[time-nuts] TBolt and Z3801A performance data

I just put the results of some tests of 2 Time-Nuts Special Thunderbolts, as well as 2 Z3801As, at http://www.febo.com/pages/gpsdo_comparison/ I learned an interesting (and important) lesson in doing these measurement. I initially measured the pairs of GPSDO against each other (e.g., one TBolt

[time-nuts] GPS shielding by power lines?

Hi all, in the process of setting up a GPS time standard for a Radio Astronomy facility (amateur) we installed a GPS receiver in a small cabin with a translucent roof, thinking that would not impede the GPS signal. After a lot of head scratching as to why we were not getting the performane we got

Re: [time-nuts] GPS shielding by power lines?

Alan Melia wrote: Hi all, in the process of setting up a GPS time standard for a Radio Astronomy facility (amateur) we installed a GPS receiver in a small cabin with a translucent roof, thinking that would not impede the GPS signal. After a lot of head scratching as to why we were not getting

Re: [time-nuts] TBolt and Z3801A performance data

These tests were made with the GPS antenna connected? At t 100 seconds, they should all look about the same, because that's where GPS disciplining comes in, no? They should not be uncorrelated in the long run. To the extent one Z3801 looks worse than the other at large values of tau, I'd

Re: [time-nuts] TBolt

Hi, Where can I purchase one or two of the time-nuts Tbolt specials? Thanks, Pieter - Original Message - From: John Ackermann N8UR [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, August 09, 2008 4:27 PM Subject:

Re: [time-nuts] TBolt and Z3801A performance data

Yes, all were made with GPS antenna connected (and running from the same antenna via an 8-port splitter). What I was mainly commenting on is the TBolt's pronounced hump that shows up in the measurements against the FTS-1050A but largely disappears in the pairwise measurement. The longer tau

Re: [time-nuts] TBolt and Z3801A performance data

Hi John, On Sat, 2008-08-09 at 17:48 -0400, John Ackermann N8UR wrote: The longer tau readings are interesting mainly to see how the GPS loop kicks in; tau below about 1000 seconds seem related to OCXO performance on the TBolts, while the Z3801A seems to have a longer time constant, and

Re: [time-nuts] TBolt and Z3801A performance data

Hi John, On Sat, 2008-08-09 at 17:48 -0400, John Ackermann N8UR wrote: The longer tau readings are interesting mainly to see how the GPS loop kicks in; tau below about 1000 seconds seem related to OCXO performance on the TBolts, while the Z3801A seems to have a longer time constant,

[time-nuts] Thunderbolt PPS output

Has anyone used the thunderbolt PPS output with a N8UR FatPPS? I'm seeing a large (+-100-300us) amount of jitter on the output of the FatPPS. This same setup works fine with the input from z3801a (using a PECL/TTL converter) or the Fury (even though the Fury's pulse is wide enough to begin

Re: [time-nuts] Thunderbolt PPS output

The TB's PPS output has something like 5 ohm output impedance. It is very desirable to terminate the coax cable with 50 ohm at the other end, otherwise you will get endless ringing The following web page uses the PPS output of the Thunderbolt to illustrate ringing in a non-matched cable:

[time-nuts] Z3801A

Hi all, I am reviving an old Z3801A that was stored for 5 years. I did the RS232 header mod and I can communicate with the unit. The power LED does not come on, but I can control the enabled and active LED. I am not able to enter a date after 2007 to speed up the adquisition process. Is there

Re: [time-nuts] GPS shielding by power lines?

The thought was that there as interference arcing or corona noise from the line insulators, and a receiver (AM) was deployed to listen for what was expected to be a substantial wide band noise signalwe didnt hear one! We are now confused about what the effect is. The signal could