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  • Author Author: IQD-Frequency
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Disciplined oscillator offers extended holdover

IQD-Frequency
Disciplined oscillator offers extended holdover

The IQCM-200 is a disciplined OCXO, incorporating sync to a 1 PPS (pulse per second) input as well as a 1 PPS output. Its exceptional holdover stability and accuracy makes this particular product a superlative Disciplined OCXO.

The IQCM-200 is part of a series of disciplined OCXOs available from IQD. This particular model is the smallest sized OCXO capable of achieving a holdover capability of 1.5µs over 24 hours meaning you can rest assured your devices can continue to function with incredible accuracy during a holdover period.

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This ‘best in class’ holdover stability of up to 1.5 μs over 24 hours across 0 – 60 °C, and 25 µs typical in 10 days at 25 ±2 °C is achieved using an adaptive algorithm. Internal parameters of the algorithm, including maintenance alarms and message functions are available to the user via a serial interface. A Frequency stability better than ±0.02 ppb is achievable.

Extensive in-house testing of the ICQM-200 has been carried out by our engineers here at our laboratory in the UK. In these controlled tests the holdover achieved by the IQCM-200 after 10 days was a very impressive 25.5 μs, ideal if your application requires a longer holdover than 24 hours. Tests also concluded ADEV figures as 2.2E-12 @ τ = 1 s.

Due to its exceptional holdover times, this product is ideal for applications that require an accurate time reference, Telecoms LTE and 5G timing, and PTP GM clocks with the required IEEE 1588 holdover support, and within White Rabbit applications. This particular model will be an excellent asset to power sector products which require increased holdover times due to the emerging changes and requirements within this sector. The IQCM-200 is compliant with MiFID II.

An IQCM Evaluation Board is also available for this series (contact . Details on all the tests carried out including the 10 day holdover can be found in the IQCM-200 handbook. For your copy please contact sales and support teams at any time.

Find IQCM-200 on Farnell

  • in reply to cstanton

    I don't know, how can you be sure it's an online store issue? I think this site modifies URLs to indicate the origin was from element14, and to me it looks like something has gone wrong with that code, it's appended e14c-direct-ugc multiple times to the URL. 

  • in reply to shabaz

    That's a whacky mess, what is the online store up to now?

  • Guys, we're sorry the internal link isn't working. Hopefully, the admins can fix this again. 

  • in reply to shabaz

    I might add a bunch of 10 MHz xtals to my next Farnell order, just to see what's feasible, since I've always wanted to try building a crystal filter. It could be a handy general-purpose project for checking phase noise of any 10 MHz source (although it still needs a lower-phase-noise reference).

  • in reply to michaelkellett

    It's a massive challege, the specs are impressive.

    Just speculating, maybe there are some ways a theoretical review/RoadTest could be done "on the cheap" (cheap being a relative term!) but still achieving an examination of short-term stability (jitter/phase noise) and longer-term stability (both with and in the absence of GPS disciplining)., and still with useful results. 

    For short term stability, the cheapest way I can think of would be to:

    (1) obtain an ultra-low-phase-noise 10 MHz clock source; Microchip have taken the Vectron product line, and theirs were quite cutting-edge. There's OX-2040-BEE-2085-10M0000000 which is just over £1k, but MOQ from Mouser is 3.

    (2) Build (1) into a reference clock source for a spectrum analyzer (your FPC1500 would work for this)

    (3) Build a relatively sharp 10 MHz crystal filter. This would probably be a couple of weeks exercise, would also need a whole load of crystals so you could bin them. This would require a basic VNA (e.g. FPC1500 or even NanoVNA; in fact NanoVNA might be a better choice for this since there's two ports). I've never built a crystal filter, but have matched a filter, and there's lots of online information regarding such filter construction since IF filters are a popular thing!

    (4) Time to add the IQCM-200! Use (3) to provide a notch for it, and feed that into the spectrum analyzer, which is being supplied with the reference from (2).

    (5) Take a noise measurement away from 10 MHz (e.g. 10 kHz offset) and then some manipulation (primarily adding the filter attenuation value to it) will get the phase noise value.

    For longer-term stability, one of the possible tests could be:

    (1) Use two IQCM-200, one with GPS loss, and measure phase difference during 24 hours (e.g. with TinyPFA, see below). This is just a relative measurement, but still useful. Also, it would be good to see what is going on from the data stream that the IQCM-200 apparently outputs.

    The tinyPFA is free firmware (not open source, unfortunately) that can be installed into a NanoVNA-H4 and used standalone or with TimeLab software, which can provide ADEV charts.


    All the above would still cost a few $k but better than several $10k! : ) But would easily consume a lot of time and effort.