GNSS, particularly the GPS and GLONASS satellite constellations are commonly used
for accurate estimation of atmospheric parameters. The high accuracy is accomplished by sophisticated analysis methods and expensive high-end receivers and antennas along with precise products and bias corrections. The recent market introduction of low-cost dual frequency
receivers that can produce raw data from multiple constellations offers an insight into the potential use of these receivers for meteorological applications. Here we demonstrate that GPS and GLONASS
measurements from a low-cost dual-frequency receiver can be used to estimate the Zenith Total Delay ( ZTD) commensurate to meteorological applications
