The paper presents the implementation details and the experimental validation of a linear state estimator based on synchrophasor measurements in a real subtransmission network. The data are provided by 15 phasor measurement units (PMUs) installed in the 125-kV grid of the city of Lausanne, Switzerland. The PMU-based monitoring infrastructure, the telecommunication and the phasor data concentrator are described in detail. We compare the performance of two different state estimation methods, i.e., the linear weighted least squares and the least absolute value estimator, with a focus on the influence of the line parameter errors on the state estimates. We further analyze the latency contribution associated to each step of the measurement chain, in order to validate its appropriateness to serve time-critical power system applications.