FAQs on RetroSign GR3 and GR1

What is tfhe difference between RetroSign GR3 and RetroSign GR1?

The only difference between RetroSign GR3 and RetroSign GR1 is the number of observation angles measured. RetroSign GR3 measures three observation angles while RetroSign GR1 measures one main observation angle.

Can a RetroSign GR1 be upgraded to RetroSign GR3?

No it is not possible to upgrade the RetroSign GR1.

How long time does it take to measure a road sign?

If you just make one retroreflection measurement it takes 2 seconds. To make a full measurement with a Barcode reading and four RL measurements will take approx. 20 seconds.

What is the benefit of measuring three observation angles?

The main observation angle (as measured by RetroSign GR1) mainly show the retroreflection as observed by the driver in a passenger car. The additional observation angles offered by RetroSign GR3 shows the retroreflection as seen by a driver in a lorry or other large vehicles.

What is the benefit of using Point Aperture Geometry over Annular Aperture Geometry?

Point Aperture Geometry ensures accurate readings that replicate real-world driving conditions and correspond to laboratory readings. Point Aperture Geometry also enables the user to determine whether a microprismatic sign sheeting material has been applied correctly. See: Technical note RS106

Does the sun affect the measurement result?

No, RetroSign has a built-in Stray Light Compensation effectively ensuring that ambient light from the sun or other light sources does not affect the accuracy of the measurement.


How fast does the battery charge?

The battery is fully charged within 15 min.

How many measurements can I take with a fully charged battery?

Depends on how the instrument is used; the use of LCD backlight, sound, GPS, RFID, Bluetooth and the measurements schedule all effects the number of measurements possible. A fully charged and fresh battery should be able to make at least 1000 measurements.

When do we know that the battery should be replaced?

A fresh battery will normally take at least 1000 readings  If the number of measurement after recharging falls low it is time to replace.

How long does a battery last before it need to be replaced?

This depends on the use pattern as mentioned above. Do not recharge every time you use the instrument. It is better for the battery to discharge between charge cycles maximizing the battery life time, which is normally several years. 

Can I change the battery myself?

Yes you can. Make sure the instrument is off, release the spring holding the battery and pull it out of the handle. Further details can be located here, RetroSign, Battery.

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Can I calibrate the RetroSign myself?

Yes you can by using the calibration unit that comes with the instrument. Please see the attached instruction, RetroSign, Calibration.

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How often does the calibration standard need to be re-calibrated?

If kept dry in storage and taken well care of when used (no dirt, no scratches on the calibration normal surface) it can last several years without needing re-calibration. DELTA, however, recommends to have a re-calibration or replacement of calibration block done at least every two years to make sure that the calibration of the instruments is correct.

Is there an alternative to sending the calibration unit for re-calibration?

Yes, you can decide to purchase a new calibration unit from DELTA for your instrument, see our price list for details.

How do I know that the calibration block needs re-calibration or needs to be changed?

When the calibration block is scratched, dirty (and cannot be properly cleaned) or otherwise damaged, it is time to replace it.

Does the retroreflectometer itself need to be re-calibrated?

The instrument comes calibrated from the factory. Unless the instrument has been damaged after e.g. being dropped or run over by a vehicle the instrument itself does not need re-calibration. 

Using the features

How do I use and enable/disable the Bluetooth function?

Please see the attached instruction for use detail, RetroSign, Bluetooth.

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How do I use and enable/disable the GPS function?

Please see the attached instruction for use details, RetroSign, GPS.

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How do I use and enable/disable the barcode reader function?

Please see the attached instruction for use details, RetroSign, barcode reader.

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How do I mount and operate the Extension Pole?

Please see the attached instruction for use details, RetroSign, Extension Pole.

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Instrument service

How often does the RetroSign need to be serviced?

RetroSign is a very robust instrument which can stand daily use without need for service. If you should have an accident with the instruments (being dropped, being hit hard and alike) DELTA recommends servicing the instrument. If you want to be sure the instruments work correctly at all times you may consider an instrument service at DELTA at regular intervals. If the instrument is used every day DELTA recommend these intervals being once a year, if used less often a service every 2-3 years will do.

How do I know if/when the instrument need service?

If the instrument doesn\’t work at all, if the instrument status inform that it has detected problems (constant errors and/or warnings) or the measurement are obviously wrong the instrument need urgent service.

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