WATERLINE 05
DECEMBER 2012
CHIRP – the sound of the future In 2011 there was a flurry of announcements from Garmin and the other major electronics manufacturers hailing in their respective new CHIRP sounders.
ing chirp, and not traditional manufacturers has led to the strange time frames. Most of the major players released recreational Chirp sounders within a few months, rare for such a major change in the market.
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.
Traditional sounders work by transmitting a single frequency sound through the transducer
CHIRP stands for “Compressed High Impact Radar Pulse” referring to its original design for use in Radar systems just after the Second World War. The same properties which improved the radar signal above the surface also improved the echo sounders performance below the waves. Military and commercial Chirp sounders have been available for many years. What 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 have taken care of the processing power, opening the door for Airmar to develop the required transducers and start the Chirp revolution. The fact it’s a transducer company push-
So how does it work?
if the two fish are within the transmission length, the reflected signals will have different frequencies when they reach the boat. This effect applied to normal sound waves sounds similar to a bird’s call - another reason for the name “Chirp”. Even if the target fish are very close together, they will appear as separate targets. As we no longer have to worry about target separation, the pulse length much can be longer, which greatly increases range.
So what does it cost?
All chirp sounders have been released so far as black box units, with the output displayed on networked screens. The boxes costs from about $2200 up, and you will also need a dedicated CHIRP transducer.
So is it any good?
for a few microseconds, and then wait for the return echo telling 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 metres in deep water. If there are two fish targets within this transmission length, they will appear as one big target, instead of two separate fish. Chirp vary the frequency of the sound through the length of the transmission. Even
CHIRP sounders are better than traditional sounders, they have better target resolution, particularly near the bottom and their range is outstanding. It is an evolutionary step, rather than a brand new technology. Most fishermen know how to read a fishfinder, 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 terakihi - which are often found near the bottom, Bluenose or Hapuka, this is technology which will help target these species.