Dear confused.com
I understand your confusion. I have been using a Deeper Pro + since they were first available roughly 10 years ago. They are an incredible bit of kit but I feel their capabilities are masked in traditional carp marketing speak. I have no experience of other models but this is what I understand.
There seems to be no such thing as a Deeper Chirp +
If the model is followed by a + sign it signifies that it is capable of using 2 different frequencies.
If the model is followed by a +2 sign it means it uses three different frequencies,
If it has a CHIRP designation it means it uses a special technology. According to Deeper, “CHIRP sends a continuous sweep of frequencies ranging from low to high, interpreting these frequencies individually upon their return.” For the life of me, I cannot understand what this means or how it is useful. The manual seems to suggest that you choose which frequency to use. There also seems to be a feature where the frequency changes according to depth of water.
If you do not understand the relevance of frequency here is some very basic information.
An echo sounder (NEVER call them fish finders, this is totally misleading marketing speak) uses a transducer (basically a combined loud speaker and microphone combined) to generate a noise and record when an echo from that noise is received.
There is a pulse rate which is the number of times a sound is generated per second. If you put your ear to the transducer you will hear a rapid clicking noise. This is 15 time per second for all the Deepers apart from the very basic (non GPS) model which uses 10 clicks per second.
The frequency of the sound determines what gets picked up. Think of a guitar. The top string E sounds a lot different from the bottom string E. The top string is a high frequency – the bottom string is a low frequency. Here is the first indication of why frequency is important. If you hear a band playing loud music from a long way off or when a car passes playing loud music, you often hear only the boom boom boom of the base and not the rest of the music.
This is because the lower the frequency – the greater the ability to penetrate the intervening space. So in an echo sounder a low frequency could be used to penetrate weed and locate the actual bottom.
Conversely, a high frequency is quickly absorbed so it might only show you the top of the weed. If you have a thermocline for example it could show up on a high frequency as a false bottom (but this is very rare)
The other feature of frequency is the area is covered by the pulse. High frequencies can be focused more accurately than low frequencies. In marketing speak this is described as a narrow cone or a wide cone from which reflections are picked up.
For example in the Pro +2
675 kHz gives 70 cone
240 kHz gives 20o cone
100 kHz gives 470 cone
I hope, Newmarket this helps you understand what the models mean. If I were on a budget, I would choose the PRO + . Even 10 years later and with GPS no longer working on it I still use it for feature identification and mapping (by attaching my phone and Deeper to a bait boat).
BTW give my love to beautiful Grays – I used to go to school there in the early 1960’s