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The main performance indicators and the meaning of the walkie talkie


Transmitter:

Frequency error:  The difference between the unmodulated carrier frequency and the assigned frequency.

Output carrier power: It means in the absence of modulation, the average power delivered by the transmitting rack to the transmission line in one RF cycle, it indicates the size of the energy emitted by the machine.

Stray radio frequency component: In addition to the modulation component near the carrier and its transmit bandwidth, there is a significant component of the signal at discrete frequencies or in narrow frequency bands. Including the harmonic, non-harmonic and parasitic components.

Adjacent channel power: The fraction of the total output power of a transmitter operating in a channel-divided system that falls within a specified bandwidth of any adjacent channel under a defined modulation condition.

Audio distortion: The ratio of the r.m.s. sinusoidal signal to its full signal r.m.s. value, expressed as a percentage, of this distorted sinusoidal signal includes the harmonic component, the power supply ripple, and the non-harmonic component.

Modulation limit: The transmitter audio circuitry prevents the modulation from exceeding the maximum permissible offset.

Receiver:

Rated audio output power: The output connected to the specified load available power, when the receiver in the specified operating conditions.

Reference sensitivity: Also known as the maximum available sensitivity, at the specified frequency and modulation, the receiver output to produce a standard signal to noise ratio (12dBSINAD) of the input signal level.

Selectivity: Characterizing the receiver has the ability to reject useful input signals against unwanted input signals. By measuring the adjacent signal selectivity, co-channel rejection, blocking, spurious response, intermodulation immunity and other properties to assess.

Signaling:

CTCSS: (Continuous Tone Coded Squelch System) A technique that adds frequencies below the audio frequency (67-250.3 Hz) to the audio signal for transmission. Because of its frequency range in the standard audio below, that is less than 300Hz, so called sub-audio.

Digital Tone: CTDSS (Continuous Digital Coded Squelch System), It Consists of a code group, sending cycle. The transmission rate is 134.4HZ, it is less than 300HZ, so it called the Digital Tone. There are 104 groups digital coding. The function is mostly same with CTCSS, while it is a digital encoding as a way to mute the conditions are turned on.

Dual tone multi frequency:

DTMFdual tone multi frequencyis composed by the high frequency group and low frequency group, 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 combinations of signals representing 0-9, *, #, A, B, C and D respectively.