unusually strong CB performance

[matthewl]

Hi All,

First time poster on this forum but a user of scanners and CB radios for about 7 years.

Could somebody please explain what factors that have coursed this sudden increase of range from my handheld Oricom units 2watt. No changes to hardware have been made

This afternoon instead of my usual range of about 5 Km to the cars GME Tx4200 unit i was able to talk to mum in her car from my handheld at home of a LOS distance of about 13KM ( Road 15Km) . As well as being able to reach the channel 7 repeater which i have never been able to do. ( I used the VHQ07 to test if i was getting through and also used a radio on 37 and having dad listen to the radio on 7)

I am Located in between Browns Plains and Beaudesert about 50 Km south of Brisbane city. and would like to know what to research about this sudden gain.

Regards Matthew

[rochedalescan]

It's probably got something to do with the term 'ducting' which is all to do with the weather, have a bit of a google or I'm sure someone can explain it a little better than me. Welcome to the forums

[dags]

us old fellows also used to call it (SKIP)

[BradT87]

Doesn't look like ducting was probable on monday.

Tropospheric Ducting maps and forecast website:
http://www.dxinfocentre.com/tropo_aus.html

[Comint]

'Skip' and 'ducting' are generally HOT weather phenomena (think the middle of Summer).

And while there have been reports of very good HF conditions, over the last week or so, what affects HF usually has little or no effect on UHF.

There were reports of a 'Solar Flare' about a week ago, but they usually 'kill' communications, rather than enhance them.

Incidently, 'Skip' and 'ducting' are two different phenomena.

--
Comint

[matthewl]

Thanks for that guys.

However this

'Skip' and 'ducting' are generally HOT weather phenomena (think the middle of Summer).

makes me even more confused as to what happened. However it teaches me to ignore the distance indication even more that is on the box.

[hotmetal1000]

Was probably some tempature inversion that caused some low distace ducting.
If I remember rightly Monday was a bit of an odd day here tempature wise.

[vkcpolice]

Uhf depends on a lot of factors including anttenas line of site and ducting. Ive archived 30km on 0.5 watts of power on a hot summer everning. Also signals can bounce of the ground giving further distance yet again

[chanjyj]

Uhf depends on a lot of factors including anttenas line of site and ducting. Ive archived 30km on 0.5 watts of power on a hot summer everning. Also signals can bounce of the ground giving further distance yet again

Bounce off the ground? I've never heard of that, could you provide me with a technical link? Much appreciated.

[Vkfour]

Yep, UHF does not "skip", and I have been at the radio caper for over 40 years and have never head of UHF bouncing off the ground, absorbed yes, but bouncing, no. Of course, like Mr Chanjyj suggests, if you can point us towards some reference, we would both appreciate it. Given the weather of late, temperature inversion is the probable cause.

[blacktown]

The other factor that may contribute to an improved signal is that the repeater owner may have upgraded the equipment on site eg receive and transmit radios, put the antenna up higher etc. One of the Sydney repeaters is now booming in to most locations as a result of the owner using a "professional" to install quality radio equipment and working on elevating the antennas above their previous height. Has made the world of difference

[chanjyj]

To clarify the terms people use, for those not familiar with RF propagation. There are 3 main methods with relevance to scanners (yes there are others but irrelevant for this subject).

1. Line-of-Sight/LOS (Sometimes called direct wave)
2. Skip (E layer ionospheric refraction, F1, F2 layer ionospheric refraction)
3. Ducting (Tropospheric ducting)

[leighbus]

I also encountered a similar occurance the other day. My company two way in my truck works in the VHF 156mhz range and won't normally work much further north than caboolture however my supervisor was able to reach me at caloundra although it was pretty crackly. But also I usually listen to nova 106.9 in the truck and I start to lose reception at beerburrum but on that same trip to caloundra I never lost reception once not even a crackle. I was wondering if maybe the recent warmer weather this week may be the cause.

[vkcpolice]

Uhf does bounce bounce of the ground any frequency will giving the right circumstances ill find a link and provide more info

[vkcpolice]

To clarify the terms people use, for those not familiar with RF propagation. There are 3 main methods with relevance to scanners (yes there are others but irrelevant for this subject).

1. Line-of-Sight/LOS (Sometimes called direct wave)
2. Skip (E layer ionospheric refraction, F1, F2 layer ionospheric refraction)
3. Ducting (Tropospheric ducting)

4. Moon bounce anyone else heard of this strange one it does exitst i assure you

[Vkfour]

Definitely, EME has been around for a long time and it's really weird to listen to. With respect to bouncing off the ground, there is a phenonomon called ground wave, but this applies to long wave, medium wave and the lower sections of shortwave.

[vkcpolice]

I have heard og ground wave propergation on uhf it is very rare but can happen majority of the time its ducting. Ive never heard moon bouncing but i read it on wiki once. I guess it would be in the higher bands ghz??