DeshengR-404PHigh sensitivity FM/medium wave/short wave radio（For the elderly）

 ●Streamline design, dignified appearance.

 ●Using excellent radio integrated circuits, high sensitivity.

 ●Fast/slow adjustment knob, more convenient and accurate channel selection.

 ●Large-diameter speakers, loud and beautiful sound.

 ●Use R20（large）Battery powered, especially power saving.

 ●Physical size: 210 wide * 115 high * 60 thick（Mm）

Common problems and solutions when radio:

1: Televisions, fluorescent lamps, silicon dimmable desk lamps, computers, automobile engines, electric motors and other electrical equipment have strong radiation interference to the radio’s medium wave and short wave. When using the radio, please keep a certain distance from the above electrical appliances. Avoid interference.

2: The interior of the steel-reinforced building and the high-rise buildings around the listening location have a certain shielding effect on the broadcast signal. Using the radio near the window can improve the receiving effect.

3: The signal emitted by the “BB” station near the listening location will seriously interfere with the listening of shortwave and TV sound. Try to appropriately shorten the length of the whip antenna and adjust the angle. At the same time, change different listening positions. To improve reception.

4: The easiest way to improve the shortwave reception capability is to add a simple external antenna to the radio, that is, use a 3-4 meter long wire with one end wrapped around the whip antenna and the other end hanging outside the window. The higher the effect, the better.

5: Listening suggestions: It is recommended that you must pay attention to your geographic location when buying a radio

a: There are many FM radio stations in the city, you can buy FM stereo radio

b: In mountainous areas and rural areas far away from cities, due to distance, it is often impossible to listen to FM, FM stereo and TV audio programs, so buy a radio with high sensitivity for medium wave and short wave

Which band of radio waves are used for radio broadcasting and television? How are they spread??  

At present, AM radio broadcasting is divided into three large wave bands: long wave, medium wave and short wave, and the signals are respectively transmitted by radio waves in the corresponding bands. my country has only two large-band radio broadcasts, medium wave and short wave. The frequency band used by medium wave broadcasting is roughly 550kHz1600kHz, which mainly relies on ground wave propagation, accompanied by some sky waves; the frequency band used by shortwave broadcasting is about 2MHz-24MHz, which mainly relies on sky waves to propagate, and is accompanied by ground waves at close range. FM radio broadcasts mostly use ultrashort wave (VHF) radio waves to transmit signals, using frequencies of about 88MHz-108MHz, mainly relying on space waves to transmit signals. At present, terrestrial broadcast and television are divided into two frequency bands: VHF (VHF or Meter Wave) and UHF (Ultra High Frequency or Decimeter Wave). In my country, the frequency range used by VHF band TV is 48.5MHz-3MHz, divided into channels 1-12, and the frequency range used by UHF band is 470MHz-956MHz, divided into channels 3-68. They basically rely on space waves to propagate. There are 6 frequency bands for satellite broadcasting and television in the international regulations, the main frequency band is 12kMHz, which is also propagated by space waves.

【AM/FM introduction】What is an amplitude modulation wave? What is FM wave?

The modulation method that changes the carrier amplitude according to the modulation signal is called amplitude modulation. The amplitude-modulated radio waves are called amplitude-modulated waves. It maintains the frequency characteristics of the high-frequency carrier, but the shape of the envelope is similar to the signal waveform. The amplitude of the amplitude modulation wave is determined by the intensity of the modulation signal. The amplitude modulation wave is represented by the English letter AM. The modulation method that changes the carrier frequency according to the modulation signal is called frequency modulation. The magnitude of the frequency change of the modulated wave is determined by the size of the modulation signal, and the period of the change is determined by the frequency of the modulation signal. The amplitude of the modulated wave remains unchanged. The waveform of the FM wave is like a spring that is compressed unevenly. The FM wave is represented by the English letter FM.

What is a TV-accompanying radio? 

The TV sound (TV SOUND) uses the FM system, and the transmission method is the same as FM broadcasting, which is also short-distance transmission.  TV audio is divided into two sections, VHF and UHF, of which: VHF: Channel 1-12 (subdivided into VHF-L 1-5 and VHF-H 6-12) UHF: Channel 13-56. The current TV-accompanying radios mainly receive VHF channels 1-5 and 6-12, and rarely receive radios above channel 13 (UHF).

What is campus radio?
Campus broadcasting is a kind of low-power FM broadcasting. Many colleges, universities, middle schools and even elementary schools have now adopted a large number of campus FM broadcasting methods to broadcast English programs or other programs. The frequency range is usually between 76-87MHz, which means that ordinary The TV-accompanying radio can be received. Now some FM radios directly extend the frequency to 76-108MHz, which can meet the needs of listening to campus radio.

What does the full band of the radio mean?

The full band is also three bands: FM fm, medium wave am（mw）, Shortwave sw. fm is generally 87-108mhz, with campus broadcasting can reach 64-108mhz; am is generally 520-1650khz; sw is generally 5-21mhz（Maximum 2-29mhz）For the convenience of use, this frequency band is often divided into several small frequency bands, and sw1, sw2, …… may appear on specific radios. So there is a so-called 9-band or 12-band radio（fm+am+n sw）.

What is Frequency Modulation (FM), Amplitude Modulation (AM), Short Wave (SW), Long Wave (LW)?

There are AM and FM bands on general radios or radio tape recorders. I believe you are already familiar with them. These two bands are used to listen to domestic broadcasts. If there is SW band on the radio, in addition to domestic shortwave radio stations , You can also listen to radio programs from all over the world. In order to give you a better understanding of the use of the radio, the following is a brief description of what are AM, FM, SW, and LW. In fact, AM and FM refer to two different modulation methods in radiology. AM: Amplitude Modulation is called amplitude modulation, and FM: Frequency Modulation is called frequency modulation. It''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''s just that general medium wave broadcasting (MW: Medium Wave) uses amplitude modulation (AM). Unconsciously, MW and AM are equal. In fact, MW is just a kind of broadcast that uses AM modulation. For example, the modulation method used in high-frequency (3-30MHz) international shortwave broadcasting is also AM, and even higher frequency aviation navigation communications than FM broadcasting (116- 136MHz) is also the AM method, but the AM band we call daily refers to the medium wave broadcasting (MW）. What about FM? It is also similar to the fate of MW. We are used to using FM to refer to general FM radio（76-108MHz, 87.5-108MHz in my country, 76-90MHz in Japan）In fact, FM is also a modulation method, even in the shortwave range of 27-30MHz, as the band for amateur radio, space, satellite communication applications, FM is also used（FM）Way. And SW? In fact, it can be said to be a simple term for shortwave. The correct term should be high frequency (HF: High Frequency) which is more appropriate. And how did the name shortwave come from? In terms of wavelength, the medium wave (MW) is between 200-600 meters (meters), while the wavelength of HF is between 10-100 meters (meters). Compared with the above-mentioned wavelengths, HF The wavelength is indeed shorter, so HF is called short wave (SW: Short Wave）. Similarly, the frequency spectrum between 150KHz-284KHz, which is lower than the medium wave MW, is also used for broadcasting. In terms of wavelength, it is approximately between 1,000 and 2,000 meters (meters), and the MW is 200- Compared with 600 meters, it is obviously "longer", so the broadcasting of this frequency spectrum is called Long Wave (LW: Long Wave). In fact, no matter long wave (LW), medium wave (MW) or short wave (SW), AM modulation is adopted. For general radios (recording), the FM, MW, and LW bands are for you to listen to domestic broadcasts, but there is currently no LW radio station in my country, while the SW band is mainly for you to listen to domestic/international long-distance broadcasts.

Band characteristics: Amplitude modulation (medium wave) to listen to local radio programs; FM (FM) to listen to local radio programs; FM stereo (FM STEREO) to listen to local FM stereo radio programs; shortwave (SW) to listen to domestic and international long-distance radio programs .