User`s manual
100-M0171X3 16 of 95
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
www.cobham.com/tcs
Level of detail and contrast
Level of motion in the video
Level of noise in the video
Existence of repeating patterns in the video
The required level of video quality will not be the same for all applications. Broadcasters often
demand high-quality while certain surveillance applications may be satisfied with much less quality.
Since we support a wide variety of applications we allow a wide range of settings. Not every set-up
configuration will be acceptable for all applications.
Through experimentation it has been found that a single 1080 resolution HD video at 30 fps can be
supported with very good video quality under most video conditions at ~16 Mbps. 720p @60 fps
needs ~14 Mbps for similar quality. Simple HD video scenes can be supported at very low bit rates,
4Mbps for example. However, they will degrade rapidly with motion or noise. The M2TE’s factory
defaults for single program/video operation are set to the aforementioned levels which can be
accomplished with 2K DVB-T transmission using 16-QAM which is reasonably robust in most wireless
environments.
The factory defaults for dual program (dual video) with 2K DVB-T run in 64-QAM operation and
allocate ~12 Mbps per program/video. At these rates the video will still be good. However, as the
videos become more demanding there will be more artifacts. Also, 64-QAM operation will reduce the
operating range and robustness of the link.
If you are using a mixture of HD and SD you can allocate more of the data bandwidth to the HD
program using the Video Bit Rate Allocation controls in the set-up configuration group parameter.
This parameter allows the user to allocate a percentage of the channel bit rate to program A vs. B.
If you want to get the video quality and range of our single program/video operation with dual HD
videos you will need to go to our 4K operation which doubles the throughput of the link. Note that
the RF bandwidth is also doubled. However, in this mode you will be able to go back to 16-QAM and
have high video quality with reasonable link range and robustness.