Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
Le 25 nov. 2014 à 19:29, Joseph Gray jg...@zianet.com a écrit : I bought one of those recently. I haven't done more than power it on to see if it works. I will probably look at it more over Thanksgiving. If you are thinking of replacing the patch antenna with a connector to external antenna as I did, be careful of mechanical bonding. For practical purposes I had place the 5 pin through hole SMA on the top of the module. This meant that I had to run a short connection up through the original patch antenna hole to connect to the board trace. Error. It worked fine, but while boxing for use as an NTP source I inadvertently put pressure on that wire and ripped off the board trace. So my NTP source has been relegated to parts. Maybe better to have the wire running on the top. Joe Gray W5JG On Nov 25, 2014 9:15 AM, Mike Cook michael.c...@sfr.fr wrote: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6-Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_JNhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox's u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can't see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I'd like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
They use the LEA-6T for DIY drone applications because it provides raw carrier phase information. The raw carrier info is compared with the raw carrier data from a nearby fixed (and surveyed for an extended period) GPS receiver. The position error of the fixed station is subtracted from the reported position of the 'roamer' , the resultant position is supposed to be accurate to within 10cm of true position. All this is done via a suite of open source applications called RTKLib. ublox was the only relatively inexpensive gps module that provided the phase data needed to make all this work. More recently a few of the other module vendors including skytraq (sp?) have provided this function. Getting a module that provided carrier data for less than $100 US was a big deal for the drone community. The only other cheap module that I know about is the synergy ssr-6t which works very well but (very minor nit) has a small pitch connector that was a nuisance to make the interconnects for. These chinese modules look to be much easier to interface. I'll probably buy one eventually just to see if the deviations from the pcb design rec's have impacted the performance in my application. Regards, Dale NV8U -Original Message- From: S. Jackson via time-nuts Sent: Tuesday, November 25, 2014 2:41 PM To: ewkeh...@aol.com ; time-nuts@febo.com Subject: Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay? Bert, the LEA-6T actually has software bugs that show up in moving applications and that need to be handled by the users' software, and they are selling it for drone applications. Without any monitoring for these bugs the units may really only be useful for stationary applications. Why they would choose the 6T unit instead of a non-T unit at half the price would only be because they got those as surplus really cheap I would think. bye, Said In a message dated 11/25/2014 09:50:12 Pacific Standard Time, time-nuts@febo.com writes: A Lea-6T is only worth any extra money if you are using the sawtooth correction data coming out of it. With out correction a $ 14 unit is just as good. Bert Kehren In a message dated 11/25/2014 11:25:34 A.M. Eastern Standard Time, michael.c...@sfr.fr writes: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6- Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_J Nhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
A Lea-6T is only worth any extra money if you are using the sawtooth correction data coming out of it. With out correction a $ 14 unit is just as good. Bert Kehren In a message dated 11/25/2014 11:25:34 A.M. Eastern Standard Time, michael.c...@sfr.fr writes: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6- Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_J Nhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
I bought one of those recently. I haven't done more than power it on to see if it works. I will probably look at it more over Thanksgiving. Joe Gray W5JG On Nov 25, 2014 9:15 AM, Mike Cook michael.c...@sfr.fr wrote: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6-Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_JNhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox's u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can't see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I'd like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
Bert, the LEA-6T actually has software bugs that show up in moving applications and that need to be handled by the users' software, and they are selling it for drone applications. Without any monitoring for these bugs the units may really only be useful for stationary applications. Why they would choose the 6T unit instead of a non-T unit at half the price would only be because they got those as surplus really cheap I would think. bye, Said In a message dated 11/25/2014 09:50:12 Pacific Standard Time, time-nuts@febo.com writes: A Lea-6T is only worth any extra money if you are using the sawtooth correction data coming out of it. With out correction a $ 14 unit is just as good. Bert Kehren In a message dated 11/25/2014 11:25:34 A.M. Eastern Standard Time, michael.c...@sfr.fr writes: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6- Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_J Nhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
Hi I looked at the boards on the eBay listing. Last time I looked at the layout guidelines for the LEA-6T’s they pretty much said “don’t do it that way” …. Who knows what they did that board for or why they did it that way. That’s not to say the boards don’t work. They probably do work. Often guidelines are a bit over restrictive….. Bob On Nov 25, 2014, at 2:41 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Bert, the LEA-6T actually has software bugs that show up in moving applications and that need to be handled by the users' software, and they are selling it for drone applications. Without any monitoring for these bugs the units may really only be useful for stationary applications. Why they would choose the 6T unit instead of a non-T unit at half the price would only be because they got those as surplus really cheap I would think. bye, Said In a message dated 11/25/2014 09:50:12 Pacific Standard Time, time-nuts@febo.com writes: A Lea-6T is only worth any extra money if you are using the sawtooth correction data coming out of it. With out correction a $ 14 unit is just as good. Bert Kehren In a message dated 11/25/2014 11:25:34 A.M. Eastern Standard Time, michael.c...@sfr.fr writes: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6- Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_J Nhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
