IBOC System Networking

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  • See the Field Service Bulletin at: http://www.nprlabs.org/servicebulletins.htm
  • [1] A LAN typically uses Ethernet . Ethernet protocol uses CSMA/CD (Carrier Sense Multiple Access with Collision Detection). [2] Any network device can access the LAN at any time. A device ‘listens’ for network traffic, then transmits when the network is ‘quiet’. If it detects traffic during transmission, it will stop, wait, and retry. Collisions occur when two devices start a transmission at the same time. [3] Each device connects to the LAN through a Network Interface Card ( NIC ), which has a unique address (MAC). [4] A NIC may support many rates (10 M, 100 Mb, Gigabit), but must be compatible with the device to which it is connected. [5] When a device is connected to the LAN, it first negotiates the rate it will use with the device to which it is connected.
  • Etherreal is freeware available at www.ethereal.com nPing can be provided by Nautel Use Ping /? To view options. Runs from windows command window. Do ping demo. Use 127.0.0.1. Also show options. Open etherreal. Ethernet MTU (maximum transfer unit) is typical ~1500
  • IBOC System Networking

    1. 1. IBOC System Networking <ul><li>April, 2006 Rev. 1.x.x Draft </li></ul>© Nautel Limited 2006 This presentation has been produced for Nautel customers and agents and is not for distribution without the expressed written consent of Nautel.
    2. 2. IBOC System Networking <ul><li>Topics </li></ul><ul><ul><li>Overview - System Architecture </li></ul></ul><ul><ul><li>Network Basics </li></ul></ul><ul><ul><li>Real Systems </li></ul></ul><ul><ul><li>Managing the Traffic </li></ul></ul><ul><ul><li>Glossary of Terms and Acronyms </li></ul></ul>
    3. 3. IBOC System Networking <ul><li>Overview - System Architecture </li></ul><ul><ul><li>Importer/NE IBOC (G2 IBOC Exciter) </li></ul></ul>TRANSMITTER STUDIO LAN STL IMPORTER AUTOMATION SYSTEMS GPS LAN AUDIO STL TRANSMITTER SITE (Low Level Combine) LAN STL M50 EXCITER AUDIO STL NE IBOC
    4. 4. IBOC System Networking <ul><li>Overview - System Architecture </li></ul><ul><ul><li>Importer/Exporter (G3 IBOC Exciter) </li></ul></ul>STUDIO LAN STL IMPORTER GPS EXPORTER AUTOMATION SYSTEMS LAN AUDIO STL TRANSMITTER SITE (Low Level Combine) LAN STL M50 EXCITER TRANSMITTER AUDIO STL
    5. 5. IBOC System Networking <ul><li>Overview - System Architecture </li></ul><ul><ul><li>G2 to G3 Conversion </li></ul></ul><ul><ul><ul><li>Install Nautel supplied replacement M50 </li></ul></ul></ul><ul><ul><ul><li>Send M50 to Nautel for upgrade. </li></ul></ul></ul><ul><ul><ul><ul><li>Exgine is added, Remote I/F is replaced </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Upgrade software </li></ul></ul></ul></ul><ul><ul><ul><li>Install LAN STL </li></ul></ul></ul><ul><ul><ul><li>Install upgraded M50. Upgrade V transmitter software. </li></ul></ul></ul><ul><ul><ul><li>Move NEIBOC to studio and reconfigure to Exporter with software upgrade. </li></ul></ul></ul>
    6. 6. IBOC System Networking <ul><li>Overview - System Architecture </li></ul><ul><ul><li>Service Modes/Logical Channels </li></ul></ul>High Level Low Level 1.4 1 P1 (98.4) P3 (49.6) 160 148 266 MP11 1.2 1 P1 (98.4) P3 (24.8) 140 123.2 228 MP3 1.1 1 P1 (98.4) P2 (12.4) 120 110.8 209 MP2 1 1 P1 (98.4) 110 98.4 190 MP1 Combined Power (Ratio) Logical Channels (kb/s) E2X B/W (kb/s) Data Capacity (kb/s) Digital Carriers (per sb) Mode
    7. 7. IBOC System Networking <ul><li>Overview - System Architecture </li></ul><ul><ul><li>Multicast is mono if < 32 kb/s </li></ul></ul><ul><ul><li>Minimum bit rate for MPS is 48 kb/s </li></ul></ul><ul><ul><li>Minimum bit rate for SPS is 12 kb/s </li></ul></ul><ul><ul><li>When assigning allocation in MP2 mode and higher, audio channel must stay within a logical channel </li></ul></ul><ul><ul><li>OOPS! </li></ul></ul><ul><ul><li>If you use MP3, you must leave 1 kb/s unassigned to prevent dropout problems with some radios. </li></ul></ul>
    8. 8. IBOC System Networking Overview - System Architecture 0 129361 198402 -129361 -198402 MP1
    9. 9. IBOC System Networking Overview - System Architecture 0 122457 198402 -122457 -198402 MP2
    10. 10. IBOC System Networking Overview - System Architecture 0 115553 198402 -115553 -198402 MP3
    11. 11. IBOC System Networking Overview - System Architecture 0 101744 198402 -101744 -198402 MP11
    12. 12. IBOC System Networking <ul><li>Network Basics </li></ul>NETWORK EQUIPMENT NETWORK EQUIPMENT SWITCH or HUB ROUTER 10.10.10.11 10.10.10.10 Gateway 10.10.10.12 External 24.24.24.24 OTHER NETWORK(S)
    13. 13. IBOC System Networking <ul><li>Network Basics </li></ul><ul><ul><li>Network equipment is normally connected to a hub, switch or router with CAT5 cable (RJ45 connectors). </li></ul></ul><ul><ul><li>A hub is the simplest LAN component. All traffic on any port is passed to all other ports . </li></ul></ul><ul><ul><li>A switch includes a high-speed processor and memory. It examines packet addresses and only forwards packets on the port that the addressed equipment is connected. </li></ul></ul><ul><ul><li>A router is used to separate networks. Separation protects networks and can be used to control traffic flow. </li></ul></ul>
    14. 14. IBOC System Networking <ul><li>Network Basics </li></ul><ul><ul><li>Applications exchange data as IP packets which can be TCP (destination acknowledges reception) or UDP (fire–and-forget). </li></ul></ul><ul><ul><ul><li>TCP is a reliable transport since the source will resend data if an acknowledgement is not received. Bidirectionality is a requirement. </li></ul></ul></ul><ul><ul><ul><li>UDP is useful for broadcasting data to many destinations and can be used on a unidirectional channel, but the applications must be able to tolerate lost data. </li></ul></ul></ul><ul><ul><li>Ethernet is a physical layer that encapsulates IP packets into Ethernet packets. </li></ul></ul><ul><ul><ul><li>Ethernet protocol uses CSMA/CD (Carrier Sense Multiple Access with Collision Detection). Delivery is not guaranteed. </li></ul></ul></ul>
    15. 15. IBOC System Networking <ul><li>Network Basics </li></ul><ul><ul><li>What if the network needs to be extended to a remote facility such as a transmitter site? </li></ul></ul>Option 1: PC PC SWITCH ROUTER INTERNET ROUTER SWITCH PC PC LOCAL OFFICE REMOTE OFFICE <ul><li>Requires connection to ISP at remote site </li></ul>
    16. 16. IBOC System Networking Network Basics (What if the network needs to be extended…?) SWITCH PC PC ROUTER INTERNET BRIDGE SWITCH PC PC <ul><li>More control over reliability, security and latency </li></ul>Option 2: LOCAL OFFICE REMOTE OFFICE
    17. 17. IBOC System Networking <ul><li>Network Basics </li></ul><ul><ul><li>What can go wrong? </li></ul></ul><ul><ul><ul><li>LAN throughput efficiency decreases as the number of devices increases. If the LAN becomes too slow, Ethernet devices may not be able to deliver packets. If the higher level protocol is TCP/IP, the packets can be resent. If the higher level protocol is UDP, the packets cannot be recovered. </li></ul></ul></ul><ul><ul><ul><li>If the data being carried contains audio, lost packets means lost audio. Even delayed packets are treated as lost if the audio they are carrying is late reaching the destination. </li></ul></ul></ul>
    18. 18. IBOC System Networking <ul><li>Network Basics (What can go wrong?) </li></ul><ul><ul><ul><li>A LAN can contain cascaded switches and/or bridges. If any segment of the path between two device groups cannot support the throughput, packets will be lost due to buffer overflow in the switches and/or bridges. </li></ul></ul></ul>SWITCH SWITCH PC PC ROUTER T1 MODEM T1 MODEM T1 1.5 Mbs PC PC 100 Mbs 100 Mbs 100 Mbs 100 Mbs 100 Mbs 100 Mbs 100 Mbs
    19. 19. IBOC System Networking <ul><li>Real Systems </li></ul><ul><ul><li>Typical G2 Installation (audio paths not shown) </li></ul></ul>IMPORTER MPS SAE SPS1 SAE SPS2 SAE STL Other Studio Devices STL E1, T1 Licensed RF Unlicensed RF TCP or Bidirectional UDP I2E LAN Switch NE IBOC (EXPORTER) GPS TRANSMITTER with M50 Not a LAN Connection! LAN Switch
    20. 20. IBOC System Networking <ul><li>Real Systems </li></ul><ul><ul><li>Typical G3 Installation (audio paths not shown) </li></ul></ul>IMPORTER EXPORTER SPS1 SAE SPS2 SAE STL Other Studio Devices STL E1, T1 Licensed RF Unlicensed RF Satellite TCP or UDP E2X LAN Switch TRANSMITTER with M50 GPS MPS SAE
    21. 21. IBOC System Networking <ul><li>Real Systems </li></ul><ul><ul><li>I2E: Importer to Exporter </li></ul></ul><ul><ul><li>Must be bidirectional STL </li></ul></ul><ul><ul><li>Exporter requests channel data from Importer </li></ul></ul><ul><ul><li>TCP or bidirectional UDP </li></ul></ul><ul><ul><li>Latency from request to reply must be less than 140 ms </li></ul></ul>
    22. 22. IBOC System Networking <ul><li>Real Systems (I2E: Importer to Exporter) </li></ul>Chnl Data * # - Packet size is 60, but only issued in MP2 and MP3 modes * - For MP1, channel data = 0 ; for MP2, channel data = 440 ; for MP3, channel data = 728 Req # Chnl Data * Chnl Data * Chnl Data * Chnl Data * Chnl Data * Chnl Data * Chnl Data * Chnl Data 9,463 Req # Req # Req # Req # Req # Req # Req # Req 60 Block 15 Block 14 Block 13 Block 12 Block 11 Block 10 Block 9 Block 8 Block 7 Block 6 Block 5 Block 4 Block 3 Block 2 Block 1 Block 0 1.48 Second Frame 2,918 82,632 MP3 2,918 70,178 MP2 324 51,151 MP1 Back Forward Data Through (bps) Mode
    23. 23. IBOC System Networking <ul><li>Real Systems </li></ul><ul><ul><li>E2X: Exporter to Exgine </li></ul></ul><ul><ul><li>TCP or UDP </li></ul></ul><ul><ul><li>Unidirectional or bidirectional STL </li></ul></ul><ul><ul><li>Includes CLOCK packets that can be used as a timing reference for the M50 master clock. </li></ul></ul><ul><ul><ul><li>M50 can be programmed to use CLOCK packets, local 10MHz or local 1PPS as a timing reference. </li></ul></ul></ul>
    24. 24. IBOC System Networking Real Systems (E2X – Exporter to Exgine) * - For MP1, channel data = 18,788 ; for MP2, channel data = 19,076 ; for MP3, channel data = 19,330 # - For MP1, channel data = 108 ; for MP2, channel data = 346 ; for MP3, channel data = 684 <> If TCP then all packets have additional 24 bytes overhead. Acknowledge packets are 66 bytes. Chnl Data 108 Chnl Data # Chnl Data 108 Chnl Data # Chnl Data 108 Chnl Data # Chnl Data 108 Chnl Data # Chnl Data 108 Chnl Data # Chnl Data 108 Chnl Data # Chnl Data 108 Chnl Data # Chnl Data 108 Chnl Data * Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Clock 60 Block 15 Block 14 Block 13 Block 12 Block 11 Block 10 Block 9 Block 8 Block 7 Block 6 Block 5 Block 4 Block 3 Block 2 Block 1 Block 0 1.48 Second Frame 140.2 MP3 128 MP2 0 if UDP <11.4 if TCP 115.5 MP1 Back Forward Data Through (kbps) Mode
    25. 25. IBOC System Networking <ul><li>Real Systems </li></ul><ul><ul><li>E2X: Reliable UDP </li></ul></ul><ul><ul><li>Many installations use main/standby exciters. TCP cannot be used because the Exporter only supports TCP connection to a single destination and you cannot use the same IP address in two or more pieces of equipment on the LAN. Even if the Exporter supported two or more exciters, STL traffic would double. </li></ul></ul><ul><ul><li>UDP can be used because it uses a broadcast IP address. Therefore, all equipment on the same subnet receives the Exporter data. This is not a robust protocol, however, unless the STL bridge BER is 0. </li></ul></ul>
    26. 26. IBOC System Networking <ul><li>Real Systems </li></ul><ul><ul><li>E2X: Reliable UDP (continued) </li></ul></ul><ul><ul><li>Nautel has implemented a bidirectional UDP protocol with programmable buffer depth. </li></ul></ul><ul><ul><ul><li>- It supports main/standby exciters </li></ul></ul></ul><ul><ul><ul><li>Each exciter tracks packet sequence number and requests a resend if a packet is lost. </li></ul></ul></ul><ul><ul><ul><li>Exciters can be programmed to buffer data up to 15 seconds so that short periods of STL interruption can be tolerated. (This increases the required diversity delay). </li></ul></ul></ul>
    27. 27. IBOC System Networking <ul><li>Managing the Traffic </li></ul><ul><ul><li>The IBOC system is sensitive to lost data between the Importer, Exporter and Exgine. </li></ul></ul><ul><ul><li>Importer to Exporter: </li></ul></ul><ul><ul><ul><li>- Audio drop-out on SPS </li></ul></ul></ul><ul><ul><ul><li>Lockup of Importer software (rare) </li></ul></ul></ul><ul><ul><li>Exporter to Exgine: </li></ul></ul><ul><ul><ul><li>Receiver loses lock, taking several seconds to recover. </li></ul></ul></ul><ul><ul><ul><li>Exporter E2X interface can lock up requiring reboot (TCP only). </li></ul></ul></ul>
    28. 28. IBOC System Networking <ul><li>Managing the Traffic </li></ul><ul><ul><li>Importer History </li></ul></ul><ul><ul><li>Problems with V1.2 resulted in one broadcast group reverting to V1.1.2 in a split configuration. It required two Importers, one at the studio and one at the transmitter site. </li></ul></ul><ul><ul><li>The next major release for Importer/Exporter is scheduled for June. The I2E and E2X interfaces should be more robust over ‘real’ LANs and STLs. </li></ul></ul>TCP Oct 27, 2005 V1.2 Split configuration and buffer Sept 09, 2005 V1.1.2 First production release Bidirectional UDP May 25, 2005 V1.1.1
    29. 29. IBOC System Networking <ul><li>Managing the Traffic </li></ul><ul><ul><li>General Recommendations </li></ul></ul><ul><ul><li>I2E and E2X paths must be virtually error free </li></ul></ul><ul><ul><ul><li>Bidirectional with resend </li></ul></ul></ul><ul><ul><ul><li>Unidirectional with very, very low BER (high SNR, FEC, etc) </li></ul></ul></ul><ul><ul><li>Prevent unnecessary traffic from passing through the STL </li></ul></ul><ul><ul><ul><li>Router to create a subnet. (some packet types go to all equipment on a subnet) </li></ul></ul></ul><ul><ul><li>Maintain adequate bandwidth capacity in the LAN STL. </li></ul></ul><ul><ul><ul><li>Understand the utilization by each application using the LAN STL. </li></ul></ul></ul><ul><ul><ul><li>Rule-of-thumb for good ethernet performance is 35% utilization. </li></ul></ul></ul>
    30. 30. IBOC System Networking <ul><li>Managing the Traffic </li></ul><ul><ul><li>How Do You Check Your LAN? </li></ul></ul><ul><ul><li>Use “ PING ” to check network latency. </li></ul></ul><ul><ul><ul><li>Run from PC command prompt. Specify destination, number of packets and packet size. Measures time for response from destination. </li></ul></ul></ul><ul><ul><ul><li>“ NAUTEL” ping can be run as a scheduled task. Creates a log. </li></ul></ul></ul><ul><ul><li>Use “ Ethereal ” to capture packet moving over any part of the LAN. </li></ul></ul><ul><ul><ul><li>Insert a hub to see all packets </li></ul></ul></ul><ul><ul><ul><li>Use Analysis>Filter on IP packets to view specific packets </li></ul></ul></ul><ul><ul><ul><li>Use Statistics>Summary to view average throughput </li></ul></ul></ul><ul><ul><ul><li>Large packets can be fragmented to meet ethernet MTU </li></ul></ul></ul>
    31. 31. IBOC System Networking <ul><li>Managing the Traffic </li></ul><ul><ul><li>M50 Web Server </li></ul></ul><ul><ul><li>The Exgine can do more than connect to an Exporter. It includes a web server with two pages to monitor network statistics and operational status. </li></ul></ul><ul><ul><li>It is also possible to use TFTP to change configuration and upgrade software from a PC anywhere on the network. </li></ul></ul><ul><ul><li>Future releases of Exgine software will provide more elaborate web pages that provide convenient controls. </li></ul></ul>
    32. 32. IBOC System Networking Managing the Traffic (M50 Web Server) <ul><li>Statistics Page </li></ul><ul><li>Running count of packets received </li></ul><ul><li>Running count of missing (discarded) packets </li></ul><ul><li>Running count of packets with CRC error </li></ul><ul><li>Running count of out-of-sequence packets. </li></ul><ul><li>Running count of packets requested (reliable UDP) </li></ul><ul><li>Running count of duplicate packets. </li></ul>
    33. 33. IBOC System Networking Managing the Traffic (M50 Web Server) <ul><li>Status Page </li></ul><ul><li>Indicates Exgine state (Reset, Init, Sync, Run) </li></ul><ul><li>Indicates buffer depth (1 count = 92.5mS) </li></ul><ul><li>Indicates timing reference (10MHz, 1PPS, 0.673Hz) </li></ul><ul><li>Indicates 10MHz VCXO lock (in/out sync). </li></ul><ul><li>Indicates std dev on clock packets (< 15mS). </li></ul>
    34. 34. IBOC System Networking <ul><li>Glossary of Terms and Acronyms </li></ul><ul><ul><li>BER Bit Error Ratio. The ratio between the number of incorrect bits transmitted to the total number of bits. </li></ul></ul><ul><ul><li>Exgine An IBOC component which resides in the exciter. The Exgine decodes the exciter link data and provides the appropriate I/Q modulation. </li></ul></ul><ul><ul><li>E2X Exporter to Exgine </li></ul></ul><ul><ul><li>FEC Forward Error Correction. A system of error control for data transmission. </li></ul></ul><ul><ul><li>GUI Graphical user Interface </li></ul></ul><ul><ul><li>IBOC Nautel In-Band-On-Channel technology provides high quality digital audio over existing AM and FM radio channels. </li></ul></ul>
    35. 35. IBOC System Networking <ul><li>Glossary of Terms and Acronyms </li></ul><ul><ul><li>IP Internet Protocol. Specifies format of packets (or datagrams). Maximum packet size is 64 K, but typically set according to limitations of physical layer (1500 for Ethernet). </li></ul></ul><ul><ul><li>I2E Importer to Exporter </li></ul></ul><ul><ul><li>LAN Local Area Network </li></ul></ul><ul><ul><li>MPS Main program Service </li></ul></ul><ul><ul><li>SPS Secondary Program Service </li></ul></ul><ul><ul><li>STL Studio-Transmitter Link </li></ul></ul>
    36. 36. IBOC System Networking <ul><li>Glossary of Terms and Acronyms </li></ul><ul><ul><li>TCP Transfer Control Protocol. Allows two hosts to establish a connection to exchange data and guarantees data delivery. </li></ul></ul><ul><ul><li>TCP/IP Guaranteed delivery; requires two-way communication for packet acknowledgement. </li></ul></ul><ul><ul><li>UDP User Datagram Protocol. This is a connection-less protocol. There are few error recovery services. Typically used for broadcasting. </li></ul></ul><ul><ul><li>UDP/IP Delivery is “fire-and-forget”. Can transmit to multiple destinations. Can be used on a one-way link. </li></ul></ul>

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