1. Satellite Communication

2. Starter In module P1 we used the equation Wave speed (v) = frequency (f) x wavelength ( ) in m/s in Hz in m V f The BBC broadcasts its World Service to Africa using wavelengths of 32m. It broadcasts Radio 1 using wavelengths of 3.06m. Calculate the frequency of the waves for both stations. (Remember waves will travel at 300 000 000m/s) Extension: can you remember why the frequency used for Radio 1 could not be used to transmit to Africa?

3. Answers: World service: – Frequency = speed/wavelength = 300 000 000/32 = 9 375 000Hz or 9 375KHz Radio 1: – Frequency = speed/wavelength = 300 000 000/3.06 = 98 039 215 or 98 MHz

4. know how information can be transmitted to satellites. Know why satellite dishes need careful alignment. Learning objectives

5. Describe how information can be transmitted to satellites. (Grade C) Describe how different electromagnetic waves behave in the atmosphere. (Grade B) Explain why satellite dishes must be carefully aligned. (Grade A) Success criteria

6. Using radio waves The higher the frequency of a radio wave, the more penetrating it is: – High frequency radio waves pass through the earth’s atmosphere. – Low frequency radio waves are stopped by the earth’s atmosphere. The highest frequency radio waves are called microwaves.

7. Demo of refraction using triangular prism

9. Read page 204-205 (new book) and answer the following in full sentences 1.How high are geostationary satellites above earth? 2.Why are microwaves, rather than radio waves, used to send information to geostationary satellites? 3.What happens to radio frequencies below 30MHz? (HIGHER – Use page 205) 4.What happens to radio frequencies above 30GHz?

10. Answers 1.36 000km 2.They are higher frequency, so are able to pass through the atmosphere. 3.They undergo a series of refractions in the ionosphere, until TIR occurs. 4.They are absorbed and scattered by rain, dust and other atmospheric effects.

11. Foundation: Complete worksheet P5e1 (old course) Higher: Complete worksheet P5e2 (old course)

12. Answers Foundation 1.C 2.G 3.A 4.J 5.B 6.E 7.H 8.I 9.D 10.F Higher 1. 300 MHz, so that waves can penetrate the ionosphere with the minimum amount of diffraction 0.24 s 1 m 2. Because they transmit at different frequencies

13. Satellite dishes Are said to be parabolic. Use page 205 (new book) to explain why it is important that satellite dishes (both transmitting and receiving) must be carefully aligned.

14. know how information can be transmitted to satellites. Know why satellite dishes need careful alignment. Learning objectives

15. Describe how information can be transmitted to satellites. (Grade C) Describe how different electromagnetic waves behave in the atmosphere. (Grade B) Explain why satellite dishes must be carefully aligned. (Grade A) Success criteria

16. Plenary Taboo with key words from lesson.