GPSDO vs Rubidium with a 53230A counter - Page 1
Forum section: electronics / general

author: TheSteve
author_rank: Unknown
timestamp: July 02, 2017, 05:06:00 am
content: I recently picked up an Agilent 53230A frequency counter. I thought I would use my GPSDO as the reference in and compare it to my Rubidium standard.This is a plot of 10000+ readings, 12 digits, 1 second gate time, the min/max are set by the first 500 readings.I know HighVoltage has the same counter,a GPSDO and Rubidium standard, hopefully he can post a shot of his to see how it compares.

author: 0.01C
author_rank: Regular Contributor
timestamp: July 02, 2017, 01:42:44 pm
content: I will try

author: Dr. Frank
author_rank: Super Contributor
timestamp: July 02, 2017, 02:13:52 pm
content: GPSDO have mediocre short - and mid-term Allan stability, compared to an Rb standard.Better use the TimeLab package and the 53230A as a T.I. counter for the 1pps signals, to adjust the Rb standard to 1E-11 level, which will at least take several hours to mitigate even these mid-term variations of the GPSDO.Frank

author: HighVoltage
author_rank: Super Contributor
timestamp: July 02, 2017, 08:48:29 pm
content: My old HP GPSDO seems to be very stable but I do not have a working Rubidium standard at the moment.I will set up this test with my stable external OCXO, it will be a good basis for a future RB test.

author: TheSteve
author_rank: Unknown
timestamp: July 02, 2017, 10:26:12 pm
content: My GPSDO is a Trimble 63090 which came from a WCDMA site in Japan. My Rubidium standard is a repaired LPFRS-01. So neither are anything super exciting. The GPSDO does have a 1 PPS output but the Rubidium is 10 MHz only. I thought it might be interesting to see how others compared.I'll certainly have to fire up TimeLab with the 53230AI left it running overnight, 59000 + samples with the GPSDO as external reference and the rubidium as the input.Here are the results:

author: HighVoltage
author_rank: Super Contributor
timestamp: July 03, 2017, 12:42:53 pm
content: I am warming up my equipment.Last time I used these three counters was many month ago.Isn't it just amazing how close they are to each other, when measuring the HP GPSDO?The HP Z3805A needs about 2 hours to be in GPS Lock mode.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 04, 2017, 02:51:27 pm
content: TheSteveHow did you get such a nice histogram of your measurement.This was just measured on one channel, right?Here is my attempt to get a good relationship between my GPSDO and external Piezo 10 MHz OCXOPlus, how did you get a screen dump on your 53230A, it seems my instrument does not want to do that.So, here is a picture of the screenAfter 3587 measurements, only 582 pHz Pk to PkI find this kind of remarkable, or I am wrong?The 53230A runs on its own internal OCXO reference.

author: VK5RC
author_rank: Unknown
timestamp: July 05, 2017, 01:48:35 am
content: When I get home I can set up a similar trial, 53230, z3805 (it stays on continuously) and a Efratom lpro Rubidium.Aren't we really comparing the different disciplining protocols, both use a quartz crystal one disciplined by the Ru RF transition, the other indirectly Caesium?

author: TheSteve
author_rank: Unknown
timestamp: July 05, 2017, 03:21:07 am
content: HighVoltage - Saving a screen shot is anything but intuitive with these things - The sequence is Utility, System Setup, Manage Files, then for the action select "capture" - you can pick internal or external memory such as a USB drive.VK5RC - I am really just looking at how my GPSDO and Rubidium references differ. Obviously any error I see can be from either device as my GPSDO is external reference for the counter and I am logging the data from the Rubidium standard.My first post is a Histogram with a readings set to 500, a 1 second gate time, 12 digits. My second is the same config but I have math enabled which can display Allan Deviation.I just bought another GPSDO today (Symmetricom 58503B), so once it arrives and has warmed up for a few days I'll compare it to my Trimble to see how much they wander around.

author: VK5RC
author_rank: Unknown
timestamp: July 08, 2017, 10:11:23 am
content: When I got home my wife had unplugged my z3805 to charge some garden tool battery.Yesterday I was getting result of 1000uHz StanDev and AllanDev of 150uHz or so in the first few hours.Quite a lot better tonight.After 24hrs warm up , I get the results below over 20mins or so.Edit; input is 50 ohms (or so) via a 3dB attenuator.