FAQ

Bias instability is the minimum point of the Allan Variance curve over a 20 hour test period.

Bias instability is measured by Allan Variance method, according to IEEE std 952.

• Modules are placed on vibration damped tables
• Test temperature is ambient (~25°C)
• Total measurement time is 20 hours
• Sample rate is 1000Hz
• LP-filter frequency is 131Hz
• Power is applied 2 hours prior to data collection
• Data are collected for 18 hours

ARW [˚/√h] is found at τ =1s averaging time
Bias instability [˚/h] is found as lowest point of curve

Time to valid data is 10s for STIM202 and 5s for STIM210.
Time to datagram transmission is 1s. A Start-up bit (bit 6) of the status byte is set while gyro data are invalid.

No. Other input ranges than those listed in product datasheets are not offered for standard products.

• Angular random walk (ARW) is improved from 0.20 to 0.10°/√h
• Bias error over temperature gradients is improved from 30 to 10°/h rms
• Maximum sample rate is increased from 1000 to 2000 samples/s
• Shielded connector improves EMI capability
• Maximum RS422 transmission bit rate is increased from 921.6 to 1,843kbits/s
• Total delay is reduced
• Time Of Validity (TOV) signal for external synchronization
• Start-up time is reduced from 10 to 1s
• Scale factor accuracy is increased from ±2000 to ±500ppm
• Non-linearity is decreased 200 to 25ppm
• Linear acceleration effect is decreased from 18 to 10°/h

• Foot prints are identical
• STIM210 is 1.5mm taller
• Connectors are different
• STIM210 is software backwards compatible with STIM202

STIM uses cascaded integrator-comb (CIC) low pass filters with linear phase response. Filter bandwidth is user selectable for each gyro axis, independent of sample rate.

The definition of group delay is equal to the group delay of the user selectable low pass filters. Depending on low pass filter -3dB frequency selections, this delay varies from 1.6ms to 23.4ms.
The definition of total delay is from data ready goes high (ref. the phrase new raw data available in datasheets) to start of datagram transmission.
Specifications for group delay and total delay can be read from STIM datasheets.

Time Of Validity (TOV) is for synchronization of datagram transmission with external events. TOV falling edge occurs synchronous to the sample rate. Raising edge occurs after last bit of datagram.

The total delay is 750µs for STIM202 measuring at 1000 samples/s, while this time is reduced to 500µs for STIM210 measuring at 2000 samples/s.

STIM firmware cannot be changed by the customer.

No. All STIMs are calibrated and tested to meet datasheet specifications.

Unit specific data can be made available following individual agreements.

The scale factor is calibrated and measured over 5 static temperatures (from -40 to 85°C). At each temperature, data is collected at 9 different rates, between -400 and +400°/s.

Time from external trigger goes low until start of datagram transmission is defined by ttx_dl (max 20µs).

The repeatability and the accuracy of sample rate is ±25ppm (0,0025%) over the full temperature range.

ARW is the noise component at the output of the gyroscope, derived from the Allan Variance plot at 1s averaging time.

The principle of operation for Sensonor gyros is based on the Coriolis effect.
The gyro contains a balanced force feedback vibrating structure, with electrostatic excitation and capacitive detection.
The structure is made in bulk micro machined mono-crystalline silicon.

No.

Yes, the gyros use internal die temperature to continuously compensate the output signal.

Bias accuracy is the output signal when the gyro is at rest. Bias accuracy specification of STIM is ±250°/h (±0.069°/s).