MIL-PRF-49118B(CR)
3.5.8 Wideband audio frequency response (Receiver). The audio response of the receiver
from the antenna input to audio output terminating in the security connector shall be 3 dB
maximum variation (from Maximum to Minimum audio output) over 10 Hz to 5 KHz. The
attenuation shall be less than 3.5 dB at 8 KHz, less than 5 dB at 10 KHz and less than 8.5 dB at
13 KHz. The attenuation shall be no more than 20 dB at 21 KHz. The output level shall be one
(1) volt peak to peak minimum with a source impedance of 100 ohms maximum and a load
impedance of 50 K ohms in parallel with 1000 pf (see 4.5.8).
3.5.9 Spurious response (Receiver). Receiver spurious response shall be at least 80 dB
down from the signal levels (with the exception of five allowable in the 60 dB to 70 dB range
and five allowable in the 70 dB to 80 dB range) which are required to produce one 10 dB signal-
plus-noise-to-noise-plus-distortion to noise-plus-distortion ratio in the respective modes of
operation in the desired channel.
3.5.9.1 Internally generated spurious responses (Receiver). The level of internally
generated spurious responses shall not cause the receiver AGC voltage to be less then the value
obtained with an equivalent RF input of 0.25 uV, except as follows: When measured in the SSB
mode, 0.6% of the channels may have an internally generated spurious response equivalent to a
signal level between 0.25 uV (-119 dBm) and 1.0 uV (-107 dBm); 0.1% of the channels may
have an internally generated spurious response equivalent to a signal input between
1 uV (-107 dBm) and 4 uV (-95 dBm); and five channels may have an internally generated
spurious response equivalent to a signal level between 4 uV (-95 dBm) and 10 uV (-87 dBmW).
If the internal spurious responses occur at two or three adjacent 1khz settings, this group of two
or three responses shall be counted as one spurious response (see 4.5.9).
3.5.10 Intermodulation (Receiver). Third order intermodulation products shall be down at
least 60 dB from either of two equal amplitude RF signals of 1 mV each. In addition, the
requirements of 4.5.10 shall apply for all other intermodulation products.
3.5.11 Cross modulation (Receiver). With the receiver operating in the AM mode, an
interfering signal, which is modulated 30 percent with a 400 Hz tone, shall not produce more
than 10 percent cross modulation on a 4 microvolt desired carrier under the following conditions
(see fig.1).
Frequency separation between
Level of undesired signals
desired and undesired signals
0.5% (but not less than 20 KHz)
7.0 millivolts
See 4.5.11
0.1 volt
1.0 MHz
0.7 volt
3.5.12 Desensitization (Receiver). The signal plus-noise-distortion to noise-plus-distortion
ratio, produced by a 5 uV signal in the 2.0000 to 19.9999 MHz tuning range and a 3.75 uV signal
in the 20.0000 to 75.9999 MHz range, shall not be degraded to less than 20 dB by an interfering
carrier signal of 50 millivolts which is removed as shown in fig.2 from the desired frequency.
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