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Tunnels are typical GNSS signal rejection environments, and existing receivers are unable to receive signals and realize reliable positioning in tunnels. Now, a method is proposed to realize tunnel positioning based on the existing receiver hardware platform and adaptive upgrading of receiver algorithm software; firstly, the signal environment for receiver positioning is built in the tunnel through leaky cables and pseudo-satellites, and then the positioning algorithm of the receiver is improved, so that the receiver can complete the positioning in the tunnel; the test results show that the carrier-to-noise ratio of the signals received in the tunnel is stable, with an upward and downward fluctuation of no more than 1 dB, and the correlation peaks of the tracked signals captured by the receiver are stable. The test results show that the carrier-to-noise ratio of the signal received by the receiver in the tunnel is stable, with an upward and downward fluctuation of no more than 1 dB, and the correlation peaks of the tracking signal captured by the receiver are stable, so that the signal environment constructed is good; and the positioning errors of the receiver in the static state and the moving state in the signal environment constructed are within 5 m, which can satisfy the requirements for positioning in tunnels.