DTMF Uses?
- Thread starter zerowatts
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RadioDaze
Member
In the pre-cheap-cellular-phone days, it was very common to use the DTMF tones in conjunction with an "autopatch" on a ham repeater, which enabled the mobile unit to place a landline telephone call. Used to be well worth the price of the repeater dues in the 1960's and 70's, to actually be able to phone home from your own car.
dwh367
Amateur Radio Operator
DTMF can also be used for selective calling, Echolink, IRLP and repeater control.
kc4jgc
Member
Some radios have DTMF paging, for either an individual or a group!
kc4jgc
Member
Your radio would be like a pager, staying quiet until it recieves the correct DTMF sequence to open the squelch. This goes back to selective calling, to which dwh367 referred.
Actually, there are (as far as I know) 3 types of selective calling:
DTMF
CTCSS (PL)
DCS
Actually, there are (as far as I know) 3 types of selective calling:
DTMF
CTCSS (PL)
DCS
Can DTMF Paging be used on radios internally? I mean can one program the PTT button to send out DTMF towards the repeater if there is no keypad? A sort of automated form of selective calling? Or is DTMF only used on radios with the keypad itself?
PeterGV
K1PGV
Yes. It can be internal.
DTMF is also used (on Motorola radios, for example) for "ANI"(automatic numeric identification) purposes. You'll hear this sometimes on police/fire radios -- a rapid burst of 3 or 4 DTMF tones before/after each transmission. The ID number is logged on the radio system console, and displayed on listening units.
There's a fire department in my area that does this. It's not as common as MDC-1200, but it's done.
Peter
K1PGV
K4APR
Member
In the commercial world, we also have: Single-Tone/Two-Tone, MDC1200, GSTAR and several other paging methods to open a receiver for a particular user or group of users.
Single/Two-Tone - Uses either a single or dual tone scheme transmitted pre-voice traffic to open the receiver.
MDC1200 - Actually a low speed data format for opening a receiver, as well as pre or post unit identification.
GSTAR - Uses a series of DTMF tones sent at a very fast speed to open recievers or pre/post unit identification.
As for the OP's question, with the explosion of mobile/cellular phones, autopatch is rarely used and seems to be a lost function in the world of amateur radio. However, DTMF probaly has the most common use for controlling and programming repeaters over the air, as mentioned already.
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n5ims
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One example of using DTMF for repeater control is this. When a the NWS requests for activation of a Skywarn net, the control operator will key in the code to indicate that the repeater is in Skywarn mode. This mode may do something as simple as removing the PL tone or changing the courtesy tone to one indicating that the repeater is in Skywarn mode. It may also activate repeater linking to allow for automatic failover or wider area coverage during that net. Once the net is over, the control operator will key in the code to return back to normal mode, unlinking the repeaters, reactivating the PL tone, etc.
Very very cool example of use!
Every tone pair corresponds to a number and those who know what a TSPS pad is know there are more pairs than on your standard telephone. OK feller, now THINK, and unless you're dumber than a box of rocks will come up with a few uses for DTMF signaling.
What do they call this?
On a list of specs for a radio it says:
Single DTMF/2 tone/MSK ANI encodes and decode programmable
In the radio world what is this type of access control called?
k8tmk
Member
Heathkit used to make a DTMF decoder box that could be used to control just about anything. I had mine connected to a 2-meter receiver that was set to an oddball frequency and used it to turn lights on and off.
Randy, K8TMK
Randy, K8TMK
PeterGV
K1PGV
zerowatts;1331481[B said:
Without any additional information, I would say it's no kind of access control. It's an automatic numeric identifier, used to identify the unit that's key their PTT. See my previous post in this thread.
Peter
K1PGV
Yes just about 35 minutes before you posted that I learned that the term itself is ANI. Looking back at your previous post I simply didn't read it thoroughly enough, I was too focused on control rather than definition. The reason I keep saying control, is I figured there certainly has to be some options in some equipment to not open the receiver unless the ANI matches a particular identifier. I think it might work if the groups themselves are defined?
Are there any portables that offer DTMF ANI without the keypad? Not all who use a radio are safe to have option menus to toy with, but the ANI would be a pretty cool feature with a group of people.
Are there any portables that offer DTMF ANI without the keypad? Not all who use a radio are safe to have option menus to toy with, but the ANI would be a pretty cool feature with a group of people.
PeterGV
K1PGV
Hmmmm... the radio can typically be programmed to belong to a particular group, and have a particular radio ID. So, when another radio sends to that group or radio ID, the squelch on the target radio opens.
Are there any portables that offer DTMF ANI without the keypad? Not all who use a radio are safe to have option menus to toy with, but the ANI would be a pretty cool feature with a group of people.
Oh, yes, sure. In fact, the keypad is almost NEVER used for this. You don't want people trying to remember the correct group code to signal during any kind of activity. So, depending on the radio, you can have aliases for the groups and select them by menu.
Now... "ANI" strictly speaking is JUST the radio ID itself... not the DTMF selective calling feature. DTMF can be used for both. You know, with ANI it's nice to be able to SEE the unit number come up on the console, when somebody just keys their radio and says "We could use some help here"
And, again, DTMF for this purpose is less common than the Motorola MDC-1200 scheme. If you're not familiar with MDC-1200, it's that 1/4 second "squawk" sound that you hear on your scanner, most often just after the PTT is pressed but before you hear somebody talk (you can hear an example of MDC-1200 in case you're note sure what it sound like on Wikipedia: MDC-1200 - Wikipedia, the free encyclopedia)
Peter
K1PGV
Exactly, this is exactly what I am looking for.
The frustrating thing about the ANI, is the radio programming software I am looking at has 3 ANI systems 2-tone, MSK and DTMF. The settings of all three are a similar set of options, except DTMF. With DTMF, under the decode settings I can type in the radio ID in alphanumeric. I can't do this at all with 2-tone, and with MSK I can only use A-E and 0-9. When PTT is pressed I don't imagine "A13E" would be as nice as "Mom" or "Johnny".
So in theory with the right set of radios, one could use FRS frequencies at a theme park and by using ANI would eliminate all possibility of bubble pack interference 100%?
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