Category Archives :Radio knowledge

Vocoders are basically used for digital coding of speech and voice simulation. The bitrate for available narrowband vocoders is from 1.2 to 64 kbps.  ...

In order to communicate with more hams, when we choose walkie-talkies, we will like to choose the highest output power as much as possible when permitted by law. However, sometimes the actual power is much lower than the nominal power. Why or how can we obtain higher output power?  ...

The squelch switch is a function specially designed to solve the contradiction between the call quality and noise of the wireless walkie-talkie.  ...

The signal report of an amateur station consists of three parts: "R" representing the discernibility of the signal, "S" representing the signal strength, and "T" (Tone, the quality of the signal) representing the signal tone, so the signal report often becomes " RST".  ...

Superheterodyne receiver is to convert the high-frequency signal received by the receiver into an intermediate frequency signal through a mixer and then output the intermediate frequency signal to the detection circuit. This intermediate frequency signal is a fixed difference signal obtained by subtracting the local oscillator frequency and the received signal frequency​.  ...

The local oscillator frequency is a term often mentioned in the superheterodyne receivers. The local oscillator frequency is generated by the local oscillator circuit. There is a local oscillator in the superheterodyne receiver, which can output a stable high-frequency electromagnetic wave, which is mixed with the received high-frequency signal to produce a different frequency. This difference frequency is Intermediate frequency, that is heterodyne, which in turn forms superheterodyne receiver.  ...

IFG is short for Intermediate Frequency Gain and is an important setting item for radio. Intermediate Frequency usually refers to a signal obtained by frequency conversion of high-frequency signals in the superheterodyne receiver Circuit.  ...

AGC is short for Automatic Gain Control,  which is used to amplify signals of different strengths with different gains so that the final output amplitude of the signal is maintained at the same standard. We know that in addition to AGC, we also have automatic level control (ALC), so why do we still need automatic gain control?  ...

Impedance is an important parameter of the antenna, which is determined by the physical structure of the antenna, such as the shape, size, material, and environment of use. The impedance matching of the antenna is the process of matching both the impedance of the antenna and transmitting the source through tuning. So, why do you need to do antenna impedance matching?  ...

Communication distance is an important indicator of walkie-talkies, but why is there no distance parameter in the parameters of walkie-talkies? There are also some descriptions that have a distance description, but the range is very large, such as 2~5 kilometers. How should I understand this communication distance?  ...