2.2.7.5.1 NXDN™ transmitter tests
The entire suite of NXDN™ transmitter tests are available in R8100 Monitor mode after the NXDN™
soft key is pressed – see Figure 3.2.8.6.1-1. During radio transmission the R8100 continuously measures
the quality of the transmitted 4FSK signal. Numerical results are displayed as Symbol Deviation and
Modulation Fidelity in the NXDN™ zone. Framing is decoded to display the Radio Access Number
(RAN).. When the Eye Diagram is selected in the Display Zone, the R8100 overlays the modulation
response over four “target” crossing points for an ideal NXDN™ signal. BER tests require use of the
manufacturer’s RSS to place the radio in a special test mode.
2.2.7.5.1.1 RF Zone
Input Level (RF Zone display)
Input Lvl displays the average power in the NXDN channel under test.
Note: When the RF input power on the RF In/Out port is above +20 dBm (100 mW), the R8100 utilizes a
broadband power detector for the measurement. The “Input Lvl” field in the RF Zone changes to “Watt
Meter” to indicate this measurement mode. For best accuracy disable the Pre-amplifier in Monitor Mode,
and set the Gen Port in Generate Mode to RF In/Out.
Freq Error (RF Zone display)
Freq Error displays the frequency difference of the received NXDN transmission carrier minus the R8100
Monitor Frequency.
Deviation (RF Zone display)
Displays the positive peak FM frequency deviation of the received modulated carrier (i.e. from the
Frequency Error mean). See negative peak frequency deviation with Display Zone Bar Graphs.
2.2.7.5.1.2 NXDN™ Zone
Symbol Deviation (NXDN™ Zone display)
NXDN™ radios broadcast voice and data using a 4 level frequency deviation of the carrier to represent
symbols containing data bits as shown in the table below. The nominal symbol deviation value for an
NXDN™ radio using 4FSK modulation is 1050 Hz in a 6.25kHz channel and 2400 Hz in a 12.5kHz
channel. Since the deviation of An NXDN™ 4FSK signal is data dependent, that aspect is factored when
measuring overall carrier deviation. The Symbol Deviation field provides the deviation measurement at
symbol decision times.
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