Question
Why should effective radiated power (ERP) be limited to a satellite that uses a linear transponder?
Answer Options
- A) To prevent creating errors in the satellite telemetry
- B) To avoid reducing the downlink power to all other users
- C) To prevent the satellite from emitting out-of-band signals
- D) To avoid interfering with terrestrial QSOs
Correct Answer: B
Explanation
A linear transponder typically shares a fixed amount of total output power among all users currently transmitting through it. If a single ground station uses too much Effective Radiated Power (ERP) on the uplink, their strong signal will consume a disproportionate amount of the satellite’s limited power budget upon retransmission.
Overpowering the uplink signal has two negative effects: it may drive the satellite’s output amplifier into non-linearity (distortion), and most importantly, it will avoid reducing the downlink power to all other users. This action, often referred to as ‘hogging the transponder,’ reduces the signal-to-noise ratio for everyone else, making it harder for weak-signal users to communicate. Operating etiquette requires minimizing ERP to only what is necessary to hear your own signal clearly on the downlink.
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