Copyright ©2007 NavSync Ltd.All Rights Reserved Specifications subject to change without notice.CW25 Software User Manual Page 29 of 50 Rev 03 Date: 06/16/088.3.9 PRTH, MMSV: MIN & MAX SATELLITES FOR A POSITION SOLUTIONPurposeThis message Sets, Queries and Responds to the minimum and maximum number of satellites the receiver will use for aposition solution. Increasing the minimum number of satellites will improve the accuracy achieved when sufficientsatellites are available, but may reduce the time when a solution can be produced. Reducing the maximum number ofsatellites may reduce the accuracy of the position solution, but will decrease the amount of processing power requiredfor the solution.Note that setting the Maximum satellites to less than 4 will prevent the receiver from performing a 3D position solution.Likewise setting the minimum number of satellites greater than 3 will prevent the receiver performing a 2-D, altitudefixed solution.The maximum must be greater than or equal to the minimum number of satellites.Query Format$PRTHQ,MMSV[*checksum]Set Format$PRTHS,MMSV,[min_NSV],[max_NSV][*checksum]Response / Acknowledge Format$PRTHR,MMSV,min_NSV,max_NSV*Explanation of Parametersmin_NSV Minimum Satellites used for a position / time solution(integer, range 0-12)max_NSV Maximum Satellites used for a position / time solution(integer, range 0-12)8.3.10 PRTH, DRLM: DEAD RECKONING LIMITPurposeThis message Sets, Queries and Responds to the limit for the forward predictive Dead Reckoning, after the last valid fix(epochs). The dead reckoning will progress at constant velocity for the first half of this period and then reduce to astandstill during the second half.Note that since this value has units of epochs, it will have a different effect on a 1Hz CW25 receiver to that on a 2Hz,5Hz or 10Hz CW25 receivers.Query Format$PRTHQ,DRLM[*checksum]Set Format$PRTHS, DRLM,DR_Limit[*checksum]Response / Acknowledge Format$PRTHR, DRLM, DR_Limit*Explanation of ParametersDR_Limit Number of epochs to dead reckon for (integer, range 0 –32768)8.3.11 PRTH, ELVM: SATELLITE ELEVATION MASKPurposeThis message Sets, Queries and Responds to the satellite elevation mask angle below which satellite data will not beused in the navigation and time solution.Query Format$PRTHQ,ELVM[*checksum]Set Format$PRTHS,ELVM,nvElevMask[*checksum]Response / Acknowledge Format$PRTHR,ELVM,nvElevMask*Explanation of ParametersnvElevMask the navigation and time solution elevation mask angle in degrees (integer, range 0 –90).
