Re: [time-nuts] TAPR TICC boxed

Also for interest the 53131a schematic is available at http://bee.mif.pg.gda.pl/ciasteczkowypotwor/HP/53131.pdf HP used a low input bias current bjt opamp, the Lt1008 to bias/dc servo a custom JFET buffer driving an AD96687 comparator. On Fri, Mar 31, 2017 at 10:34 PM Scott Stobbe

Re: [time-nuts] TAPR TICC boxed

Attempting sub nanosecond timing with an actual 1Mohm source is an exercise in futility. There are very few cases where one would want to attempt precision timing measurements with such a high impedance source. The 1M pulldown on the TICC input is merely intended to maintain a valid logic input

Re: [time-nuts] TAPR TICC boxed

Mark wrote: I thought about using the clamp diodes as protection but was a bit worried about power supply noise leaking through the diodes and adding some jitter to the input signals... It is a definite worry even with a low-noise, 50 ohm input, and a potential disaster with a 1Mohm input.

Re: [time-nuts] TAPR TICC boxed

Fwiw, for a precision comparator you'll probably want a bipolar front end for a lower flicker corner and better offset stability over cmos. For high-speeds the diffpair is going to be biased fairly rich for bandwidth. So you will more than likey have input bias currents of 100's of nA to uA on

Re: [time-nuts] TAPR TICC boxed

FJH1100 Ultra Low Leakage Diode Alex On 3/31/2017 6:00 PM, Charles Steinmetz wrote: Mark wrote: I thought about using the clamp diodes as protection but was a bit worried about power supply noise leaking through the diodes and adding some jitter to the input signals... It is a definite

Re: [time-nuts] GPS first LO need to be locked?

Hi There are a lot of GPS chips that do an I/Q mix down to a low IF. It’s then (re) sampled from there. The “LO” in this case would down convert to the low IF …. Bob > On Mar 31, 2017, at 6:08 PM, Magnus Danielson > wrote: > > God natt Attila, > > On

Re: [time-nuts] GPS first LO need to be locked?

God natt Attila, On 03/31/2017 11:29 PM, Attila Kinali wrote: God kväll Magnus, On Fri, 31 Mar 2017 21:19:00 +0200 Magnus Danielson wrote: Still fills the function of LO, as the sample and hold operates as a mixer and the fold-down can be seen as an overtone mix

Re: [time-nuts] GPS first LO need to be locked?

God kväll Magnus, On Fri, 31 Mar 2017 21:19:00 +0200 Magnus Danielson wrote: > Still fills the function of LO, as the sample and hold operates as a > mixer and the fold-down can be seen as an overtone mix followed by a > sampling of the mix product, so well, it's

Re: [time-nuts] more of a time distribution question

I'm happy to run a group buy for just the 8736.My last quote from the vendor was just a bit under $27 each, and that does not come with the board connector. I picked these boards for compatibility with Motorola footprint, but also because it doesn't insist on goofy 3.0 volt power and logic

[time-nuts] HP 5090A Frequency Standard manual available

I've just uploaded a pdf version of the HP 5090A Ops and Service manual to Didier's site at. http://www.ko4bb.com For now at least it's also available at https://www.mediafire.com/?u0bf1eips89uo3h The 5090A was an HP product designed in the UK in the early 1960s and was an off

Re: [time-nuts] GPS first LO need to be locked?

Hi Jim, On 03/31/2017 01:07 AM, jimlux wrote: BTW a lot of GPS receivers don't have a "first LO".. they are more like a Tuned RF receiver - an input BPF for L1, L2, or L5, then direct sampling at around 30-40 MHz - something that makes the GPS signals alias down somewhere convenient (and

Re: [time-nuts] more of a time distribution question

Hi The 8736 is a very nice part. I think some sort of group buy would be a good idea. Bob Sent from my iPhone > On Mar 31, 2017, at 12:14 PM, Bob Darlington wrote: > > I guess it's time for me to finish up that NTP cape for the BeagleBone. > I'm using a Furuno

Re: [time-nuts] GPS first LO need to be locked?

Hi, On 03/30/2017 03:46 PM, paul swed wrote: I am curious if the first local oscillator on a GPS receiver must actually be locked or coherent to the reference oscillator in the GPS receiver typically running at some 10 MHz approximately. Or as long as the first LO is quite stable it doesn't

[time-nuts] TAPR TICC boxed

I thought about using the clamp diodes as protection but was a bit worried about power supply noise leaking through the diodes and adding some jitter to the input signals... I'm probably just being paranoid. The TICC doesn't have the resolution for it to matter or justify a HP5370 or better

Re: [time-nuts] GPS first LO need to be locked?

links [2] and [3] give 404 errors Dave -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: 31 March 2017 12:35 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS first LO need to be locked? [2] "A

Re: [time-nuts] more of a time distribution question

I guess it's time for me to finish up that NTP cape for the BeagleBone. I'm using a Furuno GT-8736 ( http://www.furuno.com/en/ products/gnss-module/GT-8736 ) I built up a prototype about two years ago but... got married very shortly after that and haven't played with it since. Is there any

Re: [time-nuts] GPS first LO need to be locked?

On 3/31/17 4:35 AM, Attila Kinali wrote: On Thu, 30 Mar 2017 20:00:31 -0700 Peter Monta wrote: BTW a lot of GPS receivers don't have a "first LO".. they are more like a Tuned RF receiver - an input BPF for L1, L2, or L5, then direct sampling at around 30-40 MHz - something

Re: [time-nuts] GPS first LO need to be locked?

On Thu, 30 Mar 2017 19:56:31 -0400 Bob kb8tq wrote: > > Doppler is pretty big when the spacecraft is coming or going at the > > horizon, about 5 kHz (out of 1.5 GHz, so 4-5 ppm). > > Relatively speaking, GPS satellites are moving slowly (a few km/s) > > > > So somewhere in the

Re: [time-nuts] GPS first LO need to be locked?

On Thu, 30 Mar 2017 20:00:31 -0700 Peter Monta wrote: > > BTW a lot of GPS receivers don't have a "first LO".. they are more like a > >> Tuned RF receiver - an input BPF for L1, L2, or L5, then direct sampling at > >> around 30-40 MHz - something that makes the GPS signals

[time-nuts] TAPR TICC boxed

(this might be a duplicate post... the last time I sent this, the message bounced) What did you do for input protection? I want to build an input system for the TICC that incorporates some input protection, switchable terminator, possibly settable threshold and edge selects, and a

Re: [time-nuts] more of a time distribution question

From: Hal Murray That should work. I haven't found a GPS with PPS for the beaglebone. What level of accuracy do you want? If you only need 100 ms or so, then a normal junk GPS (no PPS) on USB should work. == This works with the BeagleBone:

Re: [time-nuts] TAPR Oncore M12+ kit

Norm and Bob, The M12+ GPS receivers mounted on the motherboard are indeed the timing units. Chapter 5 of the Motorola M12+ User's Guide is here: http://www.synergy-gps.com/images/stories/guides/m12+userguide.pdf The binary commands and output messages, including timing related commands, are in

Re: [time-nuts] TAPR TICC boxed

As protection circuit I have used a 51ohm from the front panel input to the TICC input than two diodes one from TICC input to gnd , other from TICC input to +5V. A swichable 51ohm from front panel input to gnd allow to have 1M or 50 ohm as input impedance. The front panel leds are