Lowrance Mark-4 HDI Operation Manual EN - Page 20

NOTE: You can make limited adjustments to the contrast level with Auto Contrast turned on. You will have to turn it off to have access to all contrast levels. view a section of the water column that does not include the water surface. Upper and lower limits must be at least 5 ft (2m) apart. Range Range settings display the section of the water column from the water surface to the selected depth range. NOTE: When using a custom range, you may not receive any digital depth readings, or you may receive incorrect depth information. Custom Range - Upper and Lower Limits Used to select the upper limit and lower limit of a section of the water column. That allows you to Frequency Controls the transducer frequency used by the unit. 800 kHz offers the best resolution, while 455 kHz has greater depth coverage. DownScan Operation | Mark-4 & Elite-4 HDI Ping Speed Controls the rate the transducer uses to send sonar waves into the water. Ping speed adjustments can help reduce interference from other transducers. 18