Frequently Asked Questions

Welcome to our frequently asked questions area, please see our question and answers database below. If there are any questions that have not been answered within our FAQs please do not hesitate to contact us

GPS & Rb
We shall include frequency & time references & calibrators under this heading.

Quartzlock specialize in both “off air” frequency, (GPS) & atomic line resonance locked “atomic clocks”. 

GNSS Global Navigation Satellite Systems now provide the preferred GLOBAL Time and Frequency National and International referenced “off air” signals. US GPS, CIS Glonass, EU Galileo, the Chinese and Japanese GNS systems will enable a choice of non-military, civilian and commercial freedom to any user looking for long term security of ‘ultimate’ frequency and time accuracy.

At this time the US GPS and CIS Glonass systems provide both carrier and CA code information for time and frequency synchronisation in addition to navigation ephemeris for position fixing at any place on the Earth’s surface. The GPS system is preferred by most users at this time.

GPS frequency standards normally provide a 10MHz (+13dBm) and 1PPS (square wave TTL, 3.3VCMOS) outputs.

Today with Quartzlock’s E8-X and E8000 line, a GPS Frequency Standard is available for the same cost as an LF tracking RX was some 25 years ago accuracy to at least 1 x 10-12/day and x 10-10 over seconds is 100 x better than even the best LF Tracking RX. With low cost OCXO options the short term stability reaches x 10-12. The objective is to have stability similar to accuracy over short usable measurement times that meet the everyday needs of calibration and frequency referencing of largely OCXO based instrumentation with external referencing inputs. Frequency Counters, Spectrum Analyzers, Digital Oscilloscopes, Network Analyzers, Microwave Analyzers, Signal Generators, Wireless Analyzers etc.

The disadvantages of GPS are few but must be addressed. No sub aqua use. The antenna should have a clear view of the sky. The cable connecting the GPS antenna to the GPS standard should be as short as practical. Low loss cable should be used. Properly assembled connectors and in precision systems, matching for lowest VSWR / highest return loss should be the aim.

The advantages of GPS are: unsurpassed accuracy both for time and frequency, no drift, nationally and internationally referenced. Some 200 atomic clocks world-wide are compared, and in an algorithmically weighted average (by satellite time transfer) system, provided by BIPM (Paris) to give UTC. GPS time is provided by USNO that is also probably the largest contributor to UTC. UTC (GPS), UTC (USNO) and other leading national timing centres NIST (USA), PTB (Germany), L'Observatoire de Paris (France), NPL (UK) have time / frequency differences of parts in 10-14.

Quartzlock is equipped with both Active and Passive Hydrogen Masers to maintain our in-house frequency reference stable to x 10-15/100s. With a NIST FMS GPS reference system installed, we recorded offsets / day of e-15 occasionally and e-14 regularly of our Quartzlock A8-M 100% carrier phase tracking GPS disciplined rubidium.

GPS frequency and time references are now available at approximately 50% of the cost of Rubidium, but have a few limitations for some users. Portable operation where fast locking is required (less than 15 minutes) is not possible with GPS that requires some 15minutes to lock after stationary antenna deployment. Rubidium may be operated in mobile applications.

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Quartzlock GPS off-air time & frequency standards 
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To receive GPS information, the antenna must be located outside. It will not work inside buildings.

The best location is where your antenna is:

  • as high as possible (e.g. on a roof or mast)
  • in clear view of the sky
  • away from any possible sources of high frequency electrical interference

If installing an external antenna is not an option consider an atomic / rubidium time and frequency standard - more>

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Quartzlock GPS off-air time and frequency standards 
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The exact length depends on:

  • Which antenna is selected:
    • Low gain - approx. 5 meters.
    • High gain - approx. 20 metres
  • Which cable specification is selected
    • RG58 or better must be used
  • The condition of any connectors in the cable.

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Quartzlock H-field loop antennas 
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Rubidium (Rb) atomic frequency references. Some notes on performance / cost comparisons.

Quartzlock has a 15 year heritage in this technology. Our latest developments include work on a CPT Coherent Population Trapping Rubidium we have a number of working prototypes. A technical description of the conventional Rubidium Oscillator is given in the A10 data sheet.

Early commercial Rubidium were appallingly unreliable, with a few exceptions. Quartzlock used Russian physics technology / Quartzlock electronics in the early days of our A10 line with excellent specifications and have fully supported low cost replacements with high reliability current western designs ever since. Quartzlock give a 3 year warranty on all Rubidium products.

Rubidium oscillators normally provide a 10MHz output frequency (+7dBm). Stabilities of e-12/100s and drift of e-10/year typify the Rubidium oscillator’s performance. Quartzlock can offer higher stability and very low phase noise Rubidium to meet demanding applications (see QL A10-Y / HSRO) our interests also lie with defence MIL spec and Space Qualified Rubidium.

The Rubidium oscillator will never have GPS accuracy or drift free operation.

In most applications the Rubidium oscillator will not need calibrating, in any event a low cost GPS reference can be used to confirm the Rubidium offset over 1000 seconds, or much shorter measurement time with a GPS disciplined Rubidium. In production test and calibration laboratories EFC (electronic frequency control), and MFC (mechanical frequency control) for adjustment purposes is possible with Rubidium oscillators.

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Quartzlock rubidium time and frequency standards 
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A5 & A5000 with input & output frequencies within the range of 1MHz to 100MHz & 1MHz to 20MHz.

The function of a distribution amplifier is to faithfully reproduce the input at a number of outputs, 4, 6, 12, 24 or 32 & up, usually at unity gain & in a 50 Ohm system. So, a Distribution Amplifier makes it possible to have multiple outputs from a frequency standard to reference all the quartz oscillator based instrumentation in, say a microwave development laboratory or production test lab. Spectrum Analyzers, Frequency Counters, Microwave Analyzers, Network Analyzers, Signal Sources, Digital Oscilloscopes etc……the performance of all these instruments can be significantly improved, very simply, by using say a Rubidium reference plus a distribution amplifier to provide a more accurate & stable 10MHz reference to the external reference input for each of the Instruments in use. A Quartzlock A10-X6 is a remarkably low cost example of Rb with built on 6 output distribution amplifier (£1500)

Quartzlock produce very high performance Distribution Amplifiers (A5) & also very low cost (A5000) units….but even these are very fully specified. Only isolation & phase noise parameters have noticeably lower specifications in our low cost A5000 instruments.

The core specifications of a Distribution Amplifier are: Isolation input to output & output to output (input to input in multi-channel amplifiers) expressed in dB. Phase Noise added to the input signal, expressed in dBc/Hz in a specific bandwidth, usually 1Hz. Distortion added to the input signal, harmonics & spurii, expressed in dBc. Phase / Temperature stability, expressed in ps/C. Short Term Stability AVAR Allan Variance, expressed in e-X /tau, ie 3x10-14/s (this is actually the spec of our Quartzlock A7-MX frequency & phase analyzer used to measure an A5 or A5000 @ typically e-13/s)

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Quartzlock distribution amplifiers
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Quartzlock products: A6, A6-CPS, A6-1PPS

The function of a frequency convertor is to convert the input frequency to a different frequency at the output while retaining the input signal characteristics. In much the same way as a distribution amplifier with the exception of the specified change in the actual frequency itself.

We have included in frequency convertors the Quartzlock latest A6-CPS Digital Phase Locked Loop with Direct Digital Synthesis in a Clean-up Loop configuration, all on a very small PCB & Quartzlock A6-1PPS Locking Module.

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Frequency Convertors
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Quartzlock Payment and Shipment Methods


Quartzlock prices are ex-works and quoted in GB Pounds (Sterling). We accept payment by the following methods:

  • Bankers Draft
  • Confirmed Letter of Credit. LC costs will be added to your invoice.
  • Cheque, in GB pounds, drawn on a UK bank only. 

Customers who do not have a recent trading history with us will be invoiced on a pro-forma basis.


  • UK shipping will be arranged by Quartzlock using our preferred carrier (standard charges apply).
  • All overseas shipments on your preferred carriers account.

Terms and Conditions

If you have any questions please contact us.

Quartzlock Terms and Conditions.

For our latest terms and conditions document please click here (pdf download)

If you have any questions or need clarification of any section of our terms and conditions please contact us.

Thank you


Which GPS antenna can I use for Quartzlock products?

Quartzlock E series GPS instruments support both 3.3V and 5V GPS antennas via a standard TNC connector. Solder link SP2 is linked for 5V (default) or open for 3.3V.

All our datasheets and manuals are provided as PDF files (Portable Document Format). This is a widely used standard which requires Adobe Acrobat Reader software to be installed on your computer. This is available to download free from:

If you already have Acrobat installed and still experience problems make sure you have at least version 5 installed. To check which version you have: open Acrobat and click Help / About Acrobat.  Quartzlock PDF's should open in version 5 and later.

We have limited information on discontinued / obsolete products. See the support page for pdf manual and datasheet downloads.