What is replacing the good old frequency counters these days? - Page 1
Forum section: electronics / testgear

author: Swake
author_rank: Frequent Contributor
timestamp: August 08, 2023, 01:18:27 pm
content: R&S; GWInstek; B&Kprecision; Siglent; and many others do not have any frequency counters in their product line anymore. Keysight still has them (for an exorbitant mountain of money as usual).How are frequencies and periods measured these days with some decent accuracy and many-digits-of-resolution, not as a by-product in a scope or multimeter?

author: coromonadalix
author_rank: Super Contributor
timestamp: August 08, 2023, 01:58:50 pm
content: many measurements are done with scopesbut if you need lots of digits, for sure you need counters, tcxo ocxo based time baseand yes they are getting hard to find, even the used ones goes for high $$$ as you wroteRacal Dana used ones come a lotAgilent / Hp ones too, and some added option board are available ...one who get some attention PENDULUM CNT-90 and its fluke counter part have some added board option to crank their frequency ranges ...With a good design, you can do them with Avr's or Pic mcu'sand some chineesium projects sold on Fleabay, Ali etc ....

author: jjoonathan
author_rank: Frequent Contributor
timestamp: August 08, 2023, 02:10:24 pm
content: Spectrum Analyzers typically come with a counter mode that will measure GHz signals down to Hz or less.That said, I think crappy counters are mostly considered Good Enough these days because counters have been displaced from most of their historical applications. Back when a PLL cost several kilobucks and kilograms, a counter and a tuner were an attractive alternative to a synthesized signal generator. Nowadays, a PLL costs several dollars and several grams. You can toss them into even the cheapest instrument and obtain all the digits effortlessly.This goes for knock-on applications too: it might have been historically attractive to creatively substitute a counter for a purpose-built piece of equipment but now that equipment has come down in price it makes more sense to use the right tool for the job. Timing? Use an oscilloscope, you can afford one now. Signal analysis? Use a spectrum/signal analyzer, you can afford one now. Filter tuning? Use a VNA, you can afford one now. Component characterization? Use an LCR meter, you can afford one now.

author: TurboTom
author_rank: Super Contributor
timestamp: August 08, 2023, 02:43:45 pm
content: Many manufacturers include a frequncy counter in their entry level arbitrary waveform generators. These counters can turn out quite advanced in some specimen with all kinds of configuration, statistics and graphical presentation (freq. vs. time) options, see the attached photo of my "pimped" Rigol DG800, fed with a 10MHz FM signal, modulated by an arbitrary Sinc of 10mHz and 1MHz deviation (Rigol forgot to implement a "Print Screen function in Counter mode, hence the "classic" screenshot). Despite the decent internal reference TCXO, a 10MHz reference input permits to get even more accurate results.For the "real business", I pull out my hp 53310a modulation domain analyzer (MDA) and hook up a rubidium atomic reference, which usually is somewhat overkill...

author: pdenisowski
author_rank: Super Contributor
timestamp: August 08, 2023, 02:49:20 pm
content: Quote from: jjoonathan on August 08, 2023, 02:10:24 pmYes, exactly this. I can't remember the last time a customer asked me for a dedicated frequency counter.

author: alm
author_rank: Super Contributor
timestamp: August 08, 2023, 03:36:50 pm
content: Maybe for people involved in precision timing / frequency that need more accuracy than the time base of a scope can provide? Or other niche applications. But they probably buy counters for several kilobucks from the big names like Keysight. I'd mention R&S but I don't think they sell counters anymore.I have a counter that I use occasionally for measurements where it's more convenient than a scope because of its dedicated display. But I wouldn't spend the money to buy one brand new.Clearly back when scopes were analog without any readouts a counter was adding much more value.

author: Bud
author_rank: Super Contributor
timestamp: August 08, 2023, 04:01:26 pm
content: for precision frequency measurements and frequency stability measurements there is still no substitute for a good counter. Almost none or none of those devices listed above they do not have OCXO of even TCXO as their clock reference.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 08, 2023, 04:20:25 pm
content: or have one(s) stabilized / synced with gps clocks "disciplined oscillators"

author: colorado.rob
author_rank: Frequent Contributor
timestamp: August 08, 2023, 04:29:15 pm
content: Quote from: Bud on August 08, 2023, 04:01:26 pmBoth my signal generator and my spectrum analyzer have a 10MHz reference input. Both have frequency measurement capability. A GPS-DO in the lab is a dirt-cheap alternative to having a dedicated OXCO in each device.

author: switchabl
author_rank: Frequent Contributor
timestamp: August 08, 2023, 04:51:26 pm
content: Quote from: Bud on August 08, 2023, 04:01:26 pmPrecision frequency measurements are a bit of a niche though. And that is still served by Keysight and Pendulum (Tektronix counters I think are made by Pendulum as well). At the other end of the market it's less clear what value a stand-alone counter still provides. TTi still has a budget counter (8 digits/s), I'm not sure they sell a lot of those.And for stability measurements there are specialized devices (like Microsemi 53100A) with much better performance.Quote from: Bud on August 08, 2023, 04:01:26 pmMost spectrum analyzers and some oscilloscopes have OCXO as an option (and usually reference inputs).

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 08, 2023, 05:05:59 pm
content: I don't know if all of them do, but Siglent's AWG line certainly does have dedicated frequency counters. I have the SDG2122X and the counter is excellent. There's a dedicated BNC for the counter on the back of the AWG.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 08, 2023, 05:08:17 pm
content: Rigol DG4102 it's a generator (AWG), though it has a BNC input too, can count/measure frequency.Doesn't have fancy features, but it's a hardware counter and can do some statistics. About 200MHz max F, either 50\$\Omega\$ or HiZ input, the instrument has an input for an external 10MHz reference clock if needed. See page 7/10 for the counter specshttps://www.batronix.com/pdf/Rigol/Datasheet/DG4000_DataSheet_EN.pdf

author: Electro Fan
author_rank: Super Contributor
timestamp: August 08, 2023, 05:29:20 pm
content: I don’t know anything about the eBay sellers but BG7TBL makes several models.https://www.ebay.com/itm/266292615921?hash=item3e0046daf1:g:3JUAAOSw~epkhnjR&amdata=enc%3AAQAIAAAA8Ac8sujh4emiUzwqHWcd4daFPItG5M3lz44k1XvpItpjxy20cFPwGBDYeTJoDBDRPrrFwy8cXcRFPP2rBXJitMtFKNYIM2uFaZDf9HXwu8N3hzvAy0kPsQmbcLc1hn2i9gTFXTRIy2C6yU7D2oKbO0ESKM46EUyv4%2Fnez7tG9CmiwA0vdSdpNbN%2Fg0sztiYt73sE0ktuIwPK%2Bazm4OIy6ga6Hx1SbxYWKAyMDncfeNWeMtGUwJwINz%2FKImuqmbp2SKHq2NY7UPKH541tiw8j%2FJzqoGrO2rn8WVVSeJObcBbLtmp2CD7tUrbK0OY1hrKYMQ%3D%3D%7Ctkp%3ABk9SR8D52uK6YgHere is another brand. Like BG7TBL it has a power meter feature that can be useful.https://www.ebay.com/itm/251635985921?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=QrfgZ5FaT7u&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=COPYBG7TBL has OCXO vs TCXO; BGTBL also has 10 MHz Ref in/out - pairs great with a GPSDO. (BG7TBL also makes GPSDOs; BG7TBL also makes distribution amplifiers in case you want to sync all your 10 MHz reference-able gear).

author: 3apw
author_rank: Contributor
timestamp: August 08, 2023, 08:25:57 pm
content: >What is replacing the good old frequency counters these days?Depends on your requirements for frequency counter.If you need to know the stability of the reference frequency sources and PLL then the measurement of the Allan deviation parameter will be mandatory.It can be as an internal application in frequency counter and an external application on a dedicated PC.I am happy with Pendulum CNT-91 with options. Recomended.

author: nctnico
author_rank: Super Contributor
timestamp: August 08, 2023, 08:42:46 pm
content: Quote from: alm on August 08, 2023, 03:36:50 pmAnd don't forget Tektronix FCA3000 / FCA3100 (rebadged Pendulum frequency counters) which are very nice counters. If you are into precission frequency / timing, you'll need a decent counter. IMHO better for real world use compared to what Keysight is offering.Quote from: pdenisowski on August 08, 2023, 02:49:20 pmOr perhaps people -like me- checked R&S' website when looking for a frequency counter and went next door quietly when nothing of interest showed on the website. There certainly is a market for high performance frequency counters. Especially models which can get to single digit or even sub-picosecond level time intervals. Time distribution systems are getting increasingly more accurate and I'm looking at the noise of time interval counters instead of the signal regulary.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 08, 2023, 08:47:02 pm
content: Here's an example from another post I made where I was testing the frequency range and accuracy of my LCR and the accuracy of the frequency mode on my DMM:

author: Electro Fan
author_rank: Super Contributor
timestamp: August 09, 2023, 02:15:51 am
content: I think you can get a lot of counter capability for less than $200.https://www.eevblog.com/forum/testgear/which-frequency-counter-gt1-0-ghz/msg3696472/#msg3696472

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: August 09, 2023, 03:58:35 am
content: Quote from: Swake on August 08, 2023, 01:18:27 pmAfter the last financial crisis, I bought a boatload of used test gear on Ebay, including HP and Agilent frequency counters. I feed these a reference clock from a GPS-disciplined Rubidiumoscillator, also bought then via Ebay. Companies were cancelling projects, closing business units, going bankrupt, and liquidating stock. So bargains were everywhere.We may get another financial crisis. This time, it might be triggered by US commercial real estate debt blowing up. Have some savings ready, to take advantage in case it does.Be prepared.