MIL-STD-188-243 Tactical Single Channel Ultra High Frequency UHF Radio CommunicationsThe purpose of this document is to establish the minimum essential interoperability and performance requirements necessary for tactical single channel UHF radio communications equipment. This standard addresses ground-to-air, air-to-air, ship-to-shore and ship-to-ship tactical single channel UHF radio communications equipment. The requirements established by this document may be exceeded in order to satisfy specific operational requirements or to incorporate technological improvements, provided that interoperability be maintained.

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MIL-STD-188-243A

5.2.3.5 Receiver Protection. The receiver, with primary power on or off, shall not be damaged when subjected to continuously applied signals of up to +50 dBm (DO +56 dBm) of available power delivered from a 50-ohm source.

5.2.3.6 Receiver Interfaces.

5.2.3.6.1 Local Audio Output Impedance. The local audio output impedance shall be 600 ohms balanced, with a minimum returnloss of 26 dB against a 600-ohm resistance over the frequency range from 300 Hz to 3500 Hz. The electrical symmetry shall be sufficient to suppress longitudinal currents to a level which is at least 40 d13 below reference level (-40 dBmO). Additional balanced or unbalanced local audio inputs and strap options shall be optional.

5.2.3.6.2 Local Audio Output Signal Level. The local audio output signal level shall be continuously variable between -20 dBm and +12.5 dBm.

NOTE: Additional signal levels different from those cited or for automatic level or gain control may be established in the applicable equipment specifications.

5.2.3.6.3 Line Audio Output Impedance. Receive radio equipment requiring a line audio output shall have at least one line output with a nominal impedance of 600 ohms, balanced, with a minimum return loss of 26 dB against a 600-ohm resistance over the frequency range of 300 Hz to 3500 Hz. The electrical balance shall be sufficient to suppress longitudinal currents at least 40 dB below the reference signal level (-40 dBmO). Additional balanced or unbalanced local audio inputs and strap options shall be optional.

5.2.3.6.4 Line Audio Output Signal Level. The nominal receiver line audio output level shall be

0 dBm. For radio equipment designed to be used for digital communications, the level of the composite audio output shall not vary by more than 1.5 dB.

5.2.3.6.5 RF Input impedance. The RF input impedance shall he a nominal 50 ohms, unbalanced to ground. The Input VSWR, with respect to 50 ohms, shall not exceed 2.0:1 over the operating frequency range.

5.2.3.7 Receiver Noise and Distortion.

5.2.3.7.1 Harmonic Distortion. The in-band harmonic distortion produced by any single frequency test signal within the operating audio input range shall be at least 23 dB below reference level (-23 dBm0). The DO shall be -33 dBm0. In the ANI mode, measurements shall be taken with an RF input signal that produces 90 percent modulation at full rated I audio output. Narrowband FM measurements shall be taken with an RF input signal that produces a peak deviation of 5 kHz at full rated audio output. Wideband FM measurements shall be taken with an RF input signal that produces a peak deviation of 20 kHz at full rated audio output.

5.2.3.7.2 Intermodulation Distortion. The intermodulation distortion products produced by any two test frequencies within the operating audio input range shall be a minimum of 20 dB below the reference level (-20 dBm0) for narrowband, and a minimum of 40 dB below the reference