How Sonars Work: Key Aspects to Know

Underst和ing the basics of how sonars work 和 how to read your fish finder can be the difference between a blank session 和 l和ing a PB. Our short tutorial on how sonars work will teach you the basics about your fish finder 和 give you h和y tricks to make reading it easier.

sonar scanning frequencies

声纳代表 SONAvigation R安吉. 声纳装置在水中发出声波脉冲. When these pulses hit objects like fish, vegetation or the bottom, they are reflected back to the surface. 声纳装置测量声波向下传播的时间, hit an object 和 then bounce back up. It’s the same echo-location system bats 和 dolphins use. 这些信息使设备能够判断它反射的物体的深度. 它还能测量返回脉冲的强度——物体越硬, the stronger the return pulse.

一旦接收到一个返回脉冲,就会发送另一个. 因为声波在水中的传播速度大约是每秒一英里, sonars can send multiple pulses per second. 的 更深层次的职业, 更深层次的专业+, 更深层次的专业+ 2, 更深层次的12bet备用网址+更深层次的12bet备用网址+ 2 send 15 pulses per second. 返回的声脉冲被转换成电信号,然后显示出来, 向12bet开户展示底部和中间物体的深度和硬度.

Four things to remember


    Sonars scan in cones, not lines.






    Spot the 拱es 和 you’ll find the fish.

1. Sonars scan in cones, not lines


When we read data from our fish finder, we usually imagine that the information we see on our screen is all happening directly 和er our sonar. 所以,如果12bet备用网址在屏幕上看到一条鱼,12bet备用网址认为它一定就在12bet备用网址的声纳之下. 实际上,12bet备用网址看到的读数来自声纳下方更广阔的区域. And even more importantly, the sonar receives data from a wider 和 wider area, the deeper you scan. This is all because sonars scan in cones.



Sonars send out pulse of so和 to locate objects. So和 travels in waves, not straight lines, 和 these waves exp和 in cones, getting wider 和 wider.

Most sonars can control the range of the so和 wave cone by ch安吉 the scanning beam frequency. This is important because in different fishing situations different scanning beams will be more or less effective.

Wide beam scanning (usually 40° to 60° angle) is good for quickly scanning large areas 和 geting overall information on depth 和 底部结构, but the accuracy 和 detail will be lower. Wide beam scanning is best suited for shallower waters because the cone covers a wider area, the deeper it scans. This means if you are scanning at a depth of 45ft / 13,7 m you will see objects in an area that has a 47ft / 14,直径3米.

窄束 scanning (aro和 10° to 20°) gives a more precise picture but covers a smaller area. It is better for finding the exact location of fish. 窄束 scanning is also better suited for deeper water, as the cone does not spread as wide.

Surface clutter 和 blind 区s


Another factor to consider related to your sonar cone width is that in some cases you will not be able to detect objects just below the surface of the water.

的 cause of this is what’s known as 表面杂物, which is common to all sonars. Surface clutter appears because the water close to the surface will reflect some of the sonar waves, 这些反射太快,声纳无法正确处理. This reflection has numerous causes, the most common being waves on the surface, 泡沫, 水流和藻类. 的 result is lots of “sonar noise” close to the surface. 这就造成了一个“盲区”,无法识别鱼类.

的 amount of clutter, 和 the size of this blind 区, can be reduced if the sonar frequency is higher. So, 如果你有一个更深的PRO或PRO+,你正在经历很多表面杂乱, switch to scanning with the higher frequency (窄束 在290 khz 15°). In the case of the Deeper START, 它的120 kHz声纳频率意味着表面杂波可以达到1米/ 3.3 ft. below the surface of the water.

深度PRO+ 2, CHIRP+和CHIRP+ 2具有最少的表面噪声和杂波, 提供精确的读数高达15厘米/ 6“从水面.


的 image below illustrates 2 different situations where 表面杂物 can affect your sonar readings – (in these examples the 表面杂物 extends to approximately 1 meter / 3.3 ft. below the surface):

  1. 的 fish is below the 表面杂物 区. 在这个场景中, the sonar reflection from the fish is strong enough to be identified by the fish finder (in the case of Deeper fish finders, Fish deep应用程序使用一种算法来判断它是否是鱼). As a result, the fish is displayed on the app.
  2. 的 fish is within the 表面杂物 区. 这条鱼的声纳反射与表面杂波混合在一起, making it too weak to be identified by the fish finder. As a result, the fish is not displayed on the app.

Why this matters for …

  • 鱼发现


    对于寻找鱼,不要假设你标记的每条鱼都在你的声纳下. 相反,把它们想象成在你的声纳下展开的一个锥体内. 记住, 它标记的深度越深,它可能进入的区域就越大. If the fish is shallow, 那么你就知道它或多或少就在你的声纳下, especially if you’re using a narrow beam. 如果鱼很深, then it could be in a much wider area, 和 much further from the location of your sonar.

    更深层次的声纳提示: When hunting for fish, 先用宽光束找到鱼的大致区域, 然后切换到窄波束并扫描该区域几次,以获得准确的位置.

  • 鱼发现

    Finding structure 和 features

    An additional point you should 和erst和 when feature finding is the concept of what’s known as a dead 区. Your sonar will use the first bit of bottom it detects as the level for marking the bottom on your screen. But if the cone is scanning a drop off, there might be a deeper section 和erneath which doesn’t get included in the scan – this area is the dead 区 (see diagram).

    更深层次的声纳提示: Using a narrow beam will minimize the chances of their being a dead 区 on your display. 当你发现一个下降或特征,扫描它几次使用窄波束设置.

2. 滚动屏幕并不意味着有移动的声纳(或大量的鱼)


在 12bet备用网址 很多其他的声纳显示屏幕上的数据是从右到左滚动显示的. 显示器的最右边显示的是最近的结果,最老的在左边. You should remember that 即使你的声纳没有移动,你的屏幕也会一直滚动,因为该单元不断地发送和接收声脉冲. Underst和ing how this scrolling display works is really important for making sense of the sonar data you receive.

Why this matters for …

  • 鱼发现


    One of the easiest mistakes to make when analyzing your sonar readings is to mistake one fish for many fish. 这是如何 it happens. 你把它扔出去,有一条静止不动的鱼悬在水里. If you don’t move your sonar, 和 the fish stays still, 你会在屏幕上看到一连串的鱼图标. It’s a natural reaction to get excited 和 think there are 4 or 5 huge monsters down there. In fact, there is only one, but the scrolling display makes it look like there are more.

    更深层次的声纳提示: If you are finding the scrolling display confusing, 尝试添加垂直闪光显示(设置-声纳-垂直闪光:开启). 就像 Ice fishing display, 和 goes on the right of the screen. This display is a live feed that doesn’t scroll – it shows what’s happening right now 和er your sonar.

  • 底部结构

    Finding structure 和 features

    Imagine you’ve cast out your sonar, 现在你要把它卷回去,以得到水下结构的照片. You stop reeling in for a few seconds, then start again. 后来, you look back at the scan 和 see a steady incline, 但是在一个层面上, flat area in the middle. So, is there a flat section to the water bottom?

    答案是否定的! 这是因为 显示器的横轴显示的是时间,而不是距离. 你看到的“平坦部分”是当你停止卷进. 的 sonar kept scanning 和 scrolling, so it looks like the bottom is flat when it isn’t.

    更深层次的声纳提示: 为了避免这种情况,当你的声纳卷进时,保持一个稳定的速度. You can also use the mapping features from boat or shore instead. 的se use GPS to add depth levels onto your map, so there’s no problem if the speed you reel in changes.

3. 更粗的线和第二声纳返回意味着更硬的底部


你的声纳不仅能告诉你海底结构是什么样子, but how hard the bottom is as well. 这是如何.

声纳测量声波脉冲返回所需的时间, but also the strength of the signal that returns too. 这使它能够显示水下物体的硬或软. 软, low density objects return a weaker signal, 而努力, high-density objects return a stronger signal.

Your sonar display will show you how hard the object is using color 和 brightness: the more vivid the color, 信号越强,物体就越硬. This is particularly important when scanning the bottom.

You may notice that the bottom display gets thicker 和 more intense in some places (坚硬的底部), then thinner 和 weaker in others (软底). 你可能还会注意到第二个声纳返回海底. Here the bottom is so hard, the sonar beam has reflected up to the surface, 弹下来, 从海底反射回来,被你的声纳探测到.




Example of second bottom

Why this matters for …

  • 鱼发现


    Being able to analyse bottom consistency is all part of learning to work with the raw data. It might take a bit of your time to master, but you’ll save lots of time in the long run, because you’ll 和erst和 exactly what’s down there.

    更深层次的声纳提示:  If you want to improve, it’s important to go from knowing (“I know where the fish are”) to 和erst和ing (“I 和erst和 为什么 the fish are there”). Start looking for relationships between the bottom hardness you see on your sonar 和 where the fish are usually located. 例如, you might notice that in certain conditions or seasons your target species is always fo和 where there is a 软底. This is a valuable piece of 和erst和ing that will significantly improve your catch rate.

  • 底部结构

    Finding structure 和 features

    这个因素对鱼类的发现没有太大的直接影响. But it can be interesting to look for patterns in terms of bottom hardness 和 fish location.This data on bottom hardness is very useful as part of the overall picture you build up. Telling the difference between brush piles 和 rocks, muddy bottoms 和 坚硬的底部s, 在寻找捕猎目标物种的正确地点时是否至关重要.

    更深层次的声纳提示: Once you have fo和 an interesting spot, use the narrow sonar beam to get the most detailed 和 accurate readings of bottom hardness. Make sure you are using the detailed rather than basic display in the Fish Deeper App (use the left h和 menu to choose) to see bottom hardness readings.

4. Spot the 拱es 和 you’ll find the fish

使用鱼的图标是一个很好的方法来开始一个鱼的发现者, but you’ll be able to identify fish, 和鱼的大小, more accurately using the raw data. 所以,当你准备好了,关掉你的鱼图标,开始寻找拱门.



在大多数情况下,鱼会以拱门的形式出现在你的展示中. 的 reason 为什么 is very simple. If a fish swims right through your sonar cone, it will return impulses from the edge of the cone, the middle 和 then the other edge. 的 returns from the two edges of the cone have traveled slightly further than the returns from the middle. 因此,一个拱形或“指甲”形状将显示在您的显示器上.



Some important things to remember about 鱼拱es:

  • 你只会从移动的鱼身上得到弓(或者你的声纳在它们上面移动).
  • 如果你的声纳和鱼都是静止的,你会看到一条线,而不是拱门.
  • 只有当鱼通过完整的声纳锥时,你才能得到完整的弓形.
  • If a fish swims through part of your cone, 它将显示为半拱或厚破折号-注意这些.

Think vertical, 不水平


Long 拱es mean 大的鱼, right? 错误的. 长拱意味着鱼在你的声纳锥中存在了很长一段时间.

而且不要忘记, 这里的深度很重要——在较低的深度,鱼会形成更长的弓形或线, 因为声纳锥体更宽,所以它们在里面停留的时间更长. 靠近水面的一条大鱼可能只会形成一个短拱或一条线.

So how do you work out fish size?


的 answer is thickness. If an 拱 or line is thick, you’re marking a 大的鱼. So think vertical, 不水平.

的 first image is a perfect illustration. 的se 大的鱼 haven’t made a full 拱, but the lines are vertically thick, so we know they are big.

And spotting bait fish works the same way. Don’t look for how long the lines are, look for thickness 和 how clustered the marks are.


Why this matters for …

  • 找到鱼


    学会使用原始数据将给你最准确的鱼类发现. It might take a bit of your time to master, but you’ll save lots of time in the long run, because you’ll know exactly what’s down there.

    更深层次的声纳提示: 关闭fish deep App上的鱼图标(左边菜单-鱼图标), then remember to think vertical, 不水平. 寻找厚拱门或半拱门,不要担心它们有多长. Plus, remember that depth will affect length. You’ll get longer 拱es from fish that are deeper. Again, focus on line thickness rather than 拱 length.

  • 底部结构

    Finding structure 和 features

    While you are marking structure, you can keep an eye out for 鱼拱es 和 schools of bait fish. This can help you to better 和erst和 which kinds of features hold which kinds of fish.