Copyright 2016,2019 Ron Economos

#

This file is part of gr-dvbgse

#

gr-dvbgse is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 3, or (at your option)

any later version.

#

gr-dvbgse is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

#

You should have received a copy of the GNU General Public License

along with gr-dvbgse; see the file COPYING. If not, write to

the Free Software Foundation, Inc., 51 Franklin Street,

Boston, MA 02110-1301, USA.

gr-dvbgse

Author: Ron Economos Email: w6rz@comcast.net

The goal of this project is to build GNU Radio blocks that implement the ETSI TS 102 606-1 V1.2.1 Generic Stream Encapsulation standard:

http://www.etsi.org/deliver/etsi_ts/102600_102699/10260601/01.02.01_60/ts_10260601v010201p.pdf

Requirements:

A DVB-S2 receiver that supports the DVB-GSE protocol. This module was tested with an Ayecka SR1 DVB-S2 receiver. Note that a special order SR1 is required. The stock SR1 only does MPE protocol. The DVB-S2 receiver is connected to the DVB-S2 transmitter with a coaxial cable and 40 dB attenuator for loopback testing.

http://www.ayecka.com/products-SR1.php

Usage:

Because the Pcap library is used to capture raw packets, the capabilities of the Python interpreter need to be increased. This only needs to be done once. Note that the specific version of Python 3 on your computer needs to be specified (for example, python3.8 for Ubuntu 20.04).

sudo setcap 'CAP_NET_RAW+eip CAP_NET_ADMIN+eip' /usr/bin/python3.x

CAUTION: This allows any Python program to open network interfaces.

The current implementation of the block uses a TAP network interface named tap0.

To add a TAP interface (with ip(8) commands):

sudo ip tuntap add dev tap0 mode tap

sudo ip link set dev tap0 address 02:00:48:55:4c:4b

sudo ip addr add 44.0.0.1/24 broadcast 44.0.0.255 dev tap0

sudo ip link set tap0 up

sudo ip link set tap0 arp off

To forward packets received in the tap0 IP address range to the default network interface (replace eth0 with your default device name):

sudo sysctl -w net.ipv4.conf.all.rp_filter=0

sudo sysctl -w net.ipv4.conf.eth0.rp_filter=0

Note: This is required for the ping reply test feature described below:

To delete the TAP interface:

sudo ip tuntap del dev tap0 mode tap

Testing features:

In order to test this block with just a single transmitter and receiver, two optional testing modes are available.

The first is a ping reply feature. In this mode, the block modifies incoming ping requests into ping replies and swaps the source and destination IP addresses. This allows a normal ping command to complete. Ping packets are very useful for testing since the size and rate can be adjusted. Also, packet latency can be easily measured.

The second feature is IP address spoofing for UDP packets. In this mode the block modifies the source and destination IP address of UDP packets to selected values. This allows for a loopback test of video/audio over RTP using VLC. The destination IP address is set to the host that the VLC RTP decoder is running on. Video is useful for testing since dropped packets will cause bit-stream errors (that VLC will report if you start it on the command line).

Here's what my video loopback flow looks like:

VLC RTP streaming to 44.0.0.3 -> tap0 interface -> DVB-GSE block -> GNU Radio DVB-S2 transmitter -> Ettus B210 -> 40 dB attenuator -> Ayecka SR1 receiver -> eth0 -> VLC RTP decoder from host address.

Both of the features should be shut off for normal full-duplex operation.

Update 03/20/2019: A DVB-GSE sink block has been added for support of a future DVB-S2 receiver in GNU Radio. The sink block can be tested with the flow graph dvbs2_rxip.grc in the /apps directory. This flow graph depends on the DVB-S2 receiver block in gr-dvbs2rx.

https://github.com/drmpeg/gr-dvbs2rx

The test flow requires two TAP interfaces to be configured:

sudo ip tuntap add dev tap0 mode tap sudo ip link set dev tap0 address 02:00:48:55:4c:55 sudo ip addr add 44.0.0.1/24 broadcast 44.0.0.255 dev tap0 sudo ip link set tap0 up sudo ip link set tap0 arp off

sudo ip tuntap add dev tap1 mode tap sudo ip link set dev tap1 address 02:00:48:55:4c:55 sudo ip addr add 44.0.1.1/24 broadcast 44.0.1.255 dev tap1 sudo ip link set tap1 up sudo ip link set tap1 arp off

sudo sysctl -w net.ipv4.conf.all.rp_filter=0 sudo sysctl -w net.ipv4.conf.tap1.rp_filter=0

Traffic can be generated with ping packets.

ping 44.0.0.2

Throughput can be tested with a ping flood. Adjust the size parameter (-s 3300) to control the rate. The printed dots should be relatively stable, If the dots increase slowly (or quickly) you're going faster than the simulated link can handle (and the size parameter should be reduced). -s 3300 corresponds to a rate of about 4 Mbps.

sudo ping 44.0.0.2 -f -i 0.001 -c 5000 -s 3300

Dependencies:

libpcap-dev

Build instructions:

mkdir build
cd build
cmake ../
make
sudo make install
sudo ldconfig

Contributions are welcome!