Why is the radio signal AM instead of a single sideband 20

AM is one of the linear modulation of analog signals, because the AM receiver can directly use envelope detection to accept the signal well, and the distortion is not large, the cost of envelope detection is low, the equipment is simple, mainly completed by RC loop, so AM can be used, and the cost is low.

The two forms of AM are bilateral band amplitude modulation and unilateral band amplitude modulation. Generally speaking, there are more single sidebands, because half of the bandwidth is saved. However, the propagation of AM is greatly affected by interference.

Because the bilateral band demodulator (receiver) is easy to make.

Both unilateral and bilateral generations are AM. (Amplitude Debugging).

The medium wave in the radio is a simple two-sided Dai amplitude modulation, which is due to historical reasons, because when the radio first appeared, the cost of the tube was extremely high and the utilization of the space frequency band was not high.

AM is single-sideband modulated, right? Bilateral bands consume too many radio resources.

Summary. Hello dear, it is mainly used to transmit voice, equal amplitude and frequency shift report. When transmitting ** signals, amplitude modulation and single-sideband modulation are used.

It is composed of a transmitter, a receiver, an antenna, a power supply and terminal equipment. Generally, it is divided into portable, vehicle-mounted and fixed radios. It has the characteristics of small size and light weight, usually uses whip antennas, uses ground waves for short-range communication, and the power is usually a few watts to tens of watts.

Hello dear, it is mainly used to transmit voice, equal amplitude and frequency shift report. When transmitting ** signals, amplitude modulation and single-sideband modulation are used. It is composed of a transmitter, a receiver, an antenna, a power supply and a terminal equipment curved cover.

Generally, it is divided into portable, vehicle-mounted and fixed radio. It has the characteristics of small size, light weight, etc., usually uses whip antennas, uses ground waves for short-range communication, and the power is usually a few watts to tens of watts.

Military shortwave radio stations are divided into portable, vehicle-mounted (or ship-based, airborne) and fixed radio stations according to their use and conditions of use. Portable radio stations are mainly used to ensure the communication and liaison of tactical detachments, with the characteristics of small size and light weight, generally using whip antennas, using ground waves for short-range communication, and the power is usually several watts to tens of watts. The vehicle-mounted stove radio is used to form a communication hub for the hidden land command post or for mobile communication, and its power is tens of watts to thousands of watts, and whip antennas and bipolar antennas are generally used.

Fixed radio stations are mainly used for strategic communications, usually composed of centralized sending stations and receiving centralized stations, with a power of hundreds of watts to thousands of watts, or even tens of kilowatts, and generally use large antennas with good performance. For the use of groundwave communications, the frequency range of portable and vehicle-mounted radios has been extended to the medium wave return code band, typically 1600 30000 kHz.

Monophonic function of ultra-shortwave radios.

Ultra-short-wave radio stations are equipped with relay or terminal stations and stations (including mobile stations) of communication equipment used to form ultra-short-wave communication circuits, also known as VHF radios. The wide family operates at a frequency of 30 300 MHz (with an operating wavelength of 1 10 m);The handheld computers, knapsack radios, and very noisy Li-frequency relay relays working in this frequency band are all ultra-short-wave radio stations.

Scatterers and meteor aftermath communication equipment, etc., are also ultra-shortwave stations. However, it usually refers to walkie-talkies, chain-based, vehicle-mounted (or airborne, ship-based) radios transmitted at ground wave or space wave visual range. It is mainly composed of parts such as transceiver, antenna, and power supply.

Ultra-short-wave radio stations can adopt amplitude modulation, frequency modulation, single sideband and other modulation systems, and the frequency modulation system is usually the main one, and its anti-imitation cherry interference performance is better than that of the amplitude modulation system and the unilateral sideband system.

When is the monophonic function used.

Monotone mainly tests the amplification performance of the power amplifier in the frequency band of monotone. For example, how about the ultra-low frequency amplification ability of the 20Hz sound test amplifier.

A shortwave single sideband station is a radio communication device that transmits and receives one of the two sideband signals of an amplitude modulation signal.

The transmission system of a single sideband radio station is divided into a prototype single sideband system and an independent single sideband system, the former only transmits the upper sideband or the first sideband information, and the latter transmits different information in the upper and lower sidebands, and a sideband (bandwidth 3 kHz) can transmit one call, multiple messages or data. Compared with AM radio, it has the advantages of saving spectrum, saving power, easy to cover and drying, and less affected by selective fading, but the land infiltration equipment is more complex. Single-sideband radio stations usually have a variety of working methods, such as equal amplitude newspapers, frequency-shift printed newspapers, unilateral sideband telephones and amplitude-modulated radios.

It is mainly used for long-distance and over-the-horizon communication.

A mode of radio communication ......