PP-5M

PP-5M transceiver in the RV-5M radio altimeter

The PP-5M is the primary transmitter–receiver unit of the RV-5M radio altimeter set. It is the core electronic block that generates, transmits, receives and processes microwave signals used to determine true aircraft altitude above ground or water. The PP-5M is used during low-altitude flight, approach, landing and other operating modes where the crew needs direct information about actual clearance below the aircraft.

Role of PP-5M in altitude measurement

In the RV-5M system, the PP-5M generates the probing microwave signal and sends it to the external antenna path. After reflection from the surface, the return signal is received through the antenna system and processed inside the transceiver. The unit extracts height information and sends it to the cockpit indicator and related aircraft systems. The PP-5M therefore performs the main signal-generation and signal-processing functions of the radio altimeter set.

Connection with AR5-1 antennas and cockpit indicator

The PP-5M operates with two AR5-1 antennas, one used for transmission and the other for reception. It also connects to the cockpit height indicator, aircraft wiring and interconnecting cables. In a typical RV-5M configuration, the transceiver works with an A-034-4 series indicator, including A-034-4-24 depending on aircraft installation. The antennas provide the microwave path, the PP-5M processes the signal, and the indicator gives the crew a readable radio-height value.

Danger Height and Failure / OK signaling

The PP-5M supports generation of Danger Height warning outputs. When the aircraft descends below the selected height threshold, the system can provide warning signals to the cockpit equipment. The unit also forms Failure / OK signaling for crew systems. This allows the aircraft equipment to show whether the radio altimeter is operating correctly or whether the indication should not be relied on. Fault logic is especially important when the system loses usable reflected signal or fails internal control.

Built-in control and reference-height check

The PP-5M includes built-in health monitoring with reference-height control. During system checking, the radio altimeter can generate a control indication value of 15 ±1.5 m. This allows the crew or maintenance personnel to verify whether the receiver, measuring path, indication circuit and related outputs respond correctly. If the system does not provide the expected control indication, the transceiver, antennas, indicator, cables and power supply should be checked according to the aircraft documentation.

Installation on RA-5 shock-mount frame

The PP-5M is installed on the RA-5 shock-isolated mounting frame. This mounting arrangement protects the transceiver from vibration and mechanical loads during aircraft operation. The unit connects to AR5-1 antennas, cockpit indication equipment and aircraft cabling through the approved wiring set, including GU4.850.668-29 / GU4.850-759 cables depending on configuration. Since the PP-5M is a replaceable block, it can be removed and replaced independently during service when allowed by documentation.

Identification and supply of PP-5M

For procurement, the designation PP-5M should be used. Alternative names such as PP5M, RV-5M TxRx unit, RB-5M transceiver unit or transceiver 5M may appear in correspondence, but the exact designation and configuration should be confirmed by documentation. Before supply, it is important to check condition, mounting frame availability, connectors, cable compatibility, operating range, associated indicator type, antenna set and passport / manual availability.

Product Name: Radio Altimeter Transceiver
Designation: PP-5M
Product Type: Microwave transmitter–receiver block
System Application: RV-5M radio altimeter set
Role: Signal generation, reception and processing
Function: Transmission of probing signal, reception of reflected energy and formation of height information
Altitude Measurement Range: 0–300 m / 0–750 m / 0–1000 m, depending on system configuration
Residual Height H₀: 5.3 m
Accuracy, 0–10 m: ±0.6 m
Accuracy Above 10 m: ±0.6H
Indicator Error: ±0.08H
Danger Height Error, 5–10 m: ±0.5 m
Danger Height Error Above 10 m: ±(1 + 0.05H) m
Sensitivity, K-5 Path: ≥87 dB
Calibration Error: ±0.3H, automatic
Control Indication Value: 15 ±1.5 m
Pulse Output “1 PC”: 10–700 m
Pulse Output “2 PC”: 10–1000 m
Failure / OK Output: 27 ±2 V
Power Supply: 27 V DC + 115 V, 400 Hz through aircraft wiring
Operating Frequency: 4200–4400 MHz
Warm-Up: Automatic
Continuous Operation: Up to 6 hours
Mass: Approx. 6.9 ±0.3 kg with mounting
Mounting: RA-5 shock-isolated frame
Connected Equipment: AR5-1 antennas, 2 pcs; A-034-4-24 indicator; aircraft wiring and interconnecting cables
Associated Cables: GU4.850.668-29 / GU4.850-759, depending on configuration
Condition: As applicable
Alternate Designations: PP-5M; PP5M; RV-5M TxRx unit; RB-5M transceiver unit; transceiver 5M
Documentation: Product passport and operating manual available

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