Levitra 5 Mg Come Si Assume — Lowest Prices

Transcript

Connecting What’s Next
Reliable IP Delivery
for
Radio STL Systems
Ted Nahil, CPBE
Business Development Manager, Intraplex
Proprietary and confidential. | 1
Background
 25 years as broadcast engineer in markets including Boston, Detroit, Denver
 CPBE; MCSE (in NT 4.0, 2000)
 Harris Broadcast Communications Division, channel and accounts manager, Intraplex products
 ERI territory manager, radio and tower products
 IBS in Dallas
 SCMS broadcast sales nationwide
 Back at GatesAir as Intraplex business development manager for the Americas, broadcast, public safety and LMR products
Intraplex® Modular Products
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Reliable Program Audio, Voice and Data transport over IP and T1 networks
Fully interoperable building blocks
SynchroCast3 for enhanced coverage
Access Servers: T1/E1 STL Systems
NetXpress LX: IP
T1
Network
T1
NetXpress: IP & T1
T1
NetXpress
NetXpress LX
IP
IP
IP
Network
Access Server
Legacy T1 to IP Migration
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CM‐30 common module and MA‐230 replaces T1 CM‐5RB and MA‐215
Retain existing channel module complement
Opens up second bus on backplane at E1 (2048 mbps) rates
Package available to convert both ends: IX‐CM‐30‐PKG for under $3,500
Converts your STL HD to a NetXpress LX
NOTE – the CM‐30 has no way to deal with fragmented packets, so MTU must be known for every device along the network path
T1 STL System
NetXpress LX System
Error Mitigation in IP Circuits
 OSI Model Review
Layer
Hint
Application
Away
Presentation
Pizza
Session
Sausage
Transport/Protocol
Throw
Network
Not
Data Link
Do
Physical
Please
 What’s where
Layer
Runs At This Layer
Application
Telnet, FTP, SMTP, SNMP, HTTP, DHCP, DNS
Presentation
MIME, SSL
Session
Peer-to-Peer (SIP, NetBIOS)
Transport/Protocol TCP, UDP, RTP, PPTP, L2TP
Network
IP, ARP, ICMP, IGMP, OSPF, RIP, IPSec
Data Link
NIC drivers, Wi-Fi, 802.11, Ethernet
Physical
NIC Cards, RS-232, V.35, 100Base-T
 Hardware Locations
Layer
Application
Presentation
Session
Transport/Protocol
Network
Layer 3 Switches, Routers
Data Link
Switches, Bridges
Physical
Hubs, Cables, Modems, Fiber, SONET
Reliable IP Transport
 Challenges
• Real‐time audio requires use of connectionless transport
– UDP or RTP
• We need a way to overcome or mitigate packet delivery errors caused by problems across the network
• This seems simple enough, but in fact, the solution involves many tactics employed by software and hardware alike
• Let’s look at some of the problems first…
Reliable IP Transport – Problems  Network Problems Transporting Audio over IP
• Jitter – packets don’t all arrive with same latency
– Router (layer 3) congestion
• Out‐of Order Packets
– Router (layer 3) events
• Network Failure (layer 1 usually, but could occur at 2 or 3)
• Lost Packets (layer 2 or 3)
– Burst packet loss or random packet loss
– Prioritizing service helps, but can’t eliminate this, especially when it’s caused by hardware issues in the path like router congestion and/or router flap
Reliable IP Transport – Tools Available
 And solutions available…
 Hardware and software tools are available to help ensure reliability
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QoS
Jitter buffering
FEC
Network diversity
Time diversity
Packet loss concealment
Packet Interleaving
LiveLook network analyzer
Reliable IP Transport – Network Choices
 What kinds of networks are – and are not – suitable for mission‐critical traffic
 Choices
• Public internet
• Private networks
• MPLS networks
Networks Available
 Public Internet
• Suitable only for low‐bandwidth occasional services
 Non‐Guaranteed‐Bandwidth Telco Services (xDSL)
• Cheap, may be suitable for backup
 Guaranteed‐Bandwidth Telco Services
• Based on MPLS (Multi‐Protocol Label Switching), a means of emulating fixed‐bandwidth services like T1 over IP networks
• Ideal for STL and other full‐time broadcast‐quality links
• Available today from AT&T and others
 Private Network or Corporate WAN
• Can be excellent if your IT people understand your needs and have sufficient bandwidth
• May be MPLS already
 Private radio link
• All yours, but subject to environmental conditions
Quality of Service Tagging
 Every IP packet has a ToS (Type of Service) field in its header, that contains information about the urgency of the contents • Real time audio or video = high priority • File transfer (web pages) = low priority
 Higher priority packets pass through with minimal delay and will not be dropped due to congestion
 Some networks use a protocol called DiffServ that allows multiple levels of prioritization
Jitter
 Sequential packets may take different routes through the network
 Thus, packets may take different amounts of time to arrive at their destination
• This transit time differential is called Jitter
 When the jitter gets too great, packets can arrive out of sequence, or even too late for playout
 Jitter is a router‐induced problem
Router Congestion
 Packets are routed through the network according to a dynamically changing routing table
• When a router is too busy due to network congestion, it lets adjacent routers know and they use different routes around it
Switch
Router
Router
Router
Source
Switch
Router
Router
Router
Destination
Jitter Buffering
 Even with high QoS, jitter may still occur.
 The solution to jitter is to add a jitter buffer at the receive end
 Jitter buffering allows you to collect out‐of‐sequence packets and correct the sequencing before playout
• Advantage: no missing bits
• Disadvantage: adds to overall throughput delay
Error Mitigation – FEC  Forward Error Correction
• FEC packets created by arranging RTP packets into a matrix and XORing the packets
Col 1
Col 2
Col 3
Col 4
Row 1
1
2
3
4
XOR (1, 2, 3,
4)
Row 2
5
6
7
8
XOR (5, 6, 7,
8)
Row 3
9
10
11
12
XOR (9, 10,
11, 12)
Row 4
13
14
15
16
XOR (13, 14,
15, 16)
XOR (2, 6, 10,
14)
XOR (3, 7, 11,
15)
XOR (4, 8, 12,
16)
F(x)
XOR (1, 5, 9,
13)
F(x)
Error Mitigation – FEC  FEC Cont’d
• For recovery of a lost packet, at the receiver, the FEC packet is XOR’d with the rest of the column or row data packets
– The algorithm to do this works over the full matrix of data and FEC packets
• This process obviously increases the bandwidth requirement of the circuit
• FEC activity is usually expressed as a percentage increase in bandwidth
• The ratio of FEC packets to data packets determines the FEC rate
– In previous slide, there are 8 FEC packets for every 16 data packets, so the FEC rate is 50%
Error Mitigation – FEC  FEC Cont’d
• FEC relies on encoder‐end buffering as well, and since the objective is to transport real‐time audio (or video), the matrix size is limited
• The column FEC packets provide burst packet loss protection
• The row FEC packets provide random packet loss protection
• FEC is reliable but can’t overcome all transport problems
Error Mitigation – Network Diversity
 Network Diversity
• Dual network paths provide another layer of packet loss protection
– One network serves as the primary path
– Second network serves as the backup path
• The receiver must be able to fail over to the backup path if certain conditions exist that prevent packet delivery via the primary path
• This can result in glitches in the audio during the switch, but if the latency in both paths is similar (or set that way at the receiver), the fail over is relatively smooth
• If the receiver has the ability to do stream splicing, this transition is seamless
Choice 1: Main/Backup Networks
Stream 1 High Fidelity
(Primary)
High Speed
Main IP
Network
One Audio Source
Stream 2 Low Fidelity
(Secondary)
Low Speed
Backup IP
Network
 One source with Multi-coded
streams
 Automatic failover between Primary
and Secondary streams at the
receiver
 Fallback to USB play-out or local
audio source
Assured Audio Delivery
Fall-back to USB Thumb-Drive
Fall-back to external audio source
Choice 2: Dynamic Stream Splicing
Stream 1
IP
Network
1
One Audio Source
Stream 2
Stream 3
IP
Network
2
IP
Network
3
 Identical streams sent with network diversity
 FEC and Time Diversity setting for each
streams
 “Hitless” operation
 Fall back to USB play-list or local audio
source
Assured Audio Delivery
Fall-back to USB
Thumb-Drive
Fall-back to external audio source
Error Mitigation – Time Diversity
 Time Diversity
• Can be used if there is only a single network path available
– First stream is sent out
– Second stream is sent out with preset delay but with identical information as the first stream
• The receiver must be able to receive both streams, buffer them, and pick packets to make “one good stream”
• This method increases latency further because both streams have to be received and compared before a good stream is decoded
• This obviously doubles the bandwidth requirement of the network path as well
Error Mitigation – Packet Loss Concealment • Conceals a lost packet by replaying the last packet
– Done at the receive end
• If consecutive packets are lost, concealment plays out silence
• This method deals with net lost packets, so…
• Concealment takes place after other error recovery methods have done their job (FEC, for example) and have attempted to recover lost packets
Error Mitigation – Interleaving  Packet Interleaving
• Complex algorithms accomplish this
– Create a block of packets
– Rearrange the blocks prior to transmission
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This requires extra buffering at both the encoder and decoder end
This also adds latency
Excellent protection against burst packet loss
Interleaving can disguise the cause of lost packets and make it more difficult to determine what exactly is causing packet loss
Error Mitigation – Interleaving Start with this matrix. The numbers represent blocks
of packets, each of which can have employed FEC.
Column 1
Column 2
Column 3
Column 4
Row 1
1
2
3
4
Row 2
5
6
7
8
Row 3
9
10
11
12
Row 4
13
14
15
16
Error Mitigation – Interleaving End with this matrix. The blocks of packets are
rearranged prior to transmission.
Column 1
Column 2
Column 3
Column 4
Row 1
15
8
5
13
Row 2
11
14
7
9
Row 3
4
2
16
12
Row 4
10
3
1
6
FEC can then be employed again to this matrix.
IP Link: Intraplex LiveLook – New Product!!
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Keeps historical logs of performance data
Provides performance of the ISP’s network
Provides analysis of the pattern of packet losses – i.e. random versus burst losses, and severity of the burst pattern
Provides real‐time feedback on how well your recovery technique is working
You use this analysis to adjust stream spicing techniques –
change time diversity, add more FEC, etc.
Intraplex® IP Link Audio Codecs
 Robust audio over IP
transport with
seamless switching
 Flexible encoding allows content to be
Multi-coded
 Multi-application
Comrex
Tieline
Worldcast
FM Composite (MPX) Over IP – Industry’s First!!
IP Link Provides reliable, error-free transport of the MPX (Stereo, RDS and
SCA baseband) from studio to transmitter
Main Channel
Programs
RDS
SCA
Studio
Transmitter
Site
RDS
SCA
MPX /AES192
MPX /AES192
Flexiva Compact Exciter / Transmitter
5 Hz-72 kHz
Baseband
Wan1
Wan2
IP Link 100 or 200
IP Link 100 or 200
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GatesAir
Thank You!
Ted Nahil, CPBE
Business Development Manager, Intraplex Products
(772) 340‐0850 – office
(772) 418‐9148 – cell
Acknowledgement and many thanks to Keyur Parikh, system architect and software lead, GatesAir, for information supplied from his 2014 NAB presentation entitled “Methods for Mitigating IP Network Packet Loss in Real Time Audio Streaming Applications”. Thanks to Chris Crump (Comrex), Tony Peterle (WorldCast), and Jacob Daniluck (Tieline) for providing supporting information, too.

Levitra 5 Mg Come Si Assume — Lowest Prices

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