User's Guide

T6T 50 W VHF Transmitter Page 7 Specification
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Mode 2
This section gives the transmitter’s specification applicable to Mode 2 operation. Mode 2 parameters are
identical to AM-Voice mode parameters with the following exceptions:
RF Power Rise Time
All models The transmitter produces more than 90% of full power output within
the first 2 symbols of the power stabilization segment, which is the first
segment of the training sequence and consists of 4 symbols each
representing 000.
RF Power Decay Time
All models The output power decays by more than 20 dB within 2.5 symbols of
the middle of the final symbol.
Channel Spacing
All models 25 kHz channel spacing only.
Transmitter Modulation Characteristics
Mode
All models Mode 2 uses Carrier Sense Multiple Access (CSMA) differentially
encoded 8-phase shift keying (D8PSK), using a raised cosine filter
with α=0.6 (nominal value), emission designator 14K0G1DE.
Information is differentially encoded with 3 bits per symbol transmitted
as changes in phase rather than absolute phase. The data stream is
divided into groups of 3 consecutive data bits, least significant bit first.
Zeros are padded to the end of transmissions if needed for the final
channel symbol.
Modulation Rate
All models The symbol rate is 10,500 symbols/second (±0.005%), resulting in a
nominal bit rate of 31,500 bits/s.
RMS Phase Error
All models The RMS phase error is less than 3°. The error vector magnitude is
less than 6%.
Phase Acceleration
All models The total frequency change during the transmission of the unique word
is less than 10 Hz. After this, the phase acceleration is less than
500 Hz/s.