ISW3000C01

DVB-ASI and DVB-IP automatic change-over switch with advanced TS failure detection functions

The ISW3000C01 module is an automated switch for DVB-ASI and DVB-over-IP streams that operates based upon the presence of signal at its inputs, the status of a diverse set of parameters of the input streams and the information received via a GPI, all based upon the priorities that the user assigns to each input.
The device provides two inputs, MAIN IN and RES IN through which two DVB-ASI streams are received, labeled ASI MAIN and ASI RES. The module also has a 1 Gbit/s Ethernet port via which it can receive two more DVB-over-IP streams (UDP and RTP, with and without FEC). These are labeled IP MAIN and IP RES.
The unit includes two processing channels known as TS1 and TS2 for simultaneous analysis of two of the four input streams available, and one of these can be selected for delivery to the output.
The Transport Stream (TS) selected for delivery to the output at any given time is distributed to four DVB-ASI outputs and can also be transmitted via IP using the Ethernet interface. In case of a power supply failure or extraction of the main board of the module from its mounting frame the rear board performs a bypass from the ASI MAIN input (MAIN IN) to one of the outputs (OUTp).
The ISW3000C01 module can function in three different operating modes depending on the type of signal received. One mode is valid for any DVB TS, another mode can only be used with DVB-T type transport streams and the third mode is only for use with DVB-T2 type transport streams. The characteristics of each operating mode are described in the following:
Generic DVB mode:
Allows both seamless and non-seamless operation.
Error detection can activate for any of the parameters indicated in ETSI TR 101 290 V1.2.1 as a First Priority, which are the following:
- TS_sync_loss. Loss of synchronization.
- Sync_byte_error. Sync_byte not equal 0x47.
- PAT_error. Errors that prevent the PAT from being obtained.
- Continuity_count_error. Errors in the packet continuity counter.
- PMT error. Errors that prevent the PMT from being obtained.
- PID_error. Referred PID does not occur for a user specified period.
The 1 pulse-per-second (1 PPS) and 10 MHz reference inputs are not used in this mode.
Dedicated DVB-T mode:
Seamless-only operation.
Error detection occurs according to all the parameters indicated in NO DVB-T mode and according to the presence of a megaframe sync (MIP packets).
The 1 PPS reference input is used to measure the delay between the input signals and to provide a reference delay for the output signal.
The output delay is set by the user and is independent of the delay from the input signals. The output delay must be greater than the input delay in order for the module to operate properly.
Each input includes a 45000 packet buffer, allowing a delay of up to one second for any TS up to 60 Mbit/s.
Dedicated DVB-T2 mode:
Seamless-only operation.
Error detection occurs according to all the parameters indicated in NO DVB-T mode and according to the presence of a superframe sync (Timestamps packets).
The 1 PPS reference input is used to measure the advance in time that the input signals arrive in with respect to the transmission time of the superframe and also for referencing the delay of the output signal. The module allows two functional modes: relative to the PPS signal or absolute within the DVB-T2 time epoch. In this second mode the timing reference can be taken from the rear bus of the mounting frame or from the 1 PPS signal itself if it provides that information. For both cases an GPS receiver from Albalá Ingenieros is required.
The output delay is set by the user and is independent of the delays with which the input signals are received. The output delay must also be greater than the greatest input delay for proper operation.
Each input provides a buffer of 45000 packets that allows them to delay any TS of up to 60 Mbit/s by up to one second.
In order to perform seamless switching for DVB-T and DVB-T2 frames the ISW3000C01 includes a 1 PPS reference input and a 10 MHz reference input for synchronization of different transport streams. The module also includes GPI inputs to flag external errors within the transport streams received and a GPO output to signal that the unit cannot deliver a valid TS at the outputs.
In addition to functioning as an automatic switch, the ISW3000C01 can be used for other functions such as conversion of DVB-ASI transport streams to DVB over IP and vice versa, elimination of jitter in the transport streams being transmitted over IP and the conversion of IP protocols such as elimination or insertion of forward error correction (FEC), conversion from UTP to RTP, etc.
The module provides three switching modes: automatic, semi-automatic or manual. All changes to the input selected or in the status of the inputs are indicated via the front panel LEDs and a beep.