Professional downrigger fishermen understand that different species of game fish prefer different temperature ranges. Additionally, they understand that maintaining a specific range of trolling speeds is not only important to attract game fish but is also important to ensure the lure is running with the proper action.
However, it can be very difficult to predict the speed and temperature of a lure when trolled at varying depths below the water surface. Surface speed and temperature gauges are ineffective at predicting sub-surface conditions since day-to-day environmental effects such as wind speed and wind direction can create underwater currents and drastically alter the sub-surface water temperature.
The Depth Raider system measures and displays this vital speed and temperature information with digital precision. The Depth Raider speed and temperature monitor tells you the exact speed and the exact temperature of your lure at it's running depth.
Theory of Operation - Upon entry into the water, the underwater sensor/transmitter probe unit continuously measures speed and temperature then periodically transmits a digitally encoded RF signal onto the coated downrigger cable. The signal is received by a receiving antenna mounted on the downrigger boom. This signal is then routed to the receiver/display unit via a coaxial cable.
The receiver/display unit continuously monitors for data transmissions from the underwater probe unit. Once a transmission is received, data is decoded from the RF signal and converted into speed and temperature which is then displayed on the LCD display.
Coated downrigger cable is necessary to prevent the lake water from absorbing (attenuating) the signal transmitted from the sensor/transmitter unit. The coating provides electrical isolation from the water since water is a conductor of electricity. Without the coating (or electrical isolation), a portion of the signal is absorbed by the water thereby reducing the signal level at the receiving antenna. Without the coating, as the depth of the probe continues to increase, the signal level at the antenna continues to degrade until it is no longer adequate for proper interpretation by the receiver/display unit. It should be noted that the actual depth of operation without a coated cable can vary greatly from installation to installation, boat to boat, water conditions, etc.
While the Depth Raider system will operate to varying depths without the coated cable; installation of the coated cable is highly recommended to provide proper operation to 200 feet.