Radio broadcasting is the transmition of audio content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began with AM radio, which came into popular use around 1920 with the spread of vacuum tube radio transmitters and receivers. Before this, all forms of electronic communication (early radio, telephone, and telegraph) were one-to-one, with the message intended for a single recipient. The term broadcasting evolved from its use as the agricultural method of sowing seeds in a field by casting them broadly about. For example, amateur ("ham") and citizens band (CB) radio operators are not allowed to broadcast. As defined, "transmitting" and "broadcasting" are not the same. Transmission of radio and television programs from a radio or television station to home receivers by radio waves is referred to as "over the air" (OTA) or terrestrial broadcasting and in most countries requires a broadcasting license. Transmissions using a wire or cable, like cable television (which also retransmits OTA stations with their consent), are also considered broadcasts but do not necessarily require a license (though in some countries, a license is required). In the 2000s, transmissions of television and radio programs via streaming digital technology have increasingly been referred to as broadcasting as well.

Radio telecommunication at sea had undergone a sea change in the last century. After the days of semaphores and flags (which is still relevant today in some cases), radio brought about a drastic change in marine communication at sea. From the early years of the last century, ships started fitting radio for communicating distress signals among themselves and with the shore. Radio telegraphy using Morse code was used in the early part of the twentieth century for marine communication.

Airband or avionic radios are primarily used by pilots and Air Traffic Control as a means of two way communication and navigation. If you already have an aircraft you probably already know how important an Airband radio is. Airband radios use VHF frequencies and channels, different to those channels that are used on the ground as they are specifically set aside for use in avionics environments. Typically between 108 and 137 MHz.

Airband radios are divided into COM for voice communication and NAV for navigation. The NAV channels are still in use for VOR (VHF Omni Directional Radio Range) even though GPS is now widely used. A VOR is a type of short-range radio navigation system for aircraft, enabling aircraft with a receiving unit to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons. There are about 3,000 VOR stations worldwide.

Airband radios also include an emergency frequency at 121.5 MHz known as the International Air Distress (IAD) also known as the ‘guard' frequency. On Icom radios this is accessed by a single button which will send out a distress signal.

1 January 2018 all aircraft operating in airspace that requires the carriage of a radio must have 8.33 kHz-compatible equipment. More details about these changes can be found in our article 'The Impact of 8.33 kHz channel spacing for the Aviation Radio User'.

Radio Etiquette

Aeronautical radio messages must be limited to those concerning flight safety or flight regularity. Public correspondence and messages relating to air carrier/company business communications and passenger service/convenience are not permitted.

For further reading about the forthcoming 8.33kHz channel spacing changes, visit the dedicated CAA 8.33kHz radio page..

Spreading sequence is generated by LFSR x^20+x^19+x^18+x^16+x^11+x^8+x^5+x^2+1 (0x1D0925):

0101001001110100111011110101111110100111001100000001001001110111010001111110100100010010100100001000

0011000001011001011111110010000001001101101110011110100000100110100001100101101100010011010111110000

1010110111001001110100110111000010110110011110001100011000101011000100011001111011100101101011000001

0011110100111000000111100111000010000001000110101110110010011100010111100101001010100010101000100001

0111010010010100100101110001001111111001010111110000100101000101111000001100001000111110110111101000

0101011111101001111011010111011011100010110010000011010111101001110100111111100001010001111010000100

1110000001111101111011000100101110001000100010111000010011010111101100011001100010011001111010110111

0101111110001100000010011101010101011001011001110101010111101111110000111011111010100011100100101111

1101001110000111001001110001000101010100101100011110110110011010111101100000110101001111011010001000

0000001101011101000110110110110001011010110111000111100010001101101100110111010000001010100011000110

11000100010011101100000

Note that data bits are not aligned to spreading sequence, 1023 chips contain 76.725 data bits. 

Frame header looks like this:

1A CF FC 1D  4C 01 2E 0B 03 00 33 00 00 (10 random bytes/IV) 00 (26x 0xFF) (more random/encrypted bytes)

1A CF FC 1D  4C 01 2E 0B 04 00 33 00 00 ...

1A CF FC 1D  4C 01 2E 0B 07 00 33 00 00 ...

1A CF FC 1D  4C 01 2E 0B 08 00 33 00 00 ...

1A CF FC 1D  4C 01 2E 0B 0B 00 33 00 00 ...

1A CF FC 1D  4C 01 2E 0B 0C 00 33 00 00 ...

1A CF FC 1D  AA AA AA AA AA AA AA AA AA ... (idle frame)

Downlink is clearly encrypted, the 10 changing bytes in the header is probably encryption IV followed by encrypted data. 

Odditities

The downlink format is not really CCSDS compatible and there some deviations from standard or design mistakes:

1. Last frame byte is always 0x55, this means one of the RS ECC block codes will always have 1 error

2. Idle frame doesn't even have valid TM transfer frame header like it should, all bytes are just filled with 0xAA

3. Spacecraft ID is 0x30 and this ID is NOT SANA registered for this mission. Actually this ID is already assigned and in use by JAXA Hisaki SPRINT-A.

The Citizens Band Radio Service (CBRS) is a private, two-way, short-distance voice communications service for personal or business activities of the general public. It also may be used for voice paging. It is authorized 40 channels between 26.965 MHz and 27.405 MHz. Similar service includes the General Mobile Radio Service (GMRS). The CB Service provides a free and  without any admition tests or charges implied a service for short-distance communications by individuals and businesses. Over the years, changes occurred to the service such as adding additional channels; however, the purpose of the service has remained the same.

PMR stands for "Personal Mobile Radio" or Personal Mobile Radio service included the General Mobile Radio Service (GMRS). It is intended to be used by all citizens, freely and free of charge, without any license or authorization. This system is similar to the Citizen's Band (CB), with the difference being in the range of communications due to several limitations: it can only emit with 500 mW, only devices with built-in antennas are allowed, the longest range in UHF reaches the best income in line of sight. Thus, this is a service used in local communications with ranges of up to 5 kilometers, under ideal conditions (in line of sight). However, in the presence of obstacles, this distance is reduced. In a city, you can often reach more than a kilometer.

🌿 All of my equipments are charged and powered via solar DC power via 360W pannel and a solar gel 110Ah batterie using a MPPT 70A