The satellite can transmit signals using both microwaves and ultraviolet waves.

(i) State one property of waves that is the same for microwaves and ultraviolet waves.

(ii) State two properties of waves that are different for microwaves and ultraviolet waves.

The graph shows five pulses of the signal received from the satellite.

![A graph showing the signal voltage in millivolts (mV) of a satellite beacon on the vertical axis against time in seconds (s) on the horizontal axis. The vertical axis is graded from 0 to 5 mV, with major gridlines every 1 mV and minor gridlines every 0.1 mV. The horizontal axis is graded from 0 to 10 s, with major gridlines every 1 s and minor gridlines every 0.1 s. There are five very narrow, triangular pulse peaks rising from a baseline of 0 mV:

1. The first peak is at exactly 0.6 s, reaching a height of 3.8 mV.
2. The second peak is at exactly 2.7 s, reaching a height of 4.2 mV.
3. The third peak is at exactly 4.9 s, reaching a height of 3.6 mV.
4. The fourth peak is at exactly 7.1 s, reaching a height of 4.0 mV.
5. The fifth peak is at exactly 9.4 s, reaching a height of 3.7 mV. Between each pulse, the signal voltage lies flat at 0 mV.](https://assets.mathsgenie.co.uk/aqa-qb/f4288066-9163-4890-a903-b21e75463c78.png)

(i) Explain how the graph shows that the signal is not digital.

(ii) Use the graph to estimate the average time between each pulse.

(iii) Calculate the frequency of the pulses in the signal. Give the unit.