Just to expound a little on what HW actually means ...
Previous Sonar technologies were derived around the science of pushing sound waves thru water at fixed frequency sound waves (as in 200kHz for single fixed frequency sonar or 83kHz/200kHz for dual fixed frequency sonar ) ...
New science is now incorporating CHIRP Sonar technology (Compressed High Intensity Radar Pulse) ... which is basically a different way to send sound pulses into the water ...
This sound pulse is comprised of a “sweep” or “sweep spectrum” of several different frequencies transmitted all at once ...
So instead of sound pulse transmit of 200kHz - the unit transmits a sweep spectrum of 175kHz- 225kHz frequencies all at the same time ...
This scientific way of sending sound into the water (CHIRP) allows for much more data to be collected and returned to the xducer for rendering into the Sonar image ... so the user sees more data (compared to fixed frequency) with less added noise (another advantage of the CHIRP technology) ...
The HW designation stands for “High/Wide” meaning the unit is capable of transmitting a “High CHIRP” sweep frequency (175kHz - 225kHz) and/or a “Wide” CHIRP sweep frequency (75kHz - 93kHz) ...
Here is more info ...
Rickie