How far with VHF?

A place to discuss all aspects of amateur radio operation.
User avatar
Gemini4
Radio Addict
Radio Addict
Posts: 901
Joined: 02 Jan 2010, 21:26
Location: Derbyshire

How far with VHF?

Post by Gemini4 » 09 Mar 2018, 12:12

Might be a bit of a thick question..but I was wondering how far you could get on vhf using repeaters?.

User avatar
ch25
Super Member
Super Member
Posts: 387
Joined: 03 Dec 2016, 11:07
Call Sign: n0call
Location: Poland

Re: How far with VHF?

Post by ch25 » 09 Mar 2018, 12:33

Worldwide.
Chris
You can't have too many antennas...

User avatar
thedeerhunter270
Top Poster
Top Poster
Posts: 1181
Joined: 13 Nov 2009, 18:47
Location: Nr Consett County Durham

Re: How far with VHF?

Post by thedeerhunter270 » 09 Mar 2018, 12:43

I always thought it was line-of-sight plus a third. But like Chris says, in the right conditions much further.
Operating in South Northumberland and Weardale.

User avatar
Metradio
Super Member
Super Member
Posts: 288
Joined: 28 Apr 2016, 19:10
Call Sign: G7HID
Location: Box 500, Slough UK

Re: How far with VHF?

Post by Metradio » 09 Mar 2018, 12:57

As has been said worldwide - but through networked repeaters..
Through a single repeater, your distance to the repeater plus line of sight + 1/3rd from the repeater...
Through multiple radio repeaters, ISTR the maximum being 12 hops before the signal becomes unusable..

Search "Backbone"... :idea:

http://www.subbrit.org.uk/rsg/features/ ... ndex.shtml


Mike
Last edited by Metradio on 09 Mar 2018, 13:09, edited 1 time in total.
Connect Systems CS750 and CS800, Hytera PD-365, Motorola DP4600.
Raspberry Pi 2 and DV4Mini HotSpot.
AOR AR-DV1 Digital Voice Receiver / eSPY on ARD V1.

Whistler WS1088 / TRX-1 / Whistler Q / UBCD3600XLT / WTR Browser.

User avatar
Gemini4
Radio Addict
Radio Addict
Posts: 901
Joined: 02 Jan 2010, 21:26
Location: Derbyshire

Re: How far with VHF?

Post by Gemini4 » 09 Mar 2018, 13:03

Will it also depend on antenna and power?.

User avatar
Metradio
Super Member
Super Member
Posts: 288
Joined: 28 Apr 2016, 19:10
Call Sign: G7HID
Location: Box 500, Slough UK

Re: How far with VHF?

Post by Metradio » 09 Mar 2018, 13:13

Yes, plus frequency...
The international Space Station can be worked on a 2M 2 Watt handheld on it's own antennta when the ISS is within range (LOS+1/3)...

Mike
Connect Systems CS750 and CS800, Hytera PD-365, Motorola DP4600.
Raspberry Pi 2 and DV4Mini HotSpot.
AOR AR-DV1 Digital Voice Receiver / eSPY on ARD V1.

Whistler WS1088 / TRX-1 / Whistler Q / UBCD3600XLT / WTR Browser.

User avatar
Gemini4
Radio Addict
Radio Addict
Posts: 901
Joined: 02 Jan 2010, 21:26
Location: Derbyshire

Re: How far with VHF?

Post by Gemini4 » 09 Mar 2018, 15:17

Well thanks for the replies.

paulears
Radio Addict
Radio Addict
Posts: 708
Joined: 10 Jun 2007, 22:41
Call Sign: G4RMT
Location: North East Suffolk
Contact:

Re: How far with VHF?

Post by paulears » 09 Mar 2018, 18:06

where on earth has this magic 1/3rd figure come from? Coverage from any location is dependent on topography. The idea of a set figure doesn't work.
distance to the repeater plus line of sight + 1/3rd from the repeater...
Unless all my education is totally wrong, it's simply signal strength at the antenna - and that's a function of the path loss, which can be predicted with software that has topographical data in it.

User avatar
Metradio
Super Member
Super Member
Posts: 288
Joined: 28 Apr 2016, 19:10
Call Sign: G7HID
Location: Box 500, Slough UK

Re: How far with VHF?

Post by Metradio » 09 Mar 2018, 19:33

Line of sight + a third is something I picked up about 50 years ago, do you know what ? As a rule of thumb it does work, on top of a mountain or on a flat plain.. If there is stuff in the way - well common sense comes into play..

Mike
Connect Systems CS750 and CS800, Hytera PD-365, Motorola DP4600.
Raspberry Pi 2 and DV4Mini HotSpot.
AOR AR-DV1 Digital Voice Receiver / eSPY on ARD V1.

Whistler WS1088 / TRX-1 / Whistler Q / UBCD3600XLT / WTR Browser.

User avatar
Tigersaw
Radio Addict
Radio Addict
Posts: 690
Joined: 19 Oct 2013, 15:48
Call Sign: GW6RRL
Location: In a valley in a hole in mid Wales
Contact:

Re: How far with VHF?

Post by Tigersaw » 09 Mar 2018, 21:44

I did some (AM) VHF trials for a new ATIS at Southampton airport, with 25w from ground station the aircraft could still pick it up at 6000ft around Manchester

User avatar
Metradio
Super Member
Super Member
Posts: 288
Joined: 28 Apr 2016, 19:10
Call Sign: G7HID
Location: Box 500, Slough UK

Re: How far with VHF?

Post by Metradio » 09 Mar 2018, 22:11

A toy for people to play with:
http://www.heywhatsthat.com/profiler.html

Mike
Connect Systems CS750 and CS800, Hytera PD-365, Motorola DP4600.
Raspberry Pi 2 and DV4Mini HotSpot.
AOR AR-DV1 Digital Voice Receiver / eSPY on ARD V1.

Whistler WS1088 / TRX-1 / Whistler Q / UBCD3600XLT / WTR Browser.

paulears
Radio Addict
Radio Addict
Posts: 708
Joined: 10 Jun 2007, 22:41
Call Sign: G4RMT
Location: North East Suffolk
Contact:

Re: How far with VHF?

Post by paulears » 10 Mar 2018, 08:50

metroradio - I still don't understand? what is 'line of sight' in this context - As tigersaw says, from the ATIS to an aircraft is line of site, and ground to the space station is line of sight, but is there a line of site at all to a repeater that makes sense? Maybe if it's on a high block of flats - but line of sight at ground level fails very quickly - line of sight for a repeater could be hundreds of yards in some cases, so this 'rule' fails in any urban location because there isn't one! Not even with binoculars.

User avatar
Metradio
Super Member
Super Member
Posts: 288
Joined: 28 Apr 2016, 19:10
Call Sign: G7HID
Location: Box 500, Slough UK

Re: How far with VHF?

Post by Metradio » 10 Mar 2018, 10:50

It was something I learned in the army when setting up temporary VHF links, where vehicle location was a mixture of good radio location and natural camouflage, plus the question of where the enemy would expect you to be. So the LOS +1/3 was used as a rule of thumb together with a common sense appreciation of intervening terrain and ground clutter.. Sometimes you did not have the luxury of setting up links in advance and had to work off of maps - no computers to work it out for you.. The LOS +1/3 expectation was under optimum conditions, everthing in between became a variable, this is where common sense and experience are heavily relied upon..

Mike
Connect Systems CS750 and CS800, Hytera PD-365, Motorola DP4600.
Raspberry Pi 2 and DV4Mini HotSpot.
AOR AR-DV1 Digital Voice Receiver / eSPY on ARD V1.

Whistler WS1088 / TRX-1 / Whistler Q / UBCD3600XLT / WTR Browser.

VintageTin
Super Member
Super Member
Posts: 188
Joined: 27 Jul 2013, 17:53
Call Sign: 26TM516
Location: Surrey

Re: How far with VHF?

Post by VintageTin » 10 Mar 2018, 12:35

paulears wrote:
10 Mar 2018, 08:50
metroradio - I still don't understand? what is 'line of sight' in this context - As tigersaw says, from the ATIS to an aircraft is line of site, and ground to the space station is line of sight, but is there a line of site at all to a repeater that makes sense? Maybe if it's on a high block of flats - but line of sight at ground level fails very quickly - line of sight for a repeater could be hundreds of yards in some cases, so this 'rule' fails in any urban location because there isn't one! Not even with binoculars.
When talking "Line of sight", it means the ground. The signal will be degraded by the presence of buildings, but it does rattle around them somewhat, depending how close those buildings are to you. If you live in a bungalow next to a tower block, you will have more of a problem than if the tower block half way between you and the other station.
Malcolm

paulears
Radio Addict
Radio Addict
Posts: 708
Joined: 10 Jun 2007, 22:41
Call Sign: G4RMT
Location: North East Suffolk
Contact:

Re: How far with VHF?

Post by paulears » 10 Mar 2018, 15:38

exactly - so what is line of sight, when you can't see it? A mile? 10 Miles? You can't have a formula to work to with an unknown variable?

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests