Re: [time-nuts] Question about frequency counter testing

Hi, Magnus! Sorry for the late answer, I injured my left eye last Monday, so had very limited abilities to use computer. From: "Magnus Danielson" As long as the sums C and D becomes correct, your path to it can be whatever. Yes. It produces the same sums. Yes please do, then I can

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Magnus Danielson" You build two sums C and D, one is the phase-samples and the other is phase-samples scaled with their index n in the block. From this you can then using the formulas I provided calculate the least-square phase and frequency, and using

Re: [time-nuts] ✘NEO-M8N vs. NEO-M8T

From: "Bob kb8tq" You have always been able to poll the time offset message on any of the uBlox modules. Getting that message to auto repeat was the traditional issue on there earlier products. A serial dump would tell you if u-center is getting the information by polling or

Re: [time-nuts] ✘NEO-M8N vs. NEO-M8T

Hi! From: "Bob kb8tq" Not by default You go through the 390 pages of their manual and eventually find the bits to turn this and that on. When you do, those magic bits will enable the data on a T version and will not enable it on a non-T version. At least that’s the way it’s

Re: [time-nuts] Question about frequency counter testing

Hi! -- From: "Magnus Danielson" From the 2.5 ns single shot resolution, I deduce a 400 MHz count clock. Yes. It is approx. 400MHz. OK, good to have that verified. Free-running or locked to a 10 MHz reference?

Re: [time-nuts] Question about frequency counter testing

Hi, Magnus! -- From: "Magnus Danielson" 2. Study how PDEV calculation fits on the used HW. If it is possible to do in real time PDEV option can be added. You build two sums C and D, one is the phase-samples and the

Re: [time-nuts] Question about frequency counter testing

Hi From: "Bob kb8tq" What I’m suggesting is that if the hardware is very simple and very cheap, simply put two chips on the board. One runs at Clock A and the other runs at Clock B. At some point in the process you move the decimated data from B over to A and finish out all

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Bob kb8tq" If such conditions detected, I avoid problem by changing the counter clock. But it does not solve the effects at "about OCXO" * N or "about OCXO" / M. It is related to HW and I can probably control it only partially. I will try to improve clock and

Re: [time-nuts] Question about frequency counter testing

Hi Bob! From: "Bob kb8tq" I think it will be more than enough for my needs, at least now. From the 2.5 ns single shot resolution, I deduce a 400 MHz count clock. Yes. It is approx. 400MHz. I think I would spend more time working out what happens at “about 400 MHz” X N or

Re: [time-nuts] Question about frequency counter testing

Hi Magnus, From: "Magnus Danielson" I would be inclined to just continue the MDEV compliant processing instead. If you want the matching ADEV, rescale it using the bias-function, which can be derived out of p.51 of that presentation. You just need to figure out the

Re: [time-nuts] Question about frequency counter testing

Hi Bob! From: "Bob kb8tq" I guess it is time to ask: Is this a commercial product you are designing? No. I have no abilities to produce it commercially and I see no market for such product. I will build one unit for myself, I may build several more units for friends or if

Re: [time-nuts] Question about frequency counter testing

Hi Magnus! From: "Magnus Danielson" The leftmost tau values are skipped and they "stay" inside the counter. If I setup counter to generate lets say 1s stamps (ADEV starts at 1s) it will generate internally 1/8sec averaged measurements, but export combined data for

Re: [time-nuts] Question about frequency counter testing

Hi Bob! From: "Bob kb8tq" It’s only useful if it is accurate. Since you can “do code” that gives you results that are better than reality, simply coming up with a number is not the full answer. To be useful as ADEV, it needs to be correct. I understand it, so I try to

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Magnus Danielson" ADEV assumes brick-wall filtering up to the Nyquist frequency as result of the sample-rate. When you filter the data as you do a Linear Regression / Least Square estimation, the actual bandwidth will be much less, so the ADEV measures

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Bob kb8tq" There is still the problem that the first post on the graph is different depending on the technique. The leftmost tau values are skipped and they "stay" inside the counter. If I setup counter to generate lets say 1s stamps (ADEV starts at 1s) it will

Re: [time-nuts] Question about frequency counter testing

Hi -- From: "Bob kb8tq" The most accurate answer is always “that depends”. The simple answer is no. I have spent the yesterday evening and quite a bit of the night :) reading many interesting papers and several related

Re: [time-nuts] Question about frequency counter testing

Bob, thanks for clarification! From: "Bob kb8tq" If you collect data over the entire second and average that down for a single point, then no, your ADEV will not be correct. That probably explains why I got so nice (and suspicious) plots :) There are a number of papers on

Re: [time-nuts] Question about frequency counter testing

Hi I have got a pair of not so bad OCXOs (Morion GK85). I did some measurements, the results may be interested to others (sorry if not), so I decided to post them. I ran a set of 5minutes long counter runs (two OCXOs were measured against each other), each point is 1sec gate frequency

Re: [time-nuts] Question about frequency counter testing

Hi From: "Bob kb8tq" Sent: Friday, April 27, 2018 4:38 PM Consider a case where the clocks and signals are all clean and stable: Both are within 2.5 ppb of an integer relationship. ( let’s say one is 10 MHz and the other is 400 MHz ). The amount of information in your data

Re: [time-nuts] Question about frequency counter testing

From: "Azelio Boriani" Sent: Friday, April 27, 2018 12:16 AM If your hardware is capable of capturing up to 10 millions of timestamps per second and calculating LR "on the fly", it is not a so simple hardware, unless you consider simple hardware a 5megagates Spartan3

Re: [time-nuts] Question about frequency counter testing

From: "Hal Murray" Sent: Thursday, April 26, 2018 10:28 PM Is there a term for what I think you are doing? I saw different terms like "omega counter" or multiple time-stamp average counter, probably there are others too. If I understand (big if), you are doing the

Re: [time-nuts] Question about frequency counter testing

From: "Azelio Boriani" Sent: Thursday, April 26, 2018 10:06 AM Very fast time-stamping like a stable 5GHz counter? No, it is not 5GHz counter. It does the trick I first saw in CNT91 counters. The hardware is capable of capturing up to 10 millions of timestamps per

[time-nuts] Question about frequency counter testing

Dear Ladies and Gentlemen, Let me tell a little story so you will be able to better understand what my question and what I am doing. I needed to check frequency in several GHz range from time to time. I do not need high absolute precision (anyway this is a reference oscillator problem, not

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

-- From: "Bruce Griffiths" You actually need to measure the filter response. OK. It is here (the frequency span is 2..102MHz, the amplitude axis is 10dB/div): http://skydan.in.ua/PNTestSet/PN_LPF1.jpg Sorry, the

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

-- From: "Bruce Griffiths" Sent: Wednesday, March 30, 2016 7:29 AM To: "Discussion of precise time and frequency measurement" Subject: Re: [time-nuts] Oleg' s PN test Re: A new member & PN test

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

Hi Magnus, Would not GNUradio be a good platform to encode the calibration stuff a little more gift-wrapped? I never used the GNUradio. Basically you can use any SA software/hardware which has the necessary capabilities. What spectrum-analyzer software do you use? (Just curious) It is an

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

Hi, Bruce, Thank you for the comments and useful link. Probably you did not understand the goal and positioning of this "project" and I did not tell the history of how it was build :) So, the solely goal of making this "test set" was to assist with the design of the synthesizer unit for my

Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

Hi, everybody! OK. Let's start. Here is the schematics of the "test set" http://skydan.in.ua/PNTestSet/PN%20Test%20set.pdf . It consists of three small boards: 1. Mixer board - a simple mixer (500MHz ADE-1+) with 200kHz pi-LPF at the mixer output. 2. LNA board - a non-inverting low noise AF

[time-nuts] A new member & PN test set

Hi list, I am in a process of making a low noise frequency synthesizer for the 1st LO for my new DSP HF transceiver (http://neon.skydan.in.ua). This list is not directly related to my project, but I found a lot of useful information in this list - thanks for all contributors! I see a discussion