Emerging Digital Radio Services

Transcription

1 Emerging Digital Radio Services Report to RTCM 2011 Annual Meeting from RTCM Special Committee 123 Ross Norsworthy, RTCM SC123 Chairman 1

2 Emerging Digital Radio Services 1. VHF data exchange a) RTCM SC123 VHF standard VHF Digital Small Message Service i. How it works, channel access scheme (voice channels) ii. FCC rulemaking status (pending, filed July 24, 2009) b) Rec. ITU-R M international standard i. Channel bandwidth, data rate, emissions spectrum, modulation ii. Communications protocol (under development) c) VHF Maritime Mobile Band MHz (ITU Radio Regulations, Appendix 18) i. World Radio Conference 2012 Agenda (CPM: VHF digital band) ii. Relevant ITU liaisons with IMO & IALA (E-Navigation) iii. Limited maritime access to RR Ap18 in the United States 2. MF ( khz) digital broadcast (safety and security related information) a) Report ITU-R M.2201 Utilization of the khz band by the maritime mobile service for the digital broadcasting of safety and security related information from shore-to-ships b) World Radio Conference 2012 Agenda (CPM: frequency allocation plans) c) Relevant ITU liaisons with IMO & IALA d) RTCM SC123 developments i. Utilization of Loran-C towers ii. Technical standard (under development) 3. HF data exchange (Rec. ITU-R M , used for , e.g., Globe Wireless) 2

3 VHF data exchange The international VHF maritime mobile band (Radio Regulations, Appendix 18) MHz MHz MHz Ship Transmitting Frequencies MHz MHz (Note 2) MHz (Note 2) MHz (Note 2) MHz (Note 2) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (b) (a) (a) (b) (b) (b) (b) (b) (c) (b) (b) (b) (b) (c) 16 (c) (c) (b) (b) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) (a) AIS 1 AIS 2 * Note MHz (Note 3) MHz Coastal Transmitting Frequencies MHz MHz Each channel is spaced by 25 khz nn = two frequency channel nn = one frequency channel nn = one frequency channel exclusive to maritime mobile distress, safety and calling Channels; 06, 08, 09, 10, 13, 15, 17, 67, 69, 72, 73, 77 are identified for inter-ship use (indicated by (b) in the above diagram) Channels; (inclusive), (inclusive), (inclusive) are identified for public correspondence (indicated by (a) in the above diagram) Note 1: Whilst the frequency range/channels appears to be within the scope of RR Appendix 18, it should be noted that the gaps as indicated are general mobile allocations with no footnote priority to maritime use. Note 2: Change as a result of WRC-97, that split the original channels; 87 and 88, into four single frequency channels. The high frequencies were identified for AIS, with the remaining low single frequencies now designated as channels 87 and 88 (i.e. no longer two frequency, duplex channels, but single frequency simplex channels). Note 3: This channel, whilst not explicitly referenced in Appendix 18, falls with the bands identified within RR Article 5 footnote, and is the upper frequency, (i.e MHz) related to channel 6. 3

4 VHF data exchange International plans for the VHF maritime mobile band World Radio Conference 2012 planned modifications to RR Ap18 Expand the simplex use of the duplex channels Satellite detection of AIS (channels 75 & 76) A digital band for data exchange on Public Correspondence channels Footnote: only six channels (24 26, 84 86) available in the US ITU liaisons with IMO and IALA Coordinating WRC-12 plans as stated above Six data channels (minimum) needed to support E-Navigation ITU technical standard for VHF data exchange Recommendation ITU-R M (includes RTCM SC123 contributions) Channel bandwidths: 25 khz, 50 khz, 100 khz (1 to 4 channels) Data rates: 28.8 kbps, 43.2 kbps, kbps, kbps Modulation: 25 khz (π/4 or π/8 DPSK), 50/100 khz (OFDM+QAM) Access protocol: CSTDMA (under development) Applicable channels: sets of 1 to 4 duplex RR Ap18 channels 4

5 VHF data exchange Availability of the international VHF maritime mobile band in the United States Channel designator Notes Transmitting frequencies (MHz) From ship From coast Inter-ship Port operations and ship movement Public correspondence Single Two stations stations frequency frequency 60 m), o) L R x x 01 m), o) R x x 61 m), o) L R x x x 02 m), o) L R x x x 62 m), o) L R x x x 03 m), o) L R x x x 63 m), o) R x x x 04 m), o) L R x x x 64 m), o) L R x x x 05 m), o) R x x x 65 m), o) R x x x 06 f) x 66 m), o) R x x 07 m), o) R x x 67 h) x x x x 09 i) x x x x 10 h), q) x x 70 f), j) Digital selective calling for distress, safety and calling 11 q) x x x 72 i) x 13 k) x x 73 h), i) x x x x 15 g) x x 75 n) x R = assigned to railroads, not available for US maritime service L = assigned to land-mobile radio services, not available for US maritime service 5

6 VHF data exchange Availability of the international VHF maritime mobile band in the United States (continued) Channel designator Notes From ship stations Transmitting frequencies (MHz) From coast stations Inter-ship Port operations and ship movement Single frequency Two frequency Public correspondence 16 f) DISTRESS, SAFETY AND CALLING 76 n) x 17 g) x x x 18 m) R x x x 78 m) R x x 19 m) R x x 79 m) R x x 20 m) x x 80 m) B x x 21 m) B x x 81 m) B x x 22 m) B x x x 82 m), o) B x x x 23 m), o) B x x x 83 m), o) B x x x 24 m), o) M M x x x 84 m), o) M M x x x 25 m), o) M M x x x 85 m), o) M M x x x 26 m), o) M M x x x 86 m), o) M M x x x M M x x M M x M M x x x AIS 1 f), l), p) AIS 2 f), l), p) R = assigned to railroads, not available for US maritime service B = assigned for Broadcast Auxiliary Remote Pickup, not available for US maritime service M = available only to one operator for US maritime service (FCC-approved for data exchange) 6

7 MF ( khz) digital broadcast International plans for the khz band World Radio Conference 2012 planned modifications for khz WRC-07 terminated this maritime allocation for distress by Morse code Maritime services seeking exclusive re-allocation for digital safety broadcast Amateurs, operating experimentally, seeking a secondary allocation ITU liaisons with IMO and IALA Coordinating WRC-12 plans as stated above IMO supports exclusive maritime re-allocation Safety and security related data broadcast needed to support E-Navigation ITU technical report for maritime digital broadcast Report ITU-R M.2201 Utilization of the khz band by the maritime mobile service for the digital broadcasting of safety and security related information from shore-to-ships (includes contributions from France and RTCM SC123): Channel bandwidth: 10 khz (9 khz occupied bandwidth) Modulation: OFDM+QAM (16/64 QAM) Data rate: kbps Broadcast protocol: TDMA or SFN (single-frequency-network) Referenced standards: DRM and Recommendation ITU-R M

8 MF ( khz) digital broadcast RTCM SC123 technical developments Prospective use of Loran-C towers US Coast Guard has terminated the Loran-C service, towers are available US coastal coverage for 500 khz service is feasible using existing towers Permission granted to experimentally use the 625-ft tower at Wildwood, NJ RTCM SC123 technical design accommodates future co-use for E-Loran RTCM SC123 technical development status and future plans Studying the ITU coverage analysis based on use of Loran-C towers Studying 500 khz tower modifications that preserve E-Loran availability Studying DRM (international digital AM broadcast standard) for applicability 9 khz DRM (conforms to technical requirements in ITU report) SFN (single-frequency-network) marine sky-wave requirements Evaluating the current state-of-the-art in digital transmitter technologies Conceptual development of DDWS (direct digital waveform synthesis) Developing a draft transmitter specification for multi-source solicitation Cost estimating the acquisition of an experimental system in the near future Contribute to a future ITU technical standard (Rec. ITU-R M.[500 khz]) Draft and coordinate petition(s) for supportive FCC rulemaking 8

9 MF ( khz) digital broadcast RTCM SC123 technical developments DRM SINGLE FREQUENCY NETWORK SYSTEM BLOCK DIAGRAMS IP Data Tunneling Input EER Inputs To DRM Tx 9

10 Direct Digital Waveform Synthesis Meeting the challenge for high data khz OFDM: Orthogonal frequency division multiplexing 204 subcarriers (41.66 Hz), each modulated with slow data Subcarriers are orthogonal (no cross-carrier interference) Modulation is via quadrature amplitude modulation (QAM) Fast aggregate data rate (30.9 kbps for 64 QAM, 9 khz bandwidth) Advantages of OFDM Spectrally efficient Each subcarrier experiences slow, flat fading Error correction compensates for the loss of a few subcarriers Disadvantages of OFDM Complex implementation Intra-symbol interference between subcarriers - Frequency relationship must be precise High peak-to-average power (PAP) at transmitter - Requires highly linear RF amplifiers Direct Digital Waveform Synthesis (DDWS): hi-efficiency precision OFDM Complex waveform is defined entirely in software Tx (super-fast hi-power DAC) directly writes the waveform 10

11 MF ( khz) digital broadcast RTCM SC123 technical development: DDWS DRM EMISSION MASK COMPLIANCE (9 khz occupied bandwidth) DDWS: 9kHz RF Emission Mask 9dB PAR, 64QAM, 30.9 kbps 11

12 MF ( khz) digital broadcast Amateurs (ARRL) Experimental Licensed Stations in the United States Mode of operation Morse PSK-31 FSK-31, WSPR MSK-31 Telegraphy Frequency band (khz), current licenses ( khz, move is planned) Necessary bandwidth and class of 150HA1A 62H0J2B 62H0F1B 62H0G1D emission (emission designator) Authorized e.i.r.p. (dbw)