Home >> March 2009 Edition >> FOCUS: Using Control Systems To Overcome SNG Signal Black-Spots
FOCUS: Using Control Systems To Overcome SNG Signal Black-Spots
by Martin Coleman, Colem

Satellite news gatherers are under constant pressure from consumers to provide up-to-the minute news coverage from across the globe. SNG equipment is becoming increasingly efficient and automated to meet with this demand. Often, SNG teams unknowingly are faced with signal black-spots, costing them valuable time and consequent loss of broadcast availability.

Up-to-the Minute News
Consumer expectations for broadcast news have increased thanks to SNG technology. Crews really can get to the action fast and be setup and filming in a fraction of time previously required, thanks to SNG. However, consumer expectations continues to increase and SNG teams are finding less and less room for errors or hold-ups.

One of the all-too-prevalent problems facing SNG crews is satellite or wireless camera black-spots, especially in city centers. The problem is many elements can get in the way of the SNG crew and its ability to broadcast, such as skyscrapers, tree cover, and so on. Having encountered a black-spot, the time it takes to pack up, move the team and equipment to another location, and then setup again can cost valuable coverage time.

The other problem is, of course, that with no prior knowledge of black-spots in the area, the SNG crew could very well go through that whole process only to once again encounter a bad signal area.

Tracking the Black-Spots
Alerting SNG crews in advance of where the black-spots are means that avoiding them becomes easy and minimizes setup time. Colem has developed a technology manage just such needs. Embedded into Colem’s X-Mobile & Camera control systems, it uses the available GPS monitoring and local area map to warn the SNG crew when they are in, or near, a black-spot area before setting up.

In the case of SNGs using Colem’s automated control system, many have a choice of operational satellites. Each satellite has its own uniquely mapped black-spot record displayed to the operator at start up and well before deployment. If the crew finds that the SNG vehicle or flyaway terminal is already in a black-spot area, they can check the map for a new, more suitable location. In a new or unmarked area, specific information displayed shows direction and elevation of the required satellite before deploying the antenna. At this point, an operator can check, manually, the “line of sight” to the satellite location and make a judgment on whether it is possible or not to deploy. If unsuitable, the location can be marked as bad. If the antenna deploys but cannot lock onto the satellite, the operator again has the opportunity to record that area as a black-spot.

For a wireless camera operator, the receiving site controller monitoring the camera operator’s location and signal level has the ability to set a threshold of receive level at which a black-spot area is marked automatically. The receive level threshold is usually set to a value of SNR between 0.0 and 9.9dB at the receive site. In this case, the control system continues to monitor the received level and mark bad signals areas when found. Implementation of this feature will be available to the next generation of Link Research HD and SD wireless camera control systems.

The system allows any operator to manually mark a bad transmission area. This is useful in situations of poor location, ambiguous signal areas, or areas where operator experience may better judge received results. Whether used for SNG or wireless cameras, the system continues to build database records and a graphical representation of both user-determined and automatically detected black-spot areas to avoid for future broadcasts.

Regaining Control
Detecting and avoiding those SNG and wireless camera black-spots means that SNG crews will be able to go to anywhere in the world and already know the areas to avoid. Of course, this will save them vital time in setting-up, rather than missing that all-important coverage.

Colem sees this application especially important for military satellite ground operations where setup time is crucial. Knowing about problems encountered in previous missions in various terrains would prove to be invaluable. Having such knowledge will allow fixed and mobile satellite installations to be set up reliably and quickly.

As Colem’s technology develops, the company’s vision is to add the ability to up or download black-spot data from any system, via the Internet, to a database managed by Colem. The database will hold a record of GPS position, satellites suitable for SNG, receive site for wireless cameras, signal level, and any other useful information noted by an operator. This will allow all compatible systems to be updated with the latest black-spot area information available to date.

For further information, visit the Company’s web site at http://www.colem.co.uk.

About the author
The author, Martin Coleman, started at Colem as an engineering services and design consult. Using his previous experience in management systems within British Telecom, he developed his own unique satellite and broadcast control system based on the industry standard iFIX Process Control platform from GE. Martin has worked with a number of broadcasters and satellite operators to help improve their processes and control projects.