Freedom R8100 SERIES, Руководство оператора

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Figure 3.2.8.6.1-1 NXDN™ Monitor mode
Bit Rate (NXDN™ submenu)
Selects the bit rate used by the NXDN™ radio, either 4800 bps (6.25 kHz channel) or 9600 bps (12.5 kHz
channel).
Test Pattern (NXDN™ submenu)
Provides selection of bit patterns for testing the radio in transmit mode while under RSS control. The
following patterns are available:
1031 Hz Tone – The framed test pattern of the 1031 Hz half-rate vocoder tone (NXDN™ CAI compliant).
1011 Hz Tone – (Only selectable for Bit Rate 9600 bps) The framed test pattern of the 1011 Hz full-rate
vocoder tone (NXDN™ CAI compliant).
Calibration (O.153 2%) – A test pattern derived from the 511 (O.153) pattern to yield a 2.005871% BER
used to verify BER measurements are operating correctly.
511 (O.153) – The unframed test pattern of continuously repeating 511-bit pseudo random number
sequences generated with a 9 bit shift register (PN9) based on ITU-T O.153 (formerly CCITT V.52) used
to perform BER testing for checking the modulation, encoding, and timing of the transmit signal
(NXDN™ CAI compliant).
BER Test (NXDN™ submenu)
Start or Stop Bit Error Rate (BER) testing in the NXDN™ mode of the R8100. This bit error rate test
checks the modulation, encoding and timing of the transmit signal during the data transmission period.
When performing the BER Test the radio transmitter under test must be placed into a test diagnostic mode
with the correct TX test pattern selected using the manufacturer’s Radio Service Software (RSS). The test
is done at nominal power with the radio transmitting the test pattern into the service monitor. (It is
acceptable to have an attenuator between the radio under test and the service monitor.) BER test results,
the percentage of bit differences between the bits of the selected Test Pattern and the bits from the received
synchronized FDMA signal, are shown in the NXDN™ zone in the BER field.
Voice Loopback (NXDN™ submenu)
This menu selection enables the Voice Loopback feature in NXDN™ mode (U.S. patent 5703479). Once
enabled the R8100 automatically records voice channel data when the radio under test transmits a signal
above the squelch level setting. A green Voice Playback Active indicator appears in the test mode zone
when Voice Loopback is enabled on the Voice Loopback screen. The Record Duration setting determines
the maximum length of the recording and a bar graph meter shows the recording’s progress – see Figure
3.2.8.6.1-2. The recording continues if the transmission is longer than the duration, but only the most
recent is retained. When the radio is un-keyed the R8100 automatically switches to Generate mode and
transmits the captured voice channel information or speech back to the radio. This provides a quick end–
to-end test of the NXDN™ radio transmitter and receiver.
Voice channel recordings can be played back at any time by pressing the Play Last Recording soft key
(this selection only appears after a recording has been made). Note: Recorded information is lost if the