bg7tbl gpsdo master reference

[motocoder]

Can't compare it to other boards/versions but it seems to work just fine. Using the uBlox software from here -> https://www.u-blox.com/en/product/u-center-windows, it seems to be locked on and FWIW, I'm most happy with the frequency stability with my radio in narrow modes.

So the serial port is directly connected to the UBlox? Is there another processor on the board?

[KA1J]

Can't compare it to other boards/versions but it seems to work just fine. Using the uBlox software from here -> https://www.u-blox.com/en/product/u-center-windows, it seems to be locked on and FWIW, I'm most happy with the frequency stability with my radio in narrow modes.

So the serial port is directly connected to the UBlox? Is there another processor on the board?

Unfortunately, I have no idea. Perhaps the chips in the photos can answer that? They don't provide any block diagram or paperwork of any kind with the unit but; connecting the RS232 to USB cable to the BG7TBL and the other to the USB port in the computer and by selecting the open port seen in the receiver setup in the uBlox software, gives me the data on the graph I posted above.

[motocoder]

Can't compare it to other boards/versions but it seems to work just fine. Using the uBlox software from here -> https://www.u-blox.com/en/product/u-center-windows, it seems to be locked on and FWIW, I'm most happy with the frequency stability with my radio in narrow modes.

So the serial port is directly connected to the UBlox? Is there another processor on the board?

Unfortunately, I have no idea. Perhaps the chips in the photos can answer that? They don't provide any block diagram or paperwork of any kind with the unit but; connecting the RS232 to USB cable to the BG7TBL and the other to the USB port in the computer and by selecting the open port seen in the receiver setup in the uBlox software, gives me the data on the graph I posted above.

Ok, I suspect it's like several of the other BG7TBL designs. There is an 8-bit micro on there which is communicating with the uBlox chip. The RS232 cable is connected. via a MAX232, to the Tx of the uBlox chip. So the PC can listen to the uBlox data, but not configure it at all (because the 8-bit micro is connected to the uBlox Rx). It's an OK set-up for most people's needs.

[jeffsf]

Has anyone tried the BG7TBL distribution amp?

[KA1J]

I've tried unsuccessfully, to find a software to sync the BG7TBL with my computer.  I've tried all that I could find and none of them work properly, some made the date crazy as in month 25 in year 1999 & 2025. The U-Blox "U-Center" displays an accurate clock but there's no method to sync it to the computer.

Any suggestions of a software that works with Windows?

Thanks.

[motocoder]

I've tried unsuccessfully, to find a software to sync the BG7TBL with my computer.  I've tried all that I could find and none of them work properly, some made the date crazy as in month 25 in year 1999 & 2025. The U-Blox "U-Center" displays an accurate clock but there's no method to sync it to the computer.

Any suggestions of a software that works with Windows?

Thanks.

I think you could attach it to a Raspberry Pi set up to be an NTP server, and then configure Windows to sync with that NTP server. Here is one article discussing using the RPi + a GPSDO as an NTP server:

http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

Windows has built-in support for syncing with an NTP server.

[KA1J]

I've tried unsuccessfully, to find a software to sync the BG7TBL with my computer.  I've tried all that I could find and none of them work properly, some made the date crazy as in month 25 in year 1999 & 2025. The U-Blox "U-Center" displays an accurate clock but there's no method to sync it to the computer.

Any suggestions of a software that works with Windows?

Thanks.

I think you could attach it to a Raspberry Pi set up to be an NTP server, and then configure Windows to sync with that NTP server. Here is one article discussing using the RPi + a GPSDO as an NTP server:

http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

Windows has built-in support for syncing with an NTP server.

I very much appreciate the reply.

First, I wanted the GPSDO to maintain the maximum frequency stability with my radio and to this end, that has been accomplished.

2nd, I've had lousy luck getting windows to sync properly. For whatever reason, it can't seem to reach their servers. As I'm not using a firewall other than native Windows 10 firewall, it should go right through. I really don't have to have the ultra close tolerance of time the GPSDO provides but I have found my computer strays a few seconds/day and if I don't keep it constantly adjusted it affects my log time in ham radio and that of contest start and stops. Having the proper time within a second is necessary for me in this regard. The old Windows adjustment was more obvious with the seconds being easy to work with, win 10 was made by people on a bad day.

3rd, Its frustrating that literally every single software that claims to sync your computer with a GPS that I have found, has failed to sync and most often, can't even find the satellites even when I put in parameters that other software accepts and finds them instantly. Not one software both IDs the satellites and syncs. So I have tried many different NTP programs and the one that always worked was the one from NIST but it had to be manually started each time I ran windows, a PITA. I finally found NetTime http://www.timesynctool.com/ an open source tool which syncs with an NTP server and corrects the time every 15 minutes. I would have rather synced via satellite but till I find something that works as advertised, this will have to do.

Thanks again for the reply and for suggesting a workable solution!

[motocoder]

I've tried unsuccessfully, to find a software to sync the BG7TBL with my computer.  I've tried all that I could find and none of them work properly, some made the date crazy as in month 25 in year 1999 & 2025. The U-Blox "U-Center" displays an accurate clock but there's no method to sync it to the computer.

Any suggestions of a software that works with Windows?

Thanks.

I think you could attach it to a Raspberry Pi set up to be an NTP server, and then configure Windows to sync with that NTP server. Here is one article discussing using the RPi + a GPSDO as an NTP server:

http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

Windows has built-in support for syncing with an NTP server.

I very much appreciate the reply.

First, I wanted the GPSDO to maintain the maximum frequency stability with my radio and to this end, that has been accomplished.

2nd, I've had lousy luck getting windows to sync properly. For whatever reason, it can't seem to reach their servers. As I'm not using a firewall other than native Windows 10 firewall, it should go right through. I really don't have to have the ultra close tolerance of time the GPSDO provides but I have found my computer strays a few seconds/day and if I don't keep it constantly adjusted it affects my log time in ham radio and that of contest start and stops. Having the proper time within a second is necessary for me in this regard. The old Windows adjustment was more obvious with the seconds being easy to work with, win 10 was made by people on a bad day.

3rd, Its frustrating that literally every single software that claims to sync your computer with a GPS that I have found, has failed to sync and most often, can't even find the satellites even when I put in parameters that other software accepts and finds them instantly. Not one software both IDs the satellites and syncs. So I have tried many different NTP programs and the one that always worked was the one from NIST but it had to be manually started each time I ran windows, a PITA. I finally found NetTime http://www.timesynctool.com/ an open source tool which syncs with an NTP server and corrects the time every 15 minutes. I would have rather synced via satellite but till I find something that works as advertised, this will have to do.

Thanks again for the reply and for suggesting a workable solution!

I've observed the behavior that you describe w.r.t. Windows being a bit out of sync with the configured time servers. I'm not sure what the behavior is in Windows 10, but I believe in Windows 7 and earlier the time synchronization only runs once per week!  For server versions of Windows, the typical configuration would have the machines synchronizing with a domain controller. I suspect the Windows team was trying to balance load on the time servers. The people operating those were probably quite fearful of tens or hundreds of windows machines all banging on their servers every few minutes.

I do know there were some NTP-related improvements in Windows 10. That web site I linked to earlier has a fair amount of info on setting up NTP on Windows. I would take a look there, and maybe even email the owner.

http://www.satsignal.eu/ntp/Win-7_to_Win-10_upgrade.html

[edpalmer42]

Have you looked at the standard NTPD package?  I don't know if there is a reference clock that understands U-blox binary format, but you might be able to find something.

I believe that there are also registry hacks to modify the operation of Windows built-in NTP client.

Ed

[motocoder]

Have you looked at the standard NTPD package?  I don't know if there is a reference clock that understands U-blox binary format, but you might be able to find something.

I believe that there are also registry hacks to modify the operation of Windows built-in NTP client.

Ed

AFAIK, the output from the BG7TBL units with UBlox are standard NMEA text strings. There will also be some Ublox specific ones in there, but it should all be text strings in NMEA format and those should just get ignored by the software.

[motocoder]

Oh, also make sure the Windows Time Service is set to run continuously. In services.msc, the Startup Type should be "Automatic". Looks like it is set to Manual by default, and is probably triggered periodically by some scheduled task. Once you've done that, this page has some info on using the w32tm utility to configure Windows to sync against a particular NTP server(s). You can point it at the RPi NTP server on your local network. There is also an example showing how to configure a laptop to sync from one server when it's available, but from an Internet server when it's not.

http://support.ntp.org/bin/view/Support/WindowsTimeService

Once this is set up,  you can run "w32tm /resync" to force Windows to start an immediate synchronization with the time server. However, it may take some time for things to actually sync up, because the OS will try and speed up or slow down the clock to gradually bring things into sync (it doesn't abruptly change the time). You can use "w32tm /query /status /verbose" to get some info on where this process is at.

Note, I found all this by searching and reading various articles online. Although I work for Microsoft, I don't have any contacts in the team that owns this. I will see if I can find someone that knows a bit more about this to validate the info I've provided here.

[edpalmer42]

AFAIK, the output from the BG7TBL units with UBlox are standard NMEA text strings. There will also be some Ublox specific ones in there, but it should all be text strings in NMEA format and those should just get ignored by the software.

Okay, I assumed that the output would be U-blox binary.  If it's NMEA, then there's an NTP reference clock that understands NMEA.  Should be easy to use NTPD to keep the PC clock on time and/or turn that PC into a Stratum 1 NTP server.

Ed

[motocoder]

Ok, I have Windows synchronizing with an NTP server reliably now. Here is how I have set things up. I am running Windows 10, but I think this should work with previous versions of Windows.

1) Set Windows Time Service to run continuously. Click Start/Run and enter "services.msc". This should open the Services control panel applet. Scroll down to "Windows Time", right click, select "Properties" in the pop-up menu, and in the properties window change "Startup type" to either "Automatic" or "Automatic (Delayed Start)". Click OK to save your changes.

2) Configure the time service to point to your NTP server. I am using a remote NTP server in the example below, but if you've set up a local NTP server linked to your GPSDO, you should use the IP address or hostname of that in this command. Open a Administrative CMD prompt and enter this:

Code: [Select]

w32tm /config /update /manualpeerlist:"0.pool.ntp.org,0x8 1.pool.ntp.org,0x8 2.pool.ntp.org,0x8 3.pool.ntp.org,0x8" /syncfromflags:MANUAL
Here we have configured the system with 4 different NTP servers, (0.pool.ntp.org, 1.pool.ntp.org, etc). It will pick one, and use the others in the event the primary server is not available. The ",0x8" on the end of the server name is a flag to tell it to operate in NTP client mode (see NTP docs on this, but this is what you want).  The /syncfromflags:MANUAL tells it to use the servers in the manualpeerlist. If your computer is on the domain,  you would instead use /syncfromflags:MANUAL,DOMHIER. This will tell the time service to use the local domain controller if it's available, but to fall back to the ntp.org time servers if not (for example if your laptop is not connected to the network with the domain controller).

3) Next we need to change some default settings for the time service. Run "regedit.exe", and change this parameter:

Code: [Select]

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\MinPollInterval
The default value for Windows machines that are not domain controllers is "10". This means the Windows NTP client will only poll the remove server for time every 2^10 = 1024 seconds. That's fine for most purposes, but it does mean it will take some time for the local time to synchronize up with the NTP server. If you want this process to move along quicker, change it to a lower value like 6 (every 64 seconds). If  your not pointing at a local NTP server, I would recommend setting it back to 10 after the initial synchronization is complete.

4) We need to tell the time service to reload configuration. I believe this should work for that, but if not you can go back into services.msc and restart the service:

Code: [Select]

w32tm /config /update
5) Now let's force the time service to start an immediate resync with this command:

Code: [Select]

w32tm /resync
You can monitor progress of the resync with this command:

Code: [Select]

w32tm /query /status /verbose
Here is the output of that command on my desktop:

Code: [Select]

Leap Indicator: 0(no warning)
Stratum: 2 (secondary reference - syncd by (S)NTP)
Precision: -6 (15.625ms per tick)
Root Delay: 0.0312500s
Root Dispersion: 0.2328713s
ReferenceId: 0x84A30465 (source IP:  132.163.4.101)
Last Successful Sync Time: 3/31/2016 2:02:53 PM
Source: 2.pool.ntp.org,0x8
Poll Interval: 9 (512s)

Phase Offset: -0.7133668s
ClockRate: 0.0156381s
State Machine: 2 (Sync)
Time Source Flags: 0 (None)
Server Role: 0 (None)
Last Sync Error: 0 (The command completed successfully.)
Time since Last Good Sync Time: 44.6045029s

The phase offset of -0.7133668s indicates that my desktop is about 0.7 seconds behind the time reported by the NTP server, 2.pool.ntp.org, during the last sync. This is because it's not done synchronzing yet.

[Nuno_pt]

Well, I down to make two GPSDO, I´ve order 2 MV89a from 2006.
I'll use the G3RUH schematic, but for the MV89 part will use the VE2ZAZ divider.
I was looking for an HP Z3805A, the but shipping is the same price of the HP or more expensive, so I'll pass on that for now.

[motocoder]

Well, I down to make two GPSDO, I´ve order 2 MV89a from 2006.
I'll use the G3RUH schematic, but for the MV89 part will use the VE2ZAZ divider.
I was looking for an HP Z3805A, the but shipping is the same price of the HP or more expensive, so I'll pass on that for now.

Could you share details on the "VE2ZAZ divider"? I am not familiar with that.

[motocoder]

Also - back on the Windows NTP client topic - one of my coworkers suggested the Meinberg NTP Server. After installing it, he disables the built-in time server sync with:

Code: [Select]

w32tm /config /syncfromflags:no
Then forces a sync and starts the NTP service with these commands:

Code: [Select]

ntpdate -b pool.ntp.org
net start ntp

https://www.meinbergglobal.com/english/sw/ntp.htm

[edpalmer42]

The software from Meinberg is actually the standard NTPD package.  They just have a convenient Windows binary and installer.  You can configure it as a client or server.

[motocoder]

The software from Meinberg is actually the standard NTPD package.  They just have a convenient Windows binary and installer.  You can configure it as a client or server.

I installed it earlier today. The installer is great, and even took care of disabling the standard windows time service. It synced up almost immediately.

[Nuno_pt]

Could you share details on the "VE2ZAZ divider"? I am not familiar with that.

It's an divider use for the MV89a, the PDF is here < http://www.ve2azx.net/technical/MV89A-1.pdf >

[eb0910]

I recently bought a BG7TBL GPSDO version 2015-09-17, it has uBlox NEO-6 GPS and Oscilloquartz 8663-XS OCXO.

A neat little unit but some problems with it:

1. you cannot send RS232 data to the GPS, it looks like the GPS is receiving commands from a controller on the board.  Some of the commands are invalid because the NMEA output includes error messages.   That means you're stuck with the default settings, you can't adjust the GPS parameters or PPS width.  That's a pity because the uBlox has a well documented and useful command set.

2. The 10MHz output is actually close to 9999999.9991 Hz, as measured against two other known reliable GPSDO.    This defect renders it useless for most applications, the whole point of a 10MHz GPS locked oscillator is that it is GPS locked!     Actually it appears locked but has some systematic error, perhaps a software defect in the firmware?  Lock is confirmed because the 10MHz output shows a periodic (about 2.89 Hz) timing variation of amplitude around 10nS.  This is typical of a working locked GPSDO.   But the average frequency should be 10MHz exactly, otherwise it is useless.

No problem if you just want NMEA and PPS, but in that case you wouldn't have bought a GPS with an OCXO for 3 times the cost of the GPS alone.

I wonder if anyone has a solution for this bug?

[KE5FX]

I recently bought a BG7TBL GPSDO version 2015-09-17, it has uBlox NEO-6 GPS and Oscilloquartz 8663-XS OCXO.

A neat little unit but some problems with it:

1. you cannot send RS232 data to the GPS, it looks like the GPS is receiving commands from a controller on the board.  Some of the commands are invalid because the NMEA output includes error messages.   That means you're stuck with the default settings, you can't adjust the GPS parameters or PPS width.  That's a pity because the uBlox has a well documented and useful command set.

2. The 10MHz output is actually close to 9999999.9991 Hz, as measured against two other known reliable GPSDO.    This defect renders it useless for most applications, the whole point of a 10MHz GPS locked oscillator is that it is GPS locked!     Actually it appears locked but has some systematic error, perhaps a software defect in the firmware?  Lock is confirmed because the 10MHz output shows a periodic (about 2.89 Hz) timing variation of amplitude around 10nS.  This is typical of a working locked GPSDO.   But the average frequency should be 10MHz exactly, otherwise it is useless.

No problem if you just want NMEA and PPS, but in that case you wouldn't have bought a GPS with an OCXO for 3 times the cost of the GPS alone.

I wonder if anyone has a solution for this bug?

My understanding is that this bug was fixed recently.  How long ago did you purchase yours, and is 2015-09-17 the latest firmware?

[eb0910]

My understanding is that this bug was fixed recently.  How long ago did you purchase yours, and is 2015-09-17 the latest firmware?

Thanks a lot. I'm very glad there's a fix, mine was bought late February so will not have the updated firmware.  Now I will try to contact the manufacturer.   The OCXO looks pretty decent so it would be nice to have firmware that does justice to it.

It may seem like a small error, but when using it to measure the phase of a 39062.5 Hz signal to 0.1 degree accuracy, it drifts by -32 degrees in seven hours.  No good at all! 

[dhiru90]

My first post Hello Guys.
I too have access to recent BG7TBL GPSDO.
I thought of using to clocktame  SDR but this GPSDO gives 10M OUTPUT :SINE WAVE,1Vrms (10-15dBm) and square wave,3.3/4.7Vpp.
And all SDRs mostly required cmos square wave for CLKIN. It requires some converter from sine/square to cmos square wave.
Like Si5338/Si5351 programmable clock can be used to take reference from GPSDO and can generate many different frequency CMOS output.
 https://www.silabs.com/Support%20Documents/TechnicalDocs/Si5338.pdf
 https://www.silabs.com/Support%20Documents/TechnicalDocs/Si5351-B.pdf
Also make sure to re-confirm square/sine output of this GPSDO.Sometime it doesn't matter whether you ordered square or sine,you can get any.

Dhiru

[Robaroni]

For you guys that have had these BG7TBL's for awhile, how are they holding up? Maybe cheaper than designing my own, why reinvent the wheel!

I'm thinking about the latest one 2015-09-17 with the Morion 89A OCXO.

Thanks,
Rob

[Robaroni]

Wow. Lots of info! Anyone know what the best model to get for use in a basement? It sounds like the Oscilloquarz would have been the way to go, but these do not seem to be available anymore.

Thanks.

none of them are likely to run from the basement. you'll need to run an antenna outside. so it won't really matter which one you get.

bg7tbl has a newer revision of the morion/ublox, which may fix the counter bug. but realistlcally speaking even with the "buggy" one the error is so small as to be largely irrelevant for hobbyist needs.

I just checked with an eBay seller and the "latest version" (2015-09-17). I asked if he had the fix in and he said no.(May 1, 2016)

Rob