Freedom R8100 SERIES, Operator'S Manual

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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 (dPMR
CAI compliant).
BER Test (DPMR submenu)
Start or Stop Bit Error Rate (BER) testing in the dPMR 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 dPMR zone in the BER field.
Voice Loopback (DPMR submenu)
This menu selection enables the Voice Loopback feature in dPMR 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
2.2.7.8-3 . 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 dPMR 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
R8100 is power cycled, or if the Generate mode is selected and a new test pattern is enabled by setting the