Beam_volume_sum

This analysis variable calculates the sum of the volumes Vp of the analysis domain that were sampled in each ping p. See also Onscreen analysis: Integration or Single targets, Exporting analyses: Integration or Single targets.

where

N = The number of pings in the analysis domain being analyzed

Vp = The beam volume of a single ping p within the analysis domain (m3)

where

	= Beam volume angle (steradians). Under Sv analysis, Echoview uses the Equivalent TWBA. Under single target analysis, Echoview uses a single target Beam volume angle.
n	= the number of boundaries Ri+1−Ri in the ping. See illustration below.
	=	0 if the interval between Ri and Ri+1 is invalid in the analysis domain, i.e., is above an Exclude above line or is below an Exclude below line or contains no data samples and Include the volume of no data samples is not selected or is within a bad data (no data) region and Include the volume of bad data (no data) regions is not selected Generally, for Single target analysis, do not select the Include the volume of bad data (no data) setting. Note: No data samples may occur in a number of ways (no data samples, samples within applied bad data (no data) regions and samples in pings with a bad line status). For further information refer to About analysis domains: Analysis based on regions and samples.
		1 otherwise, including below threshold data
Ri	= the range (measured along the beam axis of the ping) to the start of the ith boundary in the analysis domain (m)
Ri+1	= the range (measured along the beam axis of the ping) to the end of the ith boundary in the analysis domain (m)

In the example below the samples in the ranges (R1 to R2), (R3 to R4), and (Rn-2 to Rn-1) are part of bad data regions and the volume of the beam in these ranges will not be included in the overall beam volume for the ping. The red hatching marks the samples which were analyzed - see analysis hatching for details.

Notes:

Beam_volume_sum does not necessarily represent the sampled volume of water as the calculation does not take overlap between pings into account. This is of particular note in the case of a fixed transducer where two pings may represent sampling of the same volume of water.
To calculate the average number volume samples by all analyzed pings divide beam_volume_sum by the number of pings in the analysis domain.
This analysis variable was known as Volume_sampled in Echoview 3.00 and earlier and was only available for on-screen single target analyses.
Calculation of Beam_volume_sum assumes that the variable (or echogram) contains individual pings. The results of this calculation will not be valid for resampled, integrated or otherwise reduced pings.
Sv based beam volume sum export bases the calculation on the integer number of samples with respect to start range and stop range within the grid depth/range/line-referenced values.
Single target based beam volume sum export bases the calculation on the top range of single targets within the grid depth/range/line-referenced values.
Single target beam volume angle calculation prior to Echoview 13.1. See also the discussion in Single target beam volume angle prior to Echoview 13.1.