[time-nuts] GPS splitter

GPS receiver antenna alarms tend to be "informational" only. They monitor the current that the antenna is drawing. Better ones report open, short, or OK. Others provide just an OK / fault. A few have no antenna monitoring at all. The RFTG-m reports the voltages at each end of a 100

Re: [time-nuts] GPS discipline oscillator vs phase lock

sorry about, but who is 'lifespeed', a robot or a real person with a natural name? many thanks, 73, Arnold, DK2WT Am 17.06.2017 um 23:07 schrieb Lifespeed via time-nuts: Yes, one has to lock them at a high reference frequency so as to avoid multiplied-up phase noise. I can manage the

Re: [time-nuts] GPS discipline oscillator vs phase lock

Yes, one has to lock them at a high reference frequency so as to avoid multiplied-up phase noise. I can manage the tracking loop design. Some applications aren't line-of-sight, so the radio link doesn't solve every situation. Fiber optic backup plan, but everybody hates cords. This is my

Re: [time-nuts] GPS splitter

Hi There is a poorman's way of making a -3dB splitter using lengths of cable of characteristic impedance equal to the system impedance. That is to say using only 50Ω cable in a 50Ω system. It is a variant on the well known square four-port quadrature hybrid. In the standard hybrid with ports

Re: [time-nuts] GPS splitter

Hi, Yes, I knew that, but wanted to play safe. Funny how a quick hobbyist quick-and-dirty build was needed to get an operator running. Ah well. Cheers, Magnus On 06/17/2017 05:46 PM, Bob kb8tq wrote: Hi In some cases, you can get away with a 470 ohm resistor on the Tee and leave out the

Re: [time-nuts] Hints on PPS Buffer design...

Why 100R? If using a 74xxx logic part as the driver is has a maximum drive current. 100R limits current in case of a short to ground or 5V supply to only 50mA It is about the lowest value resister i'd want to use If you need 50 ohm output them go with an small RF amplifier or a transistors

Re: [time-nuts] GPS splitter

On Fri, Jun 16, 2017 at 8:54 PM, Clay Autery wrote: > This brings up some interesting questions: > > > I am assuming since this is a receive only situation, it will follow > approximately the same rules of physics that dealing with satellite > antenna installations. > And

Re: [time-nuts] GPS splitter

Hi In some cases, you can get away with a 470 ohm resistor on the Tee and leave out the inductor. A lot depends on the threshold of the detect circuit in the GPSDO. Since the signal is normally well amplified before it ever gets to the splitter, adding a small amount of loss generally is not a

Re: [time-nuts] GPS splitter

On 6/17/2017 7:40 AM, Bob kb8tq wrote: will do a pretty good job of “antenna detect” signaling. In the more general case of “I didn’t design this beast” dc blocks and dc shunts to ground is the best approach. This fairly quickly gets you headed in the direction of the HP / Symmetricom

Re: [time-nuts] GPS splitter

Hi, At one time I had to design a DC-load since the GPSDO did not experience enough antenna current due to a different antenna being used. So, a BNC-T was quickly converted with a SMD inductor and resistor to add 150 Ohm of more load, and that helped the telecom operator to get their GPS out

Re: [time-nuts] Hints on PPS Buffer design...

Clay, as to "why 20 ohms out", there is a long-time-nominal 50 ohm PPS convention that calls for 5V pulses to be delivered into a 50 ohm load. If the driving voltage was 5V and source resistance was 50 ohms, then you'd never get more than 2.5V into the load. Different references across the net

Re: [time-nuts] Hints on PPS Buffer design...

HI > On Jun 17, 2017, at 4:15 AM, Clay Autery wrote: > > Trying to pin down a reasonably optimal buffer design for bringing PPS > out... I've looked at all the references, like the i3detroit.org site > et al. > > Of the few schematics and devices I see, most are using a

Re: [time-nuts] GPS discipline oscillator vs phase lock

On 6/16/17 10:55 PM, Lifespeed via time-nuts wrote: Not too surprising to read locking two crystal oscillators together without using a physical cable is difficult to impossible. Essentially what I am looking for is the phase alignment accuracy (and phase noise) one would get PLL’ing one

Re: [time-nuts] Hints on PPS Buffer design...

On 6/17/2017 4:01 AM, Hal Murray wrote: >> Q3: It's only a 1Hz frequency, but is low inductance a desired trait of the >> chosen resistors? > It's a 1 Hz repetition rate, but the bandwidth depends upon the rise time. > If the rise time is ballpark of 1 ns, the bandwidth will be ballpark of 1 >

Re: [time-nuts] The clocks at Windsor Castle, UK

THAT was the time is the best comment >Messaggio originale >Da: "Will Kimber" >Data: 17/06/2017 4.22 >A: >Ogg: Re: [time-nuts] The clocks at Windsor Castle, UK > >And when those clocks were made there was no thought that in few >centuries time a

Re: [time-nuts] GPS discipline oscillator vs phase lock

Hi If you also need the phase noise of the OCXO’s to be quite good when operating, the PLL approach has some issues. If you are after -100 doc / Hz sort of numbers at 1 Hz offset at 100 MHz, then a PLL to GPS is not your friend. At GPS will degrade that by many 10’s of db. If the phase

Re: [time-nuts] Hints on PPS Buffer design...

Read the spec sheet on the part you are using for a driver. The size of the resistor on the paralleled driver side will be set by the maximum current of the devices. Decide how conservative a design you want. Do you want it to drive into a shorted load and survive? [If each output is rated at 20

Re: [time-nuts] GPS splitter

Hi The DC block requirement depends a lot on the design of the GPSDO’s you are using. With some GPSDO’s a 50 ohm load on the eighth port of a splitter will do a pretty good job of “antenna detect” signaling. In the more general case of “I didn’t design this beast” dc blocks and dc shunts to

[time-nuts] GPS splitter

I use an HP / Symmetricom 58517A 8 port splitter (the 58536A splitter is a 4 port version and the 58535A is a two port version). They have an amplifier built in. It is powered by any/all of the the connected GPS devices and feeds power to the antenna. It work very well... I have it driving 7

Re: [time-nuts] Hints on PPS Buffer design...

caut...@montac.com said: > Q3: It's only a 1Hz frequency, but is low inductance a desired trait of the > chosen resistors? It's a 1 Hz repetition rate, but the bandwidth depends upon the rise time. If the rise time is ballpark of 1 ns, the bandwidth will be ballpark of 1 GHz. So, yes, you

[time-nuts] Hints on PPS Buffer design...

Trying to pin down a reasonably optimal buffer design for bringing PPS out... I've looked at all the references, like the i3detroit.org site et al. Of the few schematics and devices I see, most are using a hex inverter (1 into the other 5 paralleled with series resistors for "balance" and

Re: [time-nuts] GPS discipline oscillator vs phase lock

time-nuts@febo.com said: > Not too surprising to read locking two crystal oscillators together without > using a physical cable is difficult to impossible. Essentially what I am > looking for is the phase alignment accuracy (and phase noise) one would get > PLL’ing one oscillator to the other

Re: [time-nuts] GPS discipline oscillator vs phase lock

I guess that is the obvious answer, and sort of how the problem is currently addressed up to the limits of realistic cable length, which actually cannot be very long for my application. I am trying to come up with a better way. What you describe quickly becomes impractical. Again, apologies

Re: [time-nuts] GPS splitter

> Le 17 juin 2017 à 02:26, Tim Lister a écrit : > > On Fri, Jun 16, 2017 at 4:40 PM, Gregory Beat wrote: >> I have reached the point that I need a 4-port splitter for my GPS antenna >> (outdoor 5 volt). Any recommendations of models

Re: [time-nuts] GPS splitter

Clay wrote: If sharing an active GPS antenna, do you have to DC block all but one receiver port to prevent multiple receivers trying to supply current to the antenna? Yes. Note that you may need to put DC loads on the other receivers to fool them into thinking they have an antenna attached

Re: [time-nuts] ***SPAM*** Re: GPS splitter

> Le 17 juin 2017 à 01:40, Gregory Beat a écrit : > > I have reached the point that I need a 4-port splitter for my GPS antenna > (outdoor 5 volt). Any recommendations of models (HP/Symmertricom/Microsemi) > to acquire OR to avoid?? > > greg > — I use Mini-Circuits

Re: [time-nuts] ***SPAM*** Re: GPS discipline oscillator vs phase lock

> Le 17 juin 2017 à 07:55, Lifespeed via time-nuts a écrit > : > > Not too surprising to read locking two crystal oscillators together without > using a physical cable is difficult to impossible. Essentially what I am > looking for is the phase alignment accuracy (and

Re: [time-nuts] GPS discipline oscillator vs phase lock

life-sp...@yahoo.com wrote: Perhaps I could implement an ISM band radio link for the purpose of locking the two oscillators. Of course that wouldn't reach a couple miles either. There appears to be some amount of talking past each other going on here. First, I think you may have a