bg7tbl gpsdo master reference - Page 1
Forum section: electronics / testgear

author: usagi
author_rank: Frequent Contributor
timestamp: August 03, 2015, 05:44:15 am
content: Thread to collect all the bg7tbl information into a single reference.A chinese ham "bg7tbl" designed and manufactured a series of cheap GPSDO which are being sold on alibaba and ebay, typically for around $150USD.There are a number of different versions, which can be identified by the date printed on the front panel:"2014-11-06"custom board with surplus russianmorion mv89OCXO. gps is u-blox. both sine and square wave output variants available."2014-12-09"custom board with surplus russianmorion mv89OCXO. gps isu-blox NEO-6M-0-001."2015-07-08"custom board with surplus oscilloquartz star 4 (oscilloquartz"STAR 4") gpsdo board. OCXO is oscilloquartz 8663-XS. gps is u-bloxLEA-5T-0-002."2015-07-17"custom board with surplus trimble "57963-D" gpsdo board. OCXO is trimble 73090. gps is unknown."2015-09-17"custom board with surplus russianmorion mv201OCXO. gps is u-bloxNEO-6M-0-001"2015-09-17"(variant 1 - mv89a)custom board with surplus russianmorion mv89aOCXO. gps is u-bloxNEO-6M-0-001"2015-09-17"(variant 2 - bliley nvg47a1282 )custom board with surplusbliley nvg47a1282OCXO. gps is u-bloxNEO-6M-0-001"2016-05-31"custom board with surplusbliley nvg47a1282OCXO. gps is u-bloxNEO-7M-0-000AVR dump available inthis post."2017-03-29"custom board with surplus cts 970-2178 OCXO. gps is u-bloxNEO-7M-0-000"2017-09-23"custom board with unknown OCXO. gps is unknown. compact design."2017-10-09"custom board with surplus cts 970-2178 OCXO. gps is u-bloxNEO-7M-0-000"2017-12-16"custom board with unknown OCXO. gps is unknown. backlit LCD display."2019-09-23"custom board with surplusbliley nvg47a1282OCXO. gps is unknown. compact design."2017-10-20"custom board with unknown OCXO. gps is unknown. backlit LCD display."GNSS-RB"GNSS disciplined Rubidium oscillator? gps is unknown. backlit LCD display.construction quality of these devices is quite decent in general. the custom adapter models (oscilloquartz, trimble) of course have a number of bodge wires.you get RS232, 1PPS and 10mhz outputs. wallwart PSU and active GPS antenna are included.all in all, these are great value for the money and a lot less hassle than some of the alternative GPSDO options being thrown around on the forums.

author: usagi
author_rank: Frequent Contributor
timestamp: August 03, 2015, 05:46:18 am
content: "2014-11-06"most extensively tested, so far (by ke5x and others).known bug, output frequency is not exactly 10mhz (9,999,999.999800Hz). this translates to ~2hz error at 100ghz.http://www.ke5fx.com/gpscomp.htm

author: usagi
author_rank: Frequent Contributor
timestamp: August 03, 2015, 05:47:08 am
content: "2014-12-09"review by tim tuck / VK2XAX

author: usagi
author_rank: Frequent Contributor
timestamp: August 03, 2015, 05:48:50 am
content: "2015-07-08"surplus oscilloquartz gpsdo.usesoscilloquartz star 4board.bg7tbl "uccm board" dated 2015-06-27. appears identical to board used for the trimble.rs232 interface is READ-ONLY. you cannot control the ublox with it, only monitor it.

author: usagi
author_rank: Frequent Contributor
timestamp: August 03, 2015, 05:52:27 am
content: "2015-07-17"surplus trimble gpsdo.appears to use same "uccm board" as the 2015-07-17 (oscilloquartz) model.

author: Lightages
author_rank: Unknown
timestamp: August 03, 2015, 06:14:15 am
content: I supposedly have the 2014-12-9 on the way. Delivery times to Chile are horrible and I have waited 1-1/2 months so far. I will report all that I am capable of when it gets here.

author: edpalmer42
author_rank: Super Contributor
timestamp: August 03, 2015, 05:32:03 pm
content: If you look closely at the unit with the Oscilloquartz board, it looks like he's attached a blue wire directly to the LEA-5T. That suggests that the comm port is just monitoring the GPS, not the GPSDO. You might not be able to control anything - just monitor.Does anyone have one of these boards? Can you confirm or deny any of this?Ed

author: motocoder
author_rank: Unknown
timestamp: August 04, 2015, 06:10:45 am
content: Quote from: edpalmer42 on August 03, 2015, 05:32:03 pmRead Tim's teardown - it's not for the Oscilloquartz board, but it definitely seems the RS232 port is connected to the GPS.

author: edpalmer42
author_rank: Super Contributor
timestamp: August 04, 2015, 06:57:10 am
content: Quote from: motocoder on August 04, 2015, 06:10:45 amI saw that. I don't have a problem with that. He designed it himself so I'm not expecting an intelligent controller. But I would be surprised if a commercial GPSDO didn't have some form of user access to the GPSDO functions.Ed

author: usagi
author_rank: Frequent Contributor
timestamp: August 04, 2015, 10:10:23 am
content: Quote from: edpalmer42 on August 04, 2015, 06:57:10 ameven if you could talk to the star 4 gpsdo, you would need the proprietary oscilloquartz configuration manager software. i couldn't find it anywhere.you can buysurplus star 4 boardsif you want one to experiment on.

author: motocoder
author_rank: Unknown
timestamp: August 05, 2015, 12:09:59 am
content: Quote from: usagi on August 04, 2015, 10:10:23 amLink doesn't work.

author: Vgkid
author_rank: Super Contributor
timestamp: August 05, 2015, 02:02:26 am
content: I would be interested to see the performance of the Huawei Oscilloquartz model. It potentially has the best specced ocxo.

author: usagi
author_rank: Frequent Contributor
timestamp: August 05, 2015, 07:33:59 am
content: Quote from: motocoder on August 05, 2015, 12:09:59 amhmm maybe the domain owner forgot to pay his bill. lol.https://web.archive.org/web/20150202061215/http://www.168electronics.com/oscilloquartz-star4-osa-oem-gps-clock-p-122.html

author: TSL
author_rank: Regular Contributor
timestamp: August 05, 2015, 10:19:38 am
content: Quote from: Vgkid on August 05, 2015, 02:02:26 amWhich spec ? as far as I can tell its specs do not exceed those of the Morion.

author: Selectech
author_rank: Regular Contributor
timestamp: August 05, 2015, 12:23:53 pm
content: I got a BG7TBL 2014-12-09 unit { square wave out } , arrived yesterday { 1 week }. Inside is PCB marked 2015 with a Morion MV89 from 2007.Initially unit did not lock, but traced it down to a shorted SMA cable from front panel to PCB. For now antenna direct connect to SMA on PCB. { Will fix front panel cable later }.Seems to work ok now. GPS locked up in under 3 minutes. Longer term tests on-going.

author: Fraser
author_rank: Super Contributor
timestamp: August 05, 2015, 12:36:07 pm
content: Thanks for creating this thread. It makes interesting reading and viewing.I already own a couple of Trimble Thunderbolt GPSDO units with LCD display etc. but took an interest in these reasonably priced offerings from BG7TBL.I would be interested to know more about BG7TBL. He creates some nice items and appears to be an interesting person to hear about.Aurora

author: dadler
author_rank: Unknown
timestamp: August 05, 2015, 10:31:15 pm
content: Argh, you guys are a bad influence. That plus my inability to avoid impulse purchasing...So I ordered a BG7TBL 2014-12-09 edition from eBay.I already have a modified Lucent RFTGm-II-XO, with added 10MHz output via front panel BNC. This is the single-unit GPSDO (not the other half with the back-up Rubidium unit). It's nice and works well enough, but I haven't done a detailed evaluation of its performance. It is powered via an odd DB9 connector and you have to talk to it via RS-422 (which is fine for me since I have a couple of good USB to RS-422 adapters).But I'm looking forward to a smaller, more modern unit that hopefully doesn't get as hot!

author: motocoder
author_rank: Unknown
timestamp: August 05, 2015, 11:32:27 pm
content: I ordered and have received the BG7TBL "Trimble" unit. I have it set up and running now, but I'm going to let it stabilize for a few days before looking further.Initial impressions: Much better GPS receiver than the Lucent, but not as good as I suspect the uBlox is. I wasn't able to get it to lock GPS inside the house where my test equipment is (same issue with teh Lucent). However, it locked up quickly on the other end of the house, and also when I put the antenna outside on the ground.I compared the 10Mhz output to the Lucent this morning. They seem to be in sync, although the relative phase of the two signals drifts back and forth about 17 degrees over a relatively short time. I'll do some more quantitative measurements this weekend.I really need a 3rd unit to see which unit has the phase drift. I suspect it's the Lucent, based on the crazy and constant adjustments its making to the EFC. Whoever wrote that code didn't know how to create a good PID loop.

author: usagi
author_rank: Frequent Contributor
timestamp: August 06, 2015, 08:38:18 am
content: other than excellent sensitivity, the huawei/oscilloquartz star4 speaks both NMEA and UBLX. and the UBLX is very a well documented protocol.

author: motocoder
author_rank: Unknown
timestamp: August 06, 2015, 09:35:07 pm
content: Quote from: usagi on August 06, 2015, 08:38:18 amSo the serial port is connected to the UBlox (BPS) chip then? That doesn't allow for any status on the OCXO disciplining, things like EFC or HUD.

author: usagi
author_rank: Frequent Contributor
timestamp: August 07, 2015, 01:30:15 am
content: Quote from: motocoder on August 06, 2015, 09:35:07 pmwithout the proprietary oscilloquartz configuration manager software you wouldn't be able to talk to the ocxo anyway. the protocol does not appear to be documented. nor does the software appear to be available anymore.nothing preventing anyone from modifying the bg7tbl huawei to connect rs232 to whatever chip on the board you want, if you want to try.the 168electronics guy says star4 boards are available if someone wants to buy some.

author: usagi
author_rank: Frequent Contributor
timestamp: August 12, 2015, 07:50:46 am
content: received my trimble unit, so now i have all three. lucent, oscilloquartz star4, and trimble.trimble is marginally better than the lucent, but still pretty helpless with a puck antenna in a window with full view of the sky. the oscilloquartz star4 with the same antenna in the same location absolutely obliterates them both in terms of gps sensitivity and lock.

author: motocoder
author_rank: Unknown
timestamp: August 12, 2015, 01:37:56 pm
content: Quote from: usagi on August 12, 2015, 07:50:46 amThe star4 is the same as the Huawei, right? I think it uses the ublox GPS, ao no surprise that it has better GPS sensitivity.What about stability of the actual 10 MHz output?

author: usagi
author_rank: Frequent Contributor
timestamp: August 12, 2015, 07:20:17 pm
content: Quote from: motocoder on August 12, 2015, 01:37:56 pmthe "Huawei" bg7tbl is an oscilloquartz star4 board which uses oscilloquartz ocxo and ublox gps receiver.stability is very good. I have yet to get the trimble to complete a survey due to poor receiver sensitivity, even putting the puck antenna outside didn't help (where it did with the lucent). I may have to get a timing antenna to make the lucent and trimble happy.

author: motocoder
author_rank: Unknown
timestamp: August 18, 2015, 07:34:40 pm
content: Quote from: usagi on August 05, 2015, 07:33:59 amI just want to let everyone know not to waste their time with these guys at 168electronics. I emailed them for a price quote, thinking if I can reverse engineer the GPSDO interface that it might be worth making an adapter board and buying a batch to make available to folks. But "Bob Mokia" there told me they are not interested in selling ("Don't want to sell as I do some development on it"). Not sure why they have the thing listed on their web site.