Output Power

Output power, or Transmit Power, is measured either as peak to peak (pp) or Root Mean Squared.

(PP is also a shorter term for polypropylene).

Peak to Peak (pp) is far less accurate than rms. We make the analogy of pp like being the maximum speed shown on a car speedo, achieveable only on a good day, down hill with a tail wind. In other words occassional if you are lucky.

Root Mean Squared (rms) is day in day out average continuous power. When comparing power outputs, you must compare like with like; because P-T-P numbers are 8 times higher than rms numbers.

In fishfinders/sonars, the power output is the amount of sound energy emitted into the water by the Transmitter.

Higher power output allows a higher penetration of Sonar signal through weeds and >Thermoclines, reaching greater depths and allowing better operation in noisy environments. However, the traditional way of thinking was that higher power output meant a better Fishfinder, but with the introduction of broadband transmitters using power more efficiently and alternating and spectrum scanning, the equation is no longer that simple because too much can be a disadvantage in very shallow water as with stronger signals comes more Noise.

Some brands such as Lowrance & Simrad have redefined Output Power as being the sole determinate of good performance. Their broad band technology uses less power more efficiently & reduces the background Noise, enabling small Fish to be seen at a deeper depth.