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Pause and Take a Breath

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As a two-way radio professional, I have heard the question asked numerous times “Why does the first syllable of my conversations cut off when I am using the repeater?” and sometimes people even ask this question regarding direct (simplex) radio communication. This article explains why that occurs and while the title of this article may give you a clue as to the most logical solution, the full article goes on to provide you with a thorough understanding what’s behind the delay and why it is a necessary byproduct of the normal functioning of any radio system. In order to successfully do that I necessarily had to include a brief lesson on repeater operation as well as some very fundamental two-way radio concepts. Please continue reading for the full picture.
The repeater “listens”, on the air, to a specific frequency authorized by the FCC for your organization to use. Let’s say the frequency is 456.1275 MHz. Before the repeater can “repeat” your signal, it must “hear” the appropriate “tone” or “code” which is superimposed onto the carrier frequency of your signal coming into the repeater. The code or tone is sub-audible, which means that it is below the audio cut-off filter in the repeater or radio being used. It is not something you necessarily will hear or detect, but it is there nonetheless. This “code” or “tone” keeps all other signals with different “codes” or “tones” (or signals with no encoding whatsoever) from triggering your repeater or your radio.

Side-note: Some companies call this sub-audible tone or code “privacy codes” – a term which leads some users to believe that it creates a secure, private conversation. That false assumption propagated by equipment manufacturers and marketers is a dangerous lie. All the sub-audible tone or code does is isolates your group of radios from other signals on the same frequency and allows you to hear only the units having your same tone or code. It does NOT prevent anyone else from monitoring your signal or listening in on your conversations. It does NOT create any privacy. It simply prevents you from hearing other co-channel users who have a different tone or code programmed into their radios. For more information about this please refer to an excellent article, PL Tones Explained by PJ Hunt, WQQT626.

If the right “code” (or “tone”) is received by the repeater, it actuates the transmitter of the repeater and passes the audio it is receiving (which your radio is transmitting) to the repeater’s transmitter (which in this example, would be on 451.1275 MHz) so that the radios listening on the repeater’s transmit frequency hear the intended audio transmission. This whole process takes a fraction of a second to occur.
Here's where the aforementioned delay comes from: First, the transmitter of your handheld radio takes a few milliseconds to come up to full power and to begin generating the code or tone. Once the code or tone is embedded into the transmitted signal, the receiver of the repeater must recognize that, on it’s assigned receive frequency, there is a radio signal present. This takes another couple milliseconds or so. Then it must check the incoming signal for the correct “tone” or “code”. This takes another couple of milliseconds. Then it must actuate the transmit circuit and pass the audio, all the while generating the unique transmitted “code”or “tone”, to the repeater transmitter. That’s the repeater’s function.

As for your handheld or mobile radios, the same process occurs: First the receiver in your radio must detect that, on 451.1275 MHz (let’s say that is channel 1 in your radio) a signal is present. This takes a couple milliseconds. Then it must detect that the proper tone or code is present. If an incorrect tone or code is received, the green light on your radio will light, but no signal will be decoded. The proper tone or code, when received, will actuate a circuit which allows the receiver to pass the intended signal to the audio stage of the radio. This takes another couple of milliseconds or so. At that moment the receivers of any radios in your system listening on channel 1 will “open up” and pass the intended signal to the speakers of the radios so that people will hear it. As you can see, this process is not instantaneous.
If you are using a simplex, or direct communications path, which does not go through a repeater, the delay is much less, but nonetheless a delay DOES exist. It still takes the transmitter of the sending radio time to come up to full power and generate the proper tone or code, and the receiver of the receiving radio time to recognize that there is a signal present, listen for the proper tone or code and open up the audio path to the speaker. Even though it is measured in milliseconds, there is STILL a slight delay.
This is precisely why I take extreme issue with the term “Push To Talk” or “PTT” as it is commonly used in the radio industry! It simply does not infer that there is a delay present in the process. I believe in all circumstances it should be changed to “PPTT”. My reasoning is sound and here it is: In the case of a repeater, if you add ALL of these milliseconds up, it takes about an eighth or a quarter of a second for the process to complete. Therefore people using a radio system of any kind should learn the habit of “Press” - “Pause” - Then - “Talk”. This new acronym and it’s meaning should be aggressively promoted and taught to ALL radio users of ANY radio system. Just because radio waves travel at the speed of light, does not mean that radio circuitry responds at the speed of light. There are physics involved which go beyond the grasp of most casual radio users, but nonetheless they affect the operations of the radios upon which they rely for their lifeline in times of emergency. They MUST adapt to this physical reality just as surely as they have already learned to adapt to using cell phones in their private lives. When initiating a cell phone call we all expect to wait three or four seconds (in some cases longer) before a cell phone call goes through and begins ringing the phone on the other end of a new conversation. We all have learned to adapt to the “digital” sound of cell phones compared to the much richer, clearer “analog” sound of the “old fashioned landline” phone call, and have learned many other habits as technology is integrated into our lives. This is simply a new behavioral adaptation we all MUST make in order to assure effective communications over the repeater.

For radio users with both repeater frequencies and simplex frequencies in their radios, they MUST understand that on channel 2 (or whatever the simplex channel is in the radio) the timing delay is less pronounced because the repeater is not a part of the equation, but the distance on simplex (direct) is MUCH less than through the repeater. The price they MUST learn to pay for the increased distance, penetration and reliability of communications which the repeater offers is very SMALL -it is measured in the time it takes to simply inhale. That’s all.
To reasonable people, pausing for the duration it takes to take one breath may seem like a VERY tiny price to pay, but I acknowledge that old (bad) habits are very tough to break. It takes discipline, time and repetition. These days, discipline and patience are in VERY short supply because of the culture of entitlement our society has spawned, groomed, nurtured and promoted to every living human being in this high-tech-instant-gratification world. People need to learn patience and discipline. Anything less will continue the chaos generated by kicking against the goads of the physics which rule these electronic systems upon which we rely.

I do not know of ANY way to shorten this process except try different tones and codes to see if the repeater and the radios using it handle a different tone or code faster than the ones assigned to the system one is using. Experimenting with different tones and codes to lessen the delay would be a LONG SHOT, take a LOT of trial and error and may still not render appropriate results at all.
Radio users must face the fact that this is exactly the SAME issue that EVERY single other repeater user MUST accept and adapt to. All users MUST pause before speaking. Just the time it takes to inhale one breath should be totally sufficient. Contrary to the outcries of the whiny, spoiled rotten generations that came after us “baby boomers”, pausing for a fraction of a second and taking ONE inhaled breath after pushing the talk button and before beginning to speak is NOT too high a price to pay. It will reduce frustration on the radio network, increase efficiency, and will NOT significantly reduce the amount of information that can be passed during a conversation. It will reduce errors and omissions and improve the quality of the communication.

JUST TAKE A BREATH BEFORE SPEAKING! You’ll be a better radio communicator and – who knows? – the increased oxygenation to your body may be a healthy beneficial side effect!

- Tim Mrva
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Tips & Tricks

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