Chirp Verses Broadband

Here are a few screen shots off my Simrad using Chirp with a Chirp Transducer and Broadband set on 200khz.  Broadband [200khz] sends out pings of the same frequency in a narrow cone...ping ping ping ping, kind of like shouting a semi automatic gun squeezing the trigger for every shot. Chirp on the other hand sends out multiple frequencies, 150 khz to 250 khz, on high chirp but it is more like an automatic gun sending about 100 different cone frequencies at once. In these pics I was using Medium Chirp which is 85 to 155 khz, shooting 70 cones out at once, all different frequencies. Chirp is built into my processor and you must have a transducer capable of Chirping to get the full benefits of it. If you are Chirping through a broadband transducer, 50/200 for example, in high Chirp you are probably sending out a couple of different frequencies through that transducer verses 100 with a chirp transducer set on high Chirp. With Chirp you get better resolution and much better definition on your screen. Chirp separates targets better and works especially well looking at structure such as drop offs. This is a very short and condensed explanation of Chirp and here are a few screen shots to look at.

 In this screen shot I have 200khz on the upper left screen and Medium Chirp on the right screen. I am using a HST-WSBL 83/200 for broadband and a TM 150 Airmar Chirp transducer for Chirp. On the broadband side you can clearly see the bottom, a school of fish coming up on the right side of the screen, a fish coming off the bottom coming up to look at a bait and a couple of small fish on the bottom.  Looking a Chirp I see many more fish, I see three fish streaking off the bottom, and I see my downlines set at 15 to 20 feet being pulled into the school of fish. This scenario is with a 30 foot deep bottom. When I am fishing deeper say 40 foot deep I can see as many as six different baits at a time and can watch the fish come up and hit the baits. You can also see numerous small fish on the side scan. This school was a bunch of punks 15 to 18 inches long. 

 Look at the difference in these to sonar screens. The Chirp side definitely showing more fish with better definition. If you notice I have my broadband sensitivity set at A+1 [one increment above Auto gain] and my Chirp is actually set at A-2, 3 settings below what broadband is set at. I do not use as much sensitivity or gain with Chirp because it is much more efficient. Also you can see some fish on side scan off the the left of the boat. By the way, these fish are mostly Catfish.

 Again better resolution with the Chirp

 

The Chirp screen is showing all the fish under the boat which you can distinguish the various sizes of the fish.  

   Chirp utilizes many different frequencies in each of its Low, Medium and High settings. Naturally there are different uses for all three, but basically High Chirp works better in shallower waters lets say 200 feet or less, Medium Chirp works better in mid depth ranges and Low Chirp is used in very deep waters. Most good depthfinders today are available with Chirp but make sure to match the right transducer with  it to reap all the benefits from it. Chirp is an upgraded version over broadband but is it necessary for your type of fishing...you have to decide. If you have a unit that has Chirp you may want to check it out! We will be at the Fishing Expo this weekend in the Greentop booth, come on by and check us out. Hope to see you there!