User's Manual

○
14
How to reduce the interference of
FM?
Shorten the lever, change the direction of the
antenna, change the listening position, and keep
away from personal computer equipment, to
reduce the degree of interference.
○
16
Shortwave radio
Shortwave is transmitted mainly relying on the reflection
and refraction between ionosphere and the ground,
regardless of day and night. Shortwave can be transmitted
very far, so the radio can listen to the long-range radio
sound in shortwave band.
⑮
How to achieve long distance
listening of FM radio?
Use VHF outdoor TV antenna and antenna
amplifier. Install the antenna as high as
possible, align the antenna at the direction of
the FM radio, and connect to the
radiotelescopic antenna with 75 ohm coaxial
cable, so that the receiving capacity can be
greatly improved. Some cities have used cable
television networks to transmit cable FM
programs. Attempt may be made to pull the
antenna from a cable jack.
Shortwave frequency is between 2 and 30 MHz, and is
divided into civilian broadcasting meter band and
communication dedicated band. Civil broadcast use
amplitude modulation system and shortwave
communication typically uses single sideband (SSB)
system.
⑰
Why does the shortwave radio sound
suddenly rise or decline?
The ionosphere that propagates the shortwave is unstable,
because its thickness, height and ionospheric density
change at any time, especially during daytime. The
shortwave signal arriving at the radio is sometimes strong
or weak. Therefore, when listening to shortwave
broadcasting, the sound may suddenly rise or decline. This
phenomenon may be mitigated for the radio with good
automatic gain control <AGC> performance.
⑱
Medium wave broadcasting
Medium wave is the world's first and
most widely used folk broadcasting
band, which is mainly applied in
domestic, provincial and municipal,
regional and other medium-distance
radio, and has rich programs.
Wave broadcast characteristics: short
range during daytime, and long distance
during night, easy to suffer from the
interference from lightning and
household appliances.
China medium wave broadcast
frequency: 525~1610kHz, step length
9kHz.