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."
Was a firmware update ever released for the BG7TBL to fix the minor error?
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 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
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?
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.
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.
Bought latest version of the BG7TBL.
My first freq reference.
BG7TBL 2017-03-29 teardown
OCXO: CTS 970-2178-46
GPS: u-blox NEO-7M-0-000
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.
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.
@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
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.
@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.
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.
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 !
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)
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
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.
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.