Vislink HEROCAST, User Manual

Page: 20 / 24

18
7. Q&A
1. MY VIDEO IS NOT BEING RECEIVED. WHAT SHOULD I CHECK?
Assuming the receive infrastructure is known to be working, the following is a list of
potential areas that would stop your transmission from being received:
•
Ensure that no other transmitter is on the same frequency as your transmitter.
•
Ensure that the lower status LED is solid green.
•
Ensure that the HDMI or integral HDMI interface is still connected.
•
Check for physical damage to the antenna.
2. WHAT DO THE LED COLORS INDICATE?
The LED colors indicate the status of the transmitter, as described below.
LED State Description
Upper and lower Blinking red and green Initializing
Lower Solid Green Ready to transmit
Lower Blinking green RF transmission is off
Lower Solid Amber No video from camera
Lower Blinking amber Wrong video format setting
on camera
Lower Solid Red Cannot detect camera
Lower Blinking red No camera connected
3. WHAT ARE THE TRADEOFFS BETWEEN VARIOUS SETTINGS?
The choice of modulation type, FEC, Guard Interval, and Bandwidth affect the range of the
transmission from the HEROCast transmitter, and the perceived video quality.
Modulation type – QPSK provides a more resilient RF connection than 64QAM, but the available
video data rate is reduced, lowering the perceived quality. If the distance to the receiver is small,
64QAM could give the best picture quality.
FEC (forward error correction) –
½ is more robust than 7/8, but the available video bitrate is
reduced, lowering the perceived quality. If the environment is non-reflective and distances short,
then 7/8 could give the highest picture quality.
Guard Interval –
¼ is more tolerant to echoes and reflections than 1/32, but the available video
bitrate is reduced, lowering the perceived quality.
Bandwidth – Defined by the available RF spectrum at the transmitter site. 6MHz channel
supports lower video bit rate than an 8MHz channel.
The 4 parameters should be traded off, taking into account the distance between the transmitter
and receiver, and the environment (whether it be line-of-sight or a highly reflective built up
area).