Manual squelch

Tone squelch, or other forms of selective calling, is sometimes used to solve interference problems. Where more than one user is on the same channel, selective calling addresses a subset of all receivers.

Instead of turning on the receive audio for any signal, the audio turns on only in the presence of the correct selective calling code. This is akin to the use of a lock on a door.

A carrier squelch is unlocked and will let any signal in. Selective calling locks out all signals except ones with the correct code. In non-critical uses, selective calling can also be used to hide the presence of interfering signals such as receiver-produced intermodulation.

Receivers with poor specifications—such as scanners or low-cost mobile ham radios —can not reject the strong signals present in urban environments. The interference will still be present. It will still degrade system performance but by using selective calling the user will not have to hear the noises produced by receiving the interference. Four different techniques are commonly used. Selective calling can be regarded as a form of in-band signaling.

The original tone set was 10, then 32 tonnes, and has been expanded even further over the years. There are many other company-specific names used by radio vendors to describe compatible options. Selcall Selective Calling transmits a burst of five inband audio tones at the beginning of each transmission. In the same way that a single CTCSS tone would be used on an entire group of radios, a single five-tone sequence is used in a group of radios. A Hz tone is used in European ham radio repeater systems.

Be aware that the same bit DCS word can, for example, produce three different valid DCS codes due to the encoding architecture. XTCSS fitted radios are purposed to enjoy more privacy and flexibility of operation. Squelch of any kind is used to indicate loss of signal, which is used to keep commercial and amateur radio repeaters from transmitting continually.

Since a carrier squelch receiver cannot tell a valid carrier from a spurious signal noise, etc. CTCSS is often used as well, as it avoids false keys. It is a bad idea to use any coded squelch system to hide interference issues in systems with life-safety or public-safety uses such as police, fire, search and rescue or ambulance company dispatching.

Adding tone or digital squelch to a radio system does not solve interference issues, it just covers them up. The presence of interfering signals should be corrected rather than masked. Interfering signals masked by tone squelch will produce apparently random missed messages.

We use the radios in simplex mode, generally within line of sight, so I changed the Service Settings to get really aggressive squelch:. Another ride over the Walkway with the squelch set to 4 also passed in blissful silence. As of now, our rides are quiet.

No tone squelch accessories on said radios, I take it? ICOM mobiles had pretty solid front-ends at one point. Not sure about the HT offerings over the years. Sounded like paging, but my ear for such things is limited do people still use pagers?!??! Nothing to see here…move along. Move along…. Pagers are still a thing, particularly in the medical field, for reasons I cannot imagine.

Pagers still have vastly better coverage in the bowels of the basements of hospitals in the middle of nowhere. Actually, I miss mine….