IARU Region 1 VHF Managers Handbook - UBA

Quality
Q9 Clean signal, no visible sidebar pairs
Q7 One barely visible pair
Q5 One easily visible pair
Q3 Multiple visible pairs
Q1 Splatter over much of the spectrum
8.6.3 The MOS (Mean Opinion Score) reporting scale for digitized speech:
MOS Quality Impairment
5 Excellent Imperceptible
4 Good Perceptible, but not annoying
3 Fair Slightly annoying
2 Poor Annoying
1 Bad Very annoying
0 Unusable Total
Notes:
Non-integer MOS scores like 3.5 are possible. An MOS of 3.0 is generally referred to as toll quality,
meaning good enough to pay for. Digital voice users may tolerate MOS levels less than three if they get
additional benefits, such as simultaneous voice and data services.
While evaluation of voice systems may be made based on test-bench measurements, they must ultimately
relate to the perception of the listener. A large body of voice-system evaluations exists based on MOS.
Comparisons among systems are therefore readily made. MOS relates well to the readability figures
commonly used in Amateur Radio signal reports.
8.7 ANTENNA POLARISATION ( Recommendation P.1.)
At several conferences the antenna polarisation has been discussed. Interestingly enough the use of
horizontal polarisation, almost exclusively used for non-channelised amateur traffic on VHF and higher
frequencies has never been formally recommended. Part of recommendation FM.2. recommends vertical
polarisation for FM repeaters .
At the Lausanne conference in 1953 ( this is really the oldest technical recommendation of Region 1 ) the
helical antenna thread direction was laid down. Why that was done at the time is unclear, but 30 years
later (Cefalu 1984 ) the EME community felt a need for the definition of circular polarisation for EME
contacts. 12 years later, however, it was recommended to use for EME above 3 GHz linear polarisation for
the time being.
As using circular polarisation appears to have advantages for repeater stations the matter may come up
again at future conferences.
IARU Region 1 page 118/148 Version 5.40
VHF managers handbook