Passive Sonar, HF (10-500 KHz, 20 KHz Center Frequency)
A category of signature type in the Command model.
Passive Sonar, HF (10-500 KHz, 20 KHz Center Frequency) indicates the acoustic energy signature of the target at high frequencies.
Platforms, facilities, and weapons have various compositions, construction, and geometries that interact with the combat environment in different ways. Signatures are the set of emitted and reflected energy properties of a given target. Signatures will vary depending upon the energy type (such as acoustic or electromagnetic), spectral frequency, and whether the energy is self-generated or reflected. Larger numbers indicate that more signal may be detected by a sensor.
Passive Sonar signatures describe acoustic energy that is self-generated and emitted by a target. High frequency sound will be absorbed in water more readily than low frequency sound. Hence low frequency sound will travel farther. The signature is provided in decibels.
Active Sonar signatures describe acoustic energy that is reflected by a target. This acoustic energy is typically generated by a transducer that is part of an active sonar sensor. The signature is provided in decibels.
Visual signatures describe visible light that is reflected by a target. The signature is provided in nautical miles.
Infrared signatures describe infrared radiation that is emitted and reflected by a target. Engines and exhaust as well as reflective surfaces will increase the infrared signature. The signature is provided in nautical miles.
Radar signatures describe electromagnetic radiation that is reflected by a target. This radar energy is generated by a magnetrons, klystrons, etc... that are part of an active radar sensor. The signature is provided in decibels per square meter (dBsm).
Signature type is quantified by range or by response in decibels (dB). A decibel is a ratio of power or signal amplitude expressed on a base-10 logarithmic scale. For signal amplitude, an increase in amplitude by a factor of 10 represents a 20 dB increase. For power, an increase in power by a factor of 10 represents a 10 dB increase. Negative values of decibels represent decreases and reciprocals. For example, a large negative number for a target's radar signature would indicate extreme attenuation of the reflected radar energy. This is typical for stealth aircraft.
Note: the Baloogan Campaign Database Wiki currently displays signature metrics in a rectangular table, with rows of signature type and columns of target aspect. The annotation "nm for Visual/IR, dBsm for Radar, db for Sonar" does *not* refer to columns, despite the placement at the tops of columns. Those annotations refer to the signature units for the various rows.
Command distinguishes the signature types into:
Passive Sonar, VLF (0-1000 Hz, 200 Hz Center Frequency) Passive Sonar, LF (1-5 KHz, 3 KHz Center Frequency) Passive Sonar, MF (5-10 KHz, 7.5 KHz Center Frequency) Passive Sonar, HF (10-500 KHz, 20 KHz Center Frequency) Active Sonar, VLF-HF (0-500 KHz) Visual Detection Range Visual Classification Range Infrared Detection Range Infrared Classification Range Radar, A-D Band (30-2000 MHz) Radar, E-M Band (2-100 GHz)