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RADIO advice sought for URBAN prepping
8 April 2014, 14:19,
#1
RADIO advice sought for URBAN prepping
Chaps we are currently discussing a flipping great hole in our plans for URBAN prepping and we need asistantance in working out the simplest, low profile best option for radio comms for city areas, IE which will work best PMR446, Ham, FM CB, AM CB ?

Can you chaps come up with some advice I can add to an Urban preppers guide?

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8 April 2014, 14:24,
#2
RE: RADIO advice sought for URBAN prepping
(8 April 2014, 14:19)NorthernRaider Wrote: Chaps we are currently discussing a flipping great hole in our plans for URBAN prepping and we need asistantance in working out the simplest, low profile best option for radio comms for city areas, IE which will work best PMR446, Ham, FM CB, AM CB ?

Can you chaps come up with some advice I can add to an Urban preppers guide?

You'll have limited Tx & Rx due to all the obstacles in the way in a city.

Find high ground (top of a building) and you will be able to transmit further.
As for PMR / CB / HAM, won't make too much of a difference. I'd stick with the baofeng.
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8 April 2014, 14:48,
#3
RE: RADIO advice sought for URBAN prepping
What system do mini-cab drivers use?
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8 April 2014, 14:55,
#4
RE: RADIO advice sought for URBAN prepping
Good point Dev, if they have a system that works in cities but does not require repeaters , that would be a good choice.

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8 April 2014, 14:56, (This post was last modified: 8 April 2014, 14:59 by BeardyMan.)
#5
RE: RADIO advice sought for URBAN prepping
(8 April 2014, 14:48)Devonian Wrote: What system do mini-cab drivers use?

Mobile phones...

Well, some do anyway. Others use licensed radio. Expensive bits of kit though.

The taxi cabs in Southampton (private hire, not black cabs) use mobile phones, hooked up into an onboard computer. Same with a couple of the companies in Swindon.

I think a few are moving this way, as it's cheaper to buy a phone than it is a new radio.

What's the range on those taxi cab radios? You can pick them up on PMR (if you're near the taxi anyway).
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8 April 2014, 15:00,
#6
RE: RADIO advice sought for URBAN prepping
Intek do a UK legal TAXI radio on VHF 136 -174 Mhz @ 25 watts
http://www.thunderpole.co.uk/taxi-radios...radio.html

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8 April 2014, 18:15, (This post was last modified: 8 April 2014, 18:18 by Lightspeed.)
#7
RE: RADIO advice sought for URBAN prepping
UHF ( Ultra high frequency) with its very short wave length works quite well in cities. It still gets blocked by big, tall buildings but has the ability to bounce around them. Position can be very critical. Just moving a few feet often will make a difference between perfect reception and no reception at all. The other advantage of UHF is that there are many hand held walkie-talkie type units available. Because the wavelength is so short, antennas for this band are also tiny. UHF radios can be very discreet.

Most readily available UHF radios are PMR446 units or Ham radio 430 Mhz bands.

Guerrilla repeaters constructed to operate autonomously from tower block roofs are also a good way to get signals across the cityscape. Again, UHF frequencies work well in this application. Built using one of the generic low powered Chinese radio clones, secured in a water tight box, with a small PV charging unit, this sort of installation can stay operational for a long time without need to touch it.

Another alternative is to use NVIS ( Near Vertical Incident Skywave) The idea here is to design antennas that encourage signals to be transmitted at a high elevation ( Near vertical), and for those signals to be reflected back to earth off the ionosphere, with the signals being received from overhead, so leapfrogging tall buildings. This is a system that is tried and tested. But there's a snag with it. Only certain frequencies get reflected off the ionosphere. The higher angle of incidence, the lower the frequency required. For Near-Vertical incidence frequencies of 3.5 Mhz to 7 Mhz are generally used. These frequencies have very long wavelengths and so antennas have also to be very long, and to achieve the near vertical transmission effect, those antennas must be horizontal. Basically the more manageable 7Mhz frequency requires an antenna 66ft long! Not portable at all. But anyone with a small garden could rig up the required horizontal length on top of garden fence and get viable results. This sort of antenna is a great Bug-In Antenna as its very effective, and very low profile.

Diverting a little, but on the subject of emergency bug-in antennas: Since a week ago, I've been bugged-in at our bug-out. After the foul winter, the experimental emergency coms antenna that I put up a year ago by literally throwing into a nearby tree from an upstairs window, is still in place, and still performing fine. For bug in application, simple end-fed wire antennas are worth considering as they discreet and effective.
72 de

Lightspeed
26-SUKer-17

26-TM-580


STATUS: Bugged-In at the Bug-Out
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8 April 2014, 18:25,
#8
RE: RADIO advice sought for URBAN prepping
LS can I snaffle your advice for the article on Urban rad comms?

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8 April 2014, 18:37,
#9
RE: RADIO advice sought for URBAN prepping
NR, there are a number of things to consider here:
1. You and your group want a system that is independent of outside support - cell towers, 2-meter band repeaters, commercial power, etc.
2. You want a system that works within your area - my ham rig can talk to Cuba, Jamaica, Canada, and Moose Island Maine, but can't be received a mile away due to the angle of the transmitted signal.
3. You want a system that is neither underpowered nor overpowered - you want to get the word out to your group, but not the whole world, or even the thugs with a scanner five miles away.

Possible answers:
1. 2 meter - 75 cm dual band hand-helds (Wouxan or Baofeng) - you'll need ham licenses.
2. The new 12 watt SSB CBs - you'll need good antennae.
3. 2 Meter rigs interfaces with laptop computers running PSK31 - very low power, very low bandwidth, hard to track.
4. Solar panels/generators to recharge radio and computer batteries.

I know it sounds overwhelming, but lots of us hams are happy to help you all.
If at first you don't secede, try, try again!
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8 April 2014, 18:45,
#10
RE: RADIO advice sought for URBAN prepping
Cheers Jonas, its looking like the good old UV5s are once again going to be the best option, not worried about licences after TSHTF personally, but I agree with the sentiment from chaps like you and LS that a ham licence is damn handy.

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