1 00:00:01,550 --> 00:00:03,150 Hi there, welcome back. 2 00:00:03,560 --> 00:00:11,510 In this lesson, we will see how radio frequencies are classified and their possible use in Iot architectures 3 00:00:11,510 --> 00:00:12,310 and systems. 4 00:00:13,040 --> 00:00:20,660 The table shows the entire classification of the radio frequency spectrum, from L.F. waves to gamma 5 00:00:20,660 --> 00:00:26,510 rays, highlighting the frequency ranges and the relative wavelengths. 6 00:00:29,250 --> 00:00:33,990 Let's now see the applications of radio waves to Iot devices. 7 00:00:34,470 --> 00:00:42,540 Let's start with the use of infrared in remote controls for TVs and appliances or other devices. 8 00:00:43,540 --> 00:00:50,140 Transmission of signal in infrared remote controllers use a modulation with a carrier frequency 9 00:00:50,140 --> 00:00:54,130 typical at 38 kilohertz. 10 00:00:55,120 --> 00:01:03,040 The infrared light is emitted from an IR LED controlled by the modulated signal. The modulation 11 00:01:03,040 --> 00:01:03,470 used 12 00:01:03,490 --> 00:01:15,010 is a digital modulation, the ASK (Amplitude Shift Keying) generally OOK (On-Off Keying) or FSK (Frequency 13 00:01:15,010 --> 00:01:15,970 Shift Keying). 14 00:01:16,930 --> 00:01:24,850 The limit of infrared technology is that it requires a direct and unobstructed line between the 15 00:01:24,850 --> 00:01:29,580 remote control and the device to be controlled in order to function. 16 00:01:32,100 --> 00:01:40,050 There are tools for detecting signals in the infrared and visible light spectrum for analysis and testing 17 00:01:40,620 --> 00:01:48,750 and analyzing them on PC, such as the OpticSpy tool, shown in the figure below. 18 00:01:51,900 --> 00:01:59,010 Now, let's see the frequency spectrum typically used by RF remote controls, which can be 19 00:01:59,010 --> 00:02:08,940 used, for example, to control devices such as alarms, door opening systems, air conditioners, etc., Typical 20 00:02:08,940 --> 00:02:20,400 transmission as RF carrier frequency is at 315 megahertz or four hundred thirty four megahertz 21 00:02:20,400 --> 00:02:23,670 or eight hundred sixty eight megahertz. 22 00:02:24,300 --> 00:02:27,270 Popular modulation technique used 23 00:02:27,280 --> 00:02:29,640 are again Amplitude 24 00:02:29,640 --> 00:02:35,760 Shift Keying, often implemented as OOK, and Frequency Shift Keying. 25 00:02:39,740 --> 00:02:48,350 AM broadcasting is radio broadcasting using amplitude modulation transmissions. Commercial AM radio 26 00:02:48,350 --> 00:02:56,690 stations operate at frequencies between five hundred twenty five kilohertz and one thousand six hundred 27 00:02:56,690 --> 00:03:01,280 fifteen kilohertz, separated by 10 kilohertz. 28 00:03:03,860 --> 00:03:12,350 Let's talk now about CB (Citizens Band) radio, used in many countries; is a land mobile radio system. 29 00:03:12,890 --> 00:03:20,600 Permits short-distance person-to-person bidirectional voice communication between individuals, using 30 00:03:20,600 --> 00:03:26,750 two way radios operating on 40 channels near 27 megahertz. 31 00:03:30,050 --> 00:03:39,380 And FM broadcasting is a radio broadcasting using frequency modulation transmissions. Commercial FM radio 32 00:03:39,380 --> 00:03:48,920 station operate generally on frequencies between eighty seven point five megahertz to 108 megahertz, 33 00:03:49,340 --> 00:03:53,720 separated the channels by 200 kilohertz. 34 00:03:57,310 --> 00:04:04,120 Certain subparts of the VHF band have the same use around the world. 35 00:04:04,690 --> 00:04:09,520 Some national uses are detailed in this slide. 36 00:04:13,200 --> 00:04:21,750 As regards the most used protocols in the Iot field, the slide shows a range of radio frequencies used. 37 00:04:22,530 --> 00:04:31,560 For example, Z-wave uses the frequency eight hundred sixty eight point four megahertz. Bluetooth 38 00:04:31,830 --> 00:04:40,740 uses frequencies between two point four gigahertz and two point four eight three five gigahertz and 39 00:04:40,740 --> 00:04:47,080 so on for the other popular protocols such as ZigBee, wifi 40 00:04:47,100 --> 00:04:48,120 HaLow, LoRa 41 00:04:52,320 --> 00:05:00,450 As for the instruments that can be used for SDR that is Software Defined Radio to acquire, analyze, 42 00:05:00,600 --> 00:05:10,050 retransmit radio signals in the field of security tests and diagnostics, there are several on the market, 43 00:05:10,050 --> 00:05:13,950 depending on the range of frequencies that can be analyzed. 44 00:05:14,730 --> 00:05:16,050 HackRF One 45 00:05:16,050 --> 00:05:24,630 is capable, for example, of transmitting and receiving half duplex in the range between 1 megahertz 46 00:05:24,780 --> 00:05:26,910 to 6 gigahertz. 47 00:05:29,320 --> 00:05:37,790 Another popular tool for SDR is Yard Stick one that is capable of transmitting and receiving 48 00:05:37,790 --> 00:05:46,990 in half duplex way at frequencies less than one gigahertz, and supporting modulations such 49 00:05:46,990 --> 00:05:51,580 as ASK, OOK, GFSK, etc.. 50 00:05:54,850 --> 00:05:58,930 OK, thank you for your kind attention, bye.