INS_HNTC3_ parameters

9 parameters in the INS_HNTC3_ family. ArduCopter 4.7 only — other vehicles share many of these names but not always the same ranges or meanings.

    INS_HNTC3_ATT

    Harmonic Notch Filter attenuation

    Harmonic Notch Filter attenuation in dB. Values greater than 40dB will typically produce a hard notch rather than a modest attenuation of motor noise.

    Units

    dB

    Range

    5 to 50

    User level

    Advanced

    INS_HNTC3_BW

    Harmonic Notch Filter bandwidth

    Harmonic Notch Filter bandwidth in Hz. This is typically set to half the base frequency. The ratio of base frequency to bandwidth determines the notch quality factor and is fixed across harmonics.

    Units

    Hz

    Range

    5 to 250

    User level

    Advanced

    INS_HNTC3_ENABLE

    Harmonic Notch Filter enable

    Harmonic Notch Filter enable

    User level

    Advanced

    Values

    Value

    Meaning

    0

    Disabled

    1

    Enabled

    INS_HNTC3_FM_RAT

    Throttle notch min frequency ratio

    The minimum ratio below the configured frequency to take throttle based notch filters when flying at a throttle level below the reference throttle. Note that lower frequency notch filters will have more phase lag. If you want throttle based notch filtering to be effective at a throttle up to 30% below the configured notch frequency then set this parameter to 0.7. The default of 1.0 means the notch will not go below the frequency in the FREQ parameter.

    Range

    0.1 to 1.0

    User level

    Advanced

    INS_HNTC3_FREQ

    Harmonic Notch Filter base frequency

    Harmonic Notch Filter base center frequency in Hz. This is the center frequency for static notches, the center frequency for Throttle based notches at the reference thrust value, and the minimum limit of center frequency variation for all other notch types. This should always be set lower than half the backend gyro rate (which is typically 1Khz).

    Units

    Hz

    Range

    10 to 495

    User level

    Advanced

    INS_HNTC3_HMNCS

    Harmonic Notch Filter harmonics

    Bitmask of harmonic frequencies to apply Harmonic Notch Filter to. This option takes effect on the next reboot. A value of 0 disables this filter. The first harmonic refers to the base frequency.

    Reboot required

    Yes — the change takes effect after a reboot.

    User level

    Advanced

    Bitmask

    Value

    Meaning

    0

    1st harmonic

    1

    2nd harmonic

    2

    3rd harmonic

    3

    4th harmonic

    4

    5th harmonic

    5

    6th harmonic

    6

    7th harmonic

    7

    8th harmonic

    8

    9th harmonic

    9

    10th harmonic

    10

    11th harmonic

    11

    12th harmonic

    12

    13th harmonic

    13

    14th harmonic

    14

    15th harmonic

    15

    16th harmonic

    INS_HNTC3_MODE

    Harmonic Notch Filter dynamic frequency tracking mode

    Harmonic Notch Filter dynamic frequency tracking mode. Dynamic updates can be throttle, RPM sensor, ESC telemetry or dynamic FFT based. Throttle-based harmonic notch cannot be used on fixed wing only planes. It can for Copters, QuadPlane(while in VTOL modes), and Rovers.

    Range

    0 to 5

    User level

    Advanced

    Values

    Value

    Meaning

    0

    Fixed

    1

    Throttle

    2

    RPM Sensor

    3

    ESC Telemetry

    4

    Dynamic FFT

    5

    Second RPM Sensor

    INS_HNTC3_OPTS

    Harmonic Notch Filter options

    Harmonic Notch Filter options. Triple and double-notches can provide deeper attenuation across a wider bandwidth with reduced latency than single notches and are suitable for larger aircraft. Multi-Source attaches a harmonic notch to each detected noise frequency instead of simply being multiples of the base frequency, in the case of FFT it will attach notches to each of three detected noise peaks, in the case of ESC it will attach notches to each of four motor RPM values. Loop rate update changes the notch center frequency at the scheduler loop rate rather than at the default of 200Hz. If both double and triple notches are specified only double notches will take effect.

    Reboot required

    Yes — the change takes effect after a reboot.

    User level

    Advanced

    Bitmask

    Value

    Meaning

    0

    Double notch

    1

    Multi-Source

    2

    Update at loop rate

    3

    EnableOnAllIMUs

    4

    Triple notch

    5

    Use min freq on RPM source failure

    6

    Quintuple notch

    INS_HNTC3_REF

    Harmonic Notch Filter reference value

    A reference value of zero disables dynamic updates on the Harmonic Notch Filter and a positive value enables dynamic updates on the Harmonic Notch Filter. For throttle-based scaling, this parameter is the reference value associated with the specified frequency to facilitate frequency scaling of the Harmonic Notch Filter. For RPM and ESC telemetry based tracking, this parameter is set to 1 to enable the Harmonic Notch Filter using the RPM sensor or ESC telemetry set to measure rotor speed. The sensor data is converted to Hz automatically for use in the Harmonic Notch Filter. This reference value may also be used to scale the sensor data, if required. For example, rpm sensor data is required to measure heli motor RPM. Therefore the reference value can be used to scale the RPM sensor to the rotor RPM.

    Range

    0.0 to 1.0

    Reboot required

    Yes — the change takes effect after a reboot.

    User level

    Advanced