Which instrument is used to measure the phase difference between two RF signals?

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Multiple Choice

Which instrument is used to measure the phase difference between two RF signals?

To determine how two RF signals phase relative to each other, you need to compare them in time. An oscilloscope does this best because it displays voltages versus time on two channels. With both signals visible, you can align a reference point on one waveform (like a zero crossing or a rising edge) with the corresponding point on the other and read the time difference between them. This time difference Δt translates directly into phase difference using the formulas phi = 360° × (Δt / T) or phi = 2π f Δt, where f is the signal frequency and T is the period. For example, at 1 MHz, a Δt of 0.25 microseconds corresponds to a 90° phase shift. Also, account for any delays from probes and cables, since those can add extra phase shift. A spectrum analyzer shows how signal power is distributed across frequencies and isn’t designed to reveal the time-domain relationship between two signals, so it isn’t the right tool for measuring phase difference. A digital multimeter measures voltage or resistance but not the phase relationship between two RF signals. A service monitor is great for general RF testing but typically doesn’t provide straightforward, precise two-channel time-domain phase measurements.

To determine how two RF signals phase relative to each other, you need to compare them in time. An oscilloscope does this best because it displays voltages versus time on two channels. With both signals visible, you can align a reference point on one waveform (like a zero crossing or a rising edge) with the corresponding point on the other and read the time difference between them. This time difference Δt translates directly into phase difference using the formulas phi = 360° × (Δt / T) or phi = 2π f Δt, where f is the signal frequency and T is the period. For example, at 1 MHz, a Δt of 0.25 microseconds corresponds to a 90° phase shift. Also, account for any delays from probes and cables, since those can add extra phase shift.

A spectrum analyzer shows how signal power is distributed across frequencies and isn’t designed to reveal the time-domain relationship between two signals, so it isn’t the right tool for measuring phase difference. A digital multimeter measures voltage or resistance but not the phase relationship between two RF signals. A service monitor is great for general RF testing but typically doesn’t provide straightforward, precise two-channel time-domain phase measurements.

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