The radio receiver will provide 3 beacon cutoff frequencies in the 200 to 1000 kHz range.
The general radio receiver specifications are:

• Receiver frequencies: 257 kHz, 660 kHz, and 820 kHz.
• Frequency bandwidth: 20 kHz.
• IF frequency: 455 kHz.
• Analog output: 0-5 V
• Cutoff frequency: <50 Hz
• Rx channels: 6.

Figure 3.3.4.1 shows the block diagram of the radio receiver. The pre-amplifier printed
circuit board, PCB, has a dual function. It provides preamplification of the incoming radio
frequencies, and it filters the incoming power to further reduce the power regulator ripple.
Figure 3.3.4.2 is the pre-amp circuit schematic diagram. Figure 3.3.4.3 shows the receiver
super-heterodyne circuit which produces a modulated IF frequency of 455 kHz. Figure
3.3.4.4 shows the IF amplifier schematic, while Figure 3.3.4.5 shows the detector circuit.

Interface Requirements
The radio receiver subsystem interfaces with 3 other systems: the flight computer, the
power supply, and the payload architecture. Figure 3.3.4.6 indicates the location in the nose
cone of the PCB’s and magnetic loop antenna provided by TPU. It also shows the location of
the probe on the nose cone surface. Section 3.3.5 covers the ion and electron probes.

For more information go to SRP4 Comprehensive Design Manual page 101