[time-nuts] Anyone have the source code for XL-AK GPS receivers?
Looking for the source code, can anyone help? Cheers, Corby ___ 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] T.I. questions
Jim, On 02/07/2015 12:48 AM, Jim Lux wrote: Only maximal codes have 2^n-1 states/periods. There are other configurations with shorter periods. A particularly tricky thing is that if the shift register in a maximal generator ever winds up as all zeros (e.g. from a upset or bit flip), then the generator sticks at zero. All maximal generators have an even number of taps, too. You can do all kinds of interesting things considering the generator as a polynomial (like factoring) Maximum lengths sequence (MLS) occurs with polynomials being prime numbers, which is easily shown as otherwise you get a sequence of length being a*b/gcd(a,b) where a and b is the sequence lengths of the two polynomials. There are also a plethora of schemes using multiple generators running in parallel with the outputs XORed.. Gold and Kasami codes are good examples where the two generators run at the same rate. GPS C/A and P(Y) code is an example where the generators run at different rates. In P(Y) code the go at different rates, but for C/A you have two generators running at the same rate. In C/A the two 10-bit LFSRs is started with phase difference between them depending on which code you want. For P(Y) they use a shortened sequence such that for every cycle, a different phase relationship is utilized, and that sequence is then shortened to become only a week. Cheers, Magnus ___ 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] Racal-Dana GPIB card question
Yeah, I know about the GPIB vs Airforce issue. Turns out all the seller's cards are Rev B, which I'm assuming won't work with the Rev. A counter. =/ I'll see if I can get onto the Racal-Dana group, thanks! -Ryan Stasel On Feb 6, 2015, at 10:07 , Malcolm via time-nuts time-nuts@febo.com wrote: You might want to join the Racal-Dana Yahoo group for help on this. There is a gotcha with these cards in that S4 selects which 488 protocol is used( Airforce or normal). Apparently you just have to swap it over and re-power. Sorry cannot help you with your software level matching question. Regards Malcolm ___ 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] T.I. questions
Hal, On 02/06/2015 09:42 PM, Hal Murray wrote: mag...@rubidium.dyndns.org said: The typical noise generator chips uses a PRNG based on DFFs and XOR gate(s). A typical weakness is that the chain of DFFs is to short, causing a relatively high rate of cycling, which hearable as a beating. However, for some uses, that is OK. The buzzword for the typical PRNG is LFSR - Linear Feedback Shift Register. Many years ago, Xilinx published a good app-note on this topic. There is also a section in Art of Electronics. With the right generating polynomial, you get a sequence of bits that doesn't repeat until 2^N-1 bits. The math geeks like to collect them. Each 1 bit in the polynomial turns into an XOR gate, so you will also find collections of polynomials with fewest bits. It's hard to imagine serious problems with too-short. Each FF doubles the no-repeat length. Polynomials happens to be prime numbers for a good reason. This makes them scarse, only create a few limited sequences. Combing two or more can overcome that limit, as seen in a navigation system near us. :) Cheers, Magnus ___ 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] HP 5065A questions
Joe, Your unit could be a 916 prefix with the newer physics package and 10811 added as retrofits. Look at the top of the A3 module, what is the series number? Also look at the A9 op-amp module, does it have a Epoxy block op-amp or a transistor can style op-amp? What serial number is penciled in the data log on the front panel that swings open? Last year sold was 1992 and latest serial number prefix was 2816A. With the unit in lock adjust the Oscillator fine freq to mid range and the coarse for a reading of around zero. Red lamp is not stock, the green one probably broke and that was only one they could find! Like Dan said the top cover is covered in holes and is hard to find. If you find a bottom that fits make sure you cover the inside with insulating tape. The original bottom cover has a very thin phenolic insulator covering its inside. The switch Paul mentioned is for the 1Mhz and 100Khz dividers. the rational was that if you had a power hit the clock would stop (the 1Mhz also drives the clock option) making sure you were not using a bogus time. Just leave it in the auto start position! The logic reset button is the one that will turn on the operate light! Cheers, Corby ___ 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] TimeLab with Wine: No RS232 interface available
Thank you all. Unfortunatly I'm still not able to get TimeLab in contact with any of my RS232 interfaces. Is there may an option when calling limelab.exe to force the usage of a defined port? Inbetween I tried also a lot with system.reg. HTerm is very tolerant to the names given to the ports, TimeLab still can't find any port. BTW: I use HTerm only to check if other windows programms can use the ports. When I normaly need a terminal I use a Linux program like Putty. I only use Wine with a window program if there is really no Linux alternative. So my Wine and windows knowledge is limited. In detail to your answers: Magnus Danielson mag...@rubidium.dyndns.org The trick is to link /dev/ttyS0 (or whatever) so that it occurs in ~/.wine/dosdevices/com1 which seemed to help a bit. Already did this, and tried it now also in the folder where the timelab.exe is in case that there is a problem with the path. No success. Mark Sims hol...@hotmail.com I have seen several issues with Windows programs not releasing (or perhaps not being able to releaase) the serial ports after using them. Once one of these programs accesses the serial port, no other programs can use it until you re-boot. I'm fighting windoze Hypertrm right now over this issue trying to read from a freq counter for some ADEV measurements. Once HYPERTRM runs, no other program can access the serial port. Good point, I tried TimeLab direclty after fresh reboots, but the interfaces are still invisible. Jim Lux jim...@earthlink.net One trick with Windows is to disable and then renable the serial port, in particular, USB ports sometimes get stuck, and this fixes them. There's also some power management things with USB connected ports that can get things confused. (You don't want USB selective suspend enabled) there's a command line tools that can do this, or you can use Device Manager. http://support.microsoft.com/kb/311272 describes devcon, which can do all sorts of useful stuff. Tried the program from your link, but wine devcon findall =ports was not able to find a port. Are you able to run it under Wine or only under windows? Any idea is still very welcome. Joerg ___ 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] TimeLab with Wine: No RS232 interface available
On 2/7/15 7:13 AM, joerg wrote: Thank you all. Unfortunatly I'm still not able to get TimeLab in contact with any of my RS232 interfaces. Is there may an option when calling limelab.exe to force the usage of a defined port? Inbetween I tried also a lot with system.reg. HTerm is very tolerant to the names given to the ports, TimeLab still can't find any port. BTW: I use HTerm only to check if other windows programms can use the ports. When I normaly need a terminal I use a Linux program like Putty. I only use Wine with a window program if there is really no Linux alternative. So my Wine and windows knowledge is limited. one way to tell if a port is alive and visible under windows is to try and use the mode command at the command prompt: C:\ mode com2: it will fail if the port doesn't exist, or is opened by some other process. It is NOT unusual for a port to be grabbed up by some process, which then dies without releasing it. I have a bunch of Singleboard PCs running Windows 7 with a Garmin 18 hanging on COM1. Every once in a while, the python program which I use to read it dies because COM1 is in use. There's also the whole microsoft serial mouse device problem. A typical Windows 7 install (and other versions as well) will have a MS serial mouse device in the device manager, and when booting, the device driver goes out and looks for the mouse on COM1 (and maybe other COM devices) If the wrong characters come back from the device at the wrong time (e.g. something from the GPS receiver), the mouse driver takes over the device (and randomly moves the cursor around the screen, sometimes). You need to explicitly disable the device (and/or remove it) in Device Manager. In detail to your answers: Magnus Danielson mag...@rubidium.dyndns.org The trick is to link /dev/ttyS0 (or whatever) so that it occurs in ~/.wine/dosdevices/com1 which seemed to help a bit. Already did this, and tried it now also in the folder where the timelab.exe is in case that there is a problem with the path. No success. Mark Sims hol...@hotmail.com I have seen several issues with Windows programs not releasing (or perhaps not being able to releaase) the serial ports after using them. Once one of these programs accesses the serial port, no other programs can use it until you re-boot. I'm fighting windoze Hypertrm right now over this issue trying to read from a freq counter for some ADEV measurements. Once HYPERTRM runs, no other program can access the serial port. Good point, I tried TimeLab direclty after fresh reboots, but the interfaces are still invisible. Jim Lux jim...@earthlink.net One trick with Windows is to disable and then renable the serial port, in particular, USB ports sometimes get stuck, and this fixes them. There's also some power management things with USB connected ports that can get things confused. (You don't want USB selective suspend enabled) there's a command line tools that can do this, or you can use Device Manager. http://support.microsoft.com/kb/311272 describes devcon, which can do all sorts of useful stuff. Tried the program from your link, but wine devcon findall =ports was not able to find a port. Are you able to run it under Wine or only under windows? devcon is a *windows* program, and I think (pretty sure, but I don't have a windows box here in front of me to check) has to be run with administrator privileges. (e.g. right click run as adminstrator kind of thing). (minor windows rant.. I'm glad MS is tightening up security, but it makes life hard for people running on a minimal embedded system. I wish there was an easy way to say it's' all running as root/administrator, stop asking for username/password. No better on Linux, it just manifests itself as needing to have users in the right groups, and the permissions set up properly. But on Linux, you can cheat and just always come in as root...) ___ 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] GPS active antenna delay ?
I have a white-hockey-puck style active GPS antenna, probably about 1998 vintage with no markings except 'Made in Mexico'. While compensating for cable delay is relatively straight forward by measuring the length and compensating for the velocity factor, a question is: how much amplifier / filter group delay is to be expected within the antenna itself? I'd assume that the amplifier in the antenna probably has pretty small group delay, but the RF filter may be significant. Looking through GPS SAW filter datasheets seems to show none with group delay specifications. googling leads to some research papers with delays of about: L1 - 20 MHz wide SAW filter has about 15 nsec of group delay L1 - 2 MHz wide SAW filter has about 65 nsec of group delay L1 - LC filter - can't find anything, but suspect it's probably just a few nanoseconds. I'm not sure a consumer grade antenna even has a SAW filter, it may simply be an LC filter. If it does include a SAW filter, then just using cable delay alone would seem to underestimate the actual antenna delay compensation needed for GPSDO, perhaps significantly. Has anyone on the list measured or otherwise estimated the active antenna delay including the amp and filters? -- Tom, N5EG ___ 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] TimeLab with Wine: No RS232 interface available
-Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of joerg Sent: Saturday, February 07, 2015 7:14 AM To: time-nuts@febo.com Subject: Re: [time-nuts] TimeLab with Wine: No RS232 interface available Thank you all. Unfortunatly I'm still not able to get TimeLab in contact with any of my RS232 interfaces. Is there may an option when calling limelab.exe to force the usage of a defined port? No, but what I'd suggest doing is sending a bug report/feature request to the Wine team. Ask them to have a look at the enumerate_ports() method in drivers/shared/gpibport.cpp, which is installed under the directory with the TimeLab executable (http://www.miles.io/timelab/beta.exe). They can either add support for whatever Win32 API function is failing to work properly in Wine, or, if they find that the problem is in my code, let me know directly at j...@miles.io. It's always possible that I've got a bug that just happens to work in Windows but not in Wine. If I can work around the issue without breaking anything else, that's likely to be the best solution for everyone. Also, try both timelab.exe and timelab64.exe. The 64-bit version may not have access to some driver interfaces that are only supported by 32-bit DLLs. This is mainly an issue with NI488.2 GPIB support, though, and I wouldn't expect it to apply here. Failing that, it costs about US $150 to buy a Windows laptop to dedicate to TimeLab and other Windows apps that have problems under Linux. At some point you have to start thinking seriously about what your time is worth. -- john, KE5FX Miles Design LLC ___ 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] T.I. questions
mag...@rubidium.dyndns.org said: The typical noise generator chips uses a PRNG based on DFFs and XOR gate(s). A typical weakness is that the chain of DFFs is to short, causing a relatively high rate of cycling, which hearable as a beating. However, for some uses, that is OK. The buzzword for the typical PRNG is LFSR - Linear Feedback Shift Register. Many years ago, Xilinx published a good app-note on this topic. Several, in fact. I spent some time tracking them down. Here's the previous list: xapp210 xapp211 xapp217 xapp220 But I found one more - XAPP052. It has a feedback table from N=3 to 168. The table is repeated in later app notes. Also, Xilinx has apparently lost XAPP217. It no longer appears on their web site, but I found it. Here's the updated list: XAPP052 LFSR Generators N=3 to 168 http://www.xilinx.com/support/documentation/application_notes/xapp052.pdf XAPP210 LFSR in Vertix Devices http://www.xilinx.com/support/documentation/application_notes/xapp210.pdf XAPP211 PDF PN Generators Using The SRL Macro http://www.xilinx.com/support/documentation/application_notes/xapp211.pdf XAPP217 Gold Code Generators 77-42925.pdf http://application-notes.digchip.com/077/77-42925.pdf XAPP220 LFSRs As Functional Blocks in Wireless Applications http://uglyduck.ath.cx/PDF/Xilinx/Spartan3/appnotes/xapp220.pdf Mike Monett ___ 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] Ethernet transformers for square to sine conversion 20F001N
Hello to the group a while back a discussion occurred about old ethernet 10 BT transformers for isolation and square to sine conversion. You can obtain NOS on ebay for a 14 pin dip 2 transformer block 20F001n from China quite cheap. I picked up 20. As a transformer they operate from 40 KHz to 16 Mhz and then roll off really kicks in Driving the transformer with a square wave from HCmos they do a good job of converting a square wave to a sign wave. using 2 50 ohm resistors delivers 4 Vpp into 50 Ohms. Clearly 150-200 ohms would be better to get the signal down to 1 or so volts for use. Distortion is -68 db. Most likely the products from my sig gen to logic conversion. For me at least these are pretty handy. I take no credit for the idea to use these. Just want to share the information and details from my tests. Regards Paul WB8TSL ___ 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] T.I. questions (Magnus Danielson)
A further comment on design of pseudo random code generators. At some point the code may enter the dreaded all zeros state. This clocks a zero on the input stage through all stages and the whole thing just stops. So a AND gate looking at all stages in parallel is used to detect the all zero state and get things going again. One way is to XOR the output of the AND and the input to any stage. since the all zero state is not permitted the length of the code is can be no longer than the well known 2^n -1 bits. Also if the number of codes desired is limited - some of the FFs may be replace by a delay line. Using MECL III and a delay line a 350 MHz rather long code generator was implemented in my lab with only few JK FFs. That was in about 1979. For more info see Dixon Spread Spectrum Systems. john roos k6iql ___ 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.
