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

(DO 0.2 ppm) during the first 30 day period after alignment, and 1.0ppm [DO 0.1 ppm) each 30- dsy period thereafter.

5.2.1.6 Frequency Calibration Resolution. The radio equipment shall incorporate a frequency adjustment control that will calibrate and align the radio equipment to within 1.0 ppm (DO 0.1 ppm) of its assigned frequency.

5.2.1.7 Audio Frequency Response.

5.2.1.7.1 Narrowband. The frequency response of the radio equipment over the range of 300 to

3500 Hz shall be within ±2 dB of the response at 1000 Hz.

5.2.1.7.2 Wideband. The frequency response of the radio equipment over the range of 20 Hz to

20 kHz shall be within ±3 dB with a minimum rolloff of 6 dB/octave above and below the bandpass, except that from 300 to 3500 Hz the amplitude frequency response I shall not vary by more than ±2 dB.

5.2.1.8 Morse Code Telegraphy. Equipment that is intended to operate with Morse code telegraphy shall be compatible with on-off keying of a 1000 Hz (±10 Hz) tone at rates up to 30 words per minute (wpm) in a manual mode and up to 300 wpm in a burst mode.

5.2.1.9 Digital Performance Characteristics.

5.2.1.9.1 Bit Error Ratio (BER). Not standardized. For digital radio equipment applications, the

BER shall be established by the applicable equipment specifications.

5.2.1.9.2 Character-Count and Bit-Count Integrity. For radio equipment designed to be used for digital communications, no extraneous characters or bits shall be inserted, nor shall any valid characters or bits be deleted in bit streams representing digitized voice or message texts. This requirement shall apply to all modulation and data signaling rates and shall be measured with the transmitter and receiver set up in a back-to-back configuration. This measurement shall be made over a continuous 24 hour or longer time period.

5.2.1.9.3 Protection of Signal Sense. Radio equipment designed to be used for digital communications one shall not invert the logic or signal sense of the data stream for digital applications.

NOTE: This requirement does not preclude manual selection of inverted bit streams.

5.2.1.9.4 Jitter Error. In radio equipment designed to be used for digital communications, the stability of synchronization or clock timing shall be sufficient to ensure that synchronism is maintained between received and transmitted signals within ±25 percent of the unit interval for a

24-hour time period.

NOTE: The time period, expected to be less than 100,000 seconds for single channel radio equipment, is under consideration.