CDC 3D153 v3 Flashcards
State the types of traffic an AN/TRC–170 radio terminal set might handle.
Dedicated traffic such as analog and digital channels, point-to-point circuits, facsimile circuits, and teletype circuits.
List the equipment included in an AN/TRC–170 tropospheric scatter terminal.
Antennas, transmitting and receiving equipment, digital multiplexing equipment, voice and data orderwire facilities, built-in test equipment, and communications security equipment.
List the data rates processed by the tropospheric scatter modem.
Mission traffic at 128 through 4,096 Kbps in the 512 data rate family, and 72 through 4,608 Kbps in the 576 data rate family.
Describe the upconversion process of the transmit amplifier.
The IF signal is upconverted in the transmit amplifier converter by mixing it with a local oscillator input from the synthesizers. The difference frequency is selected as the final transmit frequency of 4.4 to 5.0 GHz.
Explain the difference in the transmission power requirements between tropospheric scatter and line-of-sight.
The HPA is necessary for transmission in the tropospheric scatter mode (1 kW, 60 dBm). It is also possible to transmit in LOS mode by not using the klystron. The output is 29 dBm (800 mW).
What is the minimum spacing used to separate receive antennas in space diversity, and what is the most common amount of antenna separation used?
Minimum of 50 wavelengths; common receive antenna spacing is 100 or more wavelengths.
What principle of propagation does frequency diversity use to its advantage?
Frequency diversity uses the principle that two different microwave frequencies fade independently of each other even though they travel the same propagation path.
What is the ideal frequency separation in frequency diversity?
A separation of 5 percent is ideal.
Define polarization diversity.
In polarization diversity, the same frequency radiates simultaneously in two different planes: horizontal and vertical.
Explain quadruple diversity.
Quadruple diversity is a technique that employs a combination of two or more of the diversity types: a combination of frequency and space diversity or space and polarization diversity—or a system that uses four reception paths.
Explain the purpose of the digital data group modem.
It interfaces up to four groups of conditioned diphase signals, or up to four groups of dipulse signals, or a mixture of the two.
Describe the main purpose of the digital data group modem.
Primarily, it changes cable-side conditioned diphase or dipulse signals to balanced NRZ signals, and vice versa.
Describe the purpose of the low-speed cable driver modem.
Changes the cable-side conditioned diphase signal to NRZ for use by the AN/TRC–170 and supplies power to cable low-speed pulse restorers if required.
What data rates are used by the low-speed cable driver modem?
It accepts data at 72 to 2,048 Kbps on the equipment side; 2,304 Kbps on the cable side.
What is the range of the low-speed cable driver modem with and without pulse restorers?
Up to 40 miles with pulse restorers and 1 mile without pulse restorers.
Describe the capabilities of the trunk group multiplexer.
It multiplexes up to four groups of the 512 Kbps data rate families or four groups of 576 Kbps data rate families into one supergroup. It will not process group data rates from both families simultaneously. It demultiplexes a supergroup into separate groups at their original data rates. It can control a KG–81 trunk encryption device on both the group and supergroup side.
Describe the purpose of the KG–81 trunk encryption device.
Full-duplex encryption and/or decryption of group or supergroup mission traffic.
Describe the purpose of the KG–84 dedicated loop encryption device and the KG–84A general purpose encryption equipment.
Encrypts and/or decrypts telemetry data, processed through the alarm monitor.
Describe the purpose of the KY–58 VINSON.
Encrypts and/or decrypts digital voice orderwire traffic originating and terminating at the voice orderwire control unit.
What is the purpose of the baseband patch panel?
Connects the digital group multiplex equipment with the tropospheric scatter modem.
Describe the three divided fields of the baseband patch panel.
- The upper jack field provides timing and data connections for the trunk group multiplexer, tropospheric scatter modem, and trunk encryption device 1. The right side provides patching for black station clock. Also provided are convenience patch groups A, B, and C, that are internally hard-wired to jacks in the center jack field.
- The center jack field provides connections to the equipment side of the loop group multiplexers, group modem groups, and the low-speed cable driver modem. The black side of the trunk encryption device 2 is also available. The dejitterizer input and/or output jacks provide for patching a group timingsignal directly into the tropospheric scatter modem. Inputs to trunk group multiplexer groups 3 and 4are available. Convenience patch groups A, B, and C pass data and timing signals to the upper jackfield.
- The lower jack field provides data orderwire connections for through patching or patching to and/or from the dedicated loop encryption device patch panel by way of the level converter jacks. Also
provided are connections for the digital voice orderwire and resync commands to the group and super group trunk encryption devices.
Describe the purpose of the dedicated loop encryption device patch panel.
Provides for patching the local telemetry signals to the radio and/or cable side of the AN/TRC–170 and for monitoring baseband and dedicated loop encryption device patch panel activity.
Describe the data rates of the tropospheric scatter modem.
128 through 4,096 Kbps in the 512 data rate family and 72 through 4,608 Kbps in the 576 Kbps data rate family.
List the types of inputs to the tropospheric scatter modem.
Mission data, digital voice orderwire, and up to four data orderwires.