IPTV test and measurement with the RANGERNeo 2
The RANGERNeo 2 field strength meter provides measurements to understand, identify and fix the new problems that are emerging in multicast television networks over IP (IPTV), which are widely used in hotels and other large television networks. The metric of quality parameters in IPTV at the last stage of transmission is of great help during installation and maintenance of these networks.
The RANGER Neo 2 can receive IPTV television programs and display them on screen along with other important information service... In this way, besides an RF field strength meter it is also an advanced IPTV tester.
In addition to the IPTV receiver, other tools can be also used, such as the Transport Stream Analyser, which shows all the information contained in the PSI/SI tables related to the Transport Stream decapsulated from the IP stream.
Introduction to IPTV
IPTV means Internet Protocol Television. It is a system of distribution for digital television under the Internet Protocol that works over broadband data networks.
The main difference between traditional television and IPTV is that traditional television broadcasts simultaneously all channels (the user selects one and ignores the rest). In IPTV, the receiver only receives the channel selected. To change channel, the decoder sends a request to the content server, which sends a new data stream to the client with the selected channel.
IPTV uses two transmission modes depending on the network: Multicast and Unicast.
What are Multicast and Unicast transmission modes?
The Multicast transmission mode distributes all the programs, which will be copied and duplicated by routers to reach the receivers subscribed to that content. Receivers decide whether or not to watch one of the programs that they are receiving. This model requires more processing by network elements and it is used in closed networks such as hotels or companies.
The main advantage in Multicast mode is that an unlimited number of clients can receive the same program without increasing the bandwidth.
Multicast transmission mode
The Unicast transmission mode distributes over the network as many copies of the program or programs as receivers have requested to watch it (if a receiver has not requested a program he does not receive it). This method requires more bandwidth on the network, because the total bandwidth required is cumulative according to how many receivers request to watch the program.
Unicast transmission mode
Measures under IPTV
One of the three measurement screens for IPTV available in the RANGERNeo 2
The RANGERNeo 2, as an IPTV infrastructure tester, shows the following IPTV quality parameters:
- Measures over multicast reception: received packets / missing / fixed, buffer usage percentage, transport stream bitrate...
- Measures over received traffic: data network bitrate and IP packets received with errors.
- Internet parameters: Ethernet speed, multicast address, protocol (UDP / RTP), data about error correction (FEC), TS packets...
- IPTV service decoded.
- Server IP address and communication protocol (UDP / RTP).
Interarrival packet time
In an optimal IPTV transmission, all packets arrive at destination in a short time, more or less constant. This function checks that continuity in receiving packets for the selected transport stream.
Usually, the graph should concentrate around small time values. Spreading through the time axis may point to a network problem.
The Interarrival Packet Time shows the percentage as a function of time between packets.
It is a diagnosis tool that sends several ICMP (Internet Control Message Protocol) packets from the RANGERNeo 2 to another equipment connected to the IPTV network. Under optimal conditions, the responses will be received at similar time intervals.