ZYT GPSDO - Trimble guts - Page 1
Forum section: electronics / testgear

author: kj7e
author_rank: Frequent Contributor
timestamp: July 25, 2019, 06:36:27 pm
content: Picked up one of the recycled Trimble GPSDO units from ZYT_GPS eBay seller;https://www.ebay.com/itm/Trimble-LCD-GPSDO-10MHz-1PPS-OCXO-GPS-Disciplined-Oscillator-2019-5-8/312599997545?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649Very please with it, not had much time to play with it, but it agrees with my BG7TBL NEO-M8T modded GPSDO well within 1mHz, typically within 300uHz or 3^10-11Here are some photos, Ill have to add a few more of the various screens later;

author: kj7e
author_rank: Frequent Contributor
timestamp: July 26, 2019, 01:31:28 pm
content: Its nice to see two GPSDO's agree so closely, using the BG7TBL for the HP 53132A reference and A channel is measuring the ZYT unit. 53132A has a -10MHz offset, 100sec gate. Here, the ZYT is showing 52.7uHz lower than the BG7TBL or < 6^10-12 difference between the two.Some of the other screens and data available from the ZYT unit;The ALM2 is due the GPS antenna power is being fed from my BG7TBL GPSDO, the RF splitter has a DC block on the ZYT port so it thinks the antenna is not connected.

author: kj7e
author_rank: Frequent Contributor
timestamp: July 28, 2019, 01:32:06 pm
content: Attaching the manual.

author: videobelu
author_rank: Newbie
timestamp: August 07, 2019, 02:01:28 pm
content: I i have the model with Symmetricom unit, i send some photos....do you have some suggestion to use Lady Heather with thi unit?I tried to use it and apparently it works, but after a while the system hangs and I have to turn off the GPSDO to restart it .....

author: EV
author_rank: Frequent Contributor
timestamp: November 06, 2019, 09:03:17 am
content: Right click the Lady Heather icon. Choose propeties, write /is after object exe file. After that Lady Heather does not send anything to gps unit and it works ok.

author: samson
author_rank: Contributor
timestamp: October 19, 2021, 05:33:34 am
content: Hi there I got Trimble GPSDO ZYT_GPS-1 I don't know how to program the rs232 .I want to a just the time to local, also the back light to make it stay on longer.I am using usb to rs232 cable brand atten and running windows Vista.lady Heather only works for receiving only.Please if any one could help with this would be appreciate.

author: W3DRK
author_rank: Newbie
timestamp: December 30, 2021, 07:25:04 pm
content: Sorry to revive such an old thread but I have the "improved" version of one of these with the Trimble UCCM on the way. This will be used to replace an older non-LCD Trimble unit I've had for few years that's suddenly gone deaf and barely receives any satellites regardless of antenna/position.I was torn between the Trimble version and the Samsung version since I've heard Samsung UCCMs are actually quite good at dealing with marginal antenna situations thanks to its uBlox receiver. In the end I choose the Trimble version, but I also have a bare Samsung UCCM coming I may try in it too.What are the odds the display firmware is universal and can identify/function with any of the Trimble/Symmetricom/Samsung UCCMs?

author: W3DRK
author_rank: Newbie
timestamp: February 02, 2022, 12:33:16 am
content: I wanted to follow up to my last post as an update to my question as to whether or not the Trimble/Symmetricom/Samsung UCCM-P modules are interchangeable in these ZYT LCD GPSDO units.In my case, at least switching from Trimble to Samsung, the answer is yes. The catch was I had to swap one of the "programming" resistors for the bucking converter to bring the voltage down from 6 volts to 5.7 which make the pickier Samsung UCCM-P happy. But other than that, the display firmware is perfectly happy working with the Samsung and displays as such.

author: nctnico
author_rank: Super Contributor
timestamp: February 02, 2022, 01:23:57 am
content: I have the Trimble version but I must say it is a bit flaky. It drops out of lock and doesn't recover. I'm starting to get the feeling it is somehow broken.

author: videobelu
author_rank: Newbie
timestamp: March 14, 2022, 09:03:20 am
content: Quote from: W3DRK on December 30, 2021, 07:25:04 pmThanks for the information, I don't know if it is possible to switch to the Samsung module also from mine which is a Symmetricom.Can you give me more precise indications of the replacement procedure and also of where you bought the Samsung module?Thank youFabrizioIW1AWF

author: DJ2XH
author_rank: Newbie
timestamp: March 05, 2023, 06:23:19 pm
content: Hi Folks,I am just wondering whether the ZYT-GPSDO-2 LCD SYMMETRICOM 10MHz 1PPS OCXO GPS Diszipliniert Oszillator offered in AliExpress provides more phase stability in comparison to the BG7TBL GPSDO GNSSDO GNSS Disciplined Oscillator Disciplined Clock with 10MHz Output, also offered in AliExpress.The BG7TBL GPSDOs we tested two of those each connected with a separate GPS antenna to synchronize two RF-synthezisers at 110 MHz.We compared the phase drift of the two 110 MHz signals with a amplitude- and phase comparison meter.We measured a phase drift permanetely variating between of more than 180 deg within of app. 60 seconds.The RF-synthezisers keep their phase within 1 deg when connected with the same 10 MHz reference signal -> so, they are ok, as well as the phase comparison meter.My question would be if with the ZYT-GPSDO-2 LCD SYMMETRICOM 10MHz 1PPS OCXO GPSDOr better results can be expected in terms of phase stability?Thanks DJ2XH

author: nctnico
author_rank: Super Contributor
timestamp: March 05, 2023, 06:42:40 pm
content: GPS receivers will drift about (ballpark) +/-50ns in respect to eachother over a 24 hour period. So it is not a surprise that you are seeing large phase shifts on a signal that has a period time which is a magnitude smaller compared to the GPS drift. You'll be better of using a lower frequency that is derived from the GPS receiver. Like 1MHz or so.Comparing GPS receivers without a good reference (like a Cesium clock) is not easy but doable. You'll need to use 3 GPS receivers and run a (at least) 48 hour measurement and compare the phase offset between the receivers. The offset between each combination of GPS receivers should be within the same extremes and have similar stability (Allan deviation).Also make sure the GPS receivers have enough time to establish their fixed position and are running in fixed position mode. This means letting them run for 24 hours (rule of thumb; check the manual for exact specification) before doing any measurement.

author: DJ2XH
author_rank: Newbie
timestamp: March 05, 2023, 07:31:01 pm
content: Hi nctnico,Thank you for your quick and helpful reply.Actually the 110 MHz is a measurement frequency which can not be changed for the planned application.Further is was planned to use the 2. GPSDO with the RF-syntheziser set on board of a hovering drone.So there is no fixed position at least for one set during the measurements.We actually do not need a reference with global accuracy.For the application we only need a relative phase stability or coherence of about 10 deg between the two sets.Best RegardsDJ2XH

author: nctnico
author_rank: Super Contributor
timestamp: March 05, 2023, 08:06:04 pm
content: So you are looking for ballpark 250ps time accuracy. It is not impossible but you won't be able to do this using a GPSDO. How big is your budget? There are companies that offer wireless frequency / time transfer solutions that might be able to meet your requirements but I don't think it will be cheap.The basic idea would be to use the carrier frequency of a transmitter to convey the frequency to the drone so the drone uses the same frequency reference as the ground station but you likely need to adjust for atmospheric conditions.

author: DJ2XH
author_rank: Newbie
timestamp: March 05, 2023, 08:33:23 pm
content: Your suggestion sounds interesting.Actually the distance between the static and the hovering set is not more than 100m.I would have hoped that both sets see nearly the same atmospheric conditions.Do you think that GPSDOs also have a drift of +/-50ns?Even the solution you mentioned might be pretty expensive, can you give me a hint where to look in the internet for those companys?

author: nctnico
author_rank: Super Contributor
timestamp: March 05, 2023, 10:16:08 pm
content: Quote from: DJ2XH on March 05, 2023, 08:33:23 pmYou can try contacting Locata ( locata.com ) which is an Australian company. Other than that I don't know a company that might have an off-the-shelve solution.

author: DJ2XH
author_rank: Newbie
timestamp: March 06, 2023, 08:34:07 am
content: Thank you nctnico for your hint.The website of Locata went dark.Let's see what will happen with them in 2023.

author: probe
author_rank: Contributor
timestamp: May 20, 2023, 07:16:04 am
content: Did you manage to change the LCD backlight timeout? I have the GPSSO-3, the Samsung version, and like you I would like to have the LCD on longer. Lady heather seems to work fine , ublox u-center not so much.

author: cmu2017
author_rank: Contributor
timestamp: May 31, 2023, 08:42:35 am
content: Does anyone also know if newer firmware is available for the ZYT GPSDO 2019? The LCD backlight stays on for me. I would like the LCD backlight turns off after a while. And that the 10MHz Sine wave is immediately available.

author: nikodem
author_rank: Regular Contributor
timestamp: June 06, 2023, 01:56:38 pm
content: I have ordered the ZYT GPSDO-2 from AliExpress some time ago, it has finally arrived... or so I thought. The parcel that I received was emptySo... does anyone has any reliable AliExpress sellers? The ones that I see have no feedback... And I really want this GPSDO