The main performance indicators and meaning of the walkie-talkie
The main performance indicators and meaning of the walkie-talkie:
Frequency error: The difference between the unmodulated carrier frequency and the assigned frequency.
Output carrier power: The average power of the transmitting rack to the transmission line in one RF cycle without modulation. Indicates the amount of energy emitted by the machine.
Spurious radio frequency component: A signal having a significant component on a discrete frequency or in a narrow frequency band, in addition to the modulation component at the vicinity of the carrier and its transmission bandwidth. Includes harmonic and non-harmonic and parasitic components.
Adjacent channel power: The portion of the total output power that falls within the specified bandwidth of any adjacent channel under the specified modulation conditions for the transmitter operating in a channel-divided system.
Audio Distortion: The ratio of the rms value of the uncorrupted chord signal whose fundamental component is removed to the rms value of the full signal, expressed as a percentage. This distorted sinusoidal signal includes harmonic components, power supply ripple, and non-harmonic components. .
Modulation Limit: The transmitter audio circuitry prevents the modulation from exceeding the maximum allowable offset.
Rated audio output power: The power available when the receiver is connected to a specified load at the specified operating conditions.
Reference Sensitivity: Also known as the maximum available sensitivity, the input signal level at the receiver output produces a standard signal-to-noise ratio (12dBSINAD) at a specified frequency and modulation.
Selectivity: Characterizes the receiver's ability to resist input signals with input signals. It is evaluated by measuring the performance of adjacent signal selectivity, co-channel rejection, blocking, spurious response, and intermodulation immunity.
CTCSS: CTCSS (Continuous Tone Coded Squelch System) is a technology that adds a frequency lower than the audio frequency (67-250.3 Hz) to the audio signal. Because its frequency range is below standard audio, that is, less than 300 Hz, it is called sub-audio.
Sound digital: CDCSS (Continuous Digital Coded Squelch System), consisting of a code group, is issued cyclically. Its transmission rate is 134.4HZ, because it is also less than 300HZ, so it is called sub-tone digital. There are typically 104 sets of digital codes. Its function is the same as CTCSS, except that it is digitally encoded as a condition for whether mute is turned on.
Dual tone multi-frequency:
DTMF (dual tone multi frequency) consists of a high frequency group and a low frequency group, and the high and low frequency groups each contain four frequencies. A high frequency signal and a low frequency signal are superimposed into a combined signal, representing a number. The high and low frequency groups can be combined into 16 combined signals representing 0-9, *, #, A, B, C, and D, respectively.