How Korey Sprengel sets up his depthfinder.
Sensitivity
> “If you’re in 20′ or less, you never need to add sensitivity, and in fact, you should reduce it some…. Dialing it back just helps clean the picture up, allowing you to interpret it better. I start to add sensitivity in that 50’+ range. Let’s say if I’m salmon fishing in 150-200′, that’s where it really helps me pick up more fish down in the depths. Without the additional sensitivity, it will mark them faintly.”
Frequency
> Another important sonar setting is frequency. Many sonar manufacturers use transducers capable of 83 and 200 kilohertz. Kilohertz is a measure of frequency equivalent to 1,000 cycles per second. Anglers can set their units to operate on either 83kHz or 200kHz. It’s also possible to run both 83kHz and 200kHz together, known as dual beam or dual frequency.
> Frequency is important because it reflects the number of sound pulses that leave the transducer during a time interval. Generally, the 200kHz setting is going to offer significantly better detail. However, there are situations where 83kHz will shine. On flat, featureless lakes where fish suspend, 83kHz will outperform since it emits a broader sonar signal, which spreads out in the shape of a cone and effectively covers more area. The 200kHz setting shines when marking fish close to the bottom, when target separation and detail are important. The 200kHz setting has a narrower sonar cone angle, which helps to refine the image.
> “If you’re fishing around structure and dragging things that are tight to the bottom, the higher frequency is the way to go…. You have better target separation and better bottom separation. With the low-frequency mode, you lose detail toward the bottom, but you have a broader range because of that wider cone angle. It offers way more coverage.”
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