· What is the PMR-446?
· Which is the PMR-446 range?
· What is ON/OFF Volume?
· What is PTT?
· What is Squelch?
· What is CTCSS?
· What is VOX?
· What is Scanner?

· What is the PMR-446?:

PMR is the abbreviation for Private Mobile Radio. Are the radios known as PMR-446 and work between the 446,0 -446,1 MHz frequencies and have 8 channels. They used to have a Max transmit power of 500mW, and an approximated range of 3 km in optimal conditions.

Frequencies:

Channel 1 = 446,00625 MHz.
Channel 2 = 446,01875 MHz.
Channel 3 = 446,03125 MHz.
Channel 4 = 446,04375 MHz.
Channel 5 = 446,05625 MHz.
Channel 6 = 446,06875 MHz.
Channel 7 = 446,08125 MHz.
Channel 8 = 446,09375 MHz.

· Which is the PMR-446 range?:

The PMR can communicate in an approximated range of 3 km in open country, have an approximated range of 3 km in optimal conditions. The maximum performance is reached in open country and without obstacles, environmental factors as the altitude and temperature, orographic like buildings, vegetation and differences in height, can reduce the range appreciably. Inside a vehicle or a metallic construction the range will also reduce.

· What is ON/OFF Volume?:

Is the button for turning on and off the walkie talkie.
The volume function is only available when receiving a signal, and it's used to adjust the volume to an optimal level.

· What is PTT?:

It's usually a push button that pressing it begins the conversation. Press and hold the button to transmit. Talk to the speaker with a normal voice from a distance of about 4 - 10 cm. When you finish talking release the PTT button to wait for an incoming transmission, the radio will remain in listen mode.

· What is Squelch?:

It's a filter for eliminating the background noise. Most of the radios have an option for temporarily deactivating it by pressing the MON button, so you will be able to receive low intensity signals that are below the squelch threshold.

· What is CTCSS?:

The CTCSS tones are an inaudible signals that open the silencer. By programming two or more radios with the same CTCSS them will only receive calls matching the programmed CTCSS, that is, calls made between them. The rest of calls not matching the right tone will not be heard.
That does not mean that the communications will be private. The radios without CTCSS tones will hear us, but we can not hear them. The radios used to have 8 channels and 38 different tones per channel.

· What is VOX?:

VOX is the voice activation. The voice activated transmission (VOX) allows your voice to activate the PTT automatically. This is a useful function when used with an optional hands free accessory.

· What is Scanner?:

This function allows to automatically scan all the channels in order to identify the active ones.