DVB-RCS ODU: Multimedia Ground Terminals and Equipment

Status date

To design and manufacture production standard hardware for a range of three terminals to meet satellite operator requirements for providing Broad Band Satellite INTERNET services throughout Europe, North Africa, Western Asia and Eastern USA.

  1. Producibility in the high volumes required for the consumer Broad band data market.
  2. Cost advantage of an LNB/OMT and Transmit Filter
  3. Novel low-cost range of transmitter designs
  4. Use of cost-effective pressed steel technology in antenna production
  5. Design of a Cross Polar Compensation Feed Horn 
  6. High levels of compatibility both with existing IDU's and new IDU's 
  7. Aesthetically pleasing appearance for domestic installations 
  8. Ease of installation

Satellite operators are committed to the development of commercial satellite systems for Multimedia applications. Eutelsat for instance have ordered two satellites (e-BIRD' and HOT BIRD' 6) for launch and operation by mid 2002. Based on the progress of the DVB-RCS standard, e-BIRD' can support upwards of 100,000 terminals for broadband Internet access and other multimedia applications such as video streaming and data broadcasting.

The satellite operators have identified a lack of properly performing low-priced terminals available on the market. This is severely impacting the development of this sector. A price objective of 400


The transmitter up-converts the IF input at L-Band (950-1450MHz) to RF at 14.0 - 14.5GHz.

Unit power, DiSEqC control and frequency reference share a common F-type connector with the IF signal, and are extracted at the cable interface. The detector is followed by a gain control stage which maintains the signal level within the linear range of the IF. This stage is necessary to accommodate the wide range of signal levels possible at the input connector. A second gain-control stage operates to provide overall unit level control. The IF signal is then mixed up to the RF band using a single-balanced mixer.

A band-pass filter attenuates the mixer image and LO leak and is followed by multiple stages of RF gain including the PA. Further band-pass filters attenuate image and LO and eliminate receive band noise mixed up from the IF. The PA is followed by a printed filter to attenuate 2nd harmonic. The wave-guide filter also suppresses receive band noise generated in the output stage of the transmitter.

The ALC detector monitors the forward power flow before the wave-guide filter and is the key element in maintaining the transmitter output level within the accuracy specification. As well as compensating for input level variations, the ALC offsets the effects of temperature drift, frequency response and unit variations. The ALC detector is thus required to be both linear and highly repeatable. A temperature sensor in the unit allows the micro-controller to undertake first-order temperature compensation of the ALC detector via a look-up table.

The local oscillator system uses a phase locked S-band VCO multiplied by 4 to 13.05GHz. Use of a low-side LO avoids spectrum inversion in the transmitter The VCO is locked to a 10MHz external reference supplied up the IF cable from the indoor unit. The phase locked loop supplies a lock check line to the micro-controller to permit the TX to be disabled in the event that the PLL goes out of lock.

The microcontroller handles the DiSEqC control interface, the PLL programming and alarm condition, the transmitter levelling algorithm and enable/disable function and other housekeeping functions.

The cable interface picks off the DC and low-frequency control/reference signals at the IF connector via a simple multiplexer. Local supply uses switch-mode regulators to maintain good thermal efficiency over the wide input voltage range.


To design and manufacture production standard hardware for a range of three terminals to meet satellite operator requirements for providing Broad Band Satellite INTERNET services throughout Europe, North Africa, Western Asia and Eastern USA.

Initially, there will be an ODU with a transmit power of 2W and a 0.7 f/d antenna based on a DBS dish surface profile. This initial phase will result in the first hardware deliverable to ESA.

Following this the second phase of the project will develop the 0.5W and 1W transmit power ODU's, with a new 0.5 f/d dish.

These two designs will be the second set of deliverables to ESA at the end of the project.

Current status

The project is in its last phase.


The 2 Watt Transmitter design was fully tested and completed. The DiSEqC was also fully tested and completed.


The 0.7 f/d antenna design was also finished. This means that a complete ODU terminal has been commissioned and tested with both the down link and up link performing well during satellite tests.

The next phase of the project was to design the lower power 1 Watt and 0.5 Watt Transmitters, these are to be tested. Testing has also commenced on the smaller 0.5 f/d antenna.

The final design review has been carried out.