Why is it that when you monitor the VHF you can only hear one side of the conversations? Someone usually hails but you never hear the answer.
VHF Radio
- Thread starter Broke sailor SV Marcell
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Or if it's the Coast Guard -
they may switch the calling party over to one of the Coast Guard working channels. Then all you will hear is the Coast Guard talking and not the hailing party.
they may switch the calling party over to one of the Coast Guard working channels. Then all you will hear is the Coast Guard talking and not the hailing party.
Speaking of VHF radios . . .
. . . It seems that most sailors have their VHF radio down below near the nav station. What is a good approach to mounting a speaker so you can hear the radio from the cockpit, and how have you set up your VHF so you can use it while steering? I have a 1992 H28 with the radio at the nav station.
. . . It seems that most sailors have their VHF radio down below near the nav station. What is a good approach to mounting a speaker so you can hear the radio from the cockpit, and how have you set up your VHF so you can use it while steering? I have a 1992 H28 with the radio at the nav station.
remote mic
For some radios you can buy a remote microphone/speaker that can be attached anywhere you want. They usually have volume and channel controls, and a little LCD screen to display the channel.
For some radios you can buy a remote microphone/speaker that can be attached anywhere you want. They usually have volume and channel controls, and a little LCD screen to display the channel.
out of range
VHF is a line of sight system, ie, distance is limited by wattage of the radio and curvature of the earth. As stated previuosly, if you are only hearing one side of the conversation it is because the other boat is too far out of range (probably due more to the low wattage of the radio than surface curvature or signal blockage from another obstruction.) This is why we have moved away from the VHF radios in the fire department and now use 800MHz radios. Line-of-sight can be a big problem when working a wildfire in canyons and backcountry.
VHF is a line of sight system, ie, distance is limited by wattage of the radio and curvature of the earth. As stated previuosly, if you are only hearing one side of the conversation it is because the other boat is too far out of range (probably due more to the low wattage of the radio than surface curvature or signal blockage from another obstruction.) This is why we have moved away from the VHF radios in the fire department and now use 800MHz radios. Line-of-sight can be a big problem when working a wildfire in canyons and backcountry.
line of sight
I have a dock in a narrow channel surrounded by large buildings (NYC). Further, after I leave my marina I'm surrounded by land on both sides for 2 miles until I get to open water - is this the reason that I can't always receive on my VHF? Do I need to have line of sight with a vessel to hear it? What if there's land between me and the vessel - imagine that you're making a turn around a body of land and the target vessel that you want to reach is on the other side of the body of land. Will you reach it?
I have a dock in a narrow channel surrounded by large buildings (NYC). Further, after I leave my marina I'm surrounded by land on both sides for 2 miles until I get to open water - is this the reason that I can't always receive on my VHF? Do I need to have line of sight with a vessel to hear it? What if there's land between me and the vessel - imagine that you're making a turn around a body of land and the target vessel that you want to reach is on the other side of the body of land. Will you reach it?
remote speakers also
WM and others sell a remote speaker for VHF that can be plugged in or wired in to most Nav station radios. I have one on my boat and plug it in and lay it on top of the coach roof under the dodger when moving around. That way I can hear. I stow it when atr the dock. It does not solve the problem of answering or talking from the helm, but a handheld or remote mike would do that for you at about $150.
WM and others sell a remote speaker for VHF that can be plugged in or wired in to most Nav station radios. I have one on my boat and plug it in and lay it on top of the coach roof under the dodger when moving around. That way I can hear. I stow it when atr the dock. It does not solve the problem of answering or talking from the helm, but a handheld or remote mike would do that for you at about $150.
Tony
There are a couple of things you can do to increase the effectiveness of the receiver: 1. Make sure the antenna is as high as you can get it - typically at the mast head, and 2. If your VHF is old, it may be worth investing in a good quality new one with good dynamic range and adjacent channel rejection, two specifications which you can research on the mfg web sites before buying based solely on price. Most current production run VHFs are fairly close in specs but some of the high end ones are definitely better, particularly in intermodulation rejection which is a big problem in any metro area. As far as the so-called line-of-sight rule, it's a common misconception. Actually, VHF signals are mostly ground wave but can easily be somewhat obstructed by solid objects. If you could visualize the EM signal, you would see it reflecting and refracting off solid objects and bending around some. Long story short - there isn't much you can do which will markedly increase receive performance in NYC. Don
There are a couple of things you can do to increase the effectiveness of the receiver: 1. Make sure the antenna is as high as you can get it - typically at the mast head, and 2. If your VHF is old, it may be worth investing in a good quality new one with good dynamic range and adjacent channel rejection, two specifications which you can research on the mfg web sites before buying based solely on price. Most current production run VHFs are fairly close in specs but some of the high end ones are definitely better, particularly in intermodulation rejection which is a big problem in any metro area. As far as the so-called line-of-sight rule, it's a common misconception. Actually, VHF signals are mostly ground wave but can easily be somewhat obstructed by solid objects. If you could visualize the EM signal, you would see it reflecting and refracting off solid objects and bending around some. Long story short - there isn't much you can do which will markedly increase receive performance in NYC. Don
Simplex and duplex modes
All of the previous replies are possible plus it may be that you are listening to frequencies which are duplex mode where the transmit and receive are different frequencies. Simplex is more common and is where the transmit and receive frequencies are the same. Most VHF channels are simplex except for the marine operator which is duplex. Those are channels 24-28 and 84-88. I cannot remember if there are any others or not.
All of the previous replies are possible plus it may be that you are listening to frequencies which are duplex mode where the transmit and receive are different frequencies. Simplex is more common and is where the transmit and receive frequencies are the same. Most VHF channels are simplex except for the marine operator which is duplex. Those are channels 24-28 and 84-88. I cannot remember if there are any others or not.
radio with remote in cockpit
We installed a new vhf radio at the nav station and a "wired" remote at the cockpit. We have excellent volume and clarity up on top, its got a coiled leash wire so you don't drop it overboard(its waterproof too), has a loud PA feature for hailing other boats, you can use the intercom feature to talk to crew down below, you have independant volume controls so you can turn down either side, it interconnects with my GPS and reads out lat and long data in both sets. Its works great, and paid about $500 at WM. The wireless models didn't appeal to me because I'm always misplacing the remotes at home for the TV and I hate to be worried about bunches of AA batteries, and dropping it overboard. I'll still likely buy a wireless for the ditch bag.
We installed a new vhf radio at the nav station and a "wired" remote at the cockpit. We have excellent volume and clarity up on top, its got a coiled leash wire so you don't drop it overboard(its waterproof too), has a loud PA feature for hailing other boats, you can use the intercom feature to talk to crew down below, you have independant volume controls so you can turn down either side, it interconnects with my GPS and reads out lat and long data in both sets. Its works great, and paid about $500 at WM. The wireless models didn't appeal to me because I'm always misplacing the remotes at home for the TV and I hate to be worried about bunches of AA batteries, and dropping it overboard. I'll still likely buy a wireless for the ditch bag.
Line of Sight
VHF, as has been described, is mostly line of a sight service. Marine VHF radio frequencies are in the 160-megahertz (million cycles per second) radio frequency range. Your broadcast AM radio frequencies are 540-1620 kilohertz (thousands of cycles per second). Your FM broadcast radio range is about 88-108 megahertz. Frequencies of about 30 megahertz and above are pretty much line of sight. Below the AM radio band (below 500KHZ) you can get "groundwave" signals, where the radio signal follows the curve of the earth. That's why after dark when conditions are right you can sometimes here AM stations hundreds of miles away. Above about 3 MHZ, but below about 30MHZ you can get "skywave" or "shortwave" signals, where the signals bounce off the atmosphere to be heard hundreds or thousands of miles away. Long range marine single sideband (SSB) communications uses these frequencies. Above 30MHZ, which the marine VHF is (at 160MHZ) you mostly only get line of sight in normal conditions. Here in Stockton, NorCal, however, we can here the Coast Guard talking to boats off San Francisco 100+ miles away, as the CG antenna is on a mountain nearly around 4000 ft high, which we can see. We can't here the boats though, as they are out of our line of sight.
VHF, as has been described, is mostly line of a sight service. Marine VHF radio frequencies are in the 160-megahertz (million cycles per second) radio frequency range. Your broadcast AM radio frequencies are 540-1620 kilohertz (thousands of cycles per second). Your FM broadcast radio range is about 88-108 megahertz. Frequencies of about 30 megahertz and above are pretty much line of sight. Below the AM radio band (below 500KHZ) you can get "groundwave" signals, where the radio signal follows the curve of the earth. That's why after dark when conditions are right you can sometimes here AM stations hundreds of miles away. Above about 3 MHZ, but below about 30MHZ you can get "skywave" or "shortwave" signals, where the signals bounce off the atmosphere to be heard hundreds or thousands of miles away. Long range marine single sideband (SSB) communications uses these frequencies. Above 30MHZ, which the marine VHF is (at 160MHZ) you mostly only get line of sight in normal conditions. Here in Stockton, NorCal, however, we can here the Coast Guard talking to boats off San Francisco 100+ miles away, as the CG antenna is on a mountain nearly around 4000 ft high, which we can see. We can't here the boats though, as they are out of our line of sight.
But probably the main reason is that the radio you hear is on high power, and the one they are talking to is on low (like they should be) power. They are most likely a long way from you. Try contacting the boat you can hear, first on low power, then switch to high power to see how far away they are.
Handheld VHF
We have a VHF by the nav station, and a second one in the cockpit as a backup. That way we can also monitor 2 stations in an emergency. Also have handheld VHF (2) at the ready which paid of this summer when BOTH stationary VHF radios were on the fritz (don't ask, it was a stupid fix) and he CG was trying to hail US! But if we didn't have the 2nd VHF in the cockpit would for sure have the ram mike in the cockpit as we did on our old boat. That paid off BIG time for the helmsman calling crew down below during a hairy situation.
We have a VHF by the nav station, and a second one in the cockpit as a backup. That way we can also monitor 2 stations in an emergency. Also have handheld VHF (2) at the ready which paid of this summer when BOTH stationary VHF radios were on the fritz (don't ask, it was a stupid fix) and he CG was trying to hail US! But if we didn't have the 2nd VHF in the cockpit would for sure have the ram mike in the cockpit as we did on our old boat. That paid off BIG time for the helmsman calling crew down below during a hairy situation.
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