CHIRP screenshot

In 2011 there was a flurry of announcements from Garmin and the other major electronics manufacturers hailing in their respective new CHIRP sounders. This was quickly followed by a scramble by marine electronics experts and installers scrapping and struggling to figure out exactly what CHIRP was, and if it was worth all the effort.

 

So 12 months on, What have we discovered?

Firstly a bit of history. CHIRP actually stands for “Compressed High Impact Radar Pulse” which is a reference to its development, as it was originally designed for use in Radar systems just after the second world war. Quicky it was discovered the same properties which improved the Radar signal above the surface could be also used to improve the echo sounders performance below the waves, and military and commercial Chirp sounders have been available for a large number of years. The main things which limited Chirp technology being used in recreational systems was the huge processing power required to compute the return signal, and the availability of transducers cheap enough for the recreational market. Recent improvements in computer technology has taken care of the processing power which opened the door for Airmar to develop the required transducers and start the Chirp revolution.

The fact that it is a transducer company pushing chirp, and not the traditional manufacturers has led to the strange time frames, with most of the major players releasing recreational CHIRP sounders within a few months, which is rare for such a major change in the market.

 

So how does it work?

Traditional sounders work by transmitting a single frequency sound through the transducer for a few microseconds, and then wait for the return echo which tells the user how far away the fish, or bottom is. The length of this transmission varies with depth on most good sounders, but can be as long as a couple of meters in deep water. The problem is, if there are 2 fish targets within this transmission length, they will appear as one big target when the signal is returned, instead of two separate fish.

Chirp sounders work around this by varying the frequency of the sound through the length of the transmission. Even if the two fish are within the transmission length, the reflected signals will have different frequencies when they reach the boat. When this effect is applied to normal sound waves it sounds similar to a birds call, which is another reason for the name “Chirp”. The main points with this technology is that even if the target fish are very close together, they will apear as seperate targets, and since we no longer have to worry about target separation, we can make the pulse length much longer, which greatly increases range.

 

So what does it cost?

So far, all of the chirp sounders have been released as black box units, with the output displayed on networked screens. The cost of these boxes runs from about $2200 up, but you will also need a dedicated CHIRP transducer as well. While it is possible to run a normal transducer on a chirp black box, it is not possible to run it in CHIRP mode, meaning that it will act like a much cheaper deep chirpstandard sounder module until you hook up the correct transducer.

 

So is it any good?

To put it simply, yes it is. CHIRP sounders are better than traditional sounders, they have better target resolution, particularly near the bottom and there range is outstanding. But it is an evolutionary step, rather than a brand new technology. Most fishermen know how to read a fishfinder (If you dont, then come see us!) so most fishermen will be able to read the chirp sounders. For those of you who game fish in deep water or often fish for terakahi (which are often found near the bottom), Bluenose or Hapuka, this is technology which will help you target these species.