I’ve always wondered what the purpose of the phone ringing preamble to mdc1200 was until getting into Motorola where it clearly instructs to NEVER mess with it unless absolutely positive you know how a system operates…. Can someone show or explain the preamble in the perfect mdc1200 system and what it’s supposed to sound and appear like when being decoded and encoded?
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MDC1200 preamble use
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Best I can say it is a packet that greatly helps synch and give time for repeaters and simulcast to respond.
Really reduces errors. I think there is more info here on RR if you search.
Comes in different flavors talking Harris or Kenwood.
My nickname for it is squeak up.
TRIVIA: Long ago Aliance used this for garage door openers.
Really reduces errors. I think there is more info here on RR if you search.
Comes in different flavors talking Harris or Kenwood.
My nickname for it is squeak up.
TRIVIA: Long ago Aliance used this for garage door openers.
902
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I was working for an agency with several thousand MTS2000 portables. We noticed this feature in the programming and, what we surmised was that this allowed for better MDC detection and muting where the filtering is supposed to react rapidly to the tones and mute them. I think the criticality was more in the console to reduce dispatcher fatigue. I could be wrong.
If anyone has an authoritative answer I'd like to know. My former agency all but abandoned their conventional system.
The system I work on now uses MDC1200, but cannot mute the signaling. We are not using Motorola equipment, but the MDC1200 from our non-M equipment is displayed fine on a M portable. Likewise vice versa. Our equipment does not have the capability for a preamble.
If anyone has an authoritative answer I'd like to know. My former agency all but abandoned their conventional system.
The system I work on now uses MDC1200, but cannot mute the signaling. We are not using Motorola equipment, but the MDC1200 from our non-M equipment is displayed fine on a M portable. Likewise vice versa. Our equipment does not have the capability for a preamble.
“The system I work on now uses MDC1200, but cannot mute the signaling.“
That’s got to drive you NUTZ
And I I believe merlin said it best; synchronization packets to help awaken remote receivers/repeaters. Our system uses preamble but it’s DOS muted, so all you hear on a receiving radio is a quick “Chirp”
That’s got to drive you NUTZ
And I I believe merlin said it best; synchronization packets to help awaken remote receivers/repeaters. Our system uses preamble but it’s DOS muted, so all you hear on a receiving radio is a quick “Chirp”
Most could care less, user end honestly as long as it works. Only radio nuts make issue of this. You maybe get the 1 percent who cry about it.
Yeah it just gets annoying hearing a class bell whenever someone keys up
If it annoys you wait till someone decides to cheap out on a repeater, or lacks programming there of and you'll get the mdc long tone plus a huge squelch crash at end.
mmckenna
I ♥ Ø
Keeps the Baofengs out.
Lol, in my experience most hams hate the MDC1200 but don't really say anything about TPS.
copy pasta from one of several MDC related USPTO filings, interpret as you will.USPTO Patent Office in one of several filings said:
The preamble (AFAIK - not a patent lawyer, EE, guru...) helps with decoding the data stream, sort of like "hey, important stuff is coming your way, this is the timing standard you should be ready for so you don't need me to send it multiple times, etc". If you start dicking with the 'introduction' of the data packet, it would make decoding less than reliable - which is why they would probably put those ominous Thar Be Dragons! warnings in RSS/CPS. I could be totally off base, but thats what make sense to me, as I read it.
A feature of MDC is also like selective (or group) calling. Like tone squelch. in programming, you set this to squelch and the radio never makes a peep unless YOUR code (group code) is received. you don't hear the tones at all.
Your radio likely can be set with an alert tone when you get a call, then just voice.
Non MOTO radios may have a different name for MDC, like MaCom calls it G-Star.
Not quite the same, but tweaks with tones and timing, they are compatible. (goes from 5 tone to 2 tone.)
That preamble is not mandatory, just an added feature if you have it.
Any of the tone signaling schemes work just as well with digital as with analog.
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Your quite much on track. I never thought to use such reference.
USPTO can be an incredible resource, but it can also be the vortex to end all vortices.
True, but I have found much obsolescence, but a good place to start. When advancements are made, there is little updating. I am more hardware man and try to keep on top of the 'link layer' of all this. The actual AFSK packet stream. The convolution can be a little complex, but this is really a simple protocol. Almost like teletype of the old days.
902
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Well... GEstar is not interoperable with MDC1200. That large system I managed had a number of M-PA portables and Orion mobiles. They were all programmed with GEstar, but I needed to install a separate ANI/ENI decoder on the console for it. They are "like" MDC1200, but can't be displayed on MDC1200 capable subscriber equipment. Same with Kenwood Fleetsync. They all do a good job, and they're all similar, but they're different. In P25 digital mode, the unit ID is imbedded in the data stream. It's sent continuously.
902
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You're right, and so did some of the Maxtrac mobiles. But the GE radios didn't do Motorola signaling. If you had a system that was a mixed procurement (some from a year Motorola had the contract, some from a year GE/Ericsson/Tyco/M/A-Com/Harris/L3Harris had the contract. That made things complicated when you were looking for console compatibility.
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