Simrad ER60, Operator'S Manual

Page: 148 / 182

Simrad ER60 Operator manual
140
850-164692 / Rev.B
Sample datagram
The sample datagram contains data from just one transducer
channel. It can contain power sample data, or it can contain both
power and angle sample data.
struct SampleDatagram
{
DatagramHeaderDgHeader;
// “RAW0”
short Channel; // Channel number
short Mode;
// Datatype: 1 = Power, 2 = Angle, 3 = Both
float TransducerDepth; // [m]
float Frequency; // [Hz]
float TransmitPower; // [W]
float PulseLength; // [s]
float BandWidth; // [Hz]
float SampleInterval; // [s]
float SoundVelocity; // [m/s]
float AbsorptionCoefficient; // [dB/m]
float Heave; // [m]
float Roll; // [deg]
float Pitch; // [deg]
float Temperature; // [C]
char spare [12] // Future use
long Offset; // First sample
long Count; // Number of samples
short Power[]; // Compressed format - See below!
short Angle[]; // See below!
};
Short Power - The power data contained in the sample
datagram is compressed. In order to restore the correct value(s),
you must decompress the value according to the equation below.
x = power value derived from the datagram
y = converted value (in dB)
Short Angle - The fore-and-aft (alongship) and athwartship
electrical angles are output as one 16-bit word. The alongship
angle is the most significant byte while the athwartship angle is
the least significant byte. Angle data is expressed in 2’s
complement format, and the resolution is given in steps of
180/128 electrical degrees per unit. Positive numbers denotes
the fore and starboard directions.