9.373 Modcod-Splitter

This page describes the device driver and the device window for the Modcod-Splitter logical device. This device splits up a combined MODCOD setting into individual parameters

Modulator / demodulator devices offer parameters to select the modulation type (e.g. QPSK), the FEC setting (e.g. 3/4) and newer ones also the modulation standard aka. DVB-mode setting (e.g. DVBS2). Many device use individual parameter for this but there are also device types which combine these parameters to one MODCOD setting.

The Modcod-Splitter device may be used to split up the MODCOD setting into individual parameters. It supports MODCOD parameters like QPSK-3/4 (modulation-type followed by FEC) and like DVBS-QPSK-3/4 (DVB-mode followed by modulation-type followed by FEC). The device automatically reads and parsed the choices offered by the target parameter and sets the choices for it's individual parameters accordingly.

Best match translation

When the operator changes one of the parameters DVBMode, modulation or FEC, this may lead to a MODCOD combination the target device does not support. the sat-nms standard behaviour for such a case would be to fall back to the very first MODCOD setting of the device. This certainly is not what an operator expects when he changes parameters.

Hence, the Modcod-Splitter device implements a 'best match' translation algorithm which changes invalid MODCOD settings to a valid setting which resembles as much as possible from the combination the operator selected. This is done from left to right, so in many cases only the FEC rate is changed to a valid setting.

Because of the left to right priority of this algorithm, the best way to operate the Modcod-Splitter device manually is to set the DVB-mode first, then the modulation-type and finally the FEC.

Delayed command forwarding

In many cases the Modcod-Splitter device will be used allow the automated control of a MODCOD parameter from another logical device which expects separate parameters instead of a MODCOD setting. Such a device will send the parameters at the same time to the Modcod-Splitter , but they may arrive there in random order.

For this reason the Modcod-Splitter device does not update the target parameter immediately with each parameter change it recognizes. It waits at least 750 msec (the exact time depends on the IDLE time setting of the thread/interfaces where the device is configured) after a parameter arrived before the MODCOD setting gets combined with the 'best match' algorithm and sent to the target device.

Device window pages

The following table shows which device window pages are available with this individual device type. Tool-bar functions not mentioned here are described at the general description of device windows .

• --- Contains the individual DVB-mode, modulation-type and FEC parameters
• --- The device info page.
• --- The maintenance page. The configuration parameters described below are set at this page.

Configuration parameters

At the maintenance page of the device window there is exactly one configuration parameters which must be set to integrate the device into the VLC/M&C:

Variables defined by this device driver