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.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - 21

MIL-STD-188-243A

5.2.2.4.3 Intermodulation Distortion. Any intermodulation distortion product produced by any two equal level audio tones within the operating audio input range shall be a maximum of -38 dBm 0 at full rated RF output power. In the AM mode, measurements shall be made with the audio input signals adjusted to produce 90 percent modulation. Narrow band FM measurements shall be made with the audio input signals adjusted to produce a peak deviation of 5 kHz. Wideband FM measurements shall be made with the audio input signals adjusted to produce a peak deviation of 20 kHz.

5.2.2.4.4 Spurious Emissions. The out-of-band spurious emissions shall be at least 80 dB below the unmodulated carrier at full rated RF output power. In the AM mode, measurements shall be made with the operating audio input signal adjusted to produce 90 percent modulation. Narrow band FM measurements shall be made with the operating audio input signal adjusted to produce a peak deviation of 5 kHz. Wideband FM measurements shall be taken with the operating audio input signal adjusted to produce a peak deviation of 20 kHz. All measurements shall be taken outside the limits of 0.95f to 1.05f, where f is the carrier frequency.

5.2.3 Receiver Characteristics.

5.2.3.1 Time Delays. The time delays shall not exceed the following:

a. Receiver attack time delay 40 ms maximum b. Receiver release time delay 40 ms maximum c. Receive-after-transmit time delay 60 ms maximum

5.2.3.2 Sensitivity. The sensitivity of the receiver over the specified frequency range shall be such that an RF input test signal applied to the antenna input results in a minimum output (S+N)/N ratio of 10 dB taken at the audio output. Narrowband measurements shall be made with an RF input test signal level of -103.5 dBm (1.5 microvolts into 50 ohms). Wideband measurements shall be made with an RF input test signal level of -101.0 dBm (2.0 microvolts into 50 ohms). AM measurements shall be made with 30 percent modulation. Narrowband FM measurements shall be made with a peak deviation of 5 kHz. Wideband FM measurements shall be made with a peak deviation of 20 kHz. All measurements shall be taken with a modulation rate of 1 kHz.

5.2.3.3 Selectivity. The 6-dB bandwidth shall be at least 24 kHz, the 60-bD bandwidth shall be no more than 50 kHz and the 100-db bandwidth shall be no more than 2 MHz for narrow band modes. For wideband modes the 6-dB bandwidth shall be at least 70 kHz and the 60-dB bandwidth shall be no more than 140 kHz. The peak-to-peak ripple of the 6-dB bandwidth shall not exceed 3 dB.

5.2.3.4 Squelch. When receiver squelch is employed it shall not be dependent upon the addition of special characteristics to the transmitted signal in transceivers. The squelch circuit shall be able to control the switching of another radio for retransmission, and the attack time shall not be greater than 50 ms.