Jump to content

GMRS Band Opening


Recommended Posts

Thursday morning i was hearing some strange station id's, so i decided to give a few channels a try that had the travel tone.  On 725 i id'd my station, and got a reply......it was from a station in jacksonville, Fla.,  the owner answered, and we had a nice conversation.  Oh, i forgot to say i am in the upper midlands in SC.  I then tried my buddies repeater in myrtle beach.......it was like i was looking at the tower it was so clear.  Anyone else experience this yesterday?


Link to comment
Share on other sites

The weather front that was moving into your area from the west created the situation.  Occasionally when atmospheric conditions are just right, "tropospheric ducting" is formed. This is a temperature inversion effect created by a stable-high pressure system over oceans or very large lakes where a warm, moist air mass is sandwiched between two cool air masses. VHF and some UHF signals can be ducted through this conductive tunnel by bouncing off the dense air within the system to propagate waves for hundreds of miles. Think of it as mother nature's coaxial cable or waveguide.  This effect is usually seen only during the warm weather months.  UHF is defined as the range from 300 Mhz. to 3 Ghz., and along the shorlines of the Atlantic and Great Lakes, it is common to have this effect present several times each year where  single repeaters and trunked 400, 700 and 800 Mhz. Public Safety, business and other radio systems in the frequency range hundreds of miles apart interfere with each other so severely that communications are all but impossible - lasting for minutes to several hours. This can be a very serious situation when a trunked system with the same control channel properties affects another system a couple hundred miles away.  That is why it is essential to have a simplex backup plan in place during such events.

Link to comment
Share on other sites

Guest spd641

I too have heard those kind of band openings before.I have listened to stations in different areas of Florida and it sounded like they were outside my house.My first GMRS band opennig was several years ago and I never got a chance to see if I could make contact but the thought of UHF being able to receive signals from afar was exciting.


Like Pastor Gary said it is a warm weather senerio and will happen from minutes to hours and sometimes only for a brief period of time.If you are fortunate enough to hear it enjoy while you can,it may be gone in the next few seconds.


I am one who loves to experience new things in the radio world,while far from being a radio geek it does interest me and from the time I was small until now it has stayed with me and I will continue to enjoy anything related to radio.....William

Link to comment
Share on other sites

     We had some ducting here in Toledo, Ohio.  We were getting into a repeater south of Cleveland.  The guy in Cleveland asked for our ID's and said we were on HIS PL.  It caused a bit of an argument with the guy until the repeater operator explained to him what we were saying about the ducting.  I hear it on the ham bands once in awhile so I knew what was going on.  It was so strong that we were hitting the other repeater with just a watt or two.  Crazy.



Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use and Guidelines.