After working in communications for over 10 years I decided to shar some of my knowledge -drum roll here-
Ok so whats a better portable radio to communicate with?
A 40 channl CB radio? $40 - $100
A 14-22 channel FRS radio? $20 - $60 pair
A 49MHZ headset? $40 - $50
A 2 meter or 440 ham HT? $150 - $500
A commercial VHF, UHF or 800MHz HT? $200 - $2500
Lets start with the portable 40 channel CB..
While you have 40 channels to play with you have the problem with the amount of batteries it takes to operate the radio @ 4 watts. Next you have a very long stereoscopic antenna or rubber antenna.
Then there is the issue of frequency. CB radio operates on 26.965 t0 27.405MHz in AM. AKA 11 meter band. This classify s as a shortwave radio. In lower frequencies you need more power to cover distance, while AM allows the bending of the radio wave around things like buildings and the like. AM also means you have to speak louder to produce more output power.
[img]http://www.northerntool.com/images/product/images/162202_lg.jpg[/img]
Ok now the popular one today. The FRS handheld. 14 - 22 channels in UHF 12.5KHz GMRS splits
These max at 600mW output power and use 2 - 4 AA batteries depending on the model. Most come with rechargeable battery packs and offer features like: CTCSS, Weather reception, GPS, alert tones, battery saver, etc. Most will achieve a mile or so in LOS communications and all operate in FM. ALL have fixed rubber antennas which cannot be removed
[IMG]http://www.jesseshunting.com/images/motorola-5820-frs-gmrs-radio.jpg[/IMG]
462.500 - 467.725MHz
49MHz headsets:
These were the predecessors to the FRS radios but very limited to 1/4 mile range and shared the frequency with baby monitors, radio controlled cars, and older cordless phones. Today these are mainly kids toys. All of them used a 9V battery usually and made very useful for things like paintball teams but not in a real world environment like SWAT (They have headsets and LASH that connect to their HT's)
Some of these radios had multiple channels and some came in HT form and earbud forms
[IMG]http://www.midistributing.com/products/sound/nady/images/400/PRC1x_L.jpg[/IMG]
HAM radios HT's:
First off you MUST have an FCC license (or equivalent for your country) to operate these
Most are user programmable via the front keypad and have dual power. All should have removable battery packs that are rechargeable.
Some are dual band meaning they can operate on 2 radios bands and sometimes cross band repeat, all usually have a keypad and allows the access to repeaters and functions like phone patches.
[IMG]http://www.universal-radio.com/catalog/ht/0008pre.jpg[/IMG]
Commercial:
These radios are what your police, fire, ems, security guards etc use. They offer dealer programmable channels to match your requests and can be bought for many common bands and system formats like trunking.
Usually these radios can achieve up to 5 miles LOS maybe more depending on what band your operating on. Usually these are associated with a repeater system in a business environment.
Astro Saber by Motorola:
[IMG]http://mattshaverphotography.zenfolio.com/img/v3/p556423504-5.jpg[/IMG]
Keenwood TK-372G
[IMG]http://www.allradio.biz/oneofakindstuff/tk372big.jpg[/IMG]
It is to note that the commercial radios can be programmed to FRS and HAM channels but this violates the fcc rules for frs and HAM radio operation. Also some HAM radios can be modified to work on the commercial bands.
Info on frequencies vs power:
rule of thumb: the lower the frequency the more power you need to cover distance.
cb radio needs 12VDC to make 7 watts of power where UHF can use 12VDC to create up to 110 watts of power (All this is based on mobile radios)
Mobile versions:
CB radio - 7 watts
[IMG]https://ssl103.webhosting.optonline.net/simplyus.us/merchantmanager/images/uploads/COBRA-29LTD-CLASSIC.JPG[/IMG]
FRS - 600mW
[img]http://midland2wayradio.com/wp-content/uploads/2010/02/midland-Base-Camp-radio-image1.jpg[/img]
49MHz - 600mW
There are none..
HAM radio - 5 - 45Watts
[IMG]http://www.hamradio.co.uk/acatalog/TM-D710E_lrg.gif[/IMG]
Commercial - 5 - 110Watts
[IMG]http://metrocommnj.tripod.com/sitebuildercontent/sitebuilderpictures/.pond/spectra.jpg.w300h227.jpg[/IMG]
More images of commercial breeds here: [URL="http://www.google.com/imgres?imgurl=http://metrocommnj.tripod.com/sitebuildercontent/sitebuilderpictures/.pond/spectra.jpg.w300h227.jpg&imgrefurl=http://metrocommnj.tripod.com/id9.html&usg=__1Z7IVhhWooiqk7OvzpDDTurYOV4=&h=227&w=300&sz=20&hl=en&start=8&sig2=ExUMz-pa7YjEcauGHWiOHQ&um=1&itbs=1&tbnid=nayCU0vgnYXImM:&tbnh=88&tbnw=116&prev=/images%3Fq%3DMotorola%2Bspectra%2Bhigh%2Bpower%26um%3D1%26hl%3Den%26tbs%3Disch:1&ei=gjY1TPyaCYm4sQPmttyvAQ"]http://www.google.com/imgres?imgurl=http://metrocommnj.tripod.com/sitebuildercontent/sitebuilderpictures/.pond/spectra.jpg.w300h227.jpg&imgrefurl=http://metrocommnj.tripod.com/id9.html&usg=__1Z7IVhhWooiqk7OvzpDDTurYOV4=&h=227&w=300&sz=20&hl=en&start=8&sig2=ExUMz-pa7YjEcauGHWiOHQ&um=1&itbs=1&tbnid=nayCU0vgnYXImM:&tbnh=88&tbnw=116&prev=/images%3Fq%3DMotorola%2Bspectra%2Bhigh%2Bpower%26um%3D1%26hl%3Den%26tbs%3Disch:1&ei=gjY1TPyaCYm4sQPmttyvAQ[/URL]
Fact: Your cellular phone is a full duplex portable radio with an advanced sel-call type feature.
Pagers -
these are radio receivers that emit a beeping or a 2 tone alert, the regular beepers use a data format called POCSAG or FLEX and a CAPCODE.
The data is transmitter from a remote tower or series of towers and when you pager "hears" the preamble capcode it opens the receiver to data reception. the processor in your pager decodes the POCSAG data into numeric data or alpha numeric data for the LCD screen also it triggers the alert beep or vibrate.
2-tone used by many fire departments use a CAPCODE that when matched by the dispatcher opens the pagers receiver to accept a voice message- usually the dispatcher call for a specific fire house.
Simplex-
Radio mode that is common, transmitters and receiver are on one frequency and talk directly.. IE: frs radio units
Duplex-
Radio mode involving a repeater station. uses a different transmit frequency to go "into" the repeater and "out" to the receivers. IE: your police department systems. makes a 4 watt portable able to work across town or behind mountains.
Full Duplex -
Radio mode the same as what you cellular phone does, allows traffic to be transmitted and received at the same time.
Trunking-
The latest mode used by most governments. Variants range from Motorola type II to MPT1327. This mode uses a priority type directive. think of it like waiting in line at a bank... a ste of repeaters are in use and you can talk when one of the repeaters becomes free of traffic. In monitoring a trunking system the frequency changes every time the mic key is released. This adds security also and all are digitally formatted in some aspect today, some are still in analog format also.
One-Shot -
mainly in telemetry systems like SCADA where a device transmits real time data to a receiver. Best example is an atomic clock or a hospital biomed sensor.
I am still adding to this so check back..
That's really interesting....khhhhzzzz....you....breaking....up...khzzzzzzz
[editline]02:23AM[/editline]
On a serious note, do you know the specifics of amateur radio?
Interesting, I've been wanting to get into amateur radio, but I think I have to wait a while to save up for a decent transceiver or receiver.
[QUOTE=Dr. Fishtastic;23193962]That's really interesting....khhhhzzzz....you....breaking....up...khzzzzzzz
[editline]02:23AM[/editline]
On a serious note, do you know the specifics of amateur radio?[/QUOTE]
depends on what band your want to use
[Quote]Interesting, I've been wanting to get into amateur radio, but I think I have to wait a while to save up for a decent transceiver or receiver.[/Quote]
Look around on ebay.. you would be surprised.
for a receiver a regular police scanner can pick up some of it...but not transmit
What do amateur HAM radio operators transmit?
I'm considering getting one for my car.
When I was little I used to sing songs over my grandpa's CB radio to truckers.
Oh boy get me my HAM radio and my Dukes Of Hazard truck and go!
[QUOTE=lemon_lover;23194284]What do amateur HAM radio operators transmit?[/QUOTE]
This is mainly a hobby system BUT HAM operators also partake in operations during disasters. like hurricane Katrina in Louisiana
In shortwave bands they transmit Morse code messages, numbers, Images in PSK (phase shift key), and live TV broadcasts in SSTV (Slow scan TV), and fax messages... name it.
Their main goal is to push the envelope and see how many DX contacts they can make
[Quote]I'm considering getting one for my car.[/Quote]
I recommend a Kenwood model of some sort. They seem to be pretty easy to operate
This is trucker 15342 do you read me? I am gonna pick up some Wendy's any suggestions?
[QUOTE]FRS.....Most will achieve a mile or so in LOS communications and all operate in FM[/QUOTE]
How badly is that affected by buildings and such?
Is there any downside to FM over AM?, you said [QUOTE]AM allows the bending of the radio wave around things like buildings and the like.[/QUOTE], Is FM not capable of this?
Thanks though, informative thread.
Could you explain exactly what DX contacts are? There are a few videos on youtube from which i'm guessing they're other radio operators in distant locations.
Is this really worth forking over 100$?
[QUOTE=Mokkan13;23194600]How badly is that affected by buildings and such?
Is there any downside to FM over AM?, you said , Is FM not capable of this?
Thanks though, informative thread.[/QUOTE]
FM - Frequency Modulation - Carrier power remains the same and on frequency no matter how you speak into the mic
AM - Amplitude Modulation - More power by how louder you speak but this also makes the frequency "bleed" over onto other channels
Generally AM needs more power to be effective.
the FRS radios being in UHF will penetrate buildings to a point but then this also goes back to the transmitter power.
In urban areas they are effective to up to about a mile where a portable cb may not work a block away.
FM is the Modulation used by all police and other services in a city
[Quote]Could you explain exactly what DX contacts are? There are a few videos on youtube from which i'm guessing they're other radio operators in distant locations.[/Quote]
Yes DX - Distance contact generally
[Quote]Is this really worth forking over 100$?
[/Quote]
It depends what your intentions are for.. You could factor in the cost in a year of a cell phone bill but then your limited on who you call.. It has its up and down sides
In the event the cellular systems are knocked out the radio may be your line of communications...
My dad bought a few radios to use a long time ago, then when we were at a mall my brother and I found the radios and found out they were on the same signal as the mall radios. Oh how fun that day was.
[QUOTE=Ninja_Duck;23194854]My dad bought a few radios to use a long time ago, then when we were at a mall my brother and I found the radios and found out they were on the same signal as the mall radios. Oh how fun that day was.[/QUOTE]
probably a "DOT" channel commonly used by malls, Wal-mart, school security, etc... Cheap and easy to use radios usually having one channel and a volume / on and off pot.
red dot - 151.625
blue dot - 154.570
green dot - 154.600
brown dot - 464.500
yellow dot - 464.550
orange dot - 462.625 (REACT GMRS channel Rare to find one on this thats not GMRS radio)
A good indication on what frequency someone is using is the antenna.
VHF - 150 - 174MHz portable antennas are usually long and thick
UHF - 450 - 470MHz Portable antennas come in two main types: the thin long type with or without a ball on the end, or a short fat one
800MHz - Very similar to the UHF thin type with but Motorola types have "800MHZ' on the side of the base. The short versions is a 3 inch lookalike if the longer one
how about some radio modding, that's much more fun than just radios
two ways to do it:
manually by opening the radio and cutting this and adding that
By software - rewriting some of the code in the programming/service software to make it do things you didn't pay for.
that's pretty obvious, but you've got no detail in there.
I want modulation, supertalk, power tweaks, etc.
look them up on the internet...
No as OP it's your job
I dont have the info for every mod available lol
for one it depends on the radio you want to mod and if it can be done without damaging the unit.
Why do you need a license for those hand held HAM radios?
You need a license for any radio transmitting over 600mW
exempt is class D CB radio
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