It took me a few minutes to figure this out.. You're saying that CTCSS should be used correct?
Yes, that is correct. Sorry for not making that clear.
Murphy625 said:
When we did our test, the HT could barely make the trip at only 5 watts, but it did make it. When her voice was heard, there was static along with it as the signal was just barely above the background noise. Her words were clear, but her signal didn't completely drown out everything else.. If I turned the squelch up, I wouldn't hear her at all.
Am I to understand that if we used CTCSS, then I could turn the squelch up above the noise and her tone would open the squelch as needed?
Yes, as the tone rides the same audio as her voice does, it's just lower in frequency, and your radio filters it out before the audio comes out the speaker.
Murphy625 said:
Part of me is thinking that if the signal is that weak, the radio might not pick up the CTCSS tone at all... Is that a valid concern?
It is possible, but if there is enough of her signal to break squelch without a tone, then there should be enough for a tone decode (at least most of the time) by your radio.
Murphy625 said:
Would there be any difference if DCS (Digital Coded Squelch) was used?
Good question. I'm not familiar enough with DCS, as none of the amateur analog repeaters in my area use DCS, and most public service agencies are on a 800 MHz P25 trunked system.
Murphy625 said:
And this brings me to another curiosity, how much of the noise on the VHF/UHF bands is man-made? While I realize that the answer would probably change drastically based on one's location relevant to a metropolitan area, I'm just looking for a generalized answer. (I'm in a rural area) I mean, if all man-made noise was all of a sudden eliminated, how much would the noise floor drop assuming average natural activity?
A lot more than most people realize. Man-made sources are all around us. Just about anything electronic (or even simply electrical) make RF noise, some worse than others. The proliferation of cheap LED lighting, and florescent light bulbs have caused a large amount of RF pollution. The good thing is that FM radios, like your analog transceivers, are less susceptible to RF noise than other modulation techniques, like amplitude modulation (AM), or single side-band (SSB) modes.
Murphy625 said:
Correct me if I'm mistaken, but it's my understanding that the cosmic microwave background and solar wind interacting with the planet's magnetic field are the main sources of natural RF noise, how do these compare to what's man made at VHF/UHF frequencies?
Cosmic background radiation levels are well below most of the man-made sources, which are obviously coming from much closer to you. I listed some common sources above, but include your car electronics, computers, even your cell phones, in the list.
Murphy625 said:
After an hour of reading some very technical PDF files I barely understand, it seems to me that the amount of natural noise and the frequency measured are somewhat inversely related. The higher the frequency, the less natural noise but the more man-made noise. Did I get that correct?
I would agree with that, for the most part. When I was in the Air Force, I was a ground radar technician. One unit I was assigned to was responsible for assessing, and optimizing radar systems in their installed environments. We had to have accurate antenna beam pattern, and gain measurements for our engineers to calculate parameters. To measure that pattern, we needed a point RF source of sufficient strength, that we could move through the beam, in what is called the 'far field', while taking measurements of the received signal strength. We used an unlikely RF source, our very own Sun. It makes a very good, broadband radiator in the 2.7 - 3.0 GHz band that we were interested in. We would start our measurements before sunrise, and sunset, and measure the received signal strength each time the antenna swept across the Sun's location as the sun moved up or down in the sky. We had a computer program that integrated all of the information into a very nice plot of the beam pattern, and table of gains. Sorry for being long winded, but I wanted to illustrate an unlikely RF noise source for you. In fact, if you look at your local weather radar display (NEXRAD), either on the NWS site, or your local television station, around sunrise, and sunset, you can often see a 'Sun strobe', wedge of noise on the radar display in the direction of the Sun's location in the sky.
Murphy625 said:
I apologize in advance if I sound like an idiot.. feel free to set me straight.
Not at all sounding like an idiot, great questions, and something all amateur radio operators have an interest in.
