SurfaceInterval Sensus Ultra Info

The Sensus Ultra Info window provides device specific information for Sensus Ultra dive logging devices. The information provided includes:

  • Computer Model - This is the model number of the device from which this information was captured.
  • Serial Number - This is the unique factory registered identification for this device.
  • Firmware - The version number for the internal software on the device.
  • Manufactured - The date on which the device was manufactured. SurfaceInterval uses this value to calculate dive start time/dates by comparing it against your Macintosh's notion of the date and time at the beginning of each dive. You can get more information regarding time calculations by clicking here.
  • Dive Count - The number of dives this device has encountered. Note that this value does not represent the number of dives currently logged in the device, since the Sensus Ultra does not have unlimited memory. Rather it is the total number of dives since it was manufactured.
  • Battery Level - This is the voltage of the internal battery within the Sensus Ultra device. The battery starts out at a nominal 3 volts (d.c.) at the factory. The value in this field is updated every time you download from the device, so if you haven't downloaded in a while, it may not be entirely accurate. Another important consideration is that the battery does not discharge at a linear rate. It is impossible to calculate the remaining battery life based on the current battery voltage.
  • Read button - The information in the top panel is automatically updated whenever you download dive information from the device. However, there may be times when you wish to refresh the information based on current ambient conditions. Hitting the Read button accomplishes this. This is a quick way to check the current battery level, among other things. Of particular interest is the refreshed ambient pressure reading. If you travel to a level above sea level, this value will change. Taking note of the new value may prompt you to change the threshold setting to compensate for an impending altitude dive. Note, however, that SurfaceInterval does not currently apply any corrections for altitude dives in fresh water. All calculated depths will still be based on ambient pressure at sea-level, in salt water.
The remaining settings are editable by the user, and are described as follows;
  • Sample Interval (default = 10, valid range = 1 to 65535)
      Sensus Ultra collects depth and temperature info at the periodic rate specified by this value. Given the finite amount of memory in the Sensus Ultra, the longer the Sample Interval, the more dives can be stored in the Sensus Ultra at any given time. However, longer intervals, will decrease the resolution of the graph data that will be displayed for each dive entry downloaded. Once the Sensus Ultra's memory is filled, it will begin overwriting earlier dives, beginning with the oldest.
  • Threshold (default = 1111, range = 1 to 65535 millibar absolute)
      The activation pressure in millibar absolute. When this pressure is exceeded, the device enters dive mode and begins sampling pressure/temperature at the rate prescribed by Sample Interval. The default value of 1111 mbar corresponds to a depth of 3 feet at sea level.
  • End Count (default = 15, valid range = 1 to 65535 samples)
      The dive end count in samples. This value specifies the number of consecutive data samples shallower than Threshold which constitute the end of a dive. With the default setting of 15, a dive is terminated once the absolute pressure remains below the Threshold<\B> setting for at least 10 x 15 = 150 seconds.
  • Averaging (default = 1, valid range = 1, 2, or 4 readings)
      The device's pressure sensor is extremely sensitive. Its resolution is 1 mbar (about 1 cm of sea water!). However, due to natural electrical noise, each raw pressure reading may be off by +/- 5 mbar. This can be remedied by averaging a few "rapid-fire" readings rather than taking just one. The Averaging value specifies how many raw pressure readings are averaged per data sample. By default, no averaging is done. This is more than adequate for recreational and technical diving applications. For scientific applications where very stable pressure measurements are required, Averaging can be set to either 2 or 4. For instance, with 4x averaging, each data sample is actually the average of four pressure readings taken in quick succession.

      Averaging mitigates the effect of noise at the expense of power. 2x and 4x averaging require 2 and 4 times as many raw pressure readings, respectively. Use only if absolutely necessary!


You'll notice an update button to the right of each user adjustable parameter. Once you have changed a value, simply hit the appropriate update button. The new value will be written to the device and will be in effect on your next dive.

Finally, the Factory Defaults button restores all of the user configurable settings to their factory default values.