A balise (101, 201) suitable to be arranged fixedly between rails of a railway track to communicate wirelessly with a vehicle communication device of a railway vehicle on the railway track, the balise (101, 201) comprising: a receiver having a receiver loop and being configured to receive from the vehicle communication device via the receiver loop a receive signal having first receive signal characteristics or second receive signal characteristics different to said first receive signal characteristics; the receiver having energy storage circuitry configured to tap energy from the receive signal for powering the balise (101, 201) and having a detector configured to provide an indication of whether the receive signal has the first receive signal characteristics or the second receive signal characteristics; a transmitter (207, 307) having a transmitter loop and being configured to transmit to the vehicle communication device via the transmitter loop a first telegram signal in a Frequency Shift Keying, FSK, operational mode according to the Eurobalise specification, or a second telegram signal in an Amplitude Shift Keying, ASK, operational mode according to the KER/KVB specification; characterized by said balise further comprising: the transmitter (207, 307) having a variable capacitance, which forms a resonant circuit (209, 309, 409) together with the transmitter loop (208, 408a), an active feedback circuitry (316, 416, 317, 417, 318) having an input and an output both coupled to the resonant circuit (209, 309, 409), and a switch to selectively short-circuit the input of the active feedback circuitry (316, 416, 317, 417, 318) to render the active feedback circuitry inactive; a controller configured to cause variation of the variable capacitance of the transmitter to attain the FSK operational mode and to cause the switch to short-circuit the input of the active feedback circuitry (316, 416, 317, 417, 318) to attain the ASK operational mode. a receiver having a receiver loop and being configured to receive from the vehicle communication device via the receiver loop a receive signal having first receive signal characteristics or second receive signal characteristics different to said first receive signal characteristics; the receiver having energy storage circuitry configured to tap energy from the receive signal for powering the balise (101, 201) and having a detector configured to provide an indication of whether the receive signal has the first receive signal characteristics or the second receive signal characteristics; a transmitter (207, 307) having a transmitter loop and being configured to transmit to the vehicle communication device via the transmitter loop a first telegram signal in a Frequency Shift Keying, FSK, operational mode according to the Eurobalise specification, or a second telegram signal in an Amplitude Shift Keying, ASK, operational mode according to the KER/KVB specification; characterized by said balise further comprising: the transmitter (207, 307) having a variable capacitance, which forms a resonant circuit (209, 309, 409) together with the transmitter loop (208, 408a), an active feedback circuitry (316, 416, 317, 417, 318) having an input and an output both coupled to the resonant circuit (209, 309, 409), and a switch to selectively short-circuit the input of the active feedback circuitry (316, 416, 317, 417, 318) to render the active feedback circuitry inactive; a controller configured to cause variation of the variable capacitance of the transmitter to attain the FSK operational mode and to cause the switch to short-circuit the input of the active feedback circuitry (316, 416, 317, 417, 318) to attain the ASK operational mode. the transmitter (207, 307) having a variable capacitance, which forms a resonant circuit (209, 309, 409) together with the transmitter loop (208, 408a), an active feedback circuitry (316, 416, 317, 417, 318) having an input and an output both coupled to the resonant circuit (209, 309, 409), and a switch to selectively short-circuit the input of the active feedback circuitry (316, 416, 317, 417, 318) to render the active feedback circuitry inactive; a controller configured to cause variation of the variable capacitance of the transmitter to attain the FSK operational mode and to cause the switch to short-circuit the input of the active feedback circuitry (316, 416, 317, 417, 318) to attain the ASK operational mode.