Temperature-Induced Bias Variations of Multi-Frequency Receivers

Abstract

Precise GNSS applications, like PPP or RTK, make use of pseudorange and carrier-phase data. Traditionally, the ionospheric delays are removed to first order by using dual-frequency data. More recently, three or more frequencies are available from modernized and newly emerged systems. Most observation models assume the inter-signal biases for pseudoranges and carrierphases to be time-invariant. A violation of this assumption may be uncritical for dual-frequency processing in many cases, but with three frequencies the variations are not absorbed any more by nuisance parameters and may affect actual estimation parameters of interest. Coping with variable receiver biases is essential for many GNSS applications particularly for high-precision positioning where fast ambiguity resolution relies on the use of triple-frequency observations. This study demonstrates the effects of temperature-dependent receiver bias variations for dual-frequency and triple-frequency data. Real tracking data from geodetic receivers is used together with simulated observations. The bias variations are studied using measurement residuals from positioning solutions as well as triple-frequency signal combinations. Possible means of mitigating the variations through adaptions of the estimation parameters as well as changes in receiver operation are shown.