Re: [time-nuts] fast switching quiet synthesizer
Although the DDS settles rapidly there some filter settling time is required. These systems are combinations of DDS and direct synthesis with microsecond or sub microsecond settling. Bruce. On October 8, 2014 at 3:52 AM Hal Murray hmur...@megapathdsl.net wrote: br...@ko4bb.com said: Kratos (www.kratosepd.com) do fast switching synthesiser subsystems that can be locked to a reference.. What does fast switching mean in the context of a DDS? What does the spectrum of a DDS look like if I switch back and forth between 2 frequencies at 1 KHz? Or what question should I be asking? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] fast switching quiet synthesizer
Kratos (www.kratosepd.com) do fast switching synthesiser subsystems that can be locked to a reference.. Aeroflex (www.aeroflex.com/ASCS) do 250ns settling time synthesisers. Bruce On October 7, 2014 at 7:52 PM Jim Lux jim...@earthlink.net wrote: On 10/7/14, 1:19 PM, Don Latham wrote: I have two versions of the ADF4351 dds. One is the AD eval board, and the other the TPI synthesizer (http://www.rf-consultant.com/calibrated-signal-generator/) at $280 that might do the job. The latter device performs well. It will be as good as the 4351, I think. It has a programmable attenuator. A good price. Requires a Healthy! USB port. Don How fast does it settle? (it's a VCO-PLL, so the loop filter is probably the rate limiting step) How well can you synchronize the changes. USB is no problem. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] fast switching quiet synthesizer
http://gmcatalog.kratosepd.com/index.cfm?act=prodsforgroupgrp=45 http://ams.aeroflex.com/ASCS/micro-ASCS-prods-synthesizers.cfm are the relevant webpages Bruce On October 7, 2014 at 11:06 PM br...@ko4bb.com br...@ko4bb.com wrote: Kratos (www.kratosepd.com) do fast switching synthesiser subsystems that can be locked to a reference.. Aeroflex (www.aeroflex.com/ASCS) do 250ns settling time synthesisers. Bruce On October 7, 2014 at 7:52 PM Jim Lux jim...@earthlink.net wrote: On 10/7/14, 1:19 PM, Don Latham wrote: I have two versions of the ADF4351 dds. One is the AD eval board, and the other the TPI synthesizer (http://www.rf-consultant.com/calibrated-signal-generator/) at $280 that might do the job. The latter device performs well. It will be as good as the 4351, I think. It has a programmable attenuator. A good price. Requires a Healthy! USB port. Don How fast does it settle? (it's a VCO-PLL, so the loop filter is probably the rate limiting step) How well can you synchronize the changes. USB is no problem. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise powersupplies
I have a couple of these. however their noise spectral density tends to rise precipitously below 1Hz or so. There are regulators with significantly lower flicker noise. Bruce On August 7, 2014 at 6:35 AM Tom Van Baak t...@leapsecond.com wrote: Ole, Thanks for bringing it to our attention. For those that like to click instead of search: http://www.ti.com/tool/TPS7A4701EVM-094 http://www.ti.com/lit/ug/slvu741a/slvu741a.pdf http://www.ti.com/product/tps7a4701 http://www.ti.com/lit/ds/symlink/tps7a4701.pdf /tvb - Original Message - From: Ole Petter Ronningen olep...@gmail.com To: time-nuts@febo.com Sent: Wednesday, August 06, 2014 11:38 PM Subject: [time-nuts] Low noise powersupplies Hello, all I thought it may be of interest to some of the members of this list that TI is selling evaluation modules for some ultra low noise regulators for $20 in their estore, shipping world wide included. The specs looks pretty decent to me, and I've ordered up a couple of boards to use as clean up boxes for my bench-supplies, to use on noise-sensitive projects. 1.4-30v output TPS7A4701EVM-094 3.5µVRMS (10Hz, 100KHz) 25 nV/√Hz (10Hz, 1MHz) Maximum Output Current of 1A +-15v version TPS7A30-49EVM-567: 15v rail: Noise: 12.7µVRMS (20Hz to 20kHz) 15.4µVRMS (10Hz to 100kHz) Power-Supply Ripple Rejection: 72dB (120Hz) ≥ 52dB (10Hz to 400kHz) Maximum Output Current: 150mA -15v rail: Noise: 14µVRMS (20Hz to 20kHz) 15.1µVRMS (10Hz to 100kHz) Power-Supply Ripple Rejection: 72dB (120Hz) ≥ 55dB (10Hz to 700kHz) Maximum Output Current: 200mA Ole ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Sine to square wave converter Phase Noise
Recently I have been comparing the phase noise of the HOlzworth HX4210 and the LTC7957-4. I have found that the performance of these devices is comparable with a 10MHz sinewave input with a PN noise floor below -160dBc/Hz. For offsets below 100Hz the LTC6957-4 is quieter and for offsets below 50Hz or so is lower than that of my measurement setup. I merely mounted the LTC evaluation board in a diecast metal box to reduce the effect of air currents on the LTC7957-4 and used an ultra low noise 3.3V power supply (Abracon) to minimise the power supply contribution to the measured phase noise. Achieving a phase noise performance equal to that on the datasheet was relatively easy. In fact for low offsets the phase noise is lower than that shown on the datasheet. I've also measured the phase noise of a comparator based sine to CMOS converter and its PN floor is about 20dB higher than that of the LTC6957. On completion of measurements PN plots for the various sine to square conveters tested will be added to the web pages I maintain on Didiers site.. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sine to square wave converter Phase Noise
Sorry, I meant the LTC6957-4 of course._SELA = l FILTA = L FILTB = H ie an input stage BW of 160MHz as recommended for a 10MHz + 10dBm input. Input for the HX4210 was +14dBm. Comparator was that used in David Partridge's programmable divider (includes the 74AC04 buffers). Bruce On July 29, 2014 at 5:37 AM Magnus Danielson mag...@rubidium.dyndns.org wrote: You alternate LTC7957-4 and LTC6957-4 and it is only the later that exists. The LTC6957-4 has a single-stage amplifier stage input, with somewhat programmable bandwidth. I assume you used the 50 MHz BW setting. Cheers, Magnus On 07/29/2014 10:55 AM, br...@ko4bb.com wrote: Recently I have been comparing the phase noise of the HOlzworth HX4210 and the LTC7957-4. I have found that the performance of these devices is comparable with a 10MHz sinewave input with a PN noise floor below -160dBc/Hz. For offsets below 100Hz the LTC6957-4 is quieter and for offsets below 50Hz or so is lower than that of my measurement setup. I merely mounted the LTC evaluation board in a diecast metal box to reduce the effect of air currents on the LTC7957-4 and used an ultra low noise 3.3V power supply (Abracon) to minimise the power supply contribution to the measured phase noise. Achieving a phase noise performance equal to that on the datasheet was relatively easy. In fact for low offsets the phase noise is lower than that shown on the datasheet. I've also measured the phase noise of a comparator based sine to CMOS converter and its PN floor is about 20dB higher than that of the LTC6957. On completion of measurements PN plots for the various sine to square conveters tested will be added to the web pages I maintain on Didiers site.. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sine to square wave converter Phase Noise
However that will increase the signal transition times to significanly greater than the 300ps seen at the LTC6957 output. Bruce On July 29, 2014 at 7:54 AM Gerhard Hoffmann dk...@arcor.de wrote: Am 29.07.2014 um 13:38 schrieb David C. Partridge: Further to my previous post: I note that the LTC6957 is 3.3V CMOS rather than 5V. Do you have a recommmendation for a level converter to 5V logic? Would a 74AC04 using a 5V supply cope well enough in that role or is there a better solution? 74ACT04. Keeps the low input trip point that used to be common with TTL. http://www.fairchildsemi.com/ds/74/74ACT04.pdf regards, Gerhard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sine to square wave converter Phase Noise
I merely used the evaluation board which has a capacitively coupled input. The transformer coupled input circuit using a 1:4 (turns ratio) step up transformer as depicted on the datasheet should reduce the PN floor by at least 3dB for 10MHz input. Bruce On July 29, 2014 at 7:30 AM David C. Partridge david.partri...@perdrix.co.uk wrote: Bruce, Thank you, that was very useful information. If I ever do a re-spin of the divider I will likely use the LTC6957-3 or -4 instead of the ADCMP600 (I would need interest for at least 40 boards to be able to do this at anything like an economic price). Will you be putting the full details of the circuit you used up on Didier's web site? Did you use a transformer based circuit similar to Design Note 514 or just an input capacitor? Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of br...@ko4bb.com Sent: 29 July 2014 12:00 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Sine to square wave converter Phase Noise Sorry, I meant the LTC6957-4 of course._SELA = l FILTA = L FILTB = H ie an input stage BW of 160MHz as recommended for a 10MHz + 10dBm input. Input for the HX4210 was +14dBm. Comparator was that used in David Partridge's programmable divider (includes the 74AC04 buffers). Bruce On July 29, 2014 at 5:37 AM Magnus Danielson mag...@rubidium.dyndns.org wrote: You alternate LTC7957-4 and LTC6957-4 and it is only the later that exists. The LTC6957-4 has a single-stage amplifier stage input, with somewhat programmable bandwidth. I assume you used the 50 MHz BW setting. Cheers, Magnus On 07/29/2014 10:55 AM, br...@ko4bb.com wrote: Recently I have been comparing the phase noise of the HOlzworth HX4210 and the LTC7957-4. I have found that the performance of these devices is comparable with a 10MHz sinewave input with a PN noise floor below -160dBc/Hz. For offsets below 100Hz the LTC6957-4 is quieter and for offsets below 50Hz or so is lower than that of my measurement setup. I merely mounted the LTC evaluation board in a diecast metal box to reduce the effect of air currents on the LTC7957-4 and used an ultra low noise 3.3V power supply (Abracon) to minimise the power supply contribution to the measured phase noise. Achieving a phase noise performance equal to that on the datasheet was relatively easy. In fact for low offsets the phase noise is lower than that shown on the datasheet. I've also measured the phase noise of a comparator based sine to CMOS converter and its PN floor is about 20dB higher than that of the LTC6957. On completion of measurements PN plots for the various sine to square conveters tested will be added to the web pages I maintain on Didiers site.. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] sine to square wave converter
The Achilles heel of that biasing technique is that the emitter currents of the pair of pnp's is affected by the noise on the 20V supply. The 20V supply noise is only attenuated by a factor of 5 or so when both transistors have equal collector currents. I have both an LTC evaluation board for the LTC6957 and a Holzworth sine to CMOS converter as well as a Timepod so I could measure the phase noise of both of these for various 10MHz input signal levels. Bruce On July 10, 2014 at 8:21 PM Charles Steinmetz csteinm...@yandex.com wrote: Bruce wrote: Currently Linear Technology's sine to square wave devices with selectable filtering (LTC6957 series) are better in that they are a closer approximation to the ideal zero crossing detector. Failing that the next best is perhaps an AC coupled (both at input and between emitters) differential pair of 2N3906's or similar. My initial results with the LTC6957 did not produce lower phase noise at 10MHz than an optimized Wenzel two-PNP circuit (it may be possible to do better than my initial experiments with the 6957). Here is the circuit I use: Emacs! Using a 20v supply reduces the input feedthrough due to Q1's B-E capacitance, which tends to give the output square wave a sloping top. Using MPSH81s rather than 2N3906s helps with feedthrough, also, as well as reducing the rise and fall times (both about 2-4 nS with this circuit, depending on how hard it is driven, if it is built with proper attention to layout and stray capacitance). Some will insist that the LM329 is overkill, but the base bias can be a significant source (even the dominant source) of phase noise/jitter. The stability and low noise of the 329 improve performance materially -- even a TL431 or 1N829 is measurably inferior. An LM399 is somewhat better than the 329, but I have not found it necessary in practice. (Note that the pullup resistor is not shown -- 1.5k to 10k metal film from the 329 to +20v, not critical.) Some additional improvement can be achieved by using the PNP devices in an HFA3096 or HFA3128 array, but I have generally not seen the need for this in practic. As drawn, this circuit has lower residual PN than any 10MHz oscillator I have measured. Works best with input levels from 1 to 10Vpp (350mV to 3.5Vrms sine wave). There is a small duty cycle asymmetry (high longer than low), which depends on drive level. Using faster devices (such as HFA3096 or HFA3128) reduces the asymmetry. If this is a problem, a resistor can be added from the base of Q1 to ground to trim out the asymmetry if the input level is well controlled. Otherwise, the mean output voltage can be detected, compared to a reference, and used to adjust either base voltage with a servo loop. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] sine to square wave converter
On July 10, 2014 at 10:55 AM ewkeh...@aol.com wrote: As part of the FE 405 B project a separate output circuit is in the works. The universal controller and auxiliary board are the same as used in the FE5680A GPSDO but because of the very low ADEV a separate circuit board that divides by three and has also two ground isolated transformer outputs is in the works.The question is what is the best sine to square wave converter with the lowest ADEV contribution. I am looking at Bruce's circuit using the ADCMP600. Any other ideas? Thanks Bert Kehren ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Although CERN likes that circuit for its ruggedness and versatility its a little noisier than some alternative circuits. Currently Linear Technology's sine to square wave devices with selectable filtering (LTC6957 series) are better in that they are a closer approximation to the ideal zero crossing detector. Failing that the next best is perhaps an AC coupled (both at input and between emitters) differential pair of 2N3906's or similar. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sad news Ulrich Bangert
Sadly Ina was terminally ill and died in May 2012. Ulrich kept this to himself until about six months later in an email explaining why he had been out of touch. In respect for Ulrich's wishes I kept this news off the list. Ulrich's Obituary indicates that one parent, his in-laws and siblings as well as his nieces/nephews survive him. If requested I'll post the URL for his obituary which includes a contact address. Bruce On June 22, 2014 at 1:16 PM ewkeh...@aol.com wrote: It is a shock and a loss not just to time nuts but many others that where touched and benefited from him. Like in the case of Brooks I know what I will do and I urge those of you that knew him through any type of contact make the old fashioned proper thing by sending his wife a letter or card Frau Ina Bangert, Ortholzer Weg 1, 27243 Gross Ippener Germany Bert Kehren In a message dated 6/22/2014 12:36:22 P.M. Eastern Daylight Time, ail...@t-online.de writes: I am shocked to hear that. Urich was a very helpful friend, I've learned a lot from him. I'm so sorry to hear that. Please allow me to say some words in Ulrichs (and my) native language. Die Nachricht vom Tode Urich's hat mich sehr getroffen. Ich habe ihn als einen hilfsbereiten und offenen Menschen kennen gelernt, aber leider nie persönlich kennen lernen können. Bitte, lieber Hartmut, falls Du Kontakt hast, richte der Familie mein herzliches Beileid aus. Thank you very much. Volker - DF9PL Am 20.06.2014 22:52, schrieb Hartmut Paesler: Dear group, unfortunately I have to deliver the sad news that Ulrich Bangert, DF6JB passed away on 11/06, aged 59. Best regards, Hartmut DL1YDD ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Over optimistic PN measurements
There has been some controversy over the Phase noise of CMOS logic devices. Perhaps the apparently anomalously low PN measures are due to the use of cross correlation in the phase noise measurement equipment and the occurrence of phenomena detailed in the recent NIST papers: http://tf.boulder.nist.gov/general/pdf/2697.pdf http://tf.boulder.nist.gov/general/pdf/2698.pdf Such collapse of the cross-spectral function may also be present in the PN plots shown in the datasheets for some OCXOs. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
