A listening method used to accept weak signals. By Pressing the special key compulsive to receive signal channel, the operator use the ear to distinguish the weak sound in speaker and listen the sound.
A way to listen all the channels.
Receiving the signal one by one in the channel by pressing the special key. If the receiving time of each channel is 100ms, it is means the scanning speed is 10ch/s.
3. Priority Channel Scan
First scan the set priority channel during the scanning process.
4. Delete/Add Scan Channel
Delete or Add Scan Channel from the scan list.
No need to press PTT and through the sound start , when the function is activated.
6. TOT: Time Out Timer
This function is used to limit the user's ultra - time launch on one channel. It is avoid damage
the walkie talkie for long time launch.
To conserve electricity and extend the standby time, the walkie-talkie does not receive and press in a period of time. It will be turn off and open the machine for a period of time, which is called power saving mode. The time ratio of the switch is about 1:4. When the signal is received or press, the walkie-talkie will be immediately drop off the power saving mode and enters the normal state.
8. High/Low power
This function is allow to choose high power or low power according to the user’s actual situation.
9. Busy Channel Lockout
The user is prohibited from transmitting signals on a busy channel, When this function is starting.
10. Squelch Level
The intensity of the noise in the received signal is related to the intensity of the signal. When the signal is stronger, the noise is weaker. The max noise and the min noise are divided into several files, each files is one level. The several files are called squelch level. The users can choose according to the actual situation.
11. CTCSS/CDCSS function
This function can avoid receiving unrelated calls.
12. 2-TONE/DTMF paging function
Use 2-TONE or DTMF signaling to select a call for the walkie-talkie.
The transmission frequency and the receiving frequency will be interchanged, When the reciprocal frequency is used. And the signaling is also interchanged.
14. Talk Around
The walkie-talkie transmission frequency same as receiving frequency, When the net function is used. The transmission signaling is also converted to the same signal as the receiving signal.
It will send a signal to the caller to respond, When the walkie-talkie receives a correct code call.
16. Emergency Alarm
Press the alarm special key, the walkie-talkie will send out the alarm sound with the maximum sound or sends out the predetermined alarm code to other handsets or base stations.
17. Patrol Record
When the personnel arrive at the patrol point, the walkie-talkie will receive the query signal sent by the patrol register, then auto-activate the registration operation and send the information of identity card to the register.
The use of this function can prevent wrong operation of the key.
19. Battery Indicator
Show the battery power.
Can see the LCD display and key clearly in the dark.
The function allows data to be copied from one walkie-talkie to the same type of other.
One or several parameters of modulation signal are used to control the change of carrier parameters. According to different control parameters, modulation can be divided into amplitude modulation, frequency modulation and phase modulation.
Audio, the voice of a person, usually the frequency band is 300Hz-3400Hz.
The carrier of useful signals such as voice, digital signal and signaling.High frequency electromagnetic wave which is easy to transmit.
25. Channel and channel interval
The channel refers to the frequency value that is occupied when transmitting and receiving. The frequency difference between adjacent channels is known as the channel interval. The prescribed channel intervals are 25KHz (broadband), 20KHz, 12.5KHz (narrow band) and so on.
2-TONE, two tone signaling, consists of two audio signals, A Tone + B Tone. Firstly send A Tone then interval B Tone for a period of time. 2-TONE signaling can be used to select the corresponding walkie-talkie call.
5-TONE, 5 tone signaling, which is the same as 2 tone signaling, the difference is made up of five frequencies.
CTCSS (Continuous Tone Controlled Squelch System) is a kind of audio frequency will be lower than the frequency (67Hz-250.3Hz) added together in an audio signal transmission technology.
Its frequency range is below standard audio,so called subaudio.After the walkie-talkie demodulates received signal with intermediate frequency, the subaudio signal is filtered,reshaped and entered into the CPU, which is compared with the CTCSS frequency set by the machine to decide whether open the silence.
CDCSS (Continuous Digital Controlled Squelch System), its function and CTCSS are the same, the difference is that it is used as digital code for silence to open the condition.
DTMF (Dual Tone Multi Frequency), consists of high frequency group and low frequency group. Each of The high and low frequency group have 4 frequencies. A high frequency signal and a low frequency signal are superimposed to form a combined signal, which is representing a number. DTMF signaling has 16 codes. DTMF signaling can be used to select the corresponding walkie-talkie call