Quadruple Single Frequency Receiver System for Ambiguity Resolution On The Fly

Resolution of carrier phase ambiguities on the fly (OTF) using a pair (monitor/remote) of single frequency receivers is difficult to achieve reliably in an operational environment due to the unfavorable ratio between carrier phase noise and multipath on the one hand, and the 19 cm wavelength of the Ll carrier on the other hand. The use of the 86 cm wavelength widelane carrier is much more effective but will require, as of early 1994, the use of expensive and still evolving dual frequency codeless receivers. In order to improve the OTF ambiguity resolution time and reliability with single frequency receivers, the use of a quadruple receiver systems consisting of two static monitor units and two mobile remote units mounted on the mobile platform is investigated. The double difference carrier phase ambiguity constraints which can be imposed on such a configuration are described. The ambiguities between the two monitor and between the two remote receivers can be be determined within a few seconds due to the short and fixed baselines between the units. These ambiguities can in turn be used as constraints to reduce the number of potential monitor/remote ambiguity solutions and, therefore, to reduce the time to resolution. The results of tests carried out with a configuration of four NovAtel GPSCardTM units are described. The time to resolution is shown to decrease by 45%.