User Guide

User guide - Watch Scope

Download now

User guide - Watch Analyzer

Download now

Frequently asked questions

What is rate accuracy ?
Rate accuracy indicates the deviation of your movement in seconds per day. A watch with a rate of +2.0 s/d will run two seconds fast per day on average. A watch with a rate of -2.0 s/d will run two seconds slow per day on average. The accuracy of a watch will change over time and is highly dependent on the watch’s orientation. In fact, gravity has an effect on the movements of the balance and can slightly change the oscillation period. To measure rate accuracy, this must be taken into account and that is why it’s necessary to measure the rate in each of the 6 positions (Dial Up, Dial Down, Crown Up, Crown Down, Crown Left, Crown Right). The accuracy is determined by the average of all these measurements together.
Is my watch accurate ?
Several standards exist that may help demonstrate a watch’s accuracy. Here are two main standards to be familiar with: COSC : Controle Officiel Suisse des Chronomètres (The Official Swiss Chronometer Testing Institute) One of the goals of the COSC is to measure and survey the accuracy of watch movements in order to attribute them with an official chronometer title. To be awarded this certificate, each movement must successfully pass the testing conditions set for the standard. These tests bear absolutely no relation to a simulation of watch behaviour and performance when worn. These are statistic tests applied in laboratory conditions to movements and not to finished watches. The standard ISO 3159 provides the definition of a wrist-chronometer with a spring balance oscillator. Only movements that meet the accuracy criteria under this standard are granted an official chronometer certificate. Movements are observed for 16 consecutive days in accordance with a set series of tests. Les critères du COSC sont indiqués ci-dessous.

diameter larger than 20mm diameter thicker than 20mm
Average daily rate -4 s/j – +6s/j -5 s/j – +8s/j
Mean variation in rates 2 s/j 3,4 s/j
Greatest variation in rates 5 s/j 7 s/j
Difference between rates in horizontal and vertical positions -6s/j +8s/j -8s/j +10s/j
Largest variation in rates 10 s/j 15 s/j
Thermal variation +/- 0.6 s/j +/- 0.7 s/j
Rate resumption +/- 5 s/j +/- 6 s/j

In short, the variation in rates of a chronometer must be between -4 s/d and + 6 s/d. Poinçon de Genève (Geneva Hallmark): “ The Poinçon de Genève is a certificate awarded to timepieces with remarkable finishes and decorative details, and provides the connoisseur with proof of the authenticity and horological expertise of Geneva, passed down from generation to generation.” To satisfy the Poinçon de Genève’s standards, a watch must satisfy the following rate accuracy conditions: • Measurements on day 0 and on day 7 are compared with the aid of a vision system that was specially developed for this test. • Days 0 and 7 are compared with a reference time. • After 7 days, the watch must not exceed one minute of variation. In addition, each feature of dial’s indications (day, date, month, etc.) is examined. The variation in rates must be less than 1 minute at the end of these 7 days. The rate accuracy must not therefore surpass +/- 8.6 s/d. Conclusion: – A watch with a variation in rates between -4 s/d and +6 s/d, satisfying one of the COSC criteria, is an example of an excellent movement. –A watch with a variation in rates between -8.6 s/d and +8.6 s/d, satisfying one of the Poinçon de Genève criteria, is a very nice movement. – More generally, a watch with a variation in rates between -10 s/d and +10 s/d is very appropriate. If it goes beyond 10 s/d, it starts to become fairly inaccurate and you should certainly consider having the movement serviced.

What does the frequency indicates ?
The frequency corresponds to the number of vibrations produced by the watch’s balance in one hour. The higher the frequency is, the more accurate the balance will be. The vibrations made by the balance are what produce a watch’s ticking. Therefore, the frequency corresponds to the amount of audible ticks in one hour. Frequency is measured in vibrations per hour (vph). Frequency is a feature of the movement and the most common frequencies are: 14400 vph – 16200 vph – 18000 vph – 19600 vph – 21600 vph – 25200 vph – 28800 vph – 36000 vph – 72000 vph
What is the amplitude ?
In a running watch, the balance wheel regulates the movement of the hands. The balance wheel swings in a very steadily way and each swing of the balance wheel makes up the beat, or the watch’s famous tick-tock. When swinging, the balance wheel moves from one side to the other, forming an extreme angle on each side. The amplitude is the angle formed by the balance wheel between its resting position and one of its extreme positions. The amplitude depends on several factors such as gear friction, watch positioning or the state of winding of the movement. An appropriate amplitude angle is vital to a watch’s proper functioning.
What is a desirable amplitude ?
A general rule of thumb is that the higher the amplitude, the more stable the movement is over time. Watchmakers try to obtain the highest amplitude possible. However, if the balance wheel’s amplitude is close to 360 degrees, during the balance wheel’s oscillation, the outside part of the impulse-pin will hit the back of the pallet fork which will send the balance wheel back before the end of its rotation. The ticking will be irregular and will run much too fast. Therefore, watchmakers try to obtain a high amplitude but want to be certain that the balance wheel’s amplitude isn’t too close to 360 degrees. A desirable amplitude is between 290 and 320 degrees (in a horizontal position). Note that the balance wheel’s amplitude is dependant upon the watch’s position: – In a horizontal position, gravity doesn’t really effect the hairspring’s vibrations and the amplitude is maximal. It is in these positions (Dial Up or Dial Down) that we find the strongest amplitudes. – In a vertical position (Crown Up, Crown Down, Crown Left, Crown Right), gravity does effect the hairspring’s vibrations and the amplitude is reduced. Generally, a fall in around 30 degrees in amplitude is observed between horizontal positions.
What is beat error ?
Beat error indicates an asymmetry in the balance wheel’s vibrations. When the balance wheel’s oscillation isn’t perfectly symmetrical, it swings further in one direction than in the other. This asymmetry causes a longer amount of time between the “tics” than the “tocks”. Beat error is measured by the time difference between the “ticks” and “tocks”. Beat error is measured in milliseconds (ms). A “perfect” movement should have a beat error of 0 ms. If this is not the case, the balance wheel is swinging further in one direction than in the other.
What is the lift angle ?
When listening to the sound produced by a watch, we only hear its ticking. However, the sound of a watch’s beat is more complex and each “tick” is made up of three different pulses. The first noise occurs when the balance wheel’s impulse-pin comes in contact with the pallet forks. A second noise occurs when the pallet detaches from the escape wheel. The third and loudest noise is created when the escape-wheel meets the pallet. The angle that the balance wheel travelled between the first and third noise is called the “lift angle”. The lift angle is a geometric feature of a movement. This angle is given by the movement’s manufacturer. If you don’t know the lift angle of your watch, you can find it thanks to the link below: The lift angle is used to calculate the balance wheel’s amplitude: To calculate the balance wheel’s amplitude, the LEPSI – Watch Analyser measures the time between the first and third noise. Knowing the lift angle, meaning the angle travelled during this time, the LEPSI – Watch Analyser is able to calculate the balance wheel’s amplitude. Most common lift angles of movements are between 48 and 54 degrees. If you don’t know the exact lift angle of your watch, we suggest giving the default lift angle of 52 degrees. This will give you a very good approximation of the balance wheel’s amplitude.
Countinuous analyse your watch
To discover even more about your watches, you can activate the “Continuous Analysis” mode. With this feature, you are able to continuously measure your watch’s variations and better understand how the mechanism is performing. To activate this mode, go into the Calibration page and activate “Continuous Analysis” In Continuous Analysis mode, the measurement will take place as usual, and then after 30 seconds of measurement, a chart will appear with two curves:

  • The normal curve corresponds to the average accuracy.
  • The dotted curve corresponds to the current accuracy (for the last 30 seconds)

If you don’t move the watch, you can observe the current variations of the watch and see how the mechanism varies over time. Depending on how gears teeth engage, the way energy is transmitted to the balance wheel, the movement’s accuracy will be changed slightly. This is why accuracy will vary over time. The chart above is a typical example of this kind of measurement. The normal curve, or the average accuracy, stays constant while the dotted curve, or the current accuracy, rises and falls around the normal curve. On the contrary, if you modify the position of the watch during this measurement or use a function such as the chronograph, the measurement will be much more compelling as you can observe the movement’s “live” reaction. The following chart is a typical example of this kind of measurement: In the example above, it is easy to observe the evolution of the rate when the chronograph is engaged as well as when the watch’s position is changed. Don’t hesitate to do the same with your movements to have a better understanding of how they work.

When launching a measurement my mobile device doesn't detect the frequency
Failure to detect the watch’s frequency may have two origins: 1: The mobile device isn’t detecting Watch Analyser’s signal because another application is using the device’s microphone. For example, when Siri on iOS is launched, Watch Analyser will be ignored. To resolve this problem, you must quit the application and restart it:

  • iOS: Double click on the “Home” button and slide the Watch Analyser application upwards to close it. Then reopen the application.
  • Android: Click on the button to make currently open applications appear and slide the Watch Analyser application to the side to close it. Then reopen the application.

2: Watch Analyser is not detecting the signal coming from the watch. This could be due to the fact that the watch is not correctly placed on the electronic sensor. Reposition the watch on the Watch Analyser cushion and make sure that the watch is tightly fastened to the cushion. You can even press the watch against the detector to make sure the sound is correctly transfer to the Watch Analyser.