Sky One

Objectives

The objective of this activity is the definition and development of a universal integrated 2 watt Ku-band transceiver (KR 1216L) which will be compliant to the Sat Lab specifications.

With the Sky One SatCom transceiver platform Skyware will reach the following goals :

  • SATLABS Compliance, by modification of the IFL interfacing and TX upconverting scheme :

    1. L-band TX_IFL rather than S-band in the ACCESS-1 predecessor,

    2. External TX_LO frequency reference system rather than internal,

    3. DiSEqC communication prepared, 22 kHz modem built in,

    4. Tone switched dual band LNB according to the Universal standard.


  • Enhanced versatility, which allows the platform to address a broader market by increasing the number of options and derived versions. Four main types can be distinguished :

    1. Standard TX Ku-band; DRO type LNB for MCPC/DVB-RCS,

    2. Extended TX Ku-band; DRO type LNB for MCPC/DVB-RCS,

    3. Standard TX Ku-band; PLL type LNB for SCPC/VSAT,

    4. Extended TX Ku-band; PLL type LNB for SCPC/VSAT.

    Each of these versions would be available in both 2 and 4 watt power outputs and 8 different types of products will ultimately be available in the product capability.

Skyware Radio Systems has already developed a "1st generation" Ku band transceiver for satellite interactive terminals. Whilst this design represents a considerable cost reduction over more traditionally designed transceivers, significant opportunities for further cost reduction and performance enhancement remain. It is the purpose of this project to address these opportunities, leading to a fully integrated and more flexible product, ready for full industrialization.


As with the current Skyware satellite transceivers, this 2nd generation product will be a fully integrated unit, designed for low cost manufacturing technology, similar to those used in the

Challenges

The one box design approach is demanding in terms of tooling and tolerances, but also rewarding as it results in an easy to assemble and compact product, which is easy to handle and install.

A serious effort will be needed for the assessment of the tolerance sensitivity of the casted-in OMT. Skyware has extensive experience of handling die-casting tolerances. For example, it has been proven that with good quality die-cast tooling the repeat tolerance of critical dimensions is far less than absolute dimensional tolerance. During the filter design work packages this experience is of great value.

In the past Skyware has designed PLO's using the sampling PLL principle high phase detector frequencies. These sampling PLO's have unequalled phase noise performance, but due to the analog nature of the PLL, are sensitive to tolerances, drift and alignment error. Another problem with sampling PLO's is the emission of VCXO harmonics, which appear as spurs on the TX output.

Due to recent development in silicon bipolar semiconductor technology, high speed integrated frequency dividers and high frequency, low noise phase-frequency detectors are now available at reasonable cost. Over the past 3 years, Skyware has been working with Philips Semiconductors and NEC on the design and evaluation of such RFIC's.

The Sky One product will benefit from these developments as low phase noise divider type PLL are now feasible at low cost. This not only reduces overall BoM but also the integral assembly cost and manufacturing yield.

The double loop circuitry has a very narrow reference lock PLL [20 Hz] and a wide band VCDRO lock PLL [200 kHz]. In this way the reference PLL "cleans up" spurious and noise of the external 10 MHz reference signal, making the purity of the TX signal independent of the quality of the reference signal. This has great modem interoperability benefits.

Benefits

It is the purpose of this product is to address new Ku commercial opportunities, The new product design will lead to wider access to interactive satellite services due to improved performance and reduced BoM (lower by 35%) & manufacturing costs. Compared to existing designs, the new product will be significantly smaller and more aesthetically pleasing.

Given that most of the commercial opportunities thus far are targeted at business market, the ease of installation of a single unit as well as the size become even more important.

Features

The proposed transceiver will be the radio module of a Ku Two Way Satellite System. The transceiver will be designed to be compatible with:


  1. Market available Ku Band reflectors/feedhorns, and

  2. Modems (IDUs).

The proposed Skyware Ku band DVB-RCS transceiver platform (KR 1000 series) is shown schematically below.

Sky One Top level architecture, DRO type


 click for larger image

As shown in the diagram, the platform consists of two main circuit modules, a Ku band LNB (shown in green) and a Ku-band block upconvertor (shown in orange). The Sky One transceiver is designed around the OMT (shown in blue) which separates TX and RX polarization resulting in decoupling of TX and RX signals. A Ku band orthomode transducer (OMT) interconnects these modules. Transmit- and Receive Reject Filters are required to prevent overloading of the RX by the transmit signal as well as suppress the TX noise.

Plan

The project is now completed. 5 prototype units of each version (for a total of 40 products) have been built and fully evaluated.

Current status


  • A total of 40 pcs SKY ONE prototypes in 8 different variants have been manufactured under normal production circumstances and using original production materials.

  • The validation of the SKY ONE prototypes by acceptance testing has been completed.

  • After validation of the prototypes two minor specification non-compliances have been detected, one of them has already been addressed in 30 of the 40 pcs samples.

  • One specification non-compliance remains : the LO phase noise at 10 kHz offset of the units with PLL RX. SKYWARE are confident however that this problem can be overcome by re-design of the PLL loop parameters.

  • The FDR target of integration, manufacturing and validation of SKY ONE DVB-RCS SIT transceivers has been demonstrated.

Contacts

Status date

Thursday, April 24, 2008 - 16:58