Appendix B: A look at the SDR’s of WorldSpace and SiriusXM

(Appendix to page ‘Filling the spacethat Worldspace has left… at least to some extend’)

The world’s first L-band/S-band satellite radio is the Worldspace.

In case of SiriusXM, it is to be noted that Sirius and XM are two different broadcasters, but the two have merged into a single one – SiriusXM – although the two still use separate satellites and un-inter-operable receivers. In this appendix up (as well as the main article), both of them are together referred to simply as SiriusXM.

Worldspace and XM (of SiriusXM) works from their geostationary satellites (satellites that revolves around the earth in such a way that they appear stationary from earth), while Sirius works from satellite that follow geosynchronous highly elliptical orbit, that appear to follow an ‘8’ shaped orbit in the sky, when viewed from earth, going in and out of the radio antenna’s visibility. There are three satellites following the same orbit, so that when one goes out, the next one comes in, providing un-interrupted reception.

Worldspace and SiriusXM used the L-band and S-band respectively for its operation. Both used proprietary radio sets for reception, with Worldspace partnering with companies like Hitachi, JVC, Panasonic, Sanyo and BPL, and SiriusXM with Pioneer, Alpine, Clarion and Sony, to make sets to their specification, and fitted with the chipsets by STMicroelectronics for decoding the encryption by Worldspace  (StarMan chipset) and SiriusXM services on broadcast.

Window sill reception: The satellite radios of Worldspace and SiriusXM use patch antennae pointed at the satellites for near window (table top) or window sill reception.

The satellite radios also use high gain antennae, such as Yagi antenna used by Worldspace receivers or the outdoor antenna used by SiriusXM fitted on building rooftop, when the reception by the usual patch antenna is not possible due to either the apartment  of residence having no windows to the appropriate side, or nearby buildings obstructing the reception.

Vehicular reception: For tackling the problem of satellite directionality when driving (described in Appendix B), omni-directional rooftop antennae, like the ones for Worldspace and SiriusXM are stuck on rooftop.

When tall buildings block the antenna’s line-of-sight for the antenna on the car to the satellite (‘tall building shadows’, also known as ‘dead zones’), they require terrestrial repeaters, a technique of locally ‘relaying’ the signals transmitted from top of buildings, to fill in the lost signal. SiriusXM had this put up in the US (of course in selected cities only), but Worldspace couldn’t make it to install those in India, primarily because or lack of clarity of legal provisions in India, at that time.

               ‘Maritime’ antennae are also available for both Worldspace and SiriusXM for use in boats and luxury yachts.

Personal reception: For personal SiriusXM players (Walkman and other and handheld players), Sarantel had come up with SkyTune, a quadrifilar helix S-band antenna which is small enough to be fitted on such hand held devices. Worldspace doesn’t have one in this category.

In future, two new SDRs are expected to be launched in Europe – ONDAS Media and Onde Numerique – both expected to use the European SDR standard of the European standardization organization, ETSI (ETSI SDR standards ETSI EN 302 550-1- 1 to 3).