LIDAR sensor device and method of transmitting laser signal
A lidar sensor device according to an embodiment includes a data generation unit that generates light identification data, an optical modulation unit that generates a plurality of modulated signals for the optical identification data by performing orthogonal frequency division multiplexing (OFDM) modulation on the optical identification data and generates a plurality of laser signals respectively corresponding to the plurality of modulated signals and having different frequencies, and a transmission unit that simultaneously transmits the plurality of laser signals to different measurement points according to the frequencies, respectively.
1. A lidar sensor device comprising:
a data generation unit that generates light identification data;
an optical modulation unit that generates a plurality of modulated signals for the optical identification data by performing orthogonal frequency division multiplexing (OFDM) modulation on the optical identification data, and generates a plurality of laser signals respectively corresponding to the plurality of modulated signals and having different frequencies; and
a transmission unit that simultaneously transmits the plurality of laser signals to different measurement points according to the frequencies, respectively,
wherein the transmission unit comprises:
an optical coupler that combines the plurality of laser signals; and
a Risley prism onto which the plurality of laser signals combined by the optical coupler are incident and which transmits the plurality of laser signals by refracting the plurality of laser signals at different angles depending on the frequency,
wherein the optical modulation unit randomly selects N subcarrier frequencies among S available subcarrier frequencies, where, N is a natural number of 0<N<S, and S is a natural number of S>2, and generates each of the plurality of modulated signals by performing OFDM modulation on the optical identification data using N subcarrier signals respectively corresponding to the N subcarrier frequencies.
2. A lidar sensor device comprising:
a data generation unit that generates light identification data,
an optical modulation unit that generates a plurality of modulated signals for the optical identification data by performing orthogonal frequency division multiplexing (OFDM) modulation on the optical identification data, and generates a plurality of laser signals respectively corresponding to the plurality of modulated signals and having different frequencies; and
a transmission unit that simultaneously transmits the plurality of laser signals to different measurement points according to the frequencies, respectively,
wherein the transmission unit comprises:
an optical coupler that combines the plurality of laser signals; and
a Risley prism onto which the plurality of laser signals combined by the optical coupler are incident and which transmits the plurality of laser signals by refracting the plurality of laser signals at different angles depending on the frequency,
wherein the optical modulation unit generates the plurality of modulated signals by performing fast Hartley transform (FHT)-based flip-OFDM modulation on the optical identification data.
3. The lidar sensor device of claim 1 , wherein the plurality of modulated signals comprises a zero-padding region having a length greater than or equal to a time required to change a transmission direction of the plurality of laser signals.
4. The lidar sensor device of claim 1 , wherein the transmission unit changes a transmission direction of the plurality of laser signals by changing at least one of a rotation angle of the Risley prism using a central axis of the Risley prism as the rotation axis and a direction of the central axis.
5. The lidar sensor device of claim 4 , wherein the data generation unit generates new light identification data when the transmission direction is changed.
6. The lidar sensor device of claim 5 , wherein the optical identification data comprises first identification data randomly generated as the transmission direction is changed.
7. The lidar sensor device of claim 6 , wherein the optical identification data further comprises second identification data maintained irrespective of a change in the transmission direction.
8. The lidar sensor device of claim 1 , wherein the data generation unit encrypts the optical identification data, and the optical modulation unit generates the plurality of modulated signals by performing the OFDM modulation on the encrypted optical identification data.
9. A method of transmitting a laser signal comprising:
(a) generating light identification data;
(b) generating a plurality of modulated signals for the optical identification data by performing orthogonal frequency division multiplexing (OFDM) modulation on the optical identification data;
(c) generating a plurality of laser signals respectively corresponding to the plurality of modulated signals and having different frequencies; and
(d) simultaneously transmitting the plurality of laser signals to different measurement points according to the frequencies, respectively,
wherein the step (d) comprises:
combining the plurality of laser signals using an optical coupler; and
transmitting the plurality of laser signals combined by the optical coupler by refracting the plurality of laser signals at different angles depending on the frequency using a Risley prism,
wherein, in the step (b), N subcarrier frequencies is randomly selected among S available subcarrier frequencies, where, N is a natural number of 0<N<S, and S is a natural number of S >2, and each of the plurality of modulated signals is generated by performing OFDM modulation on the optical identification data using N subcarrier signals respectively corresponding to the N subcarrier frequencies.
10. The method of claim 9 , wherein the plurality of modulated signals comprise a zero-padding region having a length greater than or equal to a time required to change a transmission direction of the plurality of laser signals.
11. The method of claim 9 , further comprising:
(e) changing a transmission direction of the plurality of laser signals by changing at least one of a rotation angle of the Risley prism using a central axis of the Risley prism as the rotation axis and a direction of the central axis, after the step (d).
12. The method of claim 11 , further comprising:
generating new light identification data when the transmission direction is changed,
wherein the (b) to (d) steps are performed on the new light identification data.
13. The method of claim 12 , wherein the optical identification data comprises first identification data randomly generated as the transmission direction is changed.
14. The method of claim 13 , wherein the optical identification data further comprises second identification data maintained irrespective of a change in the transmission direction.
15. The method of claim 9 , wherein the (a) step comprises encrypting the optical identification data and, in the (b) step, the plurality of modulated signals are generated by performing the OFDM modulation on the encrypted optical identification data.