Author Topic: bg7tbl gpsdo master reference  (Read 62809 times)

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Offline uncle_bob

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Re: bg7tbl gpsdo master reference
« Reply #200 on: May 02, 2016, 01:35:33 AM »
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

Hi

One gotcha may be that the older boards and the newer ones have minor hardware changes between them. You certainly see jumper wires on some of the early ones ... I have not seen a "new" one.

Bob
 

Offline Robaroni

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Re: bg7tbl gpsdo master reference
« Reply #201 on: May 02, 2016, 01:43:59 AM »
Don't know. He did give me the option of the Oscilloquartz 8663 or Morion MV62 OCXO, by the way.
Rob
 

Offline D3f1ant

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Re: bg7tbl gpsdo master reference
« Reply #202 on: May 02, 2016, 05:01:32 AM »
Does anybody have a copy of the fixed firmware, surely it can't be hard to update.
 

Offline uncle_bob

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Re: bg7tbl gpsdo master reference
« Reply #203 on: May 02, 2016, 07:22:56 AM »
Does anybody have a copy of the fixed firmware, surely it can't be hard to update.

Hi

I think the practical answer is to spend some quality time on the internal Chinese ham forums. That's where most of the up to date information on all of the BG7TBL stuff is.

Bob
 

Offline burkm

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Re: bg7tbl gpsdo master reference
« Reply #204 on: May 28, 2016, 12:21:07 AM »
1st: Here is a (the) manual for the BG7TBL GPSDO. Its "offical", because i got it from BG7TBL directly with the permission to "publish" it  :-+ Its a mixed language version: Chinese/English.
http://docdro.id/EA3BHpD
2nd: A fix for that small frequency "bug" discovered earlier (KE5FX) is been tested right now as mentioned by BG7TBL Testing will go on for several months (!) and a firmware update will be available after that. A fix is not yet available as told by BG7TBL.
http://www.directupload.net/file/d/4368/fhuiqra4_jpg.htm
Note: None of the available variants of the BG7TBL GPSDO, which have been affected by this timing "bug", have a bug fix yet, not even the latest version and their variants dated 2015-09-17.

I hope this will help.

PS.: - I tried to "improve" somehow on the English side of the manual to make it more comprehensible and came up with this slightly modified version http://docdro.id/DrXNab8
« Last Edit: June 21, 2016, 03:20:59 AM by burkm »
 
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Offline uncle_bob

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Re: bg7tbl gpsdo master reference
« Reply #205 on: May 28, 2016, 02:56:15 AM »
1st: Here is a (the) manual for the BG7TBL GPSDO. Its "offical", because i got it from BG7TBL directly with the permission to "publish" it  :-+ Its a mixed language version: Chinese/English.
http://docdro.id/EA3BHpD
2nd: A fix for that small frequency "bug" discovered earlier (KE5FX) is been tested right now. Testing will go on for several months (!) and a firmware update will be available after that. A fix is not yet available as told by BG7TBL.
http://www.directupload.net/file/d/4368/fhuiqra4_jpg.htm
Note: None of the available variants of the BG7TBL GPSDO have a bug fix yet, not even the latest version and their variants dated 2015-09-17.


I hope this will help.

Hi

The testing for any GPSDO firmware mod often goes into the many months to maybe a year range. There are very few ways to speed up checking a very long time constant control loop.

Bob
 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #206 on: June 17, 2016, 09:31:53 AM »
Note: None of the available variants of the BG7TBL GPSDO have a bug fix yet, not even the latest version and their variants dated 2015-09-17.

not all of the variants have the bug.

Offline ormandj

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Re: bg7tbl gpsdo master reference
« Reply #207 on: June 17, 2016, 10:39:54 AM »
Hi

I think the practical answer is to spend some quality time on the internal Chinese ham forums. That's where most of the up to date information on all of the BG7TBL stuff is.

Bob

Do you have a link to these forums? Thank you.
 

Offline uncle_bob

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Re: bg7tbl gpsdo master reference
« Reply #208 on: June 17, 2016, 11:01:07 AM »
Hi

I think the practical answer is to spend some quality time on the internal Chinese ham forums. That's where most of the up to date information on all of the BG7TBL stuff is.

Bob

Do you have a link to these forums? Thank you.

Hi

Do a search (In Chinese) for BG7TBL. From there you will get into them. If you aren't fluent in the language, don't bother. Google Translate gets lost quickly in the tangle of idiomatic speech.

Bob
 

Offline sreeb

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Re: bg7tbl gpsdo master reference
« Reply #209 on: July 09, 2016, 07:07:49 AM »
Do you know which versions don't have the bug?

Do we know that the current versions with the bug are upgradeable when it is fixed?

I want to buy one but, even though the accuracy with the bug is still better than I need, it would always annoy me to know I had one that is flawed.

Note: None of the available variants of the BG7TBL GPSDO have a bug fix yet, not even the latest version and their variants dated 2015-09-17.

not all of the variants have the bug.
 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #210 on: July 09, 2016, 07:52:45 AM »
Do you know which versions don't have the bug?

probably any of the ones based off oscilloquartz or trimble receivers, since the unit is just tapping existing signal sources and not generating brand new ones from scratch.

Offline burkm

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Re: bg7tbl gpsdo master reference
« Reply #211 on: July 24, 2016, 08:31:52 PM »
This "bug" is supposedly not derived from the type/brand of receiver or OCXO used, but from the internal PLL (?) loop, which seems to "discipline"/pull the OCXO in use to a slight offset compared to the "absolute reference 10 MHz" for unknown reasons (rounding algorithms etc. ?). Thus it might "plague" (almost ?) all versions from my point of view, because it seems to be purely software based.
Even if a revised software will be made available by BG7TBL after finishing his tests, as stated , it is still unknown, how the existing software will be updated with the new version because of programming considerations.

 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #212 on: July 24, 2016, 10:05:03 PM »
This "bug" is supposedly not derived from the type/brand of receiver or OCXO used, but from the internal PLL (?) loop, which seems to "discipline"/pull the OCXO in use to a slight offset compared to the "absolute reference 10 MHz" for unknown reasons (rounding algorithms etc. ?). Thus it might "plague" (almost ?) all versions from my point of view, because it seems to be purely software based.
Even if a revised software will be made available by BG7TBL after finishing his tests, as stated , it is still unknown, how the existing software will be updated with the new version because of programming considerations.

no.

the oscilloquartz star based models for 100% certain do not have this bug. there is no pll involved and no ocxo discipline involved. there are no bg7tbl algorithms involved. bg7tbl isn't synthesizing any frequency nor disciplining any ocxo in these models.

i'll have to check my trimble model but i suspect it is the same.
« Last Edit: July 24, 2016, 10:11:41 PM by usagi »
 

Offline burkm

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Re: bg7tbl gpsdo master reference
« Reply #213 on: July 25, 2016, 01:39:49 AM »
As long as separate OCXOs and the U-blox GPS recevers in those GPSDo units are involved, there will be a PLL (FLL ?) loop by BG7TBL.

Looking through this thread, with few exceptions almost all GPSDO units done by BG7TBL are build this way, only intermediate deviation from this seem to be those few units sold with complete GPSDO boards from Symmetricom and Trimble some time ago. But they have their weaknesses too, because they are "famous" for their low sensitivity and the rather limited count of satellite channels they will lock onto, which has shown to be problematic for other users with less than ideal GPS antenna situations.

So you gain and loose both ways.



 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #214 on: July 25, 2016, 04:30:29 AM »
As long as separate OCXOs and the U-blox GPS recevers in those GPSDo units are involved, there will be a PLL (FLL ?) loop by BG7TBL.

Looking through this thread, with few exceptions almost all GPSDO units done by BG7TBL are build this way, only intermediate deviation from this seem to be those few units sold with complete GPSDO boards from Symmetricom and Trimble some time ago. But they have their weaknesses too, because they are "famous" for their low sensitivity and the rather limited count of satellite channels they will lock onto, which has shown to be problematic for other users with less than ideal GPS antenna situations.

So you gain and loose both ways.

no.

there are no bg7tbl with symmetricom.

the bg7tbl with the oscilloquartz star board uses a u-blox gps and has fantastic sensitivity and will easily lock on to a full constellation. there is no loose with this gpsdo. it's gain all around.

any bg7tbl using the "uccm" board does not have the timing bug, because the uccm simply is a transparent passthrough.
« Last Edit: July 25, 2016, 06:41:18 AM by usagi »
 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #215 on: July 25, 2016, 10:59:27 AM »
"2015-09-17"  (variant 2 - bliley nvg47a1282)

custom board with surplus bliley nvg47a1282 OCXO. gps is u-blox NEO-6M-0-001
« Last Edit: July 25, 2016, 11:02:21 AM by usagi »
 

Offline drdmr

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Re: bg7tbl gpsdo master reference
« Reply #216 on: July 31, 2016, 11:25:30 PM »
Hi all,

I'm new here and found this board while looking for more information about a GPSDO I bought on eBay. Mine has the Trimble board and OCXO, so I guess it's a variant of "2015-07-17". It's sold by eBay user "amoj1010" and the interface board has the seller ID marked on it. It's a nice box, with two DB9 serial ports -- one shows the UCCM command interface, and the other reports binary location data. I'm attaching some pictures from the eBay listing.

Also, I apologize if this is old news, but I discovered that the commercial software GPSCon Pro can monitor these units! It's not cheap ($77.67) but it works well, and it beats typing in commands at the "UCCM" prompt and deciphering the results. Also attached is a screenshot from GPSCon monitoring my box.
 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #217 on: August 01, 2016, 05:41:57 AM »
I'm new here and found this board while looking for more information about a GPSDO I bought on eBay. Mine has the Trimble board and OCXO, so I guess it's a variant of "2015-07-17". It's sold by eBay user "amoj1010" and the interface board has the seller ID marked on it. It's a nice box, with two DB9 serial ports -- one shows the UCCM command interface, and the other reports binary location data. I'm attaching some pictures from the eBay listing.

this gpsdo does not appear to be a variant of bg7tbl. this is a completely independent design.

Offline Safar

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Re: bg7tbl gpsdo master reference
« Reply #218 on: August 20, 2016, 06:48:02 PM »
Hi,

Does anyone know the normal values temperature on the case surface of morion mv89a OCXO?

There is a suspicion that the oven is faulty.
 

Offline uncle_bob

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Re: bg7tbl gpsdo master reference
« Reply #219 on: August 23, 2016, 08:42:56 AM »
Hi,

Does anyone know the normal values temperature on the case surface of morion mv89a OCXO?

There is a suspicion that the oven is faulty.

37C
 
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Online DaJMasta

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Re: bg7tbl gpsdo master reference
« Reply #220 on: September 16, 2016, 03:58:43 AM »
A bit of a necro, but this seems to be the right place for it.  I picked up one of these BG7TBL GPSDOs on ebay for $140 including a power pack and an antenna, haven't cracked it open yet, but it seems to be working properly and interestingly, there has been another revision labeled 2016-05-31.  I got mine from here: http://www.ebay.com/itm/171742240714

I've got the NMEA data being read out into VisualGPS (free tracking program), but it doesn't include timing information, and lady heather doesn't seem to want to communicate with it, at least in the standard configuration.  Any ideas on software to get a readout of the timing corrections and such - would be fascinating to see.  I will crack it open and get some pics, but in the mean time, enjoy the "square" wave it outputs  :D *when properly terminated it looks a lot better!*



More than I expected, it seems to be tracking 9 satellites at the moment.
« Last Edit: September 16, 2016, 04:31:50 AM by DaJMasta »
 

Online NivagSwerdna

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Re: bg7tbl gpsdo master reference
« Reply #221 on: September 16, 2016, 04:04:04 AM »
Why did you turn it on before taking it apart?    :-DD
« Last Edit: September 17, 2016, 02:57:02 AM by NivagSwerdna »
 

Online DaJMasta

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Re: bg7tbl gpsdo master reference
« Reply #222 on: September 16, 2016, 04:10:09 AM »
As a rule of thumb for ebay stuff from China.... I turn it on first to make sure it runs  :-BROKE


Oops, though, I wasn't being fair.  The input was still 1M terminated, looks much much nicer with 50 ohms set! Pretty decent rise and fall times and a fairly flat top, though there's a nice little point right after the rise completes.
« Last Edit: September 16, 2016, 04:17:48 AM by DaJMasta »
 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #223 on: September 16, 2016, 04:29:46 AM »
A bit of a necro, but this seems to be the right place for it.  I picked up one of these BG7TBL GPSDOs on ebay for $140 including a power pack and an antenna, haven't cracked it open yet, but it seems to be working properly and interestingly, there has been another revision labeled 2016-05-31.  I got mine from here: http://www.ebay.com/itm/171742240714

please crack it open, would be interested to see what's changed - if anything.  :-+

Online DaJMasta

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Re: bg7tbl gpsdo master reference
« Reply #224 on: September 16, 2016, 06:01:34 AM »
Hopefully these are good enough to be useful, the board looks the same but is marked 2016-05-01 - maybe the 31st is the first time the board was actually built up, maybe there was a part swap in that month.  Primary chips are a uBlox Neo-7M-0-000 and a Bliley NVG47A1282 oscillator.  The box is solid extruded aluminum and according to the sticker on the back, there is a sine wave output variant, but this is the square wave version.  This is the designer's store site: https://bg7tbl.world.taobao.com/ - the product image reflects this version number, I can't read any of the descriptions though :p





Looks like there isn't any timing adjust data being sent out of the thing, but it also doesn't seem like it's just an rs232 interface through to the GPU unit's comms, so maybe there's room for it in firmware.  In my brief buzzing out to try to find the serial interface passing to the uBlox module, I found that D2 was an LED.... kinda funny, but there's a blue LED on the underside of the board in the aluminum box that no one will likely see... but it blinks when the GPS locks - looks to be locked to the 1pps output or vice versa.  Tracking up to 12 satellites too!
« Last Edit: September 16, 2016, 01:45:10 PM by DaJMasta »
 


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