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What are Signal Reports? What is an s-unit? Why does this matter? But, Why? First, why does any of this matter? The General Mobile Radio Service was segmented with the concept of being a short-distance two-way communications for licensees and their immediate family members. It doesn’t require any special knowledge, exams or understanding of the science behind the magic. However, you will occasionally hear both professional and amateur radio operators who are also licensed GMRS operators, who may be using lingo more common to other services. One of the most common will be an RST style signal report. I’ve noticed that many new operators will call for a radio check, especially on a repeater. They may get a 'signal report' from a Ham that sounds like this, “I copy you five nine.” Or you may hear “You are full-quiet into the repeater.” While these answers may be true and accurate, for new operators, hearing “Your radio sounds great” or “I can hear you fine, but there is a bunch of static. How far are you from me (or the repeater)” would likely be a lot more helpful. Well, in the event that you come across me or one of my well-seasoned friends and we forget that not everyone knows what we are talking about, this may help you understand what you are hearing with regard to signal reports… and if you would like to use the same method, provide you with the best guidance I can. What are RST and Signal Reports? The RST signal reporting system is primarily used by amateur radio operators and other radio hobbyists to exchange information about the quality of a radio signal being received. The original reporting system was created to be used with Morse Code, and is a three digit number. Each digit is used for conveying an assessment of a signal's Readability, Strength and Tone (RST). Over time, amateurs adopted this reporting scheme for voice communications as well, but it was modified a bit to be more friendly to reports about voice signals. Readability is still used to define how intelligible your voice is; meaning how well can I understand what you are saying. Strength of your signal is also still used, based on the meter on the receiver’s radio. However, Tone was dropped for voice reports. Though on occasion you will hear someone tell an operator, in plain language, if their transmitted signal has too high or too low of a tone, as some radios allow the owner to adjust the tone. Readability – This part of the report is subjective, but still helpful. Readability is used to define how intelligible your words are, on a scale of 1 to 5. A readability value of 1 means that I can tell you are transmitting and talking, but I can’t make out anything you are saying. A readability value of 5 means that, regardless of anything else, I can understand every word you say. A report with 2, 3 or 4 would be some variation between 1 and 5. Some examples on how I personally would rate your readability on GMRS would include a 2, meaning I may be able to hear enough of what you’re saying that in a life or death situation, it may be enough to get help going. With a 3, I may be able to understand 3 or 4 words out of every 5 words. We can talk, but it’s kind of a hassle. A 4 would be I can hear every word but there is static. Pretty straight forward. Strength – With regard to strength in a signal report, there is nothing subjective about it, sort of. Unfortunately, if it is scientific or subjective depends on your radio meter type and if the meter is calibrated. We are actually measuring the voltage of your signal on the receiver’s radio. This voltage is measured in S-units or Signal Units. Where this can get tricky with GMRS is, not every radio has a signal strength meter designed to support the common s-unit scale. You may have a display that shows 9 units on some unknown scale, or 10, or 15. I have even seen some radios that only have 4 or 5. I’ll explain the technical parts of signal strength measurements and if you have a radio that doesn’t use a traditional calibrated s-meter, you may be able to adopt the idea to your personal radio. This meter below is a classic analog meter. The top line measures the received signal strength in s-units. If the needle were to swing to 5, you would give them a 5 as the Strength portion of the report. For example, if you understand every word and the needle stops at 5, you would provide a signal report for their voice signal of “five five” or “5 5”. If you could hear all of the words they are saying with a lot of static and the needle is on the 3, you would report a “four three” or “4 3”. Below is a newer radio with a digital s-meter. It looks a little different, but the same rules apply. In this picture, my meter is showing a signal strength of about 5.5 (almost 6) s-units. If I could hear them perfectly, I would tell them their signal report is “five five plus” or “5 5 Plus”, meaning I understand everything perfectly and their signal strength is never less than 5. Now, the next two images show a radio that I know doesn’t have a properly labeled or calibrated s-meter. This type of meter is the reason I said there is nothing subjective about it, sort of. While an s-unit is a true measurement of voltage, this radio has 10 lines and nothing in the owner’s manual tells me what the increment values are. However, you could still adapt the concept to a signal report, making it a bit subjective. In the first image, the meter is completely full. In this state, it’s very likely that I can hear the person talking perfectly and they almost certainly met or exceeded the voltage requirement of 9 s-units. So, I would tell this person that they are “five nine” (5 9) or they are “full quiet”. In the next image, below, the signal goes to the fifth line. Being familiar with this radio, there is a good possibility that I can hear everything they are saying, but with a lot of static. So, I would be providing a signal report of “four five” or “4 5”, since the meter measurement is half the total scale. In this case, the signal report is 100% based on my interpretation of what I am hearing and seeing, rather than providing a “metered result.” I hope this makes sense. For those of you who are interested in the science behind an s-unit, here is a little history and values. In the 1930s, the industry agreed that 9 s-units would correspond to 50 microvolts (50 μV) at the input of a receiver. However, based on meter design and how the value was sampled, this was not accurately measured from radio to radio because the input impedance of receivers was not standardized. This changed in 1981. The International Amateur Radio Union (IARU) agreed on a technical recommendation for S Meter calibration, separately for HF and VHF/UHF. IARU defines 9 s-units for the HF bands to be a receiver input voltage of 50.2 microvolts and impedance of the receiver of 50 ohms. For VHF and UHF bands, the IARU defines 9 s-units to be a receiver input voltage of 5.01 microvolts and impedance of the receiver of 50 ohms. For both HF and below, as well as everything over HF, the IARU defines that a difference of one S-unit corresponds to a difference of 6 decibels (dB), equivalent to a voltage ratio of two, or power ratio of four. For example, if 9 s-units equals 50.2 μV, than 8 s-units is 25.1 μV, 7 s-units is 12.6 μV, etc. Signals stronger than 9 s-units are given with an additional dB rating. For example, “20 dB over S9” or simply "20 over". You can see these values on the s-meters in the first 2 images. Repeater Caveat There are some important caveats to signal reports for repeater users. The RST style signal report is not a valid reporting method. The voice quality or 'intelligibility' of the transmission is likely not going to be valid. If the reporting operator is receiving the repeater's signal well enough that there is little to no chance that the voice quality is impaired, you may be able to give and get a valid readability report. This condition is often when you will hear signal reports such as "loud and clear" or "full-quiet." These replies indicate that you have a very good radio and voice signal into the repeater, as reported by someone who has a very good signal from the repeater. Additionally, the signal strength is not relevant through the repeater, at all. The receiver's station is going to be seeing the signal strength of the repeater, not the originating station asking for a signal report. It is not possible to know the received signal strength at the repeater site unless you are the repeater owner or admin and have the ability to see the actual repeater's receive meter. Even then, most repeaters do not have any easily visible signal strength meters. The next best method would be if the receiving station listens to the repeater input frequency (assuming the receiving radio has that feature). If the reporting station can hear you directly, they can tell you how strong your signal is at that person's location. It's still not indicative of how strong your signal is at the repeater. I hope this information helps anyone who may hear this lingo out on the General Mobile Radio Service. Quick Reference Chart for S-Units

You seem to be leaving out the requirement about who is using the repeater. If I operate a GMRS repeater, that GMRS repeater must be identified using my call sign WROM258. Nothing says that ID must be automatically performed, but it must be performed at the end of a transmission, and every 15 minutes during a conversation. The only exception is if the only people who use the repeater are those who are allowed to use my call sign WROM258 and they are following the rules for using the WROM258 call sign (end and every 15 minutes during). But, in this example, if the repeater is used by any person with different call sign than WROM258, even if they ID their own station properly, the repeater must be IDed as WROM258. So, if the twelve grandkids are all properly IDing using WROM258 it’s fine, but if my neighbor WXYZ123 gets on, then the repeater ID must be made, no matter how correctly he IDs his own station. That’s most easily done with an automated ID, but could be manually. Edited to add some brief examples: 1. Repeater WROM258, Only my family uses. They all correctly ID themselves as WROM258. The repeater doesn’t need a separate ID. 2. Repeater WROM258, Only my family uses. One of them fails to correctly ID themselves as WROM258. The repeater must have a separate ID. 3. Repeater WROM258, Although it’s primarily used by my family, sometimes someone else uses it. They all correctly ID themselves.. The repeater must have a separate ID. 4. Repeater WROM258, Open to the public. They all correctly ID themselves. The repeater must have a separate ID. 5. Repeater WROM258, Open to the public. Some fail to correctly ID themselves. The repeater must have a separate ID.

I understand your reluctance ... but here's another suggestion. Try *reading* from the radio using each cable. If you can read from it, then chances are pretty good you can write to it as well. Even if the BTECH cable doesn't work, the chances of you hurting your radio are slight (and pretty much zero if you just try reading from it). You'll just get an error message in the programming software.

Be sure to ask them what kind of access you will have to your repeater.

OffroaderX, I know this is off-topic but I love your channel and used it to learn ALOT on this topic.

So long as those stations are operating under the same license as the owner of the repeater. If not then the repeater must self identify. For a private repeater placed into service for use by a family that's the case above. The problems start when "Open Repeaters" are put into operation. The logic for the above is easy to figure out. Any station using the repeater, and operating under the owner's license, when they identify it would be the same ID used if the repeater self identified. So requiring the repeater to self identify using the same call sign would be redundant. When a station identifying itself under it's own license is not identifying the repeater with the owners ID. Thus the repeater needs to self identify. This is has all been covered and debated multiple times here. Too many people get hung up on the difference and don't understand the key point and simply spread the wrong advice around further confusing even more users. It doesn't help when the FCC has neglected it's duty to enforce the rules where people mistakenly assume the lack of enforcement as proof they're right, no they are still wrong.

§ 95.1751 GMRS station identification. Each GMRS station must be identified by transmission of its FCC-assigned call sign at the end of transmissions and at periodic intervals during transmissions except as provided in paragraph (c) of this section. A unit number may be included after the call sign in the identification. (a) The GMRS station call sign must be transmitted: (1) Following a single transmission or a series of transmissions; and, (2) After 15 minutes and at least once every 15 minutes thereafter during a series of transmissions lasting more than 15 minutes. (b) The call sign must be transmitted using voice in the English language or international Morse code telegraphy using an audible tone. (c) Any GMRS repeater station is not required to transmit station identification if: (1) It retransmits only communications from GMRS stations operating under authority of the individual license under which it operates; and, (2) The GMRS stations whose communications are retransmitted are properly identified in accordance with this section. Except it’s not confusing. It’s clearly written. You seem to forget about the word “and” (I emphasized it above) at the end of (C)(1). That means both (C)(1) and (C)(2) must be true for the exception (C) to be permitted. In general, those two conditions can only be simultaneously true for for family repeaters (and probably some grandafathered stations, but they’re completely different from new licenses.) And I have no clue why you would interpret “Each GMRS station” to exclude repeaters. Each means every.

There’s no fee, but if you decide you want to support the site there’s a Premium level membership for $50/year that has some benefits. Repeaters can be linked in to a nationwide network, but the hardware is in very short supply right now. On this site, once you have a login, the repeater listings include a function that helps you request access. The repeater listings have a separate login than the forums, which is sometimes confusing to people.

It's done all the time. You will need a calculator with a square root function. Look under the heading in the below link: "VSWR formula using forward & reflected powers" https://www.electronics-notes.com/articles/antennas-propagation/vswr-return-loss/vswr-calculations-formulas-equations.php

Why does every new license holder want to setup a repeater? I would like to shed a little light on some of the important things to consider if you recently got your GMRS license and now want your own repeater. First thing to consider, are there any open well placed repeaters in your area that you are able to use? I can assure you most repeater owners want people to use there repeater. Owning several repeaters I can assure you all are welcome and encouraged to use my machines. Do you have access to a location to host your repeater? If your answer is your garage roof you should reconsider. Your garage roof will give you about the same coverage as simplex. Unless you’re on top of a mountain and all your users are at the bottom you will never be happy with this setup. GMRS is not as popular as one would like to think, unless your repeater covers 20 miles or more you may find you only have 1 or 2 users in the area. Unless you already have a group of friends together you may want to consider this before spending money on a decent well positioned site to install your repeater. So you found a nice high site and the price is right, all you need to do is get the repeater installed, sounds simple right? Some thigs to consider first and foremost are the costs because they can add up quickly. Are you on a commercial tower that requires a license and bonded climber? If so this could be by far your largest expense depending on your area. I have spent $600 to $1200 on a climber; I have had quotes as high as $2500 depending on the amount of work and heights involved. Keep in mind commercial sites require certified mounts, hard line cable, cable clamps, engineered grounding solutions and commercial grade antennas. No tower owner is going to let you install a comet antenna and 200’ of braided shield coax. This brings me to my next point, the antenna. Because of the costs involved with climbers you will want to expend your budget on the antenna. Remember a $2000 repeater on a $200 antenna is going to work about as good as a $200 repeater. Whereas a $200 repeater on a $2000 antenna is going to work like a $2000 repeater. On my first repeater I was gifted use of a 150’ tower, I installed a DB-420 on the top and 160’ of 7/8 hardline. Total cost of equipment for the antenna install was $2500, with the climbers labor coming in at an additional $800. This left me with enough to purchase an old Motorola R100 repeater running at 25W. To my surprise it had 30 miles of coverage, all due to the cash spent on the antenna and waiting for a decent spot. Things happen, more so if you have an antenna 200’ in the air with a conductive cable connected to sensitive electronics. Antenna issues, feedline issues, repeater issues all cost money and I promise at some point you will have issues that need repair and require your money! It is my opinion that the GMRS community does not need another 2 to 5 miles repeater as it just becomes background noise. What use is a public listed repeater if somebody in a mobile can’t use it 5 miles away while moving or the portable coverage is only a mile? If after reading this you are still going to build a repeater for your garage more power to you, just don’t expect 20 people to show up if it only reaches a mile. As the owner of several GMRS and Commercial repeaters I can attest to the amount of money and effort go into my repeaters. I have only touched on the basics, if you add in any kind of testing services, duplexer tuning, addition of a combiner channel to an existing tower system, RF engineering, rent and insurance your costs can sky rocket. The best advice I can give any new licensee is to try and use the available systems in the area. Take the time to learn a little about what you’re doing and to assess the usability of the service before investing in a repeater for the sole reason of saying you own one.

That’s what HT’s do.?

You’re welcome, I think the KG-UV9G pro also. I have a couple Wouxun radios. They are quality compared to the Baofeng radios but then I like them too. All tools with a purpose. ?

I don't know if Kemp Wireless does repairs for equipment they haven't sold, but it may be worth emailing or calling them to find out. They are highly recommend for sales and support.

@WRUW275 ^^^ this is the best answer. If there was a realistic way to screw the antenna directly to the output of the radio, I would. LOL

The shorter the better.

A lot of amateurs use the space weather tools on the home page of QRZ. https://www.qrz.com/ Same data here, in the top, left corner. http://www.hamqsl.com/solar.html An my absolute ? favorite is Dr. Tamitha Skov, Space Weather Woman. https://www.spaceweatherwoman.com/

Sort of, yes. The question was about terrain blocking. In the Pinnacles scenario there is no line of sight between either of the operators, somehow we still have communications. And car with mobile radio did not have any elevation advantage, it is was actually parked lower than the trails. But, yes, this trip made me to get simplex repeater (which appears to be against the rules, so shhh don't tell anyone). It works like a charm and saves the day every time when we use it.

I agree with Alex on all points. It's too hard to predict/calculate for all but a chosen few. And to touch a bit more or the reflection idea... think of radio waves like sunlight. There isn't perfect darkness in the shadows because the sunlight, to varying degrees, scatters off of everything around the item creating the shadow. That includes dust and other things in the air. Radio wave literally do the same thing.

No, the wrap won’t hurt. Yes; you’ll have a different pattern because the ground plane is off-center, but it won’t kill your performance.

Here’s the section that defines what it means to “operate under the authority of an individual license”: (c) Individuals who may operate a GMRS station. This paragraph establishes who may operate a GMRS station under the authority of an individual license. (1) Any individual who holds an individual license may operate his or her GMRS stations. (2) Any individual who holds an individual license may allow his or her immediate family members to operate his or her GMRS station or stations. Immediate family members are the licensee's spouse, children, grandchildren, stepchildren, parents, grandparents, stepparents, brothers, sisters, aunts, uncles, nieces, nephews, and in-laws. (3) Any individual who holds an individual license may allow anyone to operate his or her GMRS station if necessary to communicate an emergency message. (4) Any non-individual person that holds a grandfathered GMRS license may allow individuals to operate its grandfathered GMRS station(s) only in accordance with the following paragraphs: (i) A partnership may allow its partners and employees to operate its GMRS station(s). (ii) A corporation may allow its officers, directors, members and employees to operate its GMRS station(s). (iii) An association may allow its members and employees to operate its GMRS station(s). (iv) A governmental unit may allow its employees to operate its GMRS station(s). Looking back at the paragraphs of the exception please note that the exact same language is used. There simply is no other way to operate “under the authority of an individual license.” And people working for a grandfathered entity cannot use the corporate license without identifying the repeater because it’s not an individual license which is a requirement for the exception: c) Any GMRS repeater station is not required to transmit station identification if: (1) It retransmits only communications from GMRS stations operating under authority of the individual license under which it operates; and, (2) The GMRS stations whose communications are retransmitted are properly identified in accordance with this section.

A friend of mine reminded me about something pretty important. I updated the original post, but wanted to include the update here as well. With new or non-technical operators, this is an often misunderstood concept. Repeater Caveat There are some important caveats to signal reports for repeater users. The RST style signal report is not a valid reporting method. The voice quality or 'intelligibility' of the transmission is likely not going to be valid. If the reporting operator is receiving the repeater's signal well enough that there is little to no chance that the voice quality is impaired, you may be able to give and get a valid readability report. This condition is often when you will hear signal reports such as "loud and clear" or "full-quiet." These replies indicate that you have a very good radio and voice signal into the repeater, as reported by someone who has a very good signal from the repeater. Additionally, the signal strength is not relevant through the repeater, at all. The receiver's station is going to be seeing the signal strength of the repeater, not the originating station asking for a signal report. It is not possible to know the received signal strength at the repeater site unless you are the repeater owner or admin and have the ability to see the actual repeater's receive meter. Even then, most repeaters do not have any easily visible signal strength meters. The next best method would be if the receiving station listens to the repeater input frequency (assuming the receiving radio has that feature). If the reporting station can hear you directly, they can tell you how strong your signal is at that person's location. It's still not indicative of how strong your signal is at the repeater.

Where do you get that from? If it meant "control and mobile stations" it would say that. It doesn't. It says "stations". Repeaters are stations. I know that's what you THINK the rules say, or what you think they SHOULD say. That's not what they say.

This is already the single most extensive thread on this site. If you're communicating with someone else who is covered by your license, they need to ID with that license. That's it. They can add their name, a number, a letter, a location, whatever they want, as long as they ID with that license. Simple.

Well, the cables may *look* the same, but they use different USB-to-serial chips. That may or may not matter ... I have run into programming software that will only work with a particular brand of chip, but most don't seem to care. I'm guessing you have a Wouxun radio but not a 9356? Have you tried programming it with the other cable?

One: there is only ONE name on the GMRS license; the regulations permit "immediate family" to use the call sign but all responsibility for correct usage is on the named licensee. Two: when multiple members are using that regulation, they all identity with the SAME call sign -- and each MUST ID (as each radio is considered a "station"). But common practice is to append some notation identifying which member is operating which "station" (KAF6045/HT1 from KAF6045/mobile...; KAF6045/mobile, KAF6045/HT1...)

Or just use the chart.

That's why we get some of the people we see here asking for help. Crap documentation from the manufacture and confusing menu selections in the radios.

Thanks for answering my earlier questions. Got the fcc license and am now just waiting upon some radios I ordered. Then I will test out my real world ranges. I have read the brief fcc rules regarding call signs, but what is the typical and good etiquette for saying our family call sign when on the air? This would be for 2 parties talking via simplex and/or via repeater. When are the recommended times to transmit a call sign if there is an extended time of communication like, say, 30 minutes, but with only a few of 5 second long transmissions every 5-10 minutes?

Correct, 8300 analog OR digital, and 8400 analog AND digital. For those that may have a Motorola XPR8300 repeater, there are still many radio shops sitting on Entitlement ID's for adding that AND function to make a 8300 into a 8400 for a reasonable price too. Does not apply to GMRS, but still something to think about. Takes more rack units of space than the newer SLR5700/8000 (50W/100W) Motorola repeaters, but can be found at a lot lower price on the slightly used market. Places like SunnyComm sometimes even have a duplexer mounted to the top of some of theirs for around $1200 or so for UHF XPR8300's.

This is absolutely excellent information, Marc. Thank you. @Lscotthit the nail on the head. Documenting technical information clearly is a gift. You did a great job. I really appreciated the historical aspect as well.

Maybe this will help. Here's the logical structure: Rule: The following requirements must be obeyed (Each station must identify itself...) Requirement 1 Requirement 2 Except under these conditions: Condition 1, and Condition 2. Because it's a conjunction, a logical AND, both conditions must be true in order to use the exception. That's the only way the regulation can be interpreted. There are other examples of regulations that have a logical OR in that same position. If it would help I'd be happy to post one. I was wrong that the ID doesn't have to be made at the beginning of a transmission. Only at the end and every 15 minutes. But I don't think anyone should flame you. Certainly not for being incorrect. God knows I'm incorrect frequently and I hope that people won't flame me for that.

Writing up technical material isn't easy to do, time consuming and trying to make it understandable takes a good bit of effort. I've done it at my work place a few times. I can appreciate what goes into it.

marcspaz You did a great write up on this. It should be required reading.

I wanted to support @rdunajewski, the owner, so for me I guess it was, at least once.

The MFJ-874 claims 5% average accuracy on 20 and 200 watt scales: https://mfjenterprises.com/products/mfj-874?pr_prod_strat=use_description&pr_rec_id=43ee72544&pr_rec_pid=4393832153187&pr_ref_pid=4393832349795&pr_seq=uniform#product-manuals It looks interesting to me. The wavenode looks interesting as well.

Exactly! That’s the only reason. I know the granularity of these five examples borders on ridiculousness, but this was the simplest way to list all the permutations.

I drove a truck coast-to-coast in the 90s, then quit in 2000 to join the Army. From what I remember of the late 90s, the RF was getting so noisy that most normal CBs couldn't get out more than a mile or two. That wasn't the case in the early 90s. I'm guessing it was even better in the 70s-80s. If that trend continued, I can see why many truckers stopped using CB unless they were in a bind somewhere. Near the end my my driving days, I rarely heard people on Ch 19, though of course you could still hear people on skip on the other channels. Hopefully the addition of FM will allow CB to make something of a comeback. But I can see why groups might switch internally to GMRS to talk between themselves.

The repeater is listed for operating temperatures - -30°C~ +60°C. There are some guy using them in solar situations also and have them outside. I have not seen major concerns of this but YMMV Yes an attic can probably get close to that but may be a good option still. 10' wont make much of a difference with LMR400 so if that's all you can do then try it. Just know the closer to the antenna the better it will work.

I'm commenting to subscribe. I have a Bird 43. From there, I have amateur grade or less. I'm curious what the pros are using.

Kinda makes my head hurt.

Depends on who offers it. Our County Sheriff (Minnesota's Ramsey County) runs a first rate program. We met weekly for 3 hrs per session and took 10 weeks to complete. I just finished 2 terms on our city council so was well-acquainted with our law enforcement/fire services/county emergency services. As a retired federal employee I've taken previous courses via FEMA. I've also done some ARES coursework. They made no pretense of us ever getting 'called up' to handle a large area disaster (the pros will do that) but we could be called to handle things like crowd control and/or media coordination. But I did get a nifty backpack w/reflective vest, a green hardhat, flashlight and a multi-tool to close gas mains and break through tempered glass (vehicle rescue). Worth it.

I think you've just learned a valuable lesson about "some people" and online "Experts" ...

After 5 months on the waiting list, I received notice my KG-UV9GX has shipped. My order # was in the 130xxx range. I also ordered the Smiley Slim Line Whip. Received my Ed Fong DBJ-UHF antenna kit last week. I completed a CERT program via our county sheriff's office a couple of months ago. Now studying for my HAM Extra class exam. Major snowstorm will impact us middle of the week. WA7HPK

Yes there is another option!!! Read: I had similar frustrations with the linking bundle being out-of-stock so I purchased a Raspberry PI from Amazon, ordered the URIxB interface direct from the manufacturer, made a DB25 cable (according to the pin outs of my repeater), installed the PI image from myGMRS and requested a node number and password (also from myGMRS) and I am now successfully linked to the network. There is ZERO support for this option but there IS plenty of documentation out there to help. It's a split image of Allstarlink's network just tweaked and used for myGMRS. I literally just finished my setup and now I am configuring it all to my likings. I will be going live in a few days. Hope this helps.... DesertRover (WRCS363)

Done.

Your heart is definitely in the right place! Alex (Axorlov) explained it well.

Good form is to use monitor function for a second or two, and/or look at the activity LED that most HTs have. LMR (Part 90) radios have Busy Channel Lockout feature, which is also can be used. Stomping on somebody's conversation is a bad form, indeed.

Handheld radios and mobile radios are not usually capable of receiving while transmitting. In order to receive distant transmissions, the receiver circuit must be sensitive to millionths of volts. Your transmitter is capable of putting out a lot more than that. They're both connected to the same antenna, so when your transmitter transmits, that power would overwhelm your receiver. So, while transmitting, your receiver is effectively disabled. Depending on the convention (and whom you're talking to) that's either called half-duplex or simplex. Repeaters however, must be able to transmit and receive at the same time in order to do their job. That's referred to as full-duplex. But the problem still remains; how do you keep the transmitter power from overwhelming the receiver. So they transmit and receive on two different frequencies and a special device called a "duplexer" provides even more isolation. So, a repeater transmits into a duplexer. The duplexer filters out everything except the frequency being transmitted (as much as it can) and routes that signal to the antenna. Simultaneously, the antenna is picking up signals over a wider bandwidth, which go to the duplexer. The duplexer filters out everything except the frequency that the repeater must receive, which it sends to the receiver. A duplexer is like a traffic cop. In order for the duplexer to do a good job, both sides of it must be pretty precisely tuned and it must be capable of aggressively filtering both signals. If your handheld or mobile radio had a duplexer, you would be able to hear what the repeater is transmitting at the same time as you are transmitting. That should also make you appreciate the fact that cell phones are full duplex. Does that help?

Heck I'd get giddy for an OLED version.

Yes. You can add some channels with different PL and can select Narrow or Wide. You can add channels 8-14 with different repeaters and PL info.