Author Topic: bg7tbl gpsdo master reference  (Read 107136 times)

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Offline Fennec

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Re: bg7tbl gpsdo master reference
« Reply #375 on: July 15, 2017, 02:59:45 AM »
Also, why not ask questions more specifically about whatever is going wrong.

I did. I wrote "the hardware works fine, GPS too, but no lock."

 

Offline D3f1ant

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Re: bg7tbl gpsdo master reference
« Reply #376 on: July 15, 2017, 08:38:57 AM »
Was a firmware update ever released for the BG7TBL to fix the minor error?
 

Offline metrologist

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Re: bg7tbl gpsdo master reference
« Reply #377 on: July 17, 2017, 05:47:33 AM »
Thanks, I'd like to know too. I was considering the 2017 model. (note that I'm not really familiar with this topic, but am interested in GPSDO)

Is it confirmed that the star4 and trimble versions do not have bug and can be controlled by Lady Heather? I read no versions can be and that there is no actual oscillator disciplining
(earlier in this thread by usagi)
http://www.ebay.com/itm/10Mhz-GPSDO-OSCILLOQUARTZ-OSA-OEM-GPS-GPSDO-10MHz-1PPS-STAR-GPS-Clock-/262861459973

There is a version with both sine and square 10M outputs, maybe not a bg7tbl variant.
http://www.ebay.com/itm/Trimble-GPS-Receiver-GPSDO-10MHz-1PPS-GPS-Disciplined-Clock-sine-and-square-wave/252162780444

Otherwise, would it be better to consider just the trimble or NEC module (no control interface?) or a trimble thunderbolt?


I forgot to put in the mix the Low Jitter Precision GPSDO Reference Oscillator if I just wanted a reference.

Thanks.
« Last Edit: July 17, 2017, 07:28:39 AM by metrologist »
 

Offline texaspyro

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Re: bg7tbl gpsdo master reference
« Reply #378 on: July 17, 2017, 08:20:56 AM »

Otherwise, would it be better to consider just the trimble or NEC module (no control interface?) or a trimble thunderbolt?


The latest version (5.01 or later) of Lady Heather works will with the Star-4 and NEC GPSDOs.  It must be connected to the "management interface" serial port... which is a logic level interface, you will need a level shifter to use it with RS-232 serial ports.
 

Offline edpalmer42

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Re: bg7tbl gpsdo master reference
« Reply #379 on: July 17, 2017, 09:27:32 AM »
The only units that had the frequency error are the ones where he built his own circuit from scratch.  Any of the units that include another GPSDO (Trimble, Symmetricom, Oscilloquartz) were fine.  I've heard that his later units fixed the frequency error, but I've never seen any test results.

Ed
 

Offline metrologist

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Re: bg7tbl gpsdo master reference
« Reply #380 on: July 18, 2017, 01:52:54 AM »
Thanks, I broke down and bought a variant of the bg7btl with a Trimble 57963 with the 73090 OCXO (I read these were updated versions of the ThunderBolt?). This one has the additional square wave output. Date code in the ebay pic anyway is 0953.? Are these serial ports really RS232 levels or 5V TTL? I recall seeing one with a USB-TTL plugged right into the top row of the connector. Maybe he was using some kind of max chip?
« Last Edit: July 18, 2017, 01:57:57 AM by metrologist »
 

Offline NivagSwerdna

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Re: bg7tbl gpsdo master reference
« Reply #381 on: July 18, 2017, 02:15:15 AM »
Thanks, I broke down and bought a ....
:clap:
 

Offline Dwaine

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Re: bg7tbl gpsdo master reference
« Reply #382 on: July 18, 2017, 09:55:29 AM »

Otherwise, would it be better to consider just the trimble or NEC module (no control interface?) or a trimble thunderbolt?


The latest version (5.01 or later) of Lady Heather works will with the Star-4 and NEC GPSDOs.  It must be connected to the "management interface" serial port... which is a logic level interface, you will need a level shifter to use it with RS-232 serial ports.

The seller of the star-4 has reworked the interface so it will work with Lady Heather.  There are screenshots of it in the auction.   I wish I had the newer unit that has that change.
 

Offline texaspyro

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Re: bg7tbl gpsdo master reference
« Reply #383 on: July 18, 2017, 10:55:13 AM »

The seller of the star-4 has reworked the interface so it will work with Lady Heather.  There are screenshots of it in the auction.   I wish I had the newer unit that has that change.


You can modify the device.  There are two pins (needles) that connect the Star-4 GPS receiver RXD and TXD to his interface board (I think that some builds used pogo pins and others may have soldered the connections).  Remove the pins to break the connection to the GPS receiver and wire the pads to the GPS management interface TXD and RXD on the Star-4 connector.  His connection to the Star-4 connector has vias  for most or all of the Star-4 connections.
 
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Offline 1audio

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Re: bg7tbl gpsdo master reference
« Reply #384 on: July 18, 2017, 02:43:46 PM »
Have you tried searching on Github to see if somebody has written a Linux version of Ucenter or similar..

Lady Heather will work with it (and just about any GPS receiver or GPSDO, including GPSD).   It should auto-detect NMEA and Ublox devices.

I have an Arbiter GPSDO 1083A similar to this: http://www.arbiter.com/catalog/product/model-1083b.php that an older version of Lady Heather didn't talk to. It seems they have their own command set etc. but its fully documented. I got it because it has a Wenzel 5 MHz streamline oscillator and a Motorola receiver. I figured I could screw around for ages and not get better results. I can supply docs if interested. I also have a Tbolt that works great with LH.
 

Offline 1Ghz

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Re: bg7tbl gpsdo master reference
« Reply #385 on: July 21, 2017, 01:38:34 AM »
Bought latest version of the BG7TBL.
My first freq reference.  8)
« Last Edit: July 30, 2017, 01:22:01 AM by 1Ghz »
 

Offline 1Ghz

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Re: bg7tbl gpsdo master reference
« Reply #386 on: July 21, 2017, 01:47:59 AM »
BG7TBL 2017-03-29 teardown

OCXO: CTS 970-2178-46
GPS: u-blox NEO-7M-0-000
« Last Edit: July 22, 2017, 04:15:38 PM by 1Ghz »
 

Offline cdev

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Re: bg7tbl gpsdo master reference
« Reply #387 on: July 21, 2017, 09:37:39 PM »
Nice

"What the large print giveth, the small print taketh away."
 

Offline K1FPV

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Re: bg7tbl gpsdo master reference
« Reply #388 on: July 22, 2017, 07:29:51 AM »
Nope! Can't get any of the 3 terminal programs to work with it. I've already tried Termite 3.2, PUTTY as well as HyperTerminal. I'll just have to see if I can locate someone with HP/Symmetricom 58531A and use that program.
 

Offline texaspyro

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Re: bg7tbl gpsdo master reference
« Reply #389 on: July 22, 2017, 09:32:13 AM »
Nope! Can't get any of the 3 terminal programs to work with it. I've already tried Termite 3.2, PUTTY as well as HyperTerminal. I'll just have to see if I can locate someone with HP/Symmetricom 58531A and use that program.

Somebody may have changed the default baud rate settings.  It can run at 1200, 2400, 9600, or 19200 baud.   even/odd/no parity,  7 or 8 data bits, 1 or 2 stop bits.  Also they had an option that changed the serial port from DTE or DCE mode.

I would try the various baud rate settings by sending the "*IDN?" command.  Try ending the command with a <CR>.  If no response, try with a <LF>.  If you get no response at that baud rate try with the different  data bit settings.   If parity is wrong, I think it sends an error code prompt.  If all that fails, try with a null modem cable.

 

Offline Fennec

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Re: bg7tbl gpsdo master reference
« Reply #390 on: July 29, 2017, 10:03:06 AM »
@1GHz

Thank you for the Pics. On a first look I see nothing differnet to my older version from 5/2016. What I see are the ovens goes cheaper and cheaper I think. I didn't take a deeper look into the datascheets between mine and yours.

@all

My Unit is fixed now. A big thanks to all of the forum members who didn't help me out with this easy copy of the GNSS File which I really needed  :--

  • I desoldered the UBlox Module and plant it directly into the case in my active antenna on the roof. Because my cable is over 100ft long and the Unit can handle active antennas 3 or 5V.
  • I plant in two cheap class1 Bluetooth modules to transfer the Data to the Unit and read them out. Not really the best Idea, I think I change them to WIFI. So I can place the Device directly close the Counter, Generator and so on.
  • I changed the cheap ass Oven to a Morion 89A (its a Double Oven) Used, but they are good quality ones for this price. $US60 (ebay)
Maybe I put a filter into the output, but I am not shure. Let's see, I am waiting for the parts.

Nope! Can't get any of the 3 terminal programs to work with it. I've already tried Termite 3.2, PUTTY as well as HyperTerminal. I'll just have to see if I can locate someone with HP/Symmetricom 58531A and use that program.

Did you read my last post? Don't think so  :palm:

 

Online TheSteve

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Re: bg7tbl gpsdo master reference
« Reply #391 on: July 29, 2017, 10:43:17 AM »
Nope! Can't get any of the 3 terminal programs to work with it. I've already tried Termite 3.2, PUTTY as well as HyperTerminal. I'll just have to see if I can locate someone with HP/Symmetricom 58531A and use that program.

I assume it is the one I sold as the 58540a isn't very common. It is 9600/8/n/1 100% for certain. I only used a terminal program with it(putty in my case), never did locate the HP Software.
VE7FM
 

Offline Lightages

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Re: bg7tbl gpsdo master reference
« Reply #392 on: July 29, 2017, 02:31:54 PM »
@all

My Unit is fixed now. A big thanks to all of the forum members who didn't help me out with this easy copy of the GNSS File which I really needed  :--

With such a petty and childish post, I for one won't be helping you with anything should I have the opportunity. Expecting everyone to jump to help you on your command is a sure way to get ignored. Perhaps an apology might be in order for being an ass to those who help for free.
I am NOT a distributor for Brymen.
 

Offline usagi

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Re: bg7tbl gpsdo master reference
« Reply #393 on: July 30, 2017, 05:22:44 PM »
With such a petty and childish post, I for one won't be helping you with anything should I have the opportunity. Expecting everyone to jump to help you on your command is a sure way to get ignored. Perhaps an apology might be in order for being an ass to those who help for free.

look at his post history.

Offline Fennec

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Re: bg7tbl gpsdo master reference
« Reply #394 on: July 30, 2017, 09:54:58 PM »
A forum Member sent me the GNSS file via PM now. Thank you very much!

It is possible to read out the AVR. It's an ATmega8L on my BG7TBL 5/31/2016

See attached files. Maybe someone would rebuild it with an Arduino and UBLOX shield. Should be easy.

If you want to use the UBLOX M8N which can receive US-GPS, GLONASS, Beidou you have to change the Antenna to a dual one! Use an active one.  With this setting I reveive over 20 SAT fixes !

« Last Edit: July 30, 2017, 10:05:19 PM by Fennec »
 

Offline cdev

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Re: bg7tbl gpsdo master reference
« Reply #395 on: July 30, 2017, 11:40:16 PM »
Its interesting how he now seems to be able to to use cheaper non-timing GPS's to discipline his hardware OCXOs.

BG7TBL has been able to push the envelope pretty far as what can be done with cheap GPS hardware.

Generally, the larger and therefore less highly optimized ceramic patch antennas are more broadband than the smaller ones.

You can make your own asymmetrical patch antenna (RHCP) using air as the dielectric.

It will be larger than the ceramic, maybe twice as large but much more likely to work ~25 MHz higher.  (GLONASS)
« Last Edit: July 30, 2017, 11:45:16 PM by cdev »
"What the large print giveth, the small print taketh away."
 

Offline edpalmer42

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Re: bg7tbl gpsdo master reference
« Reply #396 on: July 31, 2017, 01:44:17 AM »
Its interesting how he now seems to be able to to use cheaper non-timing GPS's to discipline his hardware OCXOs.

BG7TBL has been able to push the envelope pretty far as what can be done with cheap GPS hardware.

As long as a GPS receiver puts out some kind of signal, usually 1 PPS, you can use it to discipline an OCXO.  The question is what kind of performance will you see?  The long term frequency error for any properly designed GPS receiver will be zero, regardless of what type it is.  The differences, if any, should show up in short-term measurements.

For a navigation receiver, the 1 PPS output is something of a minor afterthought so it gets low priority.  On some older navigation receivers, I've seen the 1 PPS accuracy specified in the microsecond range.

On a timing receiver, the 1 PPS output is the main output while the location is sort of a minor afterthought.  The code is optimized to provide the lowest possible error on the timing output(s).  I've posted numbers in the past that showed the period of the 1 PPS output with a Standard Deviation of a few nanoseconds and a maximum range of 50 nanoseconds or less.

TBH, I've never seen a direct comparison of the output of a GPSDO built with a navigation receiver vs. a timing receiver.  It might be possible to adjust the PLL parameters for the nav-based GPSDO to minimize the short-term differences.

Ed
 

Online DaJMasta

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Re: bg7tbl gpsdo master reference
« Reply #397 on: July 31, 2017, 03:20:58 AM »
With GPS being used in phones and UAVs and such now, the line has been substantially blurred.  There are still navigation receivers that advertise 100ns or more jitter on their PPS output, but there are receivers marketed for location tracking or other non-timing uses that can do better than +-50ns jitter.

The very best timing receiver specifications I've seen are 15ns RMS on one datasheet and +-20ns on another.  Not sure which of those would actually be the better performer, I think you'd have to do some long term comparisons (and I actually have such an experiment planned with a couple of receivers) to figure out how the specs compare.

Offline metrologist

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Re: bg7tbl gpsdo master reference
« Reply #398 on: August 01, 2017, 11:18:49 AM »
non-bg7tbl gpsdo discussion:

Quote
My GPSDO came in. It is not BG7TBL, but similar with the Trimble module. http://www.ebay.com/itm/Trimble-GPS-Receiver-GPSDO-10MHz-1PPS-GPS-Disciplined-Clock-sine-and-square-wave-/252162780444

There is 2Vpp sine with 2V DC offset. The 10M square and PPS look fine. It's stable so far and my 5314A has not moved (0.1) in an hour, reads 3.9 Hz high.

I have a solid ACT led, but do not understand the RS232 output. I just poked my probe into the RX connector and it looks similar to: https://core-electronics.com.au/media/wysiwyg/rigol/ultra-scope-screenshot.png

Except the negative pulse arrives first and there is ~20us offset between the negative pulse and positive pulse. I get ~8ms pulse train like that every 2 seconds. Level is -5V to +5V. I'm trying to use Rigol DS1054Z to decode it with several baud rates.  :-//

I thought RS232 had like 12V and should look like regular serial data anyway (inverted)?

« Last Edit: August 03, 2017, 05:05:54 AM by metrologist »
 

Offline cdev

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Re: bg7tbl gpsdo master reference
« Reply #399 on: August 01, 2017, 12:19:45 PM »
Some Trimble receivers, like the Thunderbolt, have some firmware issue where they may fail to start with the right date after yesterday.

>My GPSDO came in. It is not BG7TBL, but similar with the Trimble module...

Just guessing that one can probably compensate for it in software if its basic functionality remains unchanged.
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