Trisponder is a family of short  range microwave  positioning systems which use the time difference technique to measure ranges between user vessels and up to eight shore stations. In addition to displaying measured ranges the system also computes vessel position by trilateration and provides guidance information to the vessel’s helmsman. Or interface into HypackMax.

The system comprises of two elements, the vessel equipment and the shore equipment. The vessel equipment comprises of a control unit and a Master transponder, while the shore stations comprise of a Remote transponder together with a suitable power supply. The vessel control unit (Digital Distance Measuring Unit (DDMU)) initiates range measurements by instructing the Master transponder to transmit a set of coded interrogation pulses. All remote stations receive the interrogation pulses, but only the one which recognises is own unique code replies to the interrogation. The reply is received back at the master transponder and the DDMU then computes the range from the time difference measurement (based on a constant velocity for the propagation of Radio waves through the atmosphere). Each remote station is interrogated in turn until all ranges have be measured, and up to twelve DDMU’s can use the chain of deployed Remote stations at the same time thus enabling full multi-user operation.

Accuracy of range measurements is typically ±1 metre out to the system’s maximum line of sight range of 80 Kilometres, and the measurement resolution is 0.1 metre. To compensate for small variations in the timing circuits of the Remote transponders the system must be calibrated before use. This is a simple process where the system is set up with the Master transponder and Remote transponders a known distance apart (at least 2 Km). The range between the Master and each of the Remotes is then measured in turn and compared with the true range to arrive at a ‘Calibration factor’ for each Remote unit. This calibration factor is entered into the DDMU with the remainder of the Remote station data (code, position, height, etc.) and is automatically applied to all range measurements to the remote. Did you know that GPS Differential corrections can be sent by Trisponder ?.

For more details on Del Norte Trisponder equipment go to our Products Page.

Why not use your old Trisponder to transmit Differential Corrections. 'E' Tr's must be used for Remote end. But we can upgrade 'C'.