Range of VHF

[Simon B]

I thought the CG had some whizzo relay antenaas or something so they arent just recieving on their main "twig". Stornaway CG could hear us trying transmit on 1 watt (until we realised it had been switched to "LO") from the northern tip of Skye. I'll have a look on the chart and see how far that is in a bit, me teas on; Jerk chicken, rice n peas, calalloo fritters and dumplings - the Afro Caribean carnival was here yesterday.

[peterb]

Each MRCC (Coastguard Ops Room) controls a number of aerials along their stretch of coastline.

When a call comes in, they have to switch to the best aerial before transmitting their reply.

[BogMonster]

Originally Posted by codprawn

Height makes all the difference.

Commercial airliners transmit on similar VHF frequencies and even their maximun transmit power is only 25w!!! I have often heard pilots talking to control coming into land in the Canary Islands and that is without strange conditions. That's a distance of 1800 miles - I suppose it helps when your aerial is 45,000ft above sea level.........

I don't know about 1800 miles but the principle is certainly sound - my 2 metre amateur sets (with expanded freq range) will pick up the incoming MOD flight when they call inbound at about 200 miles out and it is as clear as you could wish for. Calling from about 30,000 feet I think.

[alystra]

Originally Posted by peterb

Each MRCC (Coastguard Ops Room) controls a number of aerials along their stretch of coastline.

When a call comes in, they have to switch to the best aerial before transmitting their reply.

Yep. In my day a light lit up on whichever aerial switch received a transmission. To answer we just pressed the lit up switch and used the foot treadle instead of a PTT button to speak. If several aerials received the call, we'd choose the aerial with the most general coverage (the 'best' aerial) first. The aerials were connected to the Ops Room by dedicated telephone lines, which quite frequently got chopped up by cows/sheep/deer/JCB's/ploughs - or just blown away in a passing hurricane.