Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

On Friday, December 18, 2015 10:46:46 PM Anders Wallin wrote: > Thanks for all the useful comments! > Things improved quite a bit just by wrapping the (insulated) board in > aluminium foil: > http://www.anderswallin.net/wp-content/uploads/2015/12/alufoil_and_battery.p > ng > > Op-Amps: > Maybe it

Re: [time-nuts] SMD TADD-1 distribution amplifier

On Friday, December 18, 2015 12:27:33 PM Charles Steinmetz wrote: > Poul-Henning wrote: > >A significant reason for the TADD-1 existing in the first place was to > >break groundloops. This is incompatible with tying all the BNC's together. > > It is perfectly possible to ground coax connector bod

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

Also add 1) BNX002 (attenuates noise in 1MHz to 1GHZ region) between the dc input and the input to: 2) Simple LCR filter - attenuates from 10kHz to 10MHz (see attachment) Output of which is connected to the regulator input. 3) Like all the so called RF regulators with internal low pass filters

Re: [time-nuts] Frequency Electronics, Inc. FE-405B Oscillator Availability

Its not too difficult to setup a low noise regenerative divider  that will produce a 10 Mhz output from a 15MHz input. Bruce On Friday, 11 December 2015 2:01 PM, Skip Withrow wrote: Hello Time-Nuts, RDR Electronics has a limited supply of FEI FE-405B OCXO oscillators with digital

Re: [time-nuts] RG 6 U couplings

On Sunday, December 06, 2015 10:02:43 AM Mark Spencer wrote: > I've seen data re delay vs temperature for high end 50 ohm cables. I've > never seen it for 75 ohm CATV style cable. > > Back when I was into time nuts pursuits this was one of the main reasons I > was contemplating switching my GPS

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

Anders U101 only needs to have a gain of 1 at dc so replace R104 and R105 with a capacitor connected to ground. Adjust the other components of the gain determining network accordingly.Also the junction of the power supply divider R102 and R103 should be heavily capacitively bypassed to ground an

Re: [time-nuts] Need tiny 5MHz 10x amplifier

On Sunday, November 29, 2015 12:35:31 AM Poul-Henning Kamp wrote: > I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V > CMOS compatible logic signal. > > The "default" comparator based circuit either requires a negative > supply or 4 resitors for biasing the input and setting the ze

Re: [time-nuts] Unified VCXO Carrier Board

Charles I have a bunch of LM329's purchased from a large distributor.I guess I should make some noise measurements.Some have even been installed in low noise regulators. Another item to add to the to do list( repair mill, complete dual fibre  point diffraction interferometer, rebuild RF PN inter

Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

Ulrich Whilst I do have an original somewhere, a pdf version can be found here: http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf Bruce On Wednesday, 28 October 2015 7:07 PM, Bruce Griffiths wrote: Ulrich Surely you meant to write PN(SSB) = -177 -Pout + NF If we

Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

Ulrich Surely you meant to write PN(SSB) = -177 -Pout + NF If we attempt to apply this equation to the 10811A for which you measured a PN floor of -174dBc/Hz this implies that NF - Pout = 3dB Best case (NF = 0dB - unlikely! Pout would need to be much higher for nonn zero NF) Pout =-3dBm or

Re: [time-nuts] PN measurement of SSINE to CMOS converters

across the 200 ohm collector load. On Monday, 26 October 2015 5:04 PM, Bruce Griffiths wrote: The technique I used to measure the PN contribution of the LTC6957-4 at 10Mhz Low noise 10MHz sinewave OCXO (Trimble 37265 removed from Thunderbolt (Thunderbolt has rather noisy output

Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

As Rick has pointed out numerous times when the output signal is extracted via the crystal by a CB stage (or cascade thereof) the PN floor is determined by the ratio of the amplifier equivalent input noise current to the crystal current. That is the amplifier equivalent input noise current at fr

Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

The 10811A ocxo uses an oscillator of this type albeit with a lower crystal current, an overtone crystal. However the output stages spoil the PN floor..Cascaded transformer coupled CB stages are somewhat quieter. Bruce On Tuesday, 27 October 2015 2:31 PM, Bruce Griffiths wrote

Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

On Tuesday, 27 October 2015 2:01 PM, Bruce Griffiths wrote: On Tuesday, October 27, 2015 12:03:49 AM Attila Kinali wrote: > Hi, > > I've been trying to read up on low noise crystal oscillators and had > a closer look at the design by Bruce Griffiths[1]. There are explanat

Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

On Tuesday, October 27, 2015 12:03:49 AM Attila Kinali wrote: > Hi, > > I've been trying to read up on low noise crystal oscillators and had > a closer look at the design by Bruce Griffiths[1]. There are explanations > to how the circuit works, but I have some questions on th

[time-nuts] PN measurement of SSINE to CMOS converters

The technique I used to measure the PN contribution of the LTC6957-4 at 10Mhz Low noise 10MHz sinewave OCXO (Trimble 37265 removed from Thunderbolt (Thunderbolt has rather noisy output amplifier)). OCXO PN measured against a pair of similar OCXOs via correlation using the TimepodConnected to lo

Re: [time-nuts] Unified VCXO Carrier Board

On Sunday, October 25, 2015 11:56:13 PM Gerhard Hoffmann wrote: > Am 24.10.2015 um 22:21 schrieb Bruce Griffiths: > > On Saturday, October 24, 2015 09:03:21 AM Charles Steinmetz wrote: > >> The spec sheet says both TimePod inputs accept -5 to +20dBm into 50 > >> ohms.

Re: [time-nuts] Unified VCXO Carrier Board

On Sunday, October 25, 2015 09:21:02 AM Charles Steinmetz wrote: > I wrote: > >>According to the simulation, the resistor has no effect on the output > >>amplitude until it is well below 1k ohms > > Bruce replied: > >even 10k increases the output signal amplitude by 130mV or 2.6%. > >However that

Re: [time-nuts] Unified VCXO Carrier Board

On Saturday, October 24, 2015 09:03:21 AM Charles Steinmetz wrote: > Bruce wrote: > >The comparator circuit measured was the front end of David Partridge's > >divider. I merely measured the 10MHz output. > > The MAX999 and ADCMP600 are the two comparator options noted on > David's schematic. Bot

Re: [time-nuts] Unified VCXO Carrier Board

On Friday, October 23, 2015 03:27:39 PM Charles Steinmetz wrote: > Gerhard wrote: > >What do you consider a run-of-the-mill comparator? LM139, LMV7219, > >AD8561, ADCMP580? > > For squaring 1-10MHz sine waves, the LT1719 and 1720 are the best > that I've found. This is a matter of how much intern

Re: [time-nuts] Unified VCXO Carrier Board

On Friday, October 23, 2015 05:31:46 AM Charles Steinmetz wrote: > Bruce wrote: > >Your statement about the PN of comparators conflicts with my > >measurements. The LTC6957 evaluation board had an 18dBc/Hz lower > >phase noise floor than a comparator circuit with 10MHz 15dBm inputs. > >However I on

Re: [time-nuts] [Bulk] Unified VCXO Carrier Board

Charles Your statement about the PN of comparators conflicts with my measurements. The LTC6957 evaluation board had an 18dBc/Hz lower phase noise floor than a comparator circuit with 10MHz 15dBm inputs. However I only measured a single comparator circuit. The Holzworth sine to CMOS converter had

Re: [time-nuts] Timepod Phase Noise Measurements and 3 corner hat

On Sunday, August 30, 2015 05:06:38 PM James Flynn wrote: > Martyn Smith writes: > > MEASUREMENT TECHNIQUE > > > > We have three sources close in frequency (within 1 x 10E-8 of each > > other). > > > Two sources are connected to the Ch0 and Ch 2 inputs of the timepod, the > > unit under test t

Re: [time-nuts] Cavity frequency air filled vs vacuum?

The ratio of the resonant frequency of the evacuated cavity to that of the air filled cavity increases by the square root of the relative permittivity of the ambient air or around 300ppm or so. Bruce On Wednesday, 19 August 2015 5:06 PM, "cdel...@juno.com" wrote: Hi everyone! I'

Re: [time-nuts] Modified Allan Deviation and counter averaging

If the burst rate is high enough the interpolators will no longer be able to maintain phase lock, the question is how high a burst rate is feasible without losing lock? Bruce On Wednesday, 29 July 2015 9:51 AM, Poul-Henning Kamp wrote: Sorry this is a bit long-ish, but I figure I'

Re: [time-nuts] HP 5370a

On Saturday, July 04, 2015 05:20:45 PM paul swed wrote: > Matthias > I am afraid I am not much help here. > I did look at the a19/20 interpolators. A lot going on in that small space. > I guess i would check the 200 MHz feeding into it. The VCO is fairly simple > in using a gate and a delay line. I

Re: [time-nuts] HP 5370a

No the oscillator frequency determining delay line is a microstrip line on a ceramic substrate. The coax delay lines are used for not critical delays in the delay line vco start and stop On Saturday, July 04, 2015 05:20:45 PM paul swed wrote: > Matthias > I am afraid I am not much help here. > in

Re: [time-nuts] Using CPLD/FPGA or similar for frequency

2015 09:32:23 +1200 Bruce Griffiths wrote: > > Do you mean the technique that Panek et al. [1]  are using? > > Not quite he used an impulse to excite a saw filter rather than switching > off the dc current feed to an inductor or the equivalent. Is there any fundamental d

Re: [time-nuts] Using CPLD/FPGA or similar for frequency

On Tuesday, June 16, 2015 10:01:09 AM Attila Kinali wrote: > Hoi Bruce, > > On Tue, 16 Jun 2015 12:24:34 +1200 > > Bruce Griffiths wrote: > > Using an ADC to sample a triggered damped sinewave easily achieves 5ps > > resolution (eg Keysight Acquiris). With a bette

Re: [time-nuts] Using CPLD/FPGA or similar for frequency

Using an ADC to sample a triggered damped sinewave easily achieves 5ps resolution (eg Keysight Acquiris). With a better optimised waveform model and least squares fitting routine greater resolution is feasible. The accuracy is dependent on the ADC sampling clock stability. An optical frequency st

Re: [time-nuts] Using CPLD/FPGA or similar for frequency divider

You can always cleanup the outputs of the CPLD or FPGA by resynchronising the outputs to the input clock using a dedicated D flipflop for each output. Bruce On Wednesday, 3 June 2015 3:22 PM, Bob Camp wrote: Hi A lot depends on exactly which CPLD or which FPGA you are looking at

Re: [time-nuts] Using CPLD/FPGA or similar for frequency divider

On Tuesday, June 02, 2015 02:13:04 PM David C. Partridge wrote: > Is this a sensible thing to consider doing? Or would I be better sticking > to AC/HC/AHC/LVC logic? ` > > Regards, > David Partridge > > ___ > time-nuts mailing list -- time-nuts@febo.co

[time-nuts] LTC6957 internal architecture

The following patent hints that the LTC6957 front end probably consists of several cascaded long tailed pair differential amplifier stages each with a selectable bandwidth set by capacitors shunting the collector load resistors. : US8319551 The input limiter is in effect a Collins style limiter

Re: [time-nuts] Divider circuit for Rubidium Standard

On Friday, May 22, 2015 10:48:16 AM Gerhard Hoffmann wrote: > Am 21.05.2015 um 23:32 schrieb Magnus Danielson: > > On 05/21/2015 12:15 AM, Richard (Rick) Karlquist wrote: > >> The counter front ends seem to be modeled after scope front ends > >> and scope triggering circuits, where you can adjust t

Re: [time-nuts] Divider circuit for Rubidium Standard

The Phase noise floor (~-143dBc/Hz @ 1kHz) of the 10MHz output of that divider is about 17dBc/Hz higher than either the LTC6957-4 (demo board) or the Holzworth HX2410 (both ~ -160dBc/Hz @ 1kHz).All measured with a 10MHz +14dBm input signal.For offsets below a few Hz shielding of the circuitry fr

Re: [time-nuts] Tuning a Trimble Thunderbolt

A week is somewhat optimistic since the thunderbolt consumes around 1.68 kilowatt hours of energy. With a 12V battery a capacity of around  84 ampere hours (for an efficiency of 100%) which is somewhat larger than that provided for most UPS particularly those sold for use with personal computers

Re: [time-nuts] 00105-6013 schematic wanted

Its in the HP105A/B manual. Bruce On Thursday, February 05, 2015 03:10:03 PM tim...@timeok.it wrote: > Hi all, > > I am looking for the internal schematic of the 00105-6013 OCXO mounted in > the old series of the HP5065A. I have two of them not working and I would > like to fix it. > > thanks

Re: [time-nuts] 5>10 doubler

Unfortunately that approach degrades the phase noise floor due to crystal dissipation limitations as well as degrading the phase  noise in the flicker region due to the crystal itself,Not only is a clean (harmonic and subharmonic free) sine wave desirable so is  low phase noise.Thermal drift of

Re: [time-nuts] 5>10 doubler

Whilst the output signal of the barely class A JFET amplifier has a lower unwanted harmonic content and thus requires less filtering to achieve a given suppression of unwanted harmonics and/or subharmonics, the question of the flicker phase noise penalty incurred by the barely class A amplifier

Re: [time-nuts] 5>10 doubler

Whilst input frequency related spurs can be significantly reduced with a suitable filter incorporating a sufficient number of series tuned traps plus a low pass filter, phase noise once incurred cannot be reduced by such means. The ultimate measure of performance of the phase noise performance o

Re: [time-nuts] 10544A vs. 10811

Since the 10544A uses a PWM oven controller there are significant oven PWM frequency related sidebands.The PN noise floor of the 10811A (-160dBc/Hz) is significantly lower than that of the 10544A (-145dBc/Hz). Bruce On Sunday, 1 February 2015 2:57 PM, Bill wrote: I have a choice.

Re: [time-nuts] ***SPAM*** Re: 5>10 doubler

One issue is that to reduce flicker phase noise the 5MHz input signal output impedance should be sufficiently large to ensure that the JFET common gate input impedance is significantly smaller. ie there is significant series RF feedback in the JFET source circuit.  Bruce On Sunday, 1 Feb

Re: [time-nuts] 5>10 doubler

the maximum signal input to the crystal filter and thus degrade the output phase noise floor over that achievable using other approaches. Bruce On Wednesday, 28 January 2015 11:19 PM, Alberto di Bene wrote: On 1/27/2015 11:57 PM, Bruce Griffiths wrote: > /The only viable solut

Re: [time-nuts] 5>10 doubler

Using the square law characteristic will inevitably increase the phase noise floor particularly in the flicker region with respect to just using the switching characteristic of a JFET, diode or BJT  (non saturated).The only viable solution is to use better filtering of the output of a switching

Re: [time-nuts] question Alan deviation measured with Timelab and counters

The performance of the 2 systems should be comparable provided the similar equivalent noise bandwidths are used.Every 10Mhz edge needs to be timestamped with ps resolution and the resulting phase samples low pass filtered and decimated to achieve this.The 10MSPS picosecond or better resolution t

Re: [time-nuts] Phase Noise vs. AM noise

As long as the instrument is carefully adjusted so the that the measurement phase axis is correctly aligned with respect to the test signal an interferometer can be used to ensure that the measurement system PN noise floor is well below the thermal limit when measuring the residual noise of 2 p

Re: [time-nuts] Current state of optical clocks and the definition of the second

Although the phase noise when using optical combs to generate Rf signals is low there is no mention of the am noise. Bruce On Tuesday, January 13, 2015 02:49:33 PM Tom Knox wrote: > I think the key to this concept is an optical comb filter. > Archita Hati of the Phase Noise measurement Group at

Re: [time-nuts] VC-OCXO EFC stability.

Luis If you have sufficient headroom (input supply > 7V or so) why not use a buried zener reference chip like an LT1027? These chips also have a noise reduction pin. Otherwise a lower dropout bandgap reference like an LT1019 or similar may be useful. Bruce On Wednesday, January 07, 2015 01:35:

Re: [time-nuts] Any reason not to use one power amplifier and splitter for distribution amplifier?

On Sunday, January 04, 2015 03:39:48 AM Charles Steinmetz wrote: > Dave wrote: > >I was looking to make a 10 MHz distribution amp to feed test equipment with > >the output of a GPSDO. > > > > * * * > > > >16-way Minicircuits splitter on eBay which I got for $40. I guess the loss > >is aro

Re: [time-nuts] Any reason not to use one power amplifier and splitter for distribution amplifier?

Almost all frequency counters have an internal source which is a potential means of injection locking an external reference if the isolation between the internal source and the external source is inadequate. High impedance taps on a single terminated line ensure that the isolation between such i

Re: [time-nuts] schematics of frequency counter

The CLK1 input circuit produces an output incompatiblr with the 3.3V CMOS deice it drives.A pair of pnp transistors in an otherwise similar circuit is capable of producing a 3.3V CMOS compatible output signal. Using independent voltage dividers to bias the transistor bases is a bad idea in that

Re: [time-nuts] LNA and Alias

On Monday, December 22, 2014 09:26:15 AM Loïc wrote: > Bruce Griffiths writes: > > Are you sure that the setup is aligned to minimise AM response? > > > > Are you using cross-correlation? > > Bruce > > > > On Monday, 22 December 2014 5:08 PM, Loïc M

Re: [time-nuts] LNA and Alias

Are you sure that the setup is aligned to minimise AM response? Are you using cross-correlation? Bruce On Monday, 22 December 2014 5:08 PM, Loïc Moreau wrote: Hi all, My phase noise measurements system give erroneous  results in close in phase noise measurements, I got humps in th

Re: [time-nuts] NIST isolation amplifiers

Almost. 1:1:2 (turns ratio) transformers used in each stage and 1:1 transformer on input. This allows a lower power supply voltage to be used. One thing to watch with minicircuits transformers is core saturation due to dc flowing in the windings. Bruce On Wednesday, November 26, 2014 08:52:14 AM

Re: [time-nuts] NIST isolation amplifiers

A single 2N or equivalent transistor in a suitable circuit dissipating about 200mW or so can achieve a reverse isolation of 35dB with distortion of around -40dBc (output +13dBm) with a gain of unity, and an output impedance of 50 ohms with a PN floor of around -180dBc/Hz or so. Bruce

Re: [time-nuts] NIST isolation amplifiers

Another issue is that if even one output needs high reverse isolation and low crosstalk, then even those outputs that arent so critical will also need high reverse isolation and low crosstalk to avoid degrading the crosstalk to the critical output. Bruce On Tuesday, November 25, 2014 07:54:02

Re: [time-nuts] NIST isolation amplifiers

An alternative is to use a Norton style amp (or other low noise high linearity amp without stellar reverse isolation) to boost the signal level and drive a set of high isolation output stages. A relatively simple discrete current feedback amp may suffice. For higher reverse isolation a cascode a

Re: [time-nuts] Lucent KS-24361 Simple Doubler

Using an attenuator between the doubler output and the amplifier input degrades the phase noise significantly. Bruce On Tuesday, November 25, 2014 06:00:30 PM Bob Camp wrote: > Hi > > Based on using the same amp for other projects, I would strongly suggest > checking the phase noise / ADEV of

Re: [time-nuts] Low Additive Phase Noise 10 MHz Amps

Discrete component designs using suitable silicon BJTs offer the lowest phase noise. Reworking some old designs to incorporate lower noise dc biasing (particularly collector/emitter current ) can significantly reduce close in PN. Bruce On Sunday, November 23, 2014 08:47:44 AM Bill wrote: > What

Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop

logic. That makes them poor candidates for this sort of thing. Bob On Oct 15, 2014, at 9:13 AM, Gerhard Hoffmann wrote: > Am 15.10.2014 um 11:29 schrieb Bruce Griffiths: >> Typically a 74HC164 shift register has internal cycle to cycle sampling jitter of about 4ps or so when

Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop

On Wednesday, October 15, 2014 03:27:41 PM Javier Serrano wrote: > Do you have a precise idea of what the offset in frequency is between > your DUT(s) and the slightly-offset oscillator? If that offset is too > big compared with the jitter of your clock signals and your > flip-flops, that would exp

[time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop

The use of a synchroniser loses no information apart from fine details about the metastability response of the sampling flipflop. With a 10Hz offset and a 10MHz clock the sampling resolution is 100fs with the phase difference between the flipflop clock and data input transitions changing monoton

Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop

Original thread on DDMTD in 2008: https://www.febo.com/pipermail/time-nuts/2008-December/034955.html Later comment on using a shift register to minimise metastability issues: https://www.febo.com/pipermail/time-nuts/2011-August/058648.html Bruce On Sunday, October 12, 2014 12:14:27 AM Robert Da

Re: [time-nuts] optically excite a quartz crystal?

Optical excitation of quartz resonators: Electronics Letters , Volume 18, Issue 9 , 29 April 1982, p. 381 – 382 Bruce ___ time-nuts mai

Re: [time-nuts] Acam TDC's

GP21 eval kit about 300 Euro GP21 about 10 Euro each Bruce paul swed wrote: Angus Yes I did a fast check and couldn't find anyone in the US that seemed to carry it. The eval kit looks nice but will speculate its quite costly. That said I could see some uses for it like you say it has some thing

Re: [time-nuts] Acam TDC's

Sub 10ps resolution is achievable with a ringing LC circuit plus a suitable ADC. Bruce Don Latham wrote: AliExpress has them, 5 piece lot for $70 shipping to US $4.21. One claim I saw said in quad mode 22 ps resolution. H Don paul swed Angus Yes I did a fast check and couldn't find

Re: [time-nuts] RC TIC linearity correction?

A random source will need a lot more samples in each bucket to reduce the noise to an acceptable level. To determine the relative bucket width with a 10% error requires at least 100 samples per bucket. For 1% error at least 10,000 samples per bucket. All thats really required is a sufficiently

Re: [time-nuts] Frequency Counter using OCXO and MCU

Try: http://www.linear.com/product/LTC6957 Bruce cfo wrote: On Wed, 12 Mar 2014 09:42:05 -0700, Chris Albertson wrote: There are logic level converter chip made for this purpose or you can use a comparator and compare the 5V clock to ground. Or just a diode to clip the sine wave

Re: [time-nuts] How to measure phase noise of HCMOS oscillators?

Why not AC couple the HCMOS output to the LMH6702 input? Bruce Anders Time wrote: Thanks a lot for the input! I will try to use the LMH6702 as buffer. The correct way to measure the HCMOS oscillator would probably be to use a high impedance buffer with very low noise, to simulate driving a 10pF

Re: [time-nuts] Modeling vs reality question re my TIC

this is a typical RC charge ramp? Not trying to be argumentative, I'm just trying hard to understand. http://www.evoria.net/AE6RV/TIC/ChargeRamp.png Bob ____ From: Bruce Griffiths To: Bob Stewart; Discussion of precise time and frequency measureme

Re: [time-nuts] Modeling vs reality question re my TIC

Metastability in the Flipflops? Charge injection when tristating tristate buffers? Neither of which are included in your models. Bruce Bob Stewart wrote: Fellow Timenuts: I'm trying to square reality with the modeling that I did, and nothing makes sense. When I modeled the result of just m

Re: [time-nuts] TIC model

Now you've lost me. What 2.5 MHz synchronizer clock? Everything I have external to the PIC is 10MHz. The PIC is running HSPLL at 40MHz, though I don't think that makes any difference to this. Bob ________ From: Bruce Griffiths To: Bob Stewart; Discussion

Re: [time-nuts] TIC model

, make the value of R1 of less importance? On my PIC, they list C1 as 5pf, R2 as effectively about 7K, and C2 120pf. Bob From: Bruce Griffiths To: Discussion of precise time and frequency measurement Sent: Tuesday, February 18, 2014 9:35 PM Subject: Re

Re: [time-nuts] TIC model

000 counts as I do in the Arduino? Lars From: Bruce Griffiths Sent: ‎söndag‎ den ‎16‎ ‎februari‎ ‎2014 ‎20‎:‎14 To: time-nuts@febo.com The response time to an external asynchronous interrupt is never deterministic. The external interrupt has to be synchronous with the uP clock to av

Re: [time-nuts] TIC model

The response time to an external asynchronous interrupt is never deterministic. The external interrupt has to be synchronous with the uP clock to avoid the non deterministic synchronisation delay. Even when the external event is synchronous with the clock input to the uP and the uP uses a divide

Re: [time-nuts] TIC model

Bob Stewart wrote: Tom tried to steer me to the PICTIC recently, and I sort of brushed him off, because, quite frankly I didn't understand. Now that I've really looked at it, it's a much better idea than using a dsPIC33 and brute-forcing it. But, I don't really need everything the PICTIC offers

Re: [time-nuts] GPS W/10KHz

Bruce Griffiths wrote: Dennis Ferguson wrote: Bjorn, All I was pointing out is that at a higher output frequency, like 10 kpps, the frequency of the quantization saw tooth error will almost always be much higher as well. There's no need for the digital correction since averaging o

Re: [time-nuts] GPS W/10KHz

Dennis Ferguson wrote: Bjorn, All I was pointing out is that at a higher output frequency, like 10 kpps, the frequency of the quantization saw tooth error will almost always be much higher as well. There's no need for the digital correction since averaging over a relatively short period, l

Re: [time-nuts] GPS W/10KHz

Dennis Ferguson wrote: On 10 Feb, 2014, at 00:48 , Bruce Griffiths wrote: Instead of speculating try reading the specifications. 1Hz phase modulation of the 10kHz output is present. The receiver sawtooth error sample rate is 1Hz not 10kHz. The 10kHz output signal phase is adjusted at a 1Hz

Re: [time-nuts] GPS W/10KHz

Dennis Ferguson wrote: On 10 Feb, 2014, at 00:48 , Bruce Griffiths wrote: Dennis Ferguson wrote: On 8 Feb, 2014, at 14:50 , ewkeh...@aol.com wrote: The problem with the PLL analog version is the same as with any digital GPSDO. The saw tooth is present at 10 KHz just like 1

Re: [time-nuts] GPS W/10KHz

Dennis Ferguson wrote: On 8 Feb, 2014, at 14:50 , ewkeh...@aol.com wrote: The problem with the PLL analog version is the same as with any digital GPSDO. The saw tooth is present at 10 KHz just like 1 Hz. To the best of my knowledge there is no GPS receivers out there for less than $ 1000 wit

Re: [time-nuts] 'CPLDs for clock dividers' Thread

Another issue is whether the clock of the internal state machine used in some CPLDs to load internal RAM cells from slower EEPROM cells is turned off after power up initialisation. Some Xilinx parts for example do not turn of this clock. This clock is a potential source of spurs. Bruce Bob C

Re: [time-nuts] DMTD: Mixer DC offset will result in time offset at zero-crossing detector out?

your mixer termination ( http://www.ko4bb.com/~bruce/LowNoiseMixerPreamp.html). What is the logic in having the second balun (and connected in that way)? Regards, Stephan. On 22 November 2013 13:15, Bruce Griffiths wrote: Stephan Sandenbergh wrote: Hi, I'm playing with dual-mixer time

Re: [time-nuts] DMTD: Mixer DC offset will result in time offset at zero-crossing detector out?

mixer beat is a 10Hz sine 0.7Vpp. If you then use a Collins style zero crossing detector the first stage will have a small gain (I chose a gain of 2.83 from Bruce Griffiths pages ( http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html)). I then compare this ideal signal to that of a similar one that

Re: [time-nuts] DMTD: Mixer DC offset will result in time offset at zero-crossing detector out?

e seen? It seems standard practice to attach the filtered mixer output directly to the zero crossing detector. I did a quick simulation (see attached): The mixer beat is a 10Hz sine 0.7Vpp. If you then use a Collins style zero crossing detector the first stage will have a small gain (I chose

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Stephan Sandenbergh wrote: Something that would be interesting to know is if certain opamps are better suited toward S12 isolation than others. I guess at the expense of noise floor and 1/f corner one could cascade two opamps to improve the S12 isolation further. The flicker noise corner of

Re: [time-nuts] Looking for 1 GHz low phase noise amplifier

apitech has a range of wideband amplifiers with guaranteed phase noise specs eg,: http://micro.apitech.com/pdf/amplifier/lophase/TM9128PM.pdf http://micro.apitech.com/pdf/amplifier/lophase/QBH-1423PM.pdf http://micro.apitech.com/pdf/amplifier/lophase/TM9333PM.pdf Bruce Richard Karlquist wrot

Re: [time-nuts] Clock Driver Design

For low phase noise output at lower frequencies you should consider a lambda divider feeding a low pass filter. Although wideband opamps are convenient a discrete buffer amp can produce a higher level output with lower additive phase noisee. Bruce Tom Minnis wrote: I am looking into various de

Re: [time-nuts] HP5061B Beam Tubes

It does if you append the bit in the following line ie append ing_instructions.pdf. to form: http://www.symmetricom.com/media/files/downloads/product-datasheets/shipping_instructions.pdf Bruce Bob Camp wrote: Hi That link does not lead to anything. Bob On Sep 23, 2013, at 2:57 AM, cdel...@

Re: [time-nuts] GPS with 10KHz output

Hal Murray wrote: albertson.ch...@gmail.com said: If you ned the 10KHz, Jupiter is one that has been used. I think a 10KHz GPS will make your GPSDO converge quickly ... Does the 10KHz signal change smoothly or does it jump to a new value once per second? Has anybody looked at the f

Re: [time-nuts] Low Jitter / Phase Noise 10kHz Signal

HagaaarTheHorrible wrote: Hi there, I hope this is the correct way to post here and that its not been covered before. I've read some threads about frequency dividers, but didn't really find all the answers I'm looking for. I'm trying to generate a 10kHz sine wave thats as clean as possible, a

Re: [time-nuts] Wavecrest DTS 2070

Possibly +2V for ECL Vcc and -3.2V for ECL Vee allowing it to drive 50 ohm loads connected to ground. Otherwise with 0V Vcc and -5.2V Vee the ECL loads must be connected to -2V (or its Thevenin equivalent) Bruce paul swed wrote: 2.1 volt hmm maybe they are doing something with ECL. Say the co

Re: [time-nuts] Phase modulation question

cdel...@juno.com wrote: Hi, I'm making some phase mod index measurements as it relates to Rubidium and Cesium standards. Two questions. 1. Is a Bessel table for sine wave modulated FM used for PM also? 2. Where can I find a Bessel table that has fine resolution, the ones I'm seeing only have

Re: [time-nuts] Wavecrest DTS-2077 Teardown

z. Always trying to learn Ed On 8/20/2013 11:28 PM, Bruce Griffiths wrote: The same analysis applies however one would probably use something like cascaded longtailed pairs with well defined gain (series emitter feedback) and the low pass filter cap connected between the collectors rather

Re: [time-nuts] Wavecrest DTS-2077 Teardown

A time interval counter or equivalent with less acoustical noise and internal jitter than the Wavecrest would be nice. Bruce Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due t

Re: [time-nuts] Wavecrest DTS-2077 Teardown

The same analysis applies however one would probably use something like cascaded longtailed pairs with well defined gain (series emitter feedback) and the low pass filter cap connected between the collectors rather than opamps. Bruce Ed Palmer wrote: Does anyone know if this situation would b

Re: [time-nuts] Lead acid battery noise levels

David Kirkby wrote: On 9 July 2013 04:52, Mark Spencer wrote: Hello, I've just reviewed the thread from earlier this year regarding low noise power supplies and some related information about the noise levels of certain batteries.Has anyone ever come across any data pertaining to the

Re: [time-nuts] HP E1938A Oscillator

Magnus Danielson wrote: Hi Perry, On 07/05/2013 07:23 AM, Perry Sandeen wrote: List, I was looking on Ebay for some HP E1938A oscillators What I found listed were: HP E1938A 10 MHz Quartz Oscillator with EFC on PC board. $100 Fluke.l HP E1938-60201 Ovenized Crystal Oscillator (on a PC bo

Re: [time-nuts] OT Prototype Boards

Chris Albertson wrote: On Tue, Jun 25, 2013 at 9:17 AM, Bob Stewart wrote: Hi Hal, I had always used 25.4001 or .03937 to do my conversions. So, I looked online and found the .039370078 and did the reciprocal. It is, indeed very very close to 25.4. If you google "25.4001 conversion" yo

Re: [time-nuts] Frequency subtraction with D-flip flops

Javier Serrano wrote: On Tue, Jun 25, 2013 at 4:36 AM, ed breya wrote: 4. It seems to me that whenever fd is much higher than fc (fd>>fc), that fd could be used instead to trigger the second DFF, which would reduce the metastability of the first DFF somewhat, and also synchronize the outpu

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