Templeton

While I was traveling back from a car club driving tour outing up in the San Jacinto Mountains to the Resort where my car club is holding a week long National Convention, I came upon a multi-car traffic collision with the road almost completely blocked in a blinding curve, on State Route 74, between Palm Desert and Idyllwild, and I noticed several people trying to use their cellular telephone probably trying to report the collision. I assumed they were not having any success because we were in a cellular dead zone which was several miles long.
I did not stop to check on injuries because there was no safe place to pullover since it was a narrow mountain road with essentially no shoulders. I continued on hoping to see some bars on my cell phone.
Fortunately, I had both my portable and mobile GMRS units with me and I attempted to make contact with another station that could relay the incident to the California Highway Patrol. I knew there were two repeaters in the area so I tried Coachella Valley Repeater and called out in the blind asking if any station would relay the incident to the CHP.
A station in the Salton City Area answered up and relayed the incident and came back to tell me he was successful in making contact with the CHP. I signed off and continued my drive back to La Quinta
It pays to have a GMRS Radio as an additional means of communications to report emergencies to public safety agencies. Also, it pays to be prepared and know the GMRS system in the area you are traveling in and have your radio units programmed accordingly just in case. This was the “just in case”.

There may be other ways to get the repeater information such as the local ham/GMRS group or by scanning the input frequency with a radio that can scan for the tone, then connecting to the repeater and calling out/asking for permission, or just using it until someone tells you to not use it.

My admittedly poor attitude is that if a repeater owner doesn’t respond in a timely manner to access requests they probably won’t notice that you’re accessing their repeater unless you do something wrong. Do as Randy says and scan for the input tone. If they object to you accessing their repeater they can always say so. 

Yeah, so far, I have left receive tones off so I can hear what else is happening on the freq.  It is not hard for me to wait until the other transmissions are over, I was just more curious what the burst of beeps was.

Makes sense, I will try that! Thanks for filling me in.

for more details…
https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-E/section-95.1751

After 15 minutes of use and at least once every 15 minutes thereafter during a series of transmissions lasting more than 15 minutes.
Many repeaters will transmit the ID without tones so if you listen with the receive tones set you won’t hear the ID. Which is nice because it doesn’t interfere with your talking. 

Excellent document, and thanks for the help and input.

Excellent document, and thanks for the help and input.

This is one of my favorite short guides for grounding and bonding but there are lots of threads here that cover it in great detail. The Bible is a document from Motorola that’s available on a BLM site, but it’s pretty deep. Also ARRL has a book on grounding and bonding. 
https://reeve.com/Documents/Articles Papers/Reeve_AntennaSystemGroundingRequirements.pdf

Your question made me look for a video that would explain this better:
Stan Gibilisco passed away within the last few years but I liked his videos:
 
As for your other questions, almost all communications cable is 50 ohm. The antenna you showed is also 50 ohms. The port on your radio expects 50 ohms. 
But, there are lots of different types of cable and different types have losses that increase proportionally to length. Those losses are simply characteristics of the cable. 
Unfortunately, the rate of loss increases dramatically as frequency increases. At GMRS frequencies some cables lose half or more of their power in less than 50 feet.  
But, a good antenna, raised high can compensate for that somewhat. 
I wouldn’t select less than LMR400 and if I was going longer than 50 feet total I’d look for something even better. 

Not well. TV cable and related fittings are 75 ohm. Two way radios expect 50 ohms. Using it for your radio will introduce an impedance transition that results in a higher SWR than usually desirable. 
But, people do it. 
You can use the hole that currently exists.

If there was zero other terrain?  That would be correct.  This is exactly why RF LOS terminates about 15% further than visual line of sight.  RF is both scattered and partially refracted over the horizon.  The closer to the horizon line, the more dense the scatter is.
 
 
It's really hard to answer that question.  For example, are we talking about a building?  A small hill? or a 5,000'+ mountain?  My house is in a recess in the ground by about 100 feet, with the ridge line about 150 yards away.  I can stand in my driveway with a handheld radio and still reach another handheld about a mile away before the shadowing become to great.
 
 
There is a way, but it is way beyond my skill set and understanding.  The level of effort and all contributing factors vary too rapidly and greatly to attempt to try to calculate it in some practical time-frame, as well.  To make things worse, the results would only be valid for the exact forecasted locations of the two radios.  If you move either radio even an inch in any direction, the values are no loner valid.
 
Items in the sky like rain and fog will attenuate the signal more.  While diffraction, reflection and scattering of radio waves is the principle behind extending LOS, as those conditions increase, the amount of dilution increases, leading to more attenuation, not more extended range.  The PPM of the photons simply drops too low to receive. 

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?

first question: yes, that's correct.  i'll share a real world example from the ham side (on 70cm, which is nearly identical, signal wise, to gmrs), with the caveat that i don't do much (if any) simplex on GMRS, as the family has ZERO interest.
using my base setup (which is a pair of mobiles and a base antenna in the closet) chatting with someone who lives in the next town up the highway via the local repeater, which is 23 miles from me. discover he's in town shopping at the moment, talking in on his mobile from a shopping center 25 miles from the repeater, and just 6.5 miles from me.  i switched over to the repeater input to see if i could hear him, but not much beyond an occasional burst of static.  i can hear the repeater clearly on a handheld inside the house, and can talk in with no problem from outside in the yard, but going direct just over 6 miles apart was no go.
second question: hard to say on "reasonable"...is it possible? absolutely.  it's going to be very dependent on height, but it's a little bit of a stretch to assume radio towers.  some may be one of the users here, with a 5 watt Retevis 'repeater in a box' on a 20' top rail mast, or mounted on a barn.  dealing with the high level stuff we have in CA, i've talked into a gmrs repeater over 60 miles out from the 3rd floor of a hotel with a handheld, and managed 75ish to a ham repeater in the same area from a high spot in the hills (basically clear line of sight over the valley), but those repeaters i'm working with are on foothill ridges at 3000-4500 ft above sea level. obstructions are the biggest challenge for a largely line of sight signal like gmrs.
here's a quick edit to the diagram in the first post illustrating my example (though i'm using gmrs frequencies in the diagram, illustrating hearing via the repeater was no problem, but listening on the repeater input, no luck.

Believe it or not, 5 watt handhelds with decent antennas can reach the receivers or repeaters on the International Space Station or an AMSAT satellite which are around 200 miles up. This is because there is nothing between the handheld and the space station. Those same handhelds cannot reach more than a few miles at best at sea level because the signals are blocked by terrain, structures, foliage, and all manner of other obstacles. It's all about line of sight and how high the repeater is. My repeater is at 5,700 feet, and we can hit it with handhelds from sea level 30 miles away, probably more. 

No. You are absolutely right. The original subject concerned how GMRS repeaters worked, which was covered extensively. Your questions are many, as are our answers. The best way to get answers is to post specific questions and/or look through answered questions and forums. We're here to help. I mean that.

There are cables/interface boxes made to link 2 handhelds together. The problem there would the radio doing the retransmittimlng part can overload the receiving radio due to it's close proximity. This would cause this shoulder height repeater to be to hear you from a shorter distance than if you were just going handheld to handheld...while some are worse than others, and some handle adjacent frequencies better than others, almost any radio will desense to a degree to protect the receiver from a strong signal nearby.
You can see the same issue when transmitting from one handheld to another in close proximity;the receiving radio sees an incoming signal, but doesn't receive any audio.
As @axorlovsaid, there isn't anything magical about it, at the most basic it's a receiving radio connected to a transmitting radio. In practice, better filters against adjacent frequencies in mobile and repeater receivers help make it possible, as do things like duplexers that separate the transmit from the receive.
Does that help clarify?

Also remember that just because your handheld can hear the repeater, the repeater may not be able to hear your handheld. Repeaters put out a lot more wattage than a handheld, and do it through a much better antenna system. The repeater I maintain puts out well over 50 watts and is located at almost 6,000 feet, giving it coverage from Santa Barbara to San Diego. My Handheld at sea level cannot always reach it even if I can hear it, normally due to terrain or obstacles like buildings.

Yes, but only because repeaters, usually, located high off the ground, providing longer line-of-sight distances. And also because repeaters, usually, have much more efficient antennas and much better, by many parameters, receivers. There is nothing magical about repeater, and repeater created from two HTs placed at shoulder height will have less reach than same radios on simplex.

The ISS carries amateur radio equipment, and sometimes they chat with folks on Earth if their schedule allows it. No GMRS though. There's a few amateur radio satellites that are basically orbiting cross-band repeaters. Much too much to discuss here, but a visit to the AMSAT website is worth your time. But again, no, there are no GMRS satellites in space. It would be cool though. 

Yes, 3-30 MHz is HF; 30-300 MHz is VHF; 300 MHz to 3000 MHz is UHF. GMRS uses channels in 462 and 467 MHz ranges.
I’ve seen my satellite receiver fade out during heavy rains and snows. The higher the frequency the more moisture affects it. I haven’t range tested my GMRS radios in the woods.
People use receiver tones to filter the signals that are reproduced. So for instance if there were several people using their radios and i didn’t want to hear them, but I wanted to hear from you, I would set a tone on my receiver and tell you the tone so you could set it for your transmitter. Then, when you transmit using that tone (tones are usually under 300 Hz) my receiver will reproduce your transmitted sounds after filtering out the tone you sent. 
But if I want to hear everything transmitted on that frequency all I have to do is remove my receive tone. Nothing will be filtered. 
It’s the same way with a repeater. The receiver half of the repeater only transfers audio to the transmitter that have the right tones when received.

Most if not all repeaters will have a "squelch tail". I've heard different people call it different things. But if you can receive the repeater, when you transmit to the repeater, you will hear this "squelch tail" at the end of your transmission. Some repeaters have certain noises on their squelch tails, such as beeps, and some have none. That is why you will hear people "kerchunk" a repeater. They are just testing that they can hit it. When you unkey your mic, if you don't hear this squelch tail, you aren't hitting the repeater. It is kind of hard to explain this sound as it can be different on every repeater. One repeater in my area does a small double beep, and another one doesn't so it just sounds like a quick burst of static at the end of my transmission. 

Side Note: The squelch tail is actually the end of your own transmission. due to distance and time through the duplexer, you receive your own transmission, just a few hundredths of a second behind.

Many repeaters have some "hang-time" programmed into them to continue transmitting for a short time after a person transmitting to the repeater stops transmitting.  This is clearly audible and an indication that you have reached the repeater and that you're using the right tone.