How can a radio broadcast station extend their coverage signal with a second tower?
On an AM station with multiple towers, one is typically the primary omni-directional DAYTIME transmitting tower…and the 2nd, 3rd, 4th (or more) are just for adjusting the NIGHTIME signal. During the daytime AM signals only go a pre-licensed distance…but after sunset the earth’s ionosphere psychically lowers and terrestrial AM signals can have a tendency to “bounce”, literally hitting the ionosphere and then again the ground (and repeating) sometimes for hundreds or thousands of miles. This is why you can sometimes pick up stations in far off places late into the night (before sunrise).ON FM, a station will have a primary antenna mounted as high as possible on a tower or mountain top. FM signals are VHF, which goes “line of sight”. If terrain (a mountain), a bunch of high buildings, etc is in the way of the signal it’ll degrade and create static, “splatter” or multi-path. Sometimes a station owner will be granted a “fill in” opportunity with either: 1) and on channel “booster”, which will work unless the booster actually interferes with the original signal; or 2) an off channel “translator” which will essentially boost the original signal but on a different channel (or frequency). Both on-channel boosters and off-channel translators are on much-reduced power output for the purpose of filling in a non served area. So, these booster antennas and translator antennas will also usually be mounted on a tower at an elevated terrain area.This answer, get “into the weeds”, but I hope it answers your question.
How far off shore do FM radio signals go?
FM radio has two parts: the fact that FM or frequency modulation is used and the fact of what frequency spectrum is used in practice which happens to be the lower VHF band (VHF is 30 MHz - 300 MHz). Of these two, only the latter matters for propagation distance. The fact that FM (frequency modulation) is used has relative little or no effect on range.Lower VHF is mostly but not entirely “Line of Sight” propagating so it only goes as far as you can directly see between the transmitter and receiver. This issue why FM doesn’t work as well in hilly or mountainous terrains. Handheld radios on both ends give you only The taller the antenna, the longer the Line of Sight.If the broadcast antenna is taller than 6 feet (1.8 m), you can get a longer distance on half the radio horizon. Generally it won’t be longer than 10–20 miles because broadcast antenna heights are usually average no taller than about 250 feet (76 m). There are exceptions but those are geography-specific.Visual Line of Sight Calculations dependent on Earth's CurvatureBut other propagation features of VHF such as diffraction and tropospheric ducting/scattering. The problem with these is they are geography dependent and/or weather dependent so you can’t rely on them.Diffraction gives you distance beyond Line of Sight due to “wave effects” of the radio signal wavelength being of similar size to features on the Earth. This is why you can at all receive FM in hilly or mountainous areas: the hills or mountains themselves (or actually their peaks) help to diffract radio waves over their tops.Ducting is caused by oddities in weather so it’s very transient and unreliable. When you sometimes get a station come in that doesn’t normally heard, it’s usually scattering or ducting.
What is the longest distance one can listen to a radio station?
Radio waves travel farthest when they are lower frequencies(for any given wattage output). So, the kilohertz frequencies of AM radio and shortwave are often called sky waves because they will bounce off of the ionosphere and clouds. Nighttime signals travel better because sunlight negatively affects the wave propagation.Frequencies above 30 MHz are "line of sight". Thus, the FM band and television signals have a limit under 100 miles because curvature of the Earth blocks the line of sight.The modulation, AM or FM, is irrelevant. It is all about the frequency. AM just happens to be allocated to longer wavelengths by the government.I worked at KOMA in Oklahoma City when it was at 1520 kHz. I was able to be heard as far away as South Australia on occasion. I know this because I received song requests from fans listening on longwire antennas--they were DX'ers, or distance listeners--who had gone to remote areas to get better reception.KOMA was a 50,000-Watt clear-channel station then and could be heard every night in 22 states and as many as 38 states fairly often. That frequency(1520 kHz) is now carrying KOKC.ADDITIONAL INFO: A clear-channel station is the only station licensed on a particular frequency(often only at night). This gives the station superior range since it does not have competing signals. KOMA had three antennae. During daylight hours, two antennas created a figure eight broadcast pattern from north to south thereby permitting other US stations to broadcast on the same frequency. At night, those competitors were required to sign off, or decrease power. KOMA would switch to the center antenna and a circular pattern to cover a larger area from east to west.EDIT--Frequencies below 28 MHz exhibit both groundwave(surface wave) and skywave behavior depending upon atmospheric conditions. Above this frequency, radio signals rarely skip and are called space waves or direct waves because they are generally line of sight only.
How do tv stations broadcast content to our sets ? Is it a digital file and press play?
There is two types of television signals that are used in broadcasting, analog and digital. Analog signals are what your TV would receive if you used antennas or the old school bunny ears. Digital signals are used much more these days for TVs that use a cable or satellite subscription service like Dish Network etc.Most television networks broadcast their signals to satellites. These satellites then relay the signal to local towers or to the cable provider. Analog signals are broadcasted from the local tower via airwaves which is picked up by your televisions antenna. Digital signals are received by your cable providers satellites and routed to their local location and then sent through cable lines in the area which is what you connect your TV to.These signals are not sent and started by pressing "play". They are a continuous stream that's put together and always playing from the television network.