VHF high band skip

Flametamer · Post by **Flametamer** » Tue Dec 11, 2001 8:25 pm

Has anyone noticed skip on VHF high band? I am located 50 miles north of Jackson, MS and heard a dispacher for the Daphne, Al police Dept. on 2 seperate nights now. The freq is 154.160. Tonight, I also heard another dispacher on 154.130. I haven't determined where they were(but she did say highway 231 and tower road if anyone happens to know). Has anyone else noticed this? Both were almost as clear as our normal radio traffic.

Darrin

Jay · Post by **Jay** » Tue Dec 11, 2001 8:38 pm

What you are hearing is indeed distant stations operating on the same frequencies. On VHF-hi, this is most common during the later part of the year, especially the summer and early fall.

On 144 Mhz, not too far away from 154 where you were listening, I've been able to have contacts in the ham band in Canada from Virginia. I've also seen TV stations in Canada, Oklahoma and Louisiana during band openings.

If you can copy down the callsign of the stations you are hearing, you can go the ULS page at the FCC website and look up who you heard.

Jay

jim · Post by **jim** » Tue Dec 11, 2001 8:45 pm

I am in Pittsburgh and for the past few days I have been reliably receiving skip on 33.860 from Charleston and also on 155.430 from somewhere I haven't figured out yet. I guess none of our local 911 dispatchers know what's going on here. Every time the DX comes in, they say "unit calling repeat."
It is interesting hearing how differently things are done when you get outside of your area.

jim · Post by **jim** » Tue Dec 11, 2001 8:46 pm

....oh, and I'm getting their mobiles loud and clear on lowband!

mancow · Post by **mancow** » Wed Dec 12, 2001 12:54 am

Give this a look, should explain why. Seems the ducting in the southeast the last few days has gone wild.

http://www.iprimus.ca/%7Ehepburnw/tropo.html

raymond345 · Post by **raymond345** » Wed Dec 12, 2001 1:06 am

Yes in Ham we look at 11 years of a cycle
and skip radio signals have been great in the last couple of years in the vhf band.
10 m and 6 meters get some great distance
also.

jim · Post by **jim** » Wed Dec 12, 2001 6:30 am

I've been getting GREAT results with 6m.

RFdude · Post by **RFdude** » Wed Dec 12, 2001 4:44 pm

SKIP usually means RF bouncing off the ionosphere dozens of mile up in the sky. This is affected by the SUN. It's activity and the highest frequency that can be affected at any time is MUF or Maximum Usable Frequency. I don't think it normally (or ever) extends into the VHF High Band.

DUCTING or INVERSION is what you are probably referring too for VHF HIGH BAND. A stagnant thermal layer about 1000' or so AGL traps the RF and carries it over the horizon. Very common certain times of the year regardless of what the sun is doing in it's 11 year cycle.

Mute point... both methods provide over the horizon comms, but the mechanism is very different. Either way... enjoy it when it occurs!

RFDude.

J_L_COHEN · Post by **J_L_COHEN** » Fri Dec 14, 2001 9:08 pm

IM IN OHIO AND ON A VOLENTEER FIRE DEPT WE USE VHF HIGHBAND AND LOW BAND AND WE ARE ALWAYS GETTING SKIP, MOST OF IT WE THINK COMES FROM SOUTH AMERICA, IT WAS SO BAD THAT OUR WHOLE COUNTY HAD TO PUT PL'S ON ALL TX AND RX

JAYMZ · Post by **JAYMZ** » Fri Dec 14, 2001 9:23 pm

Here at our center on cahnnel one on lowband we have been picking up a taxi company in San Juan PR. Let me tell you it sux having to listen to it.

Bob · Post by **Bob** » Sat Dec 15, 2001 3:29 pm

Almost as bad is having a department in the midwest (I'm in the northeast) who is dispatched on the same frequency and has the same toneset for pager activation as yours. It sucks being awakenned at 3am for a call several hundred miles outside your district.

radioEd · Post by **radioEd** » Sat Dec 15, 2001 3:39 pm

Heard a Beacon for the last two weeks on 6 meters. btw. 50.060-50.080Mhz from San Francisco!

Post by Pj » Sat Dec 15, 2001 9:37 pm

My new long distant has been the CHP, here in Connecticut, on a Uniden 9000 scanner. We recently placed all our antenna's (including the scanner antenna) on a 250+ ft cell phone tower. All I have to say is WOW.

On our lowband base radio channels we get Dade County Fire/Rescue, and some stuff from the mid west, but hearing the CHP for a couple hours was kinda neat.

OX · Post by OX » Sat Dec 15, 2001 9:51 pm

And here I thought that listening to Hamilton County SO and Cincinatti PD from Columbus on a handheld scanner was special...usually about twice a month all year around.

I get them regularly and they're operating on 460.250...(for whoever said that skip rarely gets as high as VHF, it gets higher).

RFdude · Post by **RFdude** » Sun Dec 16, 2001 2:32 pm

SKIP 101... here it is spelled out... SKIP = VHF Lo band and below. It has an MUF. SKIP at VHF High Band (like 150 MHz) or UHF doesn't happen. The RF passes right through the ionoshere and the signal is lost to outer space. There are rare circumstances that this isn't the case (Aurora, or meteor scatter).

So if you are listening to a UHF signal that is 300 miles away, consider it a THERMAL INVERSION or DUCTING effect.... NOT sun related SKIP. Depending on weather conditions, if you have a warm day, followed by a cool and clear evening, this is what can create conditions for a thermal layer to DUCT RF over the horizon to your scanner or victim receiver (depending on your perspective). If the weather pattern is consistent, you can get many hundreds of miles on this sort of thing.

Some amateurs compete with each other at MICROWAVE frequencies to see who can hold the long distance record. They have achieved hundreds of miles at 10 GHz and above. For commercial microwave, the INVERSION effect causes disruptions (fading) in longer spans.

RFDude.