[time-nuts] Suggestions on getting 24 MHz?

Esteemed List Members, I have four new Midland glass encased 3.00 MHz HC 6 case style available.  Each one was given a S/N and were ordered for Hallicrafters circa.  Ovenized they would be excellent although I don't now what oven temp was specified.  Best guess is 85 C. I can send world

Re: [time-nuts] TCVCXO Adjustment

Could you use the "pips" instead of a PPS signal, again comparing them some weeks apart to give a long reference time ? https://en.wikipedia.org/wiki/Greenwich_Time_Signal If your local radio broadcaster doesn't play something like them, they could probably be generated with a web application.

Re: [time-nuts] femtosecond jitter

Thus a DDMTD using NB7V52's as the mixers should have useful performance Bruce > On 14 April 2018 at 03:54 John Larkin wrote: > > > If you walk the differential data and clock inputs of an NB7V52 CML > flipflop across one another in time, the equivalent

[time-nuts] getting accurate timing on RTL-SDR output

Note that on a lot of GPS devices that only one edge of the 1PPS pulse is stable and the other edge can jitter a bit. Also, you might want to try programming the PPS to a 50% duty cycle (but having an asymmetrical PPS pulse might have some advantages for post processing). The receiver with the

Re: [time-nuts] TCVCXO Adjustment

wayne.hol...@gmail.com said: > I believe that the "precision" of -20 value on the 4th line is supposed to > be interpreted as 2^-20 seconds which, if my math is correct, works out to > be a precision of about 1 PPM. Is that correct? That's the time between ticks or the time it takes to read the

Re: [time-nuts] TCVCXO Adjustment

Hi With NTP (or any other timing system) you really need 3 or more sources to sort things out. If you only have one source, eventually everything will converge on it. That’s not to say that it will be correct, you simply will be 100% locked to it. GPS modules are a “sub $20” sort of thing

Re: [time-nuts] WWVB information

So Doug's Spectracom WWVB receiver shows a green lock status. I didn't believe it, but he sent a photo. I then tried it here and the same thing happens to me. It's very suspicious because we know these old carrier phase WWVB receivers don't work with the enhanced WWVB broadcast format. Instead

Re: [time-nuts] TCVCXO Adjustment

Again, thanks for all the great feedback and suggestions. > Are you familiar with these devices which I just found this week? > https://tentaclesync.com/products Yes, that's one of the lower cost commercial units available. Another is the NanoLockiIt by Ambient

Re: [time-nuts] Ultralink

j...@febo.com said: > The modular cable connecting the receiver to the decoder is wired straight > through, not reversed as most telephone cables are. My fear is that > someone (like me) might at one point have used a reverse cable and thus put > reverse polarity on the board; I don't see any

Re: [time-nuts] WWVB information

Hal when I was building de-psk-ers and such I have to say I did not see the imbalance. It looked pretty solid in timing. The fact that at each minute for the first number of seconds the phase is actually fixed just before the preamble is useful. It clears out any possible buildup if it existed.

Re: [time-nuts] getting accurate timing on RTL-SDR output

On 4/13/18 1:47 PM, Magnus Danielson wrote: Hi Jim, On 04/13/2018 06:52 PM, Jim Lux wrote: I'm building a phased array receiver (actually, an interferometer) using RTL-SDR pods, where the elements are isolated from each other - there's a common WiFi network connection, and each node has a

Re: [time-nuts] getting accurate timing on RTL-SDR output

On 4/13/18 1:39 PM, Achim Gratz wrote: Jim Lux writes: So now the challenge is to "line em up". An obvious approach is to transmit an inband pilot tone with some sync pattern, received by all, and I'm working on that too. A maybe not-so obvious approach would be to use RTL-SDR that have been

Re: [time-nuts] getting accurate timing on RTL-SDR output

Hi Jim, Good for you! I love to hear about backyard radio astronomy projects. With your sample rate your GPS PPS spikes should be in the neighborhood of 1 uS duration. It's hard to say just how accurately you can glean the timing from that, but then I suspect that you're mainly interested in

Re: [time-nuts] WWVB information

The month recently changed from 3 to 4. A while ago, the bottom digit of the year changed from 8 to 7. I think the out-of-phase time is shorter for a 0 than for a 1. Would a few more 0 bits be enough to push it into sync? Is there "goodness" parameter that you can monitor? It might be

Re: [time-nuts] getting accurate timing on RTL-SDR output

Hi Jim, On 04/13/2018 06:52 PM, Jim Lux wrote: > I'm building a phased array receiver (actually, an interferometer) using > RTL-SDR pods, where the elements are isolated from each other - there's > a common WiFi network connection, and each node has a BeagleBone Green, > a uBlox OEM-7M-C, and the

Re: [time-nuts] getting accurate timing on RTL-SDR output

Jim Lux writes: > So now the challenge is to "line em up". An obvious approach is to > transmit an inband pilot tone with some sync pattern, received by all, > and I'm working on that too. A maybe not-so obvious approach would be to use RTL-SDR that have been modified for direct sampling

Re: [time-nuts] TCVCXO Adjustment

Hi If you have a GPS on your local lan, just use it for the calibration. There’s no need for NTP to get involved. If you are running NTP over a normal home setup going to the internet, then you will be doing very well to get low ms with NTP. Going back to the original post, the request is

Re: [time-nuts] getting accurate timing on RTL-SDR output

On 4/13/18 10:33 AM, Dana Whitlow wrote: Jim, I'm curious:In what RF bandwidth will you be recording? 1 MHz for now.. the RTL-SDR isn't a super flexible device - there are apparently good and bad rates - it does a DDC with 28.8 MHz I/Q NCO (with who knows what kind of performance), and

Re: [time-nuts] WWVB information

My 8161/8164 will indicate lock as well, and I suppose they may be 'locked'. But the phase stability is so poor they may as well not be. I guess it averages out close enough to zero within the time constant to turn the LED on. It's not new behavior for my units. Phase tracking receivers are still

Re: [time-nuts] TCVCXO Adjustment

Hi NTP will give you “millisecond" level accuracy / stability. If you want to set an oscillator to 0.1 ppm, you will need to run for over 10,000 seconds. It is not uncommon to have things out in the 10 ms range. That would put you at 100,000 seconds. In more common units, a couple of hours to

Re: [time-nuts] getting accurate timing on RTL-SDR output

Jim, I'm curious:In what RF bandwidth will you be recording? My first thought would be to search for a cross-correlation peak between the two antenna outputs, but quickly realized that this does not tell you anything about the timing differences between the two receivers. I think you need

[time-nuts] femtosecond jitter

If you walk the differential data and clock inputs of an NB7V52  CML flipflop across one another in time, the equivalent jitter is below 20 fs RMS. That's what we're measuring, but our test rig may well dominate the jitter, so the flop is probably better. We're using this to test the jitter

Re: [time-nuts] Pulsars, clocks, and time nuts (Jim Palfreyman)

Tom's discussion about pulsars brought back some memories... Many pulsars exhibit skipped pulses. And one curiosity that I didn't see mentioned in Tom's discussion is that some pulsars even exhibit behavior reminiscent of the "sawtooth jitter" so evident in the PPS outputs of most GPS receivers.

Re: [time-nuts] TCVCXO Adjustment

Hi Wayne, I didn't mean that you should use the PPS signal from a consumer GPS rx (though you might do that). I was thinking that you'd instead track the difference between TCXO-maintained time and GPS time over long periods - weeks or months - and use those to adjust the TCXO. This would only

Re: [time-nuts] TCVCXO Adjustment

Hi NTP will give you “millisecond" level accuracy / stability. If you want to set an oscillator to 0.1 ppm, you will need to run for over 10,000 seconds. It is not uncommon to have things out in the 10 ms range. That would put you at 100,000 seconds. In more common units, a couple of hours to

Re: [time-nuts] Pulsars, clocks, and time nuts (Jim Palfreyman)

Amazing news... 1.2.3. 1) Many of you know that pulsars are weird astronomical sources of periodic signals. Some are so accurate that they rival atomic clocks for stability! True, but I don't have a 100 foot antenna at home so I'll take their word for it. Plus, you have to account for a myriad