Author Topic: bg7tbl gpsdo master reference (Read 371152 times)

Brandon B · « **Reply #625 on:** May 17, 2018, 08:08:29 pm »

I plan on using the BG7TBL LCD-GPSDO for my setup. Would Lady Heather be compatible with it or does anyone have experience using that software with the BG7TBL LCD-GPSDO.

Thanks

kj7e · « **Reply #626 on:** May 17, 2018, 10:22:43 pm »

Yes, LadyHeather works very well here.

KA1J · « **Reply #627 on:** July 18, 2018, 04:42:46 am »

Folks,

I have a BG7TBL 2015-09-17 with the oscilloquartz OCXO & U-Blox GPS. I was able to have this one evaluated when I got it and it was surprisingly stable and accurate.

I'd like to find another one like this for my 2nd radio but this BG7TBL version isn't available as a couple years back. I need the 10MHz for calibrating my Ham Radio stability and the GPS via RS-232 keeps my computer synced using NMEATime. There's now a few more modern versions of this GPSDO but I have no idea if they are unreliable junk or worth buying.

I'd appreciate opinions on what is current, offers what I need and is relatively inexpensive. I'll be more than happy with another BG7TBL if it's as good as the one I have but anything trustworthy will be fine.

Thanks.

Gary
KA1J

texaspyro · « **Reply #628 on:** July 18, 2018, 05:04:05 am »

https://www.ebay.com/itm/10Mhz-GPSDO-OSCILLOQUARTZ-OSA-OEM-GPS-GPSDO-10MHz-1PPS-STAR-GPS-Clock/262861459973?hash=item3d33c39205%3Ag%3AsbYAAOSwh2xYAjrp&_sacat=0&_nkw=osclloquartz+gpsdo&_from=R40&rt=nc&_trksid=m570.l1313

KA1J · « **Reply #629 on:** July 18, 2018, 02:24:54 pm »

Quote from: texaspyro on July 18, 2018, 05:04:05 am

https://www.ebay.com/itm/10Mhz-GPSDO-OSCILLOQUARTZ-OSA-OEM-GPS-GPSDO-10MHz-1PPS-STAR-GPS-Clock/262861459973?hash=item3d33c39205%3Ag%3AsbYAAOSwh2xYAjrp&_sacat=0&_nkw=osclloquartz+gpsdo&_from=R40&rt=nc&_trksid=m570.l1313

Thanks so much for that link, Texas. That looks to be much of what my BG7TBL is. It doesn't come with an antenna but that won't cost much. The HP readouts looked fine but on the photo of the readout from Lady Heather it reads:

ATDC: in 2358 secs
Holdover Perf Poor.

I'm not sure how to interpret the ATDC finding or a poor Holdover performance. Maybe it is inconsequential?

Thoughts?

And thanks again.

texaspyro · « **Reply #630 on:** July 18, 2018, 03:32:10 pm »

It needs at least 24 hours or so of data to calculate the holdover compensation. Until then, it says "poor".

KA1J · « **Reply #631 on:** July 19, 2018, 04:38:07 am »

Quote from: texaspyro on July 18, 2018, 03:32:10 pm

It needs at least 24 hours or so of data to calculate the holdover compensation. Until then, it says "poor".

Thank you.

xrunner · « **Reply #632 on:** August 02, 2018, 03:53:25 pm »

Another version which has not had pics taken yet 2017-10-09.

Ohm_My · « **Reply #633 on:** August 10, 2018, 02:34:59 am »

Quote from: texaspyro on July 18, 2018, 05:04:05 am

https://www.ebay.com/itm/10Mhz-GPSDO-OSCILLOQUARTZ-OSA-OEM-GPS-GPSDO-10MHz-1PPS-STAR-GPS-Clock/262861459973?hash=item3d33c39205%3Ag%3AsbYAAOSwh2xYAjrp&_sacat=0&_nkw=osclloquartz+gpsdo&_from=R40&rt=nc&_trksid=m570.l1313

I just bought one of these units and it looks to be real nice. The lock time is reasonably quick. I'm still trying to decipher what the "ACT" LED is telling me. Any insight?

Dwaine · « **Reply #634 on:** August 10, 2018, 04:20:08 am »

I was wondering the same thing. Also, it's very dark during operation. Other than that, it's a great unit. I had mine for almost a year. No issue.

texaspyro · « **Reply #635 on:** August 10, 2018, 06:21:47 pm »

I don't know what he has connected to the ACT LED, but attached is the Star4 ATDC manual.

Ohm_My · « **Reply #636 on:** August 10, 2018, 08:48:27 pm »

Quote from: texaspyro on August 10, 2018, 06:21:47 pm

I don't know what he has connected to the ACT LED, but attached is the Star4 ATDC manual.

I took the liberty of contacting the seller (amoj1010) directly and queried him about the ACT LED. His reply, quoted, follows:

"when gps locked the act led is lighting always。 when gps try to locking ，it is Blink"

Filed for future reference.

FransW · « **Reply #637 on:** August 11, 2018, 10:03:04 am »

Question for Texaspyro:
Is it possible to create a list of OSA STAR 4+ specific parameters that are active on Lady Heather? And those which can be set by keyboard commands?
A lot of them (Heather listing) seem inoperable.
I see my temperature log making jumps of approximately 2 oC in a seemingly random manner.

Thanks in advance & regards
Frans

texaspyro · « **Reply #638 on:** August 11, 2018, 12:38:20 pm »

Most of the commands that set things are in the "P" menu. The "&" menu has a command or two for setting some disciplining parameters.

FransW · « **Reply #639 on:** August 11, 2018, 08:42:24 pm »

This answer is not very specific.
And quite difficult to find any explanations about the functionality of both ways.
I read the various Time-Nuts discussions on these subjects and found no clear, specific and itemised explanations (2015 - 2018).
Probably I have to find this out myself from the source code and the subject manuals.

Would have been nice to have the correct specifications. I see however that to compose something like this is quite a task.

Frans

rz · « **Reply #640 on:** September 11, 2018, 11:09:52 am »

A special version of BG7TBL gpsdo which outputs 44.1khz square wave.

rz · « **Reply #641 on:** September 11, 2018, 11:15:02 am »

A special version of BG7TBL gpsdo which outputs 44.1khz square wave.
A PLL board solder on the OCXO. AK8133E and ALTERA PLD on the PLL board.
The output trace is cut by removing 2 resistors, 1 inductor and 1 capacitor.

I want to restore it to output 1 PPS and 10MHz. I have soldered 2 150ohm resistors on the 1PPS trace and it works fine. But what value of inductor and capacitor should I choose to restore the 10MHz output BPF?

ted572 · « **Reply #642 on:** October 22, 2018, 11:58:44 pm »

BG7TBL LCD-GPSDO English Manual

Jörg · « **Reply #643 on:** November 18, 2018, 08:10:58 am »

Recently, a GPSDO based on the Oscilloquartz Star 4 + arrived. I have had great hope for good precision and stability.
Comparing with my HP Z 3805A, the precision of the 10 MHz output is very good. Slightly more accurate than the BG7TBL 2017-12-16 GPSDO.
I'm a bit unhappy with frequency stability. When the OSA Star4 is in GPS mode, the frequency jumps about +/-2 mHz around the 10 MHz.
Going the unit into the hold over mode, stability is at the expected level.

Jörg

jpb · « **Reply #644 on:** November 18, 2018, 02:05:45 pm »

I've not performed this experiment on my Star 4+ - I will probably try comparing it to one of my two working Rubidiums but I can't do that until I get my lab back together properly.

In the interim, a quick question, how long had the Star 4+ been running? I wonder if it was still conducting a self-survey or if its algorithms have bigger changes initially and reduce them over time.

Can you leave it running for 24 hours and see if you still get the same fluctuations?

Jörg · « **Reply #645 on:** November 18, 2018, 03:32:13 pm »

HI jpb. At the time I took the pictures, the unit was about 30 h online.
The ATDC is already active, which only happens after 24h of calculation time. The frequency of 10 MHz +/-2mHz always jumps.

Regards. Jörg

jpb · « **Reply #646 on:** November 18, 2018, 07:53:57 pm »

Quote from: Jörg on November 18, 2018, 03:32:13 pm

HI jpb. At the time I took the pictures, the unit was about 30 h online.
The ATDC is already active, which only happens after 24h of calculation time. The frequency of 10 MHz +/-2mHz always jumps.

Regards. Jörg

Thank you Jörg.

I'll have to check mine when I get the chance. I only checked mine over long gates where its average frequency is very good. If these jumps are a feature then perhaps we need to phase lock a second OCXO to it with a loop time constant of 100 seconds or so.

Looking at your plots, it looks as if it is the result of the LSB of the DAC controlling the OCXO - but doing a quick calculation:
the tuning on the 8663 is 0.3 ppm over 10V (according to the datasheet). 2mHz is 2 x 10^-3/10^7 = 2 x 10^-10
2 x 10^-10/3x10^-7 = 1/1,500 which is only about 11 bits, while I'd assume at least 16bit DAC which should give a resolution of under 50 microHertz so it can't be a resolution thing (unless they only use around 11 bits!)

Jörg · « **Reply #647 on:** November 18, 2018, 09:25:35 pm »

HI jpb. I also did the review with 10 sec avg time. The Allan Dev is as poor as at 1 sec avg.
Right now I'm taking a test with 100 sec. This looks better but about 2-3 X worse
as a BG7TBL 2017-12-16 GPSDO at 1 sec measuring time.
The manual of the OSA Star4 shows, that the PLL time constant can be varied.
Maybe that can make a better behavior of the 10 MHz output.
In Lady Heather's, I couldn't see the command.
Greeting. Jörg

texaspyro · « **Reply #648 on:** November 18, 2018, 11:24:17 pm »

Quote from: Jörg on November 18, 2018, 09:25:35 pm

In Lady Heather's, I couldn't see the command.

&t

FransW · « **Reply #649 on:** November 19, 2018, 05:35:28 pm »

Quote from: Jörg on November 18, 2018, 09:25:35 pm

HI jpb. I also did the review with 10 sec avg time. The Allan Dev is as poor as at 1 sec avg.
Right now I'm taking a test with 100 sec. This looks better but about 2-3 X worse
as a BG7TBL 2017-12-16 GPSDO at 1 sec measuring time.
The manual of the OSA Star4 shows, that the PLL time constant can be varied.
Maybe that can make a better behavior of the 10 MHz output.
In Lady Heather's, I couldn't see the command.
Greeting. Jörg

I am very interested in the manual of the OSA Star4.
Any suggestions where?
My GPSDO is exactly the same and quite satisfactory.
However, lack of a manual restricts my options and understanding.
Sofar, looking for a manual was fruitless.

Thanks in advance,
Frans


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Author Topic: bg7tbl gpsdo master reference (Read 371152 times)

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