While digital satellite news gathering (DSNG) has only recently developed into a true force, it has enjoyed a steady rate of acceptance over the last couple of years. This advancement of technology can be noted through a timeline of major news events and reality shows that relied on satellite news gathering systems.

Through technological development, satellite encoders have come down in size and have become more effective over the years. Along with these changes came smaller and more effective units. Space is always at a premium in an OB van, so even the modulation scheme to be used can be a consideration if there is a difference in required space. When using a wider bandwidth with a higher data rate, a higher order modulation scheme such as 8PSK is required to fit that data rate within a standard satellite bandwidth

MPEG encoding

Recent trends in DSNG equipment have continued to evolve. Quality video, at 4:2:2 MPEG is available in many DSNG units. One trend is creating the ability to multiplex other services into the encoders. Top-level encoding along with multiplexing services via a remix card can fit many more channels in a given bit rate or at a much higher quality using the same number of channels in that same bit rate. Any program with fast motion, camera panning and multiple zooms can be problematic, so using top-quality encoding technology creates far superior quality images for uplink.

Voice communication

IP information can be embedded in an MPEG transport stream to allow data to be uplinked from the vehicle back to corporate head office. In response, corporate head office can access a back channel to broadcast information over the same satellite and back to the van. With a two-way IP link between the central studio and the DSNG van, equipment within the van can be connected to the corporate network. This includes voice over IP (VoIP) to allow a telephone to be plugged into an IP return. Two-way IP connectivity coupled with high-quality DSNG encoding units is a key ingredient.

Motion estimation

With regard to encoding, full motion estimation is important. During motion estimation, each frame of a picture is broken up into macro-blocks, which are 16×16 pixels. Instead of re-broadcasting all information within those 16 pixels, motion estimation broadcasts just two numbers representing a magnitude and direction. These numbers communicate to the receiver on where to place the macroblock for achieving maximum compression. Noise is the biggest killer of high-quality encoding. A clean feed sent into the compression engine is an absolute necessity. MPEG finds random motion and high-frequency content ' which is how noise appears ' and which is difficult to encode, so anything that can be done to remove that noise significantly increases the end quality.

Wherever the DSNG industry heads from here will be vitally important to the length of its success. Looking at a multi-channel environment these days, news and live events are becoming an increasingly large proportion of the total output, and images are what drive news programming. And as two-way IP connectivity becomes fully realized, the possibilities are endless: from remote control of vehicle equipment from the studio to complete automation, the future of the DSNG industry is going to be incredibly interesting.