MDC 1200 question

STX 821 · Post by **STX 821** » Fri Jul 11, 2003 11:54 am

i wanted to know quickly what MDC1200 is used for and do you need a Repeater to use this and what you use it for?...i have heard of it time to time and i thought that it was some kind of tone the comes up during transmission.
I would like to learn a little bit about MDC 1200 and what it's uses are..

Jay · Post by **Jay** » Fri Jul 11, 2003 12:19 pm

A lot of your questions can be answered here:

http://www.batlabs.com/mdc1200.html

It's a method of signalling, i.e. PTT ID, paging, etc.

Jay

STX 821 · Post by **STX 821** » Fri Jul 11, 2003 12:24 pm

so is this what gives off that tone when the PTT is pressed on the radio....i listed to the poice scanner from Time to time and i noticed on the UHF system that tehy use and also on the VHF systems that there is a tone that they Emit from each radio everytime that the Ptt is pressed...sometimes it will be a long tone or 2 littel beeps...what is that?

Heterodyne · Post by **Heterodyne** » Fri Jul 11, 2003 12:29 pm

STX 821 wrote:so is this what gives off that tone when the PTT is pressed on the radio....

MDC1200="SQUWAAAAAAAK!"

STX 821 · Post by **STX 821** » Fri Jul 11, 2003 12:30 pm

awww....yessss....what is the reason for that...i read over that link and no offense...i am just a scnner head...what is this for?...and what do you need it for?

Heterodyne · Post by **Heterodyne** » Fri Jul 11, 2003 12:39 pm

MDC1200 is a signalling format. Its used for PTT-ID (the squawking heard from the radio is the radio sending out its ID number), emergency signalling (pressing the mandown button on the radio transmits the emergency signal via MDC), as we as other functions. The squawk is data being transmitted from the radio. Some people activate it on their radios because it 'sounds cool' (grin)

Here's a good site with some sound samples of different digital signalling modes: http://www.kb9ukd.com/digital/

STX 821 · Post by **STX 821** » Fri Jul 11, 2003 12:43 pm

Ok...that's cool....so if i want to put this in a radio what do i need to do when i bring it in the shop...do i need to specify that i want MDC 1200 in the radio that is capible? or do i have to have a Repeater?

Heterodyne · Post by **Heterodyne** » Fri Jul 11, 2003 12:52 pm

THere really isn't an option for 'putting it in' a radio.. A radio is either capable of MDC or it isn't. You can get boards for radios that isn't equipped with it, but its a needless expense if you don't need it.

It has nothing to do with repeaters or anything... its just a way of a radio to transmit data.

Its pretty much just an annoying noise if you don't really have any use for it.

nmfire10 · Post by **nmfire10** » Fri Jul 11, 2003 1:29 pm

To elaborate a little...

The "PTT-ID" is sending it's ID number and it is decoded by the dispatch console. The console will display the 4 digit number or a text alias for the dispatcher. Some mobile & portable radios also have the ability to decode and display the ID's. There is also the mentioned emergency ID.

Some repeaters CAN be setup with access control via MDC. The repeater will not function unless an appropriate MDC Repeater Access Code is recieved.

It can be used for short status messaging. Example...

Message 1 can mean "Responding"
Message 2 can mean "On Scene"
Message 3 can mean "HOLY $HIT!"
Etc.

It can be used to inhibit a radio. Say someone steals a portable radio. The console can send a "Radio Inhibit" MDC code to the portable. The portable will render itself totally non-functional. Only a valid "Un-Inhibit" signal or a radio shop can restore it.

Susan157 · Post by **Susan157** » Sat Jul 12, 2003 7:47 am

Well With Most Commercial Radios on Ham And They
Have MDC 1200 Signalling Abilities.
Here are two EX of Using It.
!: you have a link radio to a remote repeater operation.
You set mdc1200 for the repeater in the remote
area and when they key up you hear the mdc1200
and know that it is the remote on the local repeater.

2:Most Ham repeater are setup not to pass dtmf.
They pass single tones though.
So If you need the repeater to talk to someone
and you do not like the local traffic then you use mdc1200
to turn on the audio of the radio and only the mdc1200
programmed radios are heard.Great TOOLS.

John · Post by **John** » Sat Jul 12, 2003 3:30 pm

Does anyone know of a way to send an MDC "Radio Inhibit" from a portable instead of requiring a console. We would like the ability for supervisors in the field to be able to disable radios using MDC. We use these on a repeater system without a console or dispatch position normally involved. I haven't found a Motorola portable that will SEND a Radio Inhibit signal yet..

John

k4wtf · Post by **k4wtf** » Sat Jul 12, 2003 7:53 pm

John wrote:Does anyone know of a way to send an MDC "Radio Inhibit" from a portable instead of requiring a console. John

I don't know of a way to do it. The possibility that someone might come up with something like that is a very good reason to (on your personal radios) disable:

* Radio Check
* Selective Inhibit
* Remote Monitor

...pretty much anything that can cause your radio to do something that you don't intend for it to do.

--
John

ArmsonOeg · Post by **ArmsonOeg** » Tue Jul 15, 2003 6:51 am

I believe this can be done. I have a Spectra Newer one that has this and i killed the radio by accident, but restored it with a password. I think i used my HT1250 to kill it. I put a id # in the radio inhibit then transmitted that id,thats how i killed the radio. The only thing is the radio would have to have the Inhibit feature. I seen dozens of Spectra's but this is the first that had this Option..

G-Man

John · Post by **John** » Tue Jul 15, 2003 3:36 pm

G-Man,

How did you enter a radio ID into Radio Inhibit on an HT1250? Can you give some detail. What steps/buttons did you do to send this code?

The radios we want to inhibit are pretty much all HT1250 with a few HT750 and HT1550s. We would probably use an HT1550 to send the inhibit command if it can do it.

There no Spectras involved.....

John

ArmsonOeg · Post by **ArmsonOeg** » Tue Jul 15, 2003 6:24 pm

Hi, well it is the Spectra that has the "radio inhibit" feature, I killed the Spectra using a HT1250. The inhibit uses MDC to kill the radio, i went to "Call Alert" on the 1250 entered the Kill # on the 1250 keypad then keyed the radio(1250) to kill the Spectra...... Ive been all through the 1250's and 1550's programs and do not recall any such "Inhibit" feature in the Waris radio's............Need more let me know, however thats about all i have

Gordon

k4wtf · Post by **k4wtf** » Wed Jul 16, 2003 7:29 am

ArmsonOeg wrote:Hi, well it is the Spectra that has the "radio inhibit" feature, I killed the Spectra using a HT1250. The inhibit uses MDC to kill the radio, i went to "Call Alert" on the 1250 entered the Kill # on the 1250 keypad then keyed the radio(1250) to kill the Spectra...... Ive been all through the 1250's and 1550's programs and do not recall any such "Inhibit" feature in the Waris radio's............Need more let me know, however thats about all i have

Gordon

OK. And what is the kill number? For example, if your MDC ID on the Spectra was "1234", and I went into call alert on a 1250, if I send a call alert to MDC ID 1234, it is simply going to alert the Spectra, not inhibit it. Of the 32 bits of information in an MDC packet, 16 are used for addressing, 8 define the function of the packet (PTT ID, Call Alert, etc) and the remaining 8 carry "optional" information.

Simply sending a call-alert isn't the same as sending the radio inhibit code to a radio. Perhaps you managed to be the one in one million that had a cross-code false and in your case, it was one of the "function" bits that flipped and that bit was the one that made the packet a "radio inhibit" packet.

I'm just not buying that the 1250 has the native ability to send a "radio inhibit" packet. The potential for abuse is just far too high to put this ability in the hands of "Joe radio owner". For that matter, neither of the two Centracom consoles I've played with in the past week seemed to have the ability to send a "radio inhibit" packet either.

So, are you SURE you killed a Spectra with an HT 1250 or are you just pulling our legs?

--
John

Cowthief · Post by **Cowthief** » Wed Jul 16, 2003 8:59 am

Hello.

First, a touch of history.
/\/\ bought Mobile Data Communications, a Canadian company, in part, for the MDC protocol, used with the Mobile Data Terminals.
The MDC protocol is very robust, having several error checks built in.
Radio Inhibit, because of what it does, is set up as a confirmed command, that is to say, one complete wordset will not turn a radio off, several confirmed wordsets would have to hit the radio in question.
A 9100-386 MDT can be made to send the inhibit command, if it is set as a server, but they run Win3.1, 16 Megs RAM max, and will not address a hard drive bigger than 500 Meg, without something like EZ drive.
Simply put, a one bit error, or even several, would not corrupt enough to inhibit, and the chance that you would corrupt several wordsets, to the point that the packet was still valid, but changed the value?.

k4wtf · Post by **k4wtf** » Wed Jul 16, 2003 9:59 am

So, what you're saying is that the chances of him using a HT to send the inhibit command are far less likely than the chances that he's full of $h!t?

ArmsonOeg · Post by **ArmsonOeg** » Fri Jul 18, 2003 6:14 pm

Hi, sorry for the delay. NO im not pulling your leg or Full of Sh*#. First its been about 6-7 months ago since i did this, thats when i got this Spectra with the Inhibit feature. If i remember right i just entered a 4 digit ID in the Inhibit screen ( just playing around ) since i never seen this before then i went into MDC Call alert or Selective Call (don't remember) entered the same ID from the Keypad from the HT1250 and it killed the radio. Im not sure exactly what it did but it would not allow me to do anything with the radio until i entered a password. Mabe at some time in the near future i will do it again and make note of it. By the way MDC 4 digits is 10,000 combinations ( 9,999 ) to be precise. Thats alot, someone would have to be pretty dedicated to to try all of these. Anyway i did kill the radio,and sounds like you all know more about MDC than i do. Im just relaying what i did. I have a EF Johnson Avenger that has a kill option to, works the same way but with 5 Tone Sel Cal.

Gordon

k4wtf · Post by **k4wtf** » Fri Jul 18, 2003 8:37 pm

ArmsonOeg wrote:Hi, sorry for the delay. NO im not pulling your leg or Full of Sh*#. First its been about 6-7 months ago since i did this, thats when i got this Spectra with the Inhibit feature. If i remember right i just entered a 4 digit ID in the Inhibit screen ( just playing around ) since i never seen this before then i went into MDC Call alert or Selective Call (don't remember) entered the same ID from the Keypad from the HT1250 and it killed the radio.

Um, WHICH Inhibit screen? On which radio did you have an inhibit screen?

Im not sure exactly what it did but it would not allow me to do anything with the radio until i entered a password. Mabe at some time in the near future i will do it again and make note of it.

Um, how did you enter a password? With RSS? Into the radio keypad? Are you being intentionally vague or what?

By the way MDC 4 digits is 10,000 combinations ( 9,999 ) to be precise.

There are 65,536 possible MDC IDs unless I'm missing something. 0000 through FFFF. It is possible that some IDs are reserved for special use but, the MDC ID is a 4-digit HEX (base 16) number. I have used "BAD1" as an MDC ID on my Systems Saber. This would indicate that IDs from 0000 through BAD1 are most likely valid. BAD1 is 47825 decimal. If we assume, based on this ID that digits 0-B are valid in the first two fields and digits 0-D are valid in the second two fields, this still gives us 23,716 possible MDC IDs - which is a boat-load more than 9,999.

Thats alot, someone would have to be pretty dedicated to to try all of these. Anyway i did kill the radio,and sounds like you all know more about MDC than i do. Im just relaying what i did.

If I understand how the function works, if the radio is transmitting an MDC PTT ID, it would be pretty simple.

--
John

ArmsonOeg · Post by **ArmsonOeg** » Sun Jul 20, 2003 7:31 pm

Um, WHICH Inhibit screen? On which radio did you have an inhibit screen?

The Spectra

Um, how did you enter a password? With RSS? Into the radio keypad? Are you being intentionally vague or what?

Entered the Password just as in the Service Menu, on the Spectra KeyPad like the front panel Password ....NO, I thought i was rather clear................
This Direct from the RSS, "Enabling feature will allow the base station to disable the radio over the air by sending the MDC 1200 Selective radio Inhibit command. The base station may also Re enable the radio over the air, however once the radio has been inhibited it will no longer function until it receives the MDC 1200 Selective radio Uninhibit command. The service portion of the RSS can be used to restore the radio provided the user knows the front panel password". After going thru the Menu i do not see where to enter a ID just Disabled and Enabled. I must have enabled it then transmiited the Radio ID, so that may be the Kill #. Its a bit hard for me to type alot, I suggest you find a Spectra with this option and try it yourself or call me. ask for Gordon[/quote]

Cowthief · Post by **Cowthief** » Sun Jul 20, 2003 10:30 pm

Hello.

This spectra, the service menu.
Can you roll to a screen that says, enter, with what looks like a flashing curser?.
If you can do this, look for a zero option, do not select yes, exit, and read what it says.

SmilnDon · Post by **SmilnDon** » Mon Jan 19, 2004 8:32 pm

Ok, Im reading all this messages posted about MDC1200 and I still dont understand much about it. From what it sounds, its pretty cool. Being able to ID whos calling, etc. But how do I know if my Maxtracs will do it? Both Maxtracs I have are the UHF model with 16 pin connector. I think that means that it has MDC capabilities correct?

Ok, so how do I program this, and do I need a 'controller'? Or would I be able to just program my 32 ch Maxtracs so that when they talk back and forth they can ID themselves? How about using the different features? Would the RSS programming manual tell me how to do this?

Thanks,
Don

walt10 · Post by **walt10** » Tue Jan 20, 2004 11:26 pm

I am using MDC1200 with two Maxtracs. My wife does not like to listen to the chatter on the repeaters, so she turns down the radio. Might as well turn it off. SO I set her radio up to only unsquelch when It receives the MDC signal from my radio. When she picks up the mike it puts the radio in Monitor mode. It can also be set up so it will ack back to let you know that It received your signal. This way she only hears me when the mic is on the hang up box.
I have used this on my 900 Meg spectras and Maxtracs.

Walt

SmilnDon · Post by **SmilnDon** » Fri Aug 27, 2004 12:42 pm

Walt, how did you program this? I am having a hard time figuring out how to program useful MDC1200 signalilng into my Maxtracs and HT1000's. Ive been searching the internet and cant find any information on the programming of MDC in a Motorola radio.

Can you tell me step by step what needs to be entered to do what you have done with your Maxtracs?

MDC 1200 question

MDC 1200 question

MDC in THe Ham World "YES"

MDC

Service menu

MDC1200

MDC1200

MDC-1200