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I was reading up on a radio review, and it mentioned something I was not familiar with, "Busy Channel Lockout".
Unfamiliar with the term, I did an Internet Search, but didn't get back much, and for some reason the most promising results did not work. This page seems to be product specific, but it appears that it's a way to prevent radios from transmitting on top of each other.
What is Busy Channel Lockout? Why do I want, or not want, this feature? Is this feature often abbreviated to BCL?
In my experience, the Busy Channel Lockout or Busy Channel is the name for a feature which is completely different from what Cranky Emu describes.
The Busy Channel Lockout prevents transmission on a frequency which is, or appears to be, already in use.
Normally, you'd be able to hear the other side which is transmitting using your receiver, and avoid transmitting until the channel is free.
However, with more complex squelch systems, such as CTCSS and DCS, becoming more common, it can happen that your receiver is receiving another signal, but is muted due to squelch settings.
This might lead you to believe that the channel is free and that you can transmit on it. If you do transmit on it, you could create interference to the transmission already in progress. Do note that some radios, especially those without screens, might not have any way, other than audio, to signal that there is another squelched user on the channel.
Additionally, depending on the implementation, the busy channel lockout feature might also work even if the CTCSS or DCS are not in use. It might prevent radio from transmitting as long as there's some signal on the frequency. This can cause issues which prevent the radio from transmitting in case where the radio is picking up interference which is not related to communication.
Also a bit of background:
In some jurisdictions, commercial users might receive licenses for frequencies shared with other users, but with each group having different squelch settings. With receive squelch, and busy channel lockout, it's possible to create a feeling of privacy, in sense that members of other talk groups won't be able to just listen in to the traffic which is not from their own group.
Additionally, in some parts of Europe, the 2 m amateur band, and the 70 cm amateur band are still used for analog cable television and digital to analog set top boxes. The cable TV infrastructure might radiate, creating large number of carriers which might break squelch of radios and also trigger busy channel lockout.
In respect to Andre's answer, it is really going to depend on the radio. Different companies use different terminology, or the same terminology differently.
For example, in your experience of BCL, this is also commonly referred to as TX Inhibit. Same thing, different way of saying it.
In the case of this radio, Andre is correct. It disables tx when the frequency is busy, the review says it cannot be disabled, which is not correct. When you program the radio via software, there will be a setting to disable the BCL
BCL or LO is a common term (and feature) with most - if not all, scanner receivers. Some amateur radio equipment has this feature as well.
Basically it's primary function is to 'lock-out' (exclude) that particular memory channel from the memory scanning, when you have the radio in 'scan' mode.
For example, there might be a particular channel you have programmed into memories that you don't wish to listen to at the time, therefore you can lock it out and stop the radio's scan from stopping on that memory channel each rotation.
