SOURCEFORGE » RALF » 2014 ACM testing using channel emulation

h1. EL470 Configuration

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h2. IP Network Model

Modems will be interconnecting two IP network segments using Ethernet bridging. This means the following:

* At both ends of the satellite link the same subnet will exist.

* Routers/hosts at both ends of the satellite link are "neighbouring routers/hosts"

Both modems will be working in L2 Ethernet bridging mode. 

!{width: 60%}ModemSetup.png!

(SOMEWHERE ADD 2.1.1 Ethernet Bridging Inside the Satellite Subnet from Manual)

h2. EL470 Configuration

Both HUB and station modems will be configured as layer 2 ethernet bridges. 

h3. HUB Configuration

As an initial step, one can start by using the Setup Wizard configuration option on the management interface (accessed by a web browser on the management IP of the HUB modem). In this wizard we can input the following options:

* Network Topology: Point-to-Point

* Bridge Type: L2 Ethernet Bridge

* Interface and Encapsulation Settings:

** Ethernet Port: A (needs to be consistent with wiring)

** Encapsulation: XPE

** CRC: Disabled

* Modulation Settings:

** Output Frequency: 1750 MHz

** Symbol Rate: 256 KBaud

** Roll Off Factor: 20%

** Output Level: -35.0 dBm

** FEC Frame Type: Normal

** ModCod: QPSK - 1/4

** Pilots Insertion: Disabled

* Demodulation Settings:

** Demod input: IFL 1 in

** Input Frequency: 1500 MHHz

** Symbol Rate: 256 KBaud

** Roll Off Factor: 20%

After this initial setup, the *Overview* tab in the management interface looks like this:

!{width: 80%}HUB-AfterWizard.png!

Notice that first of all, the modem is not transmitting (Modulator.TX = Disabled). Secondly, the demodulator is configured in ACM mode, we will take care of this by using the Tree tab and defining more specific options relating to the modulation and demodulation schemes. Note that the following only the stated options are to be changed, the rest must remain with their default values which result from the setup wizard.

h4. General Settings

# Go to Tree >> EL470 >> Modem >> Control >>  *Common* 

## Set  *Processing Mode* is to @Eth(IP)<->Air(S2BBF)@.

h4. Modulator Settings:

# Go to Tree >> EL470 >> Modem >> Control >>  Modulation >> *Main*

## Set *DVB-S2 Mode* to @ACM@.

## Set *L-Band Transmit* to @Enabled@ (This will enable the modulator output signal). 

# Go to Tree >> EL470 >> Modem >> Control >>  Modulation >> *ACM Control*

## Set *ACM Ctrl* to @Enabled@.

## Set *MIN Modcod* to the minimum MODCOD parameter desired in the forward link.

## Set *MAX Modcod* to the maximum MODCOD parameter desired in the forward link.

## Set *Comm Failure Modcod* to the default MODCOD parameter utilized if no ACM signalling is able to take place.

## Set *Min Margin*, *Tgt margin*, *Distortion*. For an explanation of FlexACM refer to [[FlexACM Functionality]].

## Set *MODCOD selection algo.* to @Link margin@.

## Set *ACM FW Sig Plane* to @Inband RF@.

# Go to Tree >> EL470 >> Modem >> Control >>  Modulation >> ACM Control >> *Demod table*

## Set the Demodulator IP of the first entry with the *Virtual ACM client id* IP address to be specified later on in the station parameters (we will be using 10.0.0.254).

!{width: 80%}HUB-TreeOptions.png!

h4. Demodulator Settings:

Return link will always be CCM and we will use QPSK-1/4 with short FEC-Frame types.

# Go to Tree >> EL470 >> Modem >> Control >> Demodulation

## Set *DVB-S2 Mode* to @CCM@.

## Set *FEC-Rate and Mod* to @QPSK-1/4@

## Set *FEC-Frame Type* to @Short@

h3. Station Configuration

* Network Topology: Point-to-Point

* Bridge Type: L2 Ethernet Bridge

* Interface and Encapsulation Settings:

** Ethernet Port: A (needs to be consistent with wiring)

** Encapsulation: XPE

** CRC: Disabled

* Modulation Settings:

** Output Frequency: 1500 MHz

** Symbol Rate: 256 KBaud

** Roll Off Factor: 20%

** Output Level: -35.0 dBm

** FEC Frame Type: Normal

** ModCod: QPSK - 1/4

** Pilots Insertion: Disabled

* Demodulation Settings:

** Demod input: IFL 1 in

** Input Frequency: 1750 MHHz

** Symbol Rate: 256 KBaud

** Roll Off Factor: 20%

Management interface after setup wizard:

!{width: 80%}Station-AfterWizard.png!

As with the HUB, we must further define some other options:

h4. General Settings

# Go to Tree >> EL470 >> Modem >> Control >>  *Common* 

## Set  *Processing Mode* is to @Eth(IP)<->Air(S2BBF)@.

h4. Modulator Settings:

# Go to Tree >> EL470 >> Modem >> Control >>  Modulation >> *Main*

## Set *DVB-S2 Mode* to @CCM@.

## Set *L-Band Transmit* to @Enabled@ (This will enable the modulator output signal). 

# Go to Tree >> EL470 >> Modem >> Control >>  Modulation >> DVB-S2 Streams >> *DVB-S2 Streams*

## Enable (*Active* field) the first stream entry and set *FEC-Rate and Mod.* and *FEC-Frame Type* according with whatever settings the HUB demodulator is using.

h4. Demodulator Settings:

# Go to Tree >> EL470 >> Modem >> Control >> *Demodulation*

## Set *DVB-S2 Mode* to @ACM@.

## Set *Max Achievable ModCod* to preferred value.

# Go to Tree >> EL470 >> Modem >> Control >> Demodulation >> *ACM Client*

## Set *Virtual ACM Client ID* to @10.0.0.254@.

## Set *ACM RT Sig Plane* to @Inband RF@.

## Set *MODCOD Selection Algo.* to @Link Margin@

## Set *Delta Margin* and *Fade Prediction* fields accordingly. For an explanation of FlexACM refer to [[FlexACM Functionality]].

!{width: 80%}Station-TreeOptions.png!

h2. Good Link Example

In the following screenshots we can see the management interface when a link has been established. Es/N0 estimates are of around 30dB and FW link is ACM while RT link is CCM with short QPSK - 1/2 FEC-frames.

Station:

!{width: 80%}Station-LinkGood.png!

HUB:

 !{width: 80%}HUB-LinkGood.png!