Posted: 12/25/2009 6:47:30 AM EDT
| Iam just getting into HAM radio (Just got my Tech. a few weeks ago), so I was looking at a few differnet radios and noticed that some had the option of a DTMF Decoder. So Iam asking what is a DTMF Decoder and why would I want one? |
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Quoted: Iam just getting into HAM radio (Just got my Tech. a few weeks ago), so I was looking at a few differnet radios and noticed that some had the option of a DTMF Decoder. So Iam asking what is a DTMF Decoder and why would I want one? DTMF are the buttons on the phone. So you can decode those tones back to numbers. |
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DTMF: Dual Tone Multi Function
We use DTMF in the fire service mostly for our pagers and alerting equipment. One radio sends out a set of tones, which are interpreted by a receiving radio and triggers it to perform a function. For example, when the tones for my station are transmitted, the station alert is overhead, the pagers alert and the station lights come on. It can be used for all sorts of stuff though, for example the local sheriff's office uses DTMF to open the doors to the squad garage. ETA: Not sure what the use in HAM would be, but you could program in the local weather channels with the DTMF codes to have your HAM radio act the same as a weather radio does when it alerts. When they set off weather alerts they are using DTMF to activate the alarm on a weather radio the same as our pagers go off. |
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Basically, it's touch tone dialing for ham radio, such as access to Echolink over the air through a repeater, a phone patch, access via IRLP, etc.
Echolink http://www.echolink.org/ "For licensed hams, EchoLink® software opens up new possibilities for communicating around the world with other amateurs. Your PC links you or your local repeater to any of thousands of other stations over the Internet. "There are several different ways you can use the EchoLink software. You can set up a "simplex link" in your shack, with a VHF or UHF transceiver connected to your PC, to allow anyone in range of your station to communicate by voice with any other EchoLink station around the world." Internet Radio Linking Project http://www.irlp.net/ "The IRLP uses Voice-Over-IP (VoIP) custom software and hardware. Coupled with the power of the Internet, IRLP will link your repeater site or simplex station to the world in a simple and cost effective way." |
| To be clear..a DTMF decoder is different from a DTMF encoder. Most rigs have the encoder (to transmit DTMF tones) already in them. The decoder is so your rig can decode DTMF to accept programming/control functions either through the mic(Icom) or over the air via HT. Many decoders are optional..or used to be...I'm old school. |
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Quoted:
DTMF: Dual Tone Multi Function We use DTMF in the fire service mostly for our pagers and alerting equipment. One radio sends out a set of tones, which are interpreted by a receiving radio and triggers it to perform a function. For example, when the tones for my station are transmitted, the station alert is overhead, the pagers alert and the station lights come on. It can be used for all sorts of stuff though, for example the local sheriff's office uses DTMF to open the doors to the squad garage. ETA: Not sure what the use in HAM would be, but you could program in the local weather channels with the DTMF codes to have your HAM radio act the same as a weather radio does when it alerts. When they set off weather alerts they are using DTMF to activate the alarm on a weather radio the same as our pagers go off. My local PD needs to do that, the most common radio transmission I hear is "Open the garage door please" 
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Quoted:
Quoted:
DTMF: Dual Tone Multi Function We use DTMF in the fire service mostly for our pagers and alerting equipment. One radio sends out a set of tones, which are interpreted by a receiving radio and triggers it to perform a function. For example, when the tones for my station are transmitted, the station alert is overhead, the pagers alert and the station lights come on. It can be used for all sorts of stuff though, for example the local sheriff's office uses DTMF to open the doors to the squad garage. ETA: Not sure what the use in HAM would be, but you could program in the local weather channels with the DTMF codes to have your HAM radio act the same as a weather radio does when it alerts. When they set off weather alerts they are using DTMF to activate the alarm on a weather radio the same as our pagers go off. My local PD needs to do that, the most common radio transmission I hear is "Open the garage door please" And cost Fred his job? I think not! 
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Quoted:
DTMF: Dual Tone Multi Function not quite. see http://en.wikipedia.org/wiki/DTMF ar-jedi <–– telecom R&D guy 
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Quoted:
Quoted:
DTMF: Dual Tone Multi Function not quite. see http://en.wikipedia.org/wiki/DTMF ar-jedi <–– telecom R&D guy
I stand corrected, thanks!  My heart was in the right place though 
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DTMF paging can actually be quite handy if used correctly.
If you have a group of friends who you want to be able to get a hold of, they can all set their radios for DTMF paging, and then the squelch does not open unless the correct tones are heard- you can block the chatter n the repeater, but at 0230 hit the right DTMF sequence and wake them up. The same basic idea that most fire departments are still paged with. |
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FIre/EMS/Rescue services use two tone sequential paging. Enough different from DTMF so someone doesn't call up the FD volunteers on a ham radio. DTMF is what the touch tone phone in your house uses. However, the radio DTMF encoders/decoders will work the same way: a series of tones are sent and a squelch is opened. You can "alert" but not page on public safety, amateur radio, and GMRS. A page is a one way transmission only. Someone "alerted" is expected to answer back on the radio frequency. DTMF decoders would be cool to have but I have never heard anyone tone someone up using DTMF. Only for control of repeaters, etc. I heard a two tone sequential transmission on 442.250 the other day followed by KB4*** this is KB4***. A YL answered back to his call. She either had a Minitor or a public safety radio set on "alert only" so as not to listen to the usual radio chatter, but be available for comms.
RS |
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Quoted:
FIre/EMS/Rescue services use two tone sequential paging. Enough different from DTMF so someone doesn't call up the FD volunteers on a ham radio. DTMF is what the touch tone phone in your house uses. However, the radio DTMF encoders/decoders will work the same way: a series of tones are sent and a squelch is opened. You can "alert" but not page on public safety, amateur radio, and GMRS. A page is a one way transmission only. Someone "alerted" is expected to answer back on the radio frequency. DTMF decoders would be cool to have but I have never heard anyone tone someone up using DTMF. Only for control of repeaters, etc. I heard a two tone sequential transmission on 442.250 the other day followed by KB4*** this is KB4***. A YL answered back to his call. She either had a Minitor or a public safety radio set on "alert only" so as not to listen to the usual radio chatter, but be available for comms. RS Several departments aroudn here actually use DTMF as well as 2-tone for their paging. I think it is a holdoff from the days when Kenwood and others offered radios with DTMF paging but did not offer QC2/ two tone paging- and I wouldn't be suprised if it carries over today so some folks can use modified ham rigs..... |
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Quoted:
DTMF: Dual Tone Multi Function 
Dual Tone - Multi Frequency http://www.genave.com/dtmf.htm Do'h somebody beat me to it... But hey he won't forget now
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