's?


Thanks again,

Frank


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