|
range of VHF
Hello, I need to set up a communication link between a shore station
and a dive boat that is at most 30nm (50 km) distance from the shorestation (the shore station is on the beach i.e. there are no obstacles between shore and ship) Can somebody advice me if it is possible to do this with for exemple 2 Uniden Oceanus DSC VHF radioos and two 6 feet 6dB antennas? The Top of the antenna would be about 16 feet aove sealevel on the boat and about 30 feet on the shorestation? Is there a better solution to assure the communiication . The radios would be need for emergency cases) Thanx fopr any input |
range of VHF
|
range of VHF
GregS wrote:
Standard distances suggest up to 111 kM for high antennas and high power. Power's not very important here. 111 kM represents combined Rx + Tx antenna heights of 3,000 feet! I don't know whats legal for your shore station. I think a 100 foot twin stacked yagis might work. Yagis have the same effect as increased power. They can't make the signal bend over the visual horizon. I would use it only for backup. Don't bother with the shore station even as backup. The boat ought to have a VHF in any case. If the boat moves, then a tall vertical is going to be iffy. Yes. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
range of VHF
In article , Chuck wrote:
GregS wrote: Standard distances suggest up to 111 kM for high antennas and high power. Power's not very important here. 111 kM represents combined Rx + Tx antenna heights of 3,000 feet! I don't know whats legal for your shore station. I think a 100 foot twin stacked yagis might work. Yagis have the same effect as increased power. They can't make the signal bend over the visual horizon. I would use it only for backup. Don't bother with the shore station even as backup. The boat ought to have a VHF in any case. If the boat moves, then a tall vertical is going to be iffy. Yes. I used the reference at... http://en.wikipedia.org/wiki/Marine_VHF_radio Do you have a table for distances? I always get about 60 miles from the cell phone up on Lake Erie. A problem getting into Canada's system. I'm more familiar about talking hundreds of miles through the dessert 2 meter amateur rigs. greg ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
range of VHF
GregS wrote:
I used the reference at... http://en.wikipedia.org/wiki/Marine_VHF_radio The 60 nm maximum range quoted is not likely to be realized if one of the antennas is virtually at sea level. An antenna on a 1000 foot hill could do it. The 5 nm range given for small boats is Do you have a table for distances? The range is ~ 1.4 times the square root of the sum of the antenna heights. Now you can verify some of your assertions. I always get about 60 miles from the cell phone up on Lake Erie. Sure you do. A problem getting into Canada's system. I'm more familiar about talking hundreds of miles through the dessert 2 meter amateur rigs. Sure thing. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
range of VHF
|
range of VHF
In article , Chuck wrote:
GregS wrote: I used the reference at... http://en.wikipedia.org/wiki/Marine_VHF_radio The 60 nm maximum range quoted is not likely to be realized if one of the antennas is virtually at sea level. An antenna on a 1000 foot hill could do it. The 5 nm range given for small boats is Do you have a table for distances? The range is ~ 1.4 times the square root of the sum of the antenna heights. Now you can verify some of your assertions. These calculations seem to be line of sight measurments, and I can agree with that. Talking power or antenna types then would not matter. I see no calculation for power in the formula. greg I always get about 60 miles from the cell phone up on Lake Erie. Sure you do. A problem getting into Canada's system. I'm more familiar about talking hundreds of miles through the dessert 2 meter amateur rigs. Sure thing. The problem I used to have, when I talked on the cell through Canada, I never got billed. That was back in the analog days. The cell tower was over 50 miles away from the US shore. I got very poor reception from that shore, but out 5-10 miles from shore, cell reception was steller. |
range of VHF
Chuck wrote in news:1181052689_15255
@sp12lax.superfeed.net: Antenna heights are insufficient for reliable communication over that distance. The combined antenna heights would need to be more than 400 feet for marginal line-of-sight communication. I agree with Chuck. Marine radio is useless over-the-horizon more than 5% of optical line-of-sight. Contact your local 2-way radio shop and ask them about installing TRUNK RADIOS in both the shore installation and on the boat. The trunk radio systems use very-high-up digital repeater stations that are widely interconnected by computers that talk to the trunk radios, not unlike what a Nextel iDen phone does, but on a much more powerful scale. These trunk radio systems are shared by many diverse users, who rent service on them for a pittance of what the entire trunk radio system costs. Look in your local phone book under "2-way radio" or "trunk radio systems" or "radio communications". Professional communications, especially where life and limb might be in danger, is well worth paying for. It's why the cops all use trunk radio systems! Larry -- If electricity comes from electrons, does morality come from morons? |
range of VHF
Chuck wrote in news:1181064796_15805
@sp12lax.superfeed.net: An antenna on a 1000 foot hill could do it. You're never going to get a Shore Station Marine Radio license, which is REQUIRED to operate a marine radio from shore with a 1000' tall antenna that will cause interference in many conditions. VHF was never intended for range. Larry -- If electricity comes from electrons, does morality come from morons? |
range of VHF
Chuck wrote:
The range is ~ 1.4 times the square root of the sum of the antenna heights. This should've said ~1.4 times the sum of the square roots of the antenna heights. Range is in statute miles; heights are in feet. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
range of VHF
In article ,
Larry wrote: Chuck wrote in news:1181052689_15255 @sp12lax.superfeed.net: Antenna heights are insufficient for reliable communication over that distance. The combined antenna heights would need to be more than 400 feet for marginal line-of-sight communication. I agree with Chuck. Marine radio is useless over-the-horizon more than 5% of optical line-of-sight. Contact your local 2-way radio shop and ask them about installing TRUNK RADIOS in both the shore installation and on the boat. The trunk radio systems use very-high-up digital repeater stations that are widely interconnected by computers that talk to the trunk radios, not unlike what a Nextel iDen phone does, but on a much more powerful scale. These trunk radio systems are shared by many diverse users, who rent service on them for a pittance of what the entire trunk radio system costs. Look in your local phone book under "2-way radio" or "trunk radio systems" or "radio communications". Professional communications, especially where life and limb might be in danger, is well worth paying for. It's why the cops all use trunk radio systems! Larry Ok, another Note here, from years of Parctical Experiencein the North Pacific, 50 Statute Miles VHF Range is very common between Commerical Shipping, WHERE the antennas are mounted on the TOP of the Masts, and about 75 to 100 Feet above the water. Comms with HIghSite USCG Stations that are in the 3000 Ft Range, above SeaLevel, are routinely carried out out to 90 Statute Miles from these Commercial Ships. In the Bering Sea it is very typical for the Crab Feet (Deadliest Catch type vessels) to have good VHF Comms in the 30 to 45 Statute Mile range, and significantly farther is they both are on TOP of the 30Ft Seas that typically run in the winter storms. I have Installed, Licensed,and Inspected, both Public and Private Coast Station, that have typical 30 to 45 Statute Mile coverage, to typical Fishing Fleet (less than 200 Tons) Vessels where the Coast Station Antennas are at the 75 to 100Ft above Sealevel and the Vessel Antennas are in the 30 to 45 Ft level range. In the US, VHF Limited Coast Stations are allowed 50 Watts Carrier Power AT the Antenna Terminal, which allows for higher powers at the Radio to make up for Feedline Losses. A good OmniDirectional High Gain VHF Antenna (Cellwave/Phelps Dodge Super Station Master) at the end of a 150ft run of 7/8" Heliax, with Beldon 9913 Jumpers, is about the best that can be done for a Limited Coast Station. It makes sense to put it (the coast Station) on the closest Hill, to the Coast, as possible for whatever elevation gain you can get, without sacraficing you limited range to Sea. Beyound that you loking at SSB, or in the modern era, a TracPhone or similar. These are going to cost you $2k to 3K by the tme you get them installed and provisioned. Bruce in alaska -- add a 2 before @ |
range of VHF
Makes me wonder how high "Sea tow" in southflorida has their antennas.
I regularly talk to them from Bimini (40 NM from Miami) and Freeport (55NM from WPB) for radio checks. I have a 21' 9db 9 ft off the water (30' tall) sqrt of 30 = 5.5 NM (My boat) That translates to 2500 ft... .Hmmmm not possible. Never really thought of it before but I bet they must have repeaters in the islands. Wayne.B wrote: On Tue, 05 Jun 2007 06:40:26 -0700, wrote: Hello, I need to set up a communication link between a shore station and a dive boat that is at most 30nm (50 km) distance from the shorestation (the shore station is on the beach i.e. there are no obstacles between shore and ship) Can somebody advice me if it is possible to do this with for exemple 2 Uniden Oceanus DSC VHF radioos and two 6 feet 6dB antennas? The Top of the antenna would be about 16 feet aove sealevel on the boat and about 30 feet on the shorestation? Is there a better solution to assure the communiication . The radios would be need for emergency cases) Thanx fopr any input 6 db antennas and 30 feet of shore station height are not going to get the job done reliably. The standard equation for VHF range is 1.15 * SQRT height, with the two calculated ranges added together. The boat has a clculated range of about 5 NM and the shore station about 7 NM, for a total reliable range of 12 NM. I'd go with 9 db antennas at each end and increase shore station height to at least 100 feet. Even that will be marginal, and you will need to use low loss coax cable at the shore station tower. A tower mounted pre-amp/amplifier would be even better. |
range of VHF
Ed wrote:
Makes me wonder how high "Sea tow" in southflorida has their antennas. I regularly talk to them from Bimini (40 NM from Miami) and Freeport (55NM from WPB) for radio checks. I have a 21' 9db 9 ft off the water (30' tall) sqrt of 30 = 5.5 NM (My boat) That translates to 2500 ft... .Hmmmm not possible. Never really thought of it before but I bet they must have repeaters in the islands. Hi Ed, The Sea Smart network uses 300' - 400' towers in a radio-over-internet system. I don't know if they have transmitters on the islands, but if so, they are probably linked by internet rather than radio. The website mentions only US coastal areas as their service territory. http://www.seasmartvhf.com/pressroom...nes020606.html Welcome to Sea Smart - "Who knew your VHF was so powerful?" Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
range of VHF
On Jun 7, 12:38 pm, Chuck wrote:
Ed wrote: Makes me wonder how high "Sea tow" in southflorida has their antennas. I regularly talk to them from Bimini (40 NM from Miami) and Freeport (55NM from WPB) for radio checks. I have a 21' 9db 9 ft off the water (30' tall) sqrt of 30 = 5.5 NM (My boat) That translates to 2500 ft... .Hmmmm not possible. Never really thought of it before but I bet they must have repeaters in the islands. Hi Ed, The Sea Smart network uses 300' - 400' towers in a radio-over-internet system. I don't know if they have transmitters on the islands, but if so, they are probably linked by internet rather than radio. The website mentions only US coastal areas as their service territory. http://www.seasmartvhf.com/pressroom...nes020606.html Welcome to Sea Smart - "Who knew your VHF was so powerful?" Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----http://www.newsfeeds.comThe #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- VHF radios are meant to have a range of about 80 miles. Radio waves travel really well over the water and there is very little loss over long distances. I would try VHF first before investing in SSB or HF. |
| All times are GMT +1. The time now is 10:43 PM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 BoatBanter.com