Trimble Thunderbolt E - Page 1
Forum section: electronics / general

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 04, 2020, 11:35:56 pm
content: After my recent foray into BG7TBL GNSSDO and finding I like it. (It sure locks fast and tracks birds like a bloodhound) One disappointing feature is it's 1PPS signal coming directly off the GPS Ublox module. This got me more interested GPSDO with 1PPS driven by the DO. Also it wouldn't hurt if it was a smarter device with more sensors and even a binary communication protocol (hello TSIP!). I'm not sure if mine, made in 2007, has a newer or the older type of temperature sensor?Another question about using HP or Symmetricom 58536A GPS distribution amplifier... If I put a higher voltage 12V Symmetricom active antenna on the antenna port and say a Symmetricom 12V Syncserver on port one is it safe to put a Trimble Thunderbolt on port 2 and a BG7TBL GNSSDO on port 3 (both are 5V units)? I'm 95%+ sure this is fine but wanted to see if anyone has done this and knows for sure. I was thinking putting the higher volt unit on port 1 made the most sense but anyone with experience with this it would be a big help that would lessen my concern over frying anything?I love the additional data in Lady Heather it shows. It doesn't pick up as much as the little BG7TBL but I'm thinking I need to get this bigger active antenna outside and on the roof vs. where it is now in my window sill.Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 04, 2020, 11:46:32 pm
content: From what I understand the older models had more sensitive temp sensor. So there's a trade off... more accurate temp sensor or newer hardware it seems. It was harder to find a newer unit... I found plenty of old ones. This was the latest model I could find without breaking the bank for what I didn't see as a really good reason right now. I know people build additional ovens for these as well. I've read about the shoe box trick.Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 04, 2020, 11:51:47 pm
content: I shouldn't have said the Thunderbolt doesn't pick up as much as the BG7TBL... it picks up less SATs but in all reality it picks up a lot more because it's doing a LOT more inside than what the little ublox does. It seems to have more functionality despite maybe being even older.

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 05, 2020, 12:04:31 am
content: Another thing I'm wondering about. It came with a switched mode power supply that looks pretty cheap. I know with rubidium standards these aren't really good. Wouldn't it improve performance to have a better linear power supply? I'm in the process of building up an Efretom FRK-L with a linear power supply sized perfectly for it... would the Trimble Thuderbolt E benefit from this as well?B

author: ArthurDent
author_rank: Super Contributor
timestamp: March 05, 2020, 03:30:01 am
content: I use SMPSs with all my Tbolts and my Rb frequency standards and haven't had any problems. Maybe I'm not as fussy as everyone else and haven't noticed any problems, but I doubt that. The 911 units I removed all my Tbolts from had a large SMPS that supplied power for the entire complicated piece of equipment. If the designers of these mission critical units used SMPSs to power them, I'm sure they are good enough for my uses.Looking at your graph, you have far more serious problems than power supplies. Your signal is terrible. Take a look at the graph from one of my Trimble units (not a Tbolt, but similar) and you will see the signal graph shows much stronger signals over most of the sky where satellites could be. I also set the receiver elevation mask to ignore satellites close to the horizon.I have a externally powered antenna distribution amp that also feeds a receiver powered amp to allow me to check plenty of GPSDOs at one time and some of the outputs are modified with a capacitor in series and a parallel resistor for receiver antenna load so I don't get an 'antenna open' error message. I used resistors that gives the correct load for my 5 vdc antenna supply.

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 05, 2020, 03:57:09 am
content: My antenna is inside right now with little view of the sky where it is. That's why the signals aren't strong. I need to move it but still haven't figured out the best way to get the cable through the wall or window frame to go up the side of the house. It's between two buildings down low with almost zero view of any thing but obstructions. The ironic thing is the little BG7TBL on cheap antenna in the window gets 20+ SATs full strength. Maybe I'll try that on the Thunderbolt but it seems like the bigger outdoor on the roof makes the most sense. That's what it's made for after all.The docs for the FRZ say to minimize ripple on any power for a better signal from the rubidium and basically seem to say you can correlate the ripple to noise and instability in the signals it generates. Garbage in garbage out is the way I read it. Maybe it's more sensitive to that kind of thing idk?Thanks for those pics of the splitting you're doing.Bill

author: ArthurDent
author_rank: Super Contributor
timestamp: March 05, 2020, 04:27:20 am
content: Notice the very interesting photo behind the splitters.....

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 05, 2020, 04:54:56 am
content: That's cool picture of the leap second it looks like on a classic Dell! Is it a Polaroid?B

author: ArthurDent
author_rank: Super Contributor
timestamp: March 05, 2020, 01:20:43 pm
content: Leap second. You can hear ticks with the volume way up.

author: testpoint1
author_rank: Frequent Contributor
timestamp: March 05, 2020, 02:18:42 pm
content: Ublox module? the GPSDO use its own Trimble module, and can not be replaced, soldering at the PCB.

author: grizewald
author_rank: Frequent Contributor
timestamp: March 05, 2020, 02:33:43 pm
content: Quote from: notfaded1 on March 05, 2020, 03:57:09 amI had exactly the same problem Bill, but managed to find this little gem locally.It has an SMA male on one end and an SMA female on the other end. The actual cable is about 1mm thick and is quite happy to be crushed by the closed window and the bottom of the window frame.

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 05, 2020, 07:33:34 pm
content: Hi Bill,your Time Constant is much too low with 10sec only.You should use 500sec at least.I also use a meanwell SMPS for my Trimble thunderbolt,(with trimble OCXO), but a linear supply for my Rb clock.The antenna cable goes from the roof top down to the basement, and I drilled several holes through the window or the door frame to get it through.Frank

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 05, 2020, 11:29:37 pm
content: Quote from: grizewald on March 05, 2020, 02:33:43 pmThis is neat... I found some Type F ones called Ghost cable. It doesn't look like anyone makes a TNC one... no surprise really. The ghost cable is even thinner than 1mm I think. I'm going to order some of these and experiment some.Another idea I have. I have an old DISH TV dish on the house. I'm using COX cable for internet and TV now that doesn't need the DISH network coax. I could mount my high gain GPS outdoor antenna on the old DISH frame with perfect view of the sky. Can I then re-use the Type F style RG-6 coax that's already coming down and routed almost perfectly down to the corner of the room where my lab is located??? I'll still need to make that jump into the room somehow but the cable is already there in place and hidden and painted to match my house color. I'm guessing it's RG-6 coax. GPS is well within the frequency range? DISH coax is swept to 2.5-3 GHz I seem to remember. Has anyone tried something like this? In a perfect world I'd use the cable that came with the antenna from Symmetricom. It's TNC on both ends factory made.Bill

author: Vgkid
author_rank: Super Contributor
timestamp: March 06, 2020, 12:07:00 am
content: RG-6 will work

author: grizewald
author_rank: Frequent Contributor
timestamp: March 06, 2020, 08:42:27 am
content: Oh how I wish I had access to the roof. Unfortunately, I live in a three story apartment block in the middle apartment and there is no access to the roof. Even worse, I only have north or east facing windows that have any view of the sky and that's limited by trees and the other apartments.Initially, I tried using the ceramic antenna that came with my BG7TBL GPSDO, but had such poor reception I could not even get a lock.My final solution is a small quadrifilar GPS antenna on a short mast from my balcony.The little antenna has an LNA built in and actually delivers some quite impressive results, considering how little sky it can actually see.

author: ArthurDent
author_rank: Super Contributor
timestamp: March 07, 2020, 07:59:47 pm
content: I have two PCTEL 26 dB GPS antennas on my house. The highest one is probably 50 feet above ground level and the second about 45 feet. Both are mounted on 10 foot long thinwall steel pipe that was intended to be the top rail of a section of chain link fence and the antennas I have fit nicely on it with the RG-6 coax feeding down the inside of the pipe. The pipe is designed for outdoor use and was available and cheap at Home Depot.Below are photos of the antennas and a signal strength graph showing good signal strength after going through my GPS distribution amplifiers and showing a pretty good view of the whole sky.

author: grizewald
author_rank: Frequent Contributor
timestamp: March 07, 2020, 10:06:02 pm
content: Colour me 48dBc!

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 08, 2020, 01:41:59 am
content: I really appreciate the photos! I'm going to reuse the RG-6 DISH coax to get down to my lab and attach my antenna to the frame there. Did either of you put a lightning arrestor in line too? Dr. Frank mentioned the time constant. I need to figure out the flag or / command for lady heather to set the constant. Once I get these different flags figured out I'll add a script to launch it that way. I just got some additional USB to DB9 cables with FTDI chipset. Seems to work fine with multiples running. I'm going to be running two instances of lady heather so I suppose editing the config file won't work then since I need two different configs?It looks like the little ublox picks up signals great on this BG7TBL compared to the Thunderbolt if their antenna are majorly blocked. Once I get the main antenna on the roof I'll hook them both to it and I'll be good.Bill

author: james_s
author_rank: Super Contributor
timestamp: March 08, 2020, 04:27:23 am
content: Is it better to use RG6 or RG58? I've seen a lot of people mention RG58 for GPS antennas, it's the correct 50 ohm impedance but I recall that RG6 is lower loss. I used RG6Q for my scanner antenna because it was suggested that the lower loss would more than offset the impedance mismatch for receive-only use and also I got a box of it for free. I think I still have enough of that left that I could use it, but the RG58 is thinner and more flexible. I have a 35dB active antenna which in theory ought to more than offset the losses of a run of RG58.

author: tkamiya
author_rank: Super Contributor
timestamp: March 08, 2020, 05:26:09 am
content: I think it's called tboltmon, but Trimble itself has a utility posted on its website to set parameters on Tbolt and Tbolt-e. You can change the time constant there and save it to NVRAM. I've been enjoying LH for quite some time now. If you want to do it that way, it's easier to manage later on to put most of tweaks on command line, rather than the config file.As to cable, either works. RG6 has lower loss and is cheaper. I've used 50 feet of RG58 and it worked fine, too. Now, I use much thicker cable but that's only because I had it. Unless your antenna condition is very poor, you won't notice any difference.

author: Helix70
author_rank: Unknown
timestamp: March 08, 2020, 06:35:56 am
content: Quote from: james_s on March 08, 2020, 04:27:23 amThe "signal strength" reported by the GPS module has less to do with the absolute strength of the signal, and more to do with the signal to carrier ratio (dBc) or Carrier to Noise (C/N). The loss of the cable has no effect if the signal level is above the threshold of the GPS unit's sensitivity.

author: grizewald
author_rank: Frequent Contributor
timestamp: March 08, 2020, 08:55:59 am
content: Quote from: notfaded1 on March 08, 2020, 01:41:59 amI didn't use one as I'm way below roof and tree level, so I don't really see a lighting strike being much of a risk for me. I hope ArthurDent has lightning arrestors though as his antennas are prime targets.

author: ArthurDent
author_rank: Super Contributor
timestamp: March 08, 2020, 03:36:02 pm
content: Besides other protection, my highest antenna mast is mounted on a 6 inch diameter cast iron vent pipe that is a very good ground. If you look at the signal strength chart you will see a coverage gap at due south and another at SSE. These signal gaps are caused by some of the huge trees surrounding my house. While the trees are far higher than the house, they don’t interfere that much with the reception but definitely give me some added protection against lightning. Although no guarantee, the fact that the house hasn't had any lightning strikes in its first 110 years is also a little reassuring.

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 09, 2020, 01:50:07 am
content: In lady heather is the time constant the PLL time constant? &t - sets the PLL time constant?Bill

author: ArthurDent
author_rank: Super Contributor
timestamp: March 09, 2020, 03:45:07 am
content: You can use &a to autotune some of the key functions.https://time-nuts.febo.narkive.com/6y63fagZ/lady-heather-s-tbolt-oscillator-auto-tune-function

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 15, 2020, 10:16:43 pm
content: I'm going to try the autotune once this stabilizes some but I put the antenna on the roof today! HUGE improvement. I can actually shorten the cable inside to improve it some more as right now I have a coil of TNC cable inside that's not really needed to be hooked up but it was easiest at first. I can shorten the run by about 20 feet by removing it.Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 15, 2020, 10:21:01 pm
content: Thank you D I S H network for the cabling I reused.

author: ArthurDent
author_rank: Super Contributor
timestamp: March 16, 2020, 01:15:32 am
content: You have done the first thing I recommended and that was get a stronger signal with an improved antenna location to allow making meaningful comparison test. I also found when I got my first GPS that having adapters and other connectors in the antenna line causes losses that I could easily see. I would drill a hole next to the window frame and have a single run of RG-6 foam from the arrester to the receiver or distribution amp rather than have the flat line adapter you have going through the window. My RG-6 foam line is 53 feet long and I have several feet coiled up that I don't worry about. Knowing the exact cable length allows me to correct for cable delay in the receiver set-up if I want to.

author: Mark19960
author_rank: Regular Contributor
timestamp: March 16, 2020, 01:52:46 am
content: Interesting. I never considered using my existing RG6 for a GPS antenna.When we moved house I pulled new cable outside and one was for a timing antenna.I left an existing RG6 run in place and added several LMR240 runs. One of those LMR240 runs was for the timing antenna.My curiousity has been peaked. I may have to give the RG6 that's there unused a go.It's lower loss @ 1Ghz than the LMR240 IIRC.Never considered it. In my mind... the GPSDOs are 50 ohm, the timing antenna is 50 ohm... I need 50 ohm cable.I like the Trimble. I have one of the older models.Tempting

author: tkamiya
author_rank: Super Contributor
timestamp: March 16, 2020, 04:25:00 am
content: Trimble manual actually states, using 75 ohm and the resultant mismatch is not going to cause problem. It actually recommends using RG-6 because of reduced loss.I say the signal chart.... It's MUCH better but still not great. With installation like that, the graph should show much better result. Would you like to (just for testing) eliminate that flexible PCB thingie and test? If that works, you can use a short piece of very thin coax and thread it through the gap in your window. It can be done. I've done it before.

author: Mark19960
author_rank: Regular Contributor
timestamp: March 16, 2020, 09:48:45 am
content: It sure does.Never paid that bit any attention.In my case the run is not that long @ around 50 feet so I might not gain that much moving over to the RG6 but I am curious now.

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 16, 2020, 11:05:45 am
content: Hello Bill,you still have completely messy parameters, which prohibit good ADEV values!These strange oscillations of pps and DAC value indicate that there's a big problem.Please run the autotune function, or set EL =20..25°, AMU = 1, TC = 500 sec, Gain ~ 1..2Hz/V, like ArthurDents receiver.I suppose you meanwhile know, that these parameters can be stored into Thunderbolts EEPROM, so that these are available at startup.Just a silly idea: Have you made a precise position survey (24..48h) and stored this correctly?Frank

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 16, 2020, 11:39:20 am
content: Quote from: Dr. Frank on March 16, 2020, 11:05:45 amThat's the next step Dr. Frank... I wanted to let it run overnight and stabilize before kicking off the autotune because that's what i've read you're supposed to do? I'll read up about the position suvey today.Thanks,Bill

author: Theboel
author_rank: Frequent Contributor
timestamp: March 16, 2020, 11:53:58 am
content: Hi notfaded1,if You have spare time in the future please put the tv disc back in place and use it as solid ground plane You will find interesting result

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 19, 2020, 10:03:40 pm
content: I made some changes (Dr. Frank suggested making mine more like AuthurDent's) then followed the directions and the graphs looks much much better than before. You can see the before and after on the graph here. Now I can focus on what I can do to improve signals any further. So far I removed the long TNC cable and replaced it with a 10 Ft. Type F cable like the other RG-6 in the run.Bill

author: notfaded1
author_rank: Frequent Contributor
timestamp: March 19, 2020, 10:08:44 pm
content: Props to John aka KE5FX for the Thuderbolt tuning functionality in the lady heather software... it works a treat!

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 21, 2020, 01:35:05 pm
content: Hi Bill,the signal strength looks good. I doubt that you will achieve better results here. Maybe you better chose EL >= 20°, if you're surrounded by other buildings.Anyhow the ADEV parameters, and also the OSC value are not stable enough. I'm still wondering, why.Which version of OCXO do you have in your TB?The original, black labelled Trimble one, or this red labelled 'piezo' one?The Trimble version would much better.http://www.ke5fx.com/tbolt.htmFrank

author: ArthurDent
author_rank: Super Contributor
timestamp: March 21, 2020, 02:49:45 pm
content: Until you change the parameters you are plotting to be the same as mine you can’t make a real comparison between your Tbolt and mine. First, the view you are using is set to 1 minute/division but you can see in my graph in post #4 that I have my view set to 120 minutes/division to show 44 hours of information that is much more meaningful. Starting off you could try 15 minutes/division until you know if your Tbolt is working properly or not.You also should enable plotting the 10 Mhz signal that I mentioned in another thread so you can check the health of the oscillator as well. Having the resolution of the PPS set too high only gives meaningless wild swings in the graph that are hard to understand.It is easy to make these changes in Lady Heather and you will be able to interpret the displayed data easier and compare your graph to others.

author: notfaded1
author_rank: Frequent Contributor
timestamp: April 10, 2020, 04:45:49 am
content: I wanted to post an update. It's getting better. I'm considering replacing the DS 1620 with a 9748C2 datecode. This would, I think, improve the temperature regulation to 0.01 C steps. I think the current DS 1620 in it has less resolution.Bill

author: ArthurDent
author_rank: Super Contributor
timestamp: April 10, 2020, 12:51:02 pm
content: I wouldn't change the DS1620. That has basically nothing to do with how the Tbolt functions but just reports the temp on the board, not the OCXO temp and until you make the following changes, you aren't sure it's bad. Scale of all parameters have to be meaningful as I've mentioned before. Change the T sensitivity to 500mC/div, 1pps to 20 ns/div, DAC to 200 uV/div, O to 500ppt/div, and elevation mask to 20 degrees before you do anything else.

author: notfaded1
author_rank: Frequent Contributor
timestamp: April 11, 2020, 05:03:09 pm
content: I'm working on the elevation mask @AuthurDent. I just downloaded TimbleVTS.Bill