User's Manual
Table Of Contents
- 1: Introduction
- 1.1 Documentation notes
- 1.2 Product introduction
- 1.3 General product handling and operation
- 1.3.1 Powering on/off and sleep mode
- 1.3.2 Attaching, detaching, and handling modules
- 1.3.3 Attaching the Wi-Fi antenna
- 1.3.4 Attaching the strap
- 1.3.5 About the touchscreen display
- 1.3.6 Selecting the active interface
- 1.3.7 Starting a function or test
- 1.3.8 Stopping a test
- 1.3.9 Saving results
- 1.3.10 Interpreting results
- 1.4 Maintenance
- 1.5 Technical support
- 2: Wi-Fi Testing Menu
- 3: 10/100 Testing Menu
- 4: System Menu
- 5: IP and Video Testing
- 5.1 IP Network Setup
- 5.2 Connection Information
- 5.3 Ping
- 5.4 Traceroute
- 5.5 Web Browser
- 5.6 IP Video testing
- 6: Specifications
Base Unit User Guide Issue 1 Tech-X Flex™
5-28 5: IP and Video Testing
Intro
Wi-Fi
10/100
System
IP/Video
Specs
• Other problems related to network impairments, such as packet delay variation and out-of-sequence
packets.
• The inherent abilities of the codec and associated equipment to conceal network impairments such
as packet loss.
• The structure and length of GOPs (MPEG Groups of Pictures), especially with regards to the varied
effects of packet loss on different frame types.
• The bit rate and frame size (or resolution) used at the encoder, as smaller rates and lower resolutions
can degrade the quality of the image even if transport is flawless.
• The impact of recency. Recency is the trend of human viewers to judge audio/video quality to be
lower immediately following a disturbance to the signal, and the subsequent trend for that perception
to improve gradually if time passes with no further disturbance.
• Packet loss distribution. Bursty packet loss events in which consecutive packets are dropped have a
different effect on perceived audio/video quality than packet loss events in which single packets are
dropped and the time (or "distance") between the single loss events is significant.
• Loss of synchronization between the audio and video signals.
While it does not measure signal-to-noise directly, the analysis does use codec and packet loss/discard
information to calculate an estimated peak signal/noise ratio (EPSNR). The EPSNR is then used as a
key input for quality score calculations.
About MOS
MOS (mean opinion score) is a numerical system used to grade the subjective perceptual quality of an
audio, video, or multimedia user experience. Originally based on ITU-T recommendations for the
evaluation of voice quality, it uses a scale of 1 - 5 to indicate viewer experience with the following typical
benchmarks:
Score Quality Human perception of degradation
5 Excellent Imperceptible. No degradation of video quality can be
detected by a human viewer.
4 Good Perceptible. Degradation can detected, but does not
adversely impact the viewing experience.
3 Fair Slightly annoying
2 Poor Annoying
1 Bad Very annoying or no stream present