SOURCEFORGE » RALF » 2015 Evaluation and test of an optical / L-band tranceiver

Proposal of structure: 

Introduction - tell what is the aim of the project

State of art - talk about how L-band reception systems work currently

Project - Present our results, discuss them point by point

-Linearity - what is, show results, compare to the technical specification provided.

-Intermodulation - what is, show results, explain and compare to coax (theoretically)

-Phase/noise - what is, show results, explain and compare to coax (theoretically)

-Application

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h1. 1. Introduction

Earth stations are based on an indoor/outdoor unit architecture. The outdoor unit comprises antennas and the RF frontend (amplifier and up/down converter). The indoor unit includes the receiver, modem and network/application appliances. On typical consumer systems, the outdoor and indoor units are connected by means of a 75-ohm coaxial cable. The cable conveys the intermediate frequency (typically L band) signal between the indoor/outdoor units. 

This approach, while being cost effective, is not optimal from a signal quality standpoint and might severely impair the end-to-end link budget. For example, typical attenuation values for a coaxial cable at a frequency of 1 GHz are in the order of 15 dB/100 m.

The objective of this project is to test and evaluate a system that makes possible to convert the L-band RF signal from/to optical and use an optical fibre (up to 10 km) as primary interconnection media.  The signal is converted from optical back to RF in the indoor unit. As such, it is directed to DTH (Direct-To-Home) TV systems.

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h1. 2. State of the art

h1. 3. Measures

h2. 3.1 Linearity

h2. 3.2 Intermodulation

h2. 3.3 Phase/Noise

h1. 4. Results

h1. 5. Conclusions

h1. 6. Application

This section explains how the Outdoor system has been installed and the results obtained measuring a real TV signal from a Satellite. 

h2. 6.1 Preparation

The optical transmitter has been put in an hermetic box.

Its interface consists of :

* The power supply plug to be connected to the mains ;

* The optical fiber harness (2 fibers) : only the red fiber is actually connected to optical transmitter ; the black fiber is not used, it will enable to have a b ;

* The type F coaxial cable to connect the Antenna Low Noise Block, LNB, to optical transmitter.

Optical transmitter is set to :

* To supply 18 V to LNB, which selects Horizontale polarization ;

* To provide 0 kHz tone to LNB, which set its Local Oscillator to 9.75 GHz to transpose lower Ku Band from  10.7 to 11.7 GHz into IF Band.

* This hermetic box has been mounted on Antenna mast. This Antenna is pointing to Astra 1KR/1L/1M/1N colocalized satellites on 19.2° East.

h2. 6.2 Trials

h3. 6.2.1 IF Spectrum with Optical Link

RF output from Optical receiver has been analyzed with Rohde & Schwartz FSV spectrum analyzer :

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_IF Band, 1 Channel (with Optical Link)_

It is possible to distinguish several channels within the Inter Frequency, IF, band. There is a zoom on left side. The 3 dB channel bandwdith is 22 MHz.

The power is about -32 dBm for the channel centered around 1141 MHz.

!rsz_tv_channel.png!

_TV channel at 1141 MHz_

h3. 6.2.2 Link Quality with Optical link

First, optical link performance enables to have a good TV quality (for example, Eins Plus on 10744H). More deeply, physical link quality has been assessed with the information provided by IPRICOT SCB router.

This data has been compared with data from website like [[www.lingsat.com]] :

|_.Category |_.Make |_.Model |_.Remarks |

| Software defined radio | National Instruments | NI USRP 2920 | Freq. coverage: 50-2200 MHz, BW: 20-40 MHz, Ethernet connectivity|

| Software defined radio | National Instruments | NI USRP 2920 | |

| Software defined radio | National Instruments | NI USRP 2920 | |

| Software defined radio | National Instruments | NI USRP 2950R | Freq. coverage: 50-2200 MHz, BW: 20-40 MHz, Ethernet and PXIe connectivity, GPS DO|

| Software defined radio | National Instruments | NI USRP 2950R | Freq. coverage: 50-2200 MHz, BW: 20-40 MHz, Ethernet and PXIe connectivity, GPS DO|

| Software defined radio | National Instruments | NI PXIe 5644R |Freq. coverage: 65-6000 MHz, BW: 80 MHz, PXIe connectivity, programmable FPGA, in a PXIe 1078 chassis|

| Software defined radio | National Instruments | NI PXIe 5644R | In the same chassis as the prior one|

| Satellite modem | Newtec | Elevation 470 | DVB-S/S2 modem with ACM option, L-band IF |

| Satellite modem | Newtec | Elevation 470 | DVB-S/S2 modem with ACM option, L-band IF |

| Satellite modem | Newtec | MDM 6000 | DVB-S/S2/S2x modem with ACM option, L-band IF |

| Satellite modem | Newtec | MDM 6000 | DVB-S/S2/S2x modem with ACM & BBF on Ethernet  L-band IF |

| Satellite modem | ViaSat | RM 4100 | TooWay KA SAT modem |

| Satellite receiver | IPricot | IPR-SC | DVB-S/IP receiver |

| Satellite antenna | AVL | AVL 9600K | Ku band drive-away antenna with LNB, BUC and controller |

| Satellite antenna | IGP | VPS-2 | Ku band 1.2 m drive-away antenna with LNB and controller |

| Satellite antenna | IGP | ? | Ku band 0.9 m fly-away antenna with LNB and BUC |

| Satellite antenna | Andrew | ? | Direct-to-home TV 1.2 m antenna with universal LNB |

| Satellite antenna | Satcomm | KA-75D | Ka band fly away antenna with Viasat Tria |

| Satellite antenna | ? | ? | Ka band fixed antenna with Viasat Tria |

| Measurement instrument | Rohde & Schwarz | FSL-3 | Spectrum analyzer 3 GHz |

| Measurement instrument | Rohde & Schwarz | FSV-3 | Signal analyzer 3 GHz including K70 option (digital demod) |

| Measurement instrument | Agilent | 34405 | Tabletop multimeter |

| Measurement instrument | Agilent | DSO5052A |Digital storage oscilloscope 500 MHz / 4 Gsample/s |

| Measurement instrument | Agilent | E3646A | Power supply |

| Measurement instrument | NI | myRio 1900 | All purpose D/A A/D instrument programmable with LabVIEW |

| Measurement instrument | NI | myRio 1900 | All purpose D/A A/D instrument programmable with LabVIEW |

| Networking | CISCO | 2811 serie | Router with 4+2 port ethernet/100 switch |

| Networking | CISCO | 2811 serie | Router with 4+2 port ethernet/100 switch |

| Networking | CISCO | Catalyst 500 | Managed 24 port ethernet/100 switch |

| Networking | DELL | PowerConnect 3324 | Managed 24 port ethernet/100 switch |

| Networking | NORTEL | BayStack 470-48T | Managed 48 port ethernet/100 switch |

| Networking | Netgear | FS726T | Managed 24 port Ethernet/100 + 2 port Ethernet/1000 switch, fact default: 192.168.0.239 password is password |

| Networking | Leadtek | BVP 8770 | Videoconference terminal |

| Networking | Leadtek | BVP 8770 | Videoconference terminal |

| Networking | Mikrotik | SXT Lite5 | Wifi 5 GHz transceiver with 16 dBi narrow aperture antenna and full stack support |

| Networking | Mikrotik | SXT Lite5 | Wifi 5 GHz transceiver with 16 dBi narrow aperture antenna and full stack support |

| Networking | Mikrotik | SXT SA5 | Wifi 5 GHz transceiver with 13 dBi wide aperture antenna and full stack support |

| RF | Lynx Technik | OTX 1900 | L-Band to Optical converter |

| RF | Lynx Technik | ORX 1900 | Optical to L-band converter |

| Radio communications | AOR | AR5000A | Analog radio receiver 0-1300 MHz (AM, FM, SSB) |

| Embedded computing| Raspberry foundation | Raspberry PI model B+ | |

| Embedded computing | Texas Instrument | TMS320VC5505 eZdsp USB stick | A DSP on a USB stick with audio I/O and expansion connector |

| Embedded computing| PC ENGINES GmbH | 19" rack with 2 x APU1D4 PC engine | 2 x embedded PC with 3 NIC for each PC |

| Misc | None | None | "Maxibox" field terminal providing LAN, WLAN, fixed phone and wireless phones in a ruggedised case |