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successfully maintained the entire SNDCF context to the new
call being established, it shall set the M/I bit to 1; otherwise,
the M bit shall be set to 0.
YlVOO
No. 75
Part II Annex 10 - Aeronautical Telecommunications
wantedlunwanted ratio of 15 dB, with a 50 per cent amplitude
modulated (A3E) radio signal having a field strength of
20 microvolts per metre (minus 120 d13w/m2) or more.
2.2.2.3 Efective acceptance bandwidth. When tuned to a
channel having a width of 25 kHz, 50 kHz or 100 Hz, the
receiving system shall provide an adequate and intelligible
audio output when the signal specified at 2.2.2.2 above has a
carrier frequency within plus or minus 0.005 per cent of the
assigned frequency. When tuned to a channel having a width
of 8.33 kHz, the receiving system shall provide an adequate
and intelligible audio output when the signal specified at
2.2.2.2 above has a carrier frequency within plus or minus
0.0005 per cent of the assigned frequency. Further information
on the effective acceptance bandwidth is contained in
Attachment A to Part II.
Note.- The efective acceptance bandwidth includes
Doppler shift.
2.2.2.4 Adjacent channel rejectiotz. The receiving system
shall ensure an effective rejection of 60 dl3 or more at he next
assignable channel.
Note.- The next assignable frequency will normally be plus
or minus 50 kfi. where this channel spacing will nd suflce,
the next assignable frequency will be plus or minus 25 kHz, or
plus or minus 8.33 ~ H Lim plemented in accordance with the
provisions of Volume V It is recognized that in certain ureas of
the world receivers designed for 25 kHz, 50 kHz or 100 kHz
channel spacing may continue to be used.
2.3 SYSTEM CHARACTERISTICS OF
THE AIRBORNE INSTALLATION
2.3.1 Transmitting function
2.3.1.1 Frequency sfability The radio frequency of
operation shall not vary more than plus or minus 0.005 per
cent from the assigned frequency. Wherc 25 kHz channel
spacing is introduced, the radio frequency of operation shall
not vary more than plus or minus 0.003 per cent from the
assigned frequency. Whcre 8.33 HZ channel spacing is
introduced, the radio frequency of operation shall not vary
more than plus or minus 0.0005 per cenl from the assigned
frequency.
2.3.1.2 Power; On a high percentage of occasions, the
effective radiated power shall be such as to provide a
field strengtlh of at least 20 rnicrovolls per metre (minus
120 dBW/m') on the basis of free space propagation, at
ranges and altitudes appropriate to he operational conditions
pertaining to the areas over which the aircraft is operated.
2.3.1.3 Adjacent channel power. The amount of power
from a 8.33 kHz airborne transmitter under all operating
conditions when measured over a 7 kHz channel bandwidth
centred on the first 8.33 kHz adjacent channel shall not exceed
-45 dB below the lransrnitter carrier power. The above
adjacent channel power shall take into account the typical
voice spectrum.
Note.- The voice spectrum is assumed to be a constant
level between 300 and 800 Hz and attenuated by 10 dB per
octave above 800 Hz.
2.3.1.4 Modulation. A peak modulation factor of at least
0.85 shall be achievable.
2.3.1.5 Recommendation.- Means should be pmvided
to maintain the average rnudulation factor at the highest
practicable value without overmodulation.
2.3.2 Receiving function
2.3.2.1 Frequency stability. Where 8.33 kHz channel
spacing is introduced in accordance with Volume V, the radio
frequency of operation shall not vary more than plus or minus
0.0005 per cent from the assigned frequency.
2.3.2.2.1 Recommendation.- Afrer due allowance has
been mnde for aircraft feeder mismatch, attenuation loss and
antenna polar diagram ~wiation, the sensitivity of the
receiving function shoiild be such as to provide on a high
percentage of occasions an airdio output signal with a wanted/
unwanted ratio of 15 dB, with a 50 per cent amplitude
modulated (A3E) radio signal having a field strength of 75
microvolts per metre (minus 109 dl3 w/m2).
Note.- For planning extended range VHF facilities, an
airborne receiving function sensitivity of 30 microvolts per
metre nray bc assumed.
2.3.2.3 EfSective acceptance hnndwidth for 100 kHz,
50 kHz and 25 kHz channel spacing receiving installations.
When tuned to a channel designated in Volume V as having a
width of 25 kHz, 50 kHz or 100 kHz, the receiving function
shall ensure an effective acceptance bandwidth as follows:
a) in areas where offset carrier systems are employed, the
receiving function shall provide an adequate audio
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