Re: [time-nuts] GPSDO vs Rb standard

2013-09-20 Thread Bob Stewart
measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 7:25 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi When I want to tune an Rb, I just hook up to it with a terminal program and hack away at it. There's not a lot to the protocol. Bob

Re: [time-nuts] GPSDO vs Rb standard

2013-09-20 Thread Bob Camp
: [time-nuts] GPSDO vs Rb standard Hi When I want to tune an Rb, I just hook up to it with a terminal program and hack away at it. There's not a lot to the protocol. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe

Re: [time-nuts] GPSDO vs Rb standard

2013-09-20 Thread Bob Stewart
li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, September 20, 2013 5:34 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi All of my FE Rb's have serial out of a 9 pin D connector. They bring power (+15 and +5) in on that connector

[time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Stewart
I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it.  The 10MHz is marching right to left about 1 cycle every 20 seconds.  So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb?

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Camp
Hi One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns per 20 seconds would indeed be 5 ppb. Since the Rb is *stable* but not *accurate*, the real question is - how much does the 5 ppb change by? The Rb can't tell you if the GPSDO is correct. The best it can do is

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Stewart
and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 5:01 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns per 20 seconds would indeed be 5 ppb. Since the Rb is *stable

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Azelio Boriani
Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455,

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread John C. Westmoreland, P.E.
Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Stewart
is time consuming to say the least. Bob From: John C. Westmoreland, P.E. j...@westmorelandengineering.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 6:13 PM Subject: Re: [time-nuts] GPSDO vs Rb

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Azelio Boriani
, P.E. j...@westmorelandengineering.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 6:13 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Camp
Hi The Rb's have a couple of issues: 1) Its been years since they were set on frequency and they do have a yearly drift rate 2) They have a temperature coefficient of drift that may be fairly large (0.1 ppb over -30 to +70) 3) They self heat quite a bit, so they do move temperature / need a

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Camp
...@westmorelandengineering.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 6:13 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Camp
, 2013 5:01 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns per 20 seconds would indeed be 5 ppb. Since the Rb is *stable* but not *accurate*, the real question is - how much does the 5 ppb change

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Stewart
time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 7:22 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi The Rb's have a couple of issues: 1) Its been years since they were set on frequency and they do have a yearly drift rate 2) They have a temperature

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Camp
to the heat sink. Good idea? Anybody got a busted one? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 7:22 PM Subject: Re: [time-nuts] GPSDO vs Rb

Re: [time-nuts] GPSDO vs Rb standard

2013-09-18 Thread Bob Camp
of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 7:22 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi The Rb's have a couple of issues: 1) Its been years since they were set on frequency and they do have a yearly drift rate 2