MDC signalling on GMRS.

[Lscott]

1 hour ago, jwilkers said:

I call MDC "whacker tone" because whackers use it to sound "official". I really see no legitimate use for it at all.

Sent from my SM-A125U using Tapatalk
 

Well one Ham got tired of people using cheap Baofeng radios, and other similar CCR’s, on his repeater. So, he switched over to require a MDC sequence to activate it. The cheap Chinese radios typically don’t have it. It effectively kept them off his repeater it seems. Of course he got branded as a Motorola snob. However some of the other main stream commercial radio manufacturers have it as well, not universally on all models, so it’s not that huge of a limitation. I have it on some of my Kenwood’s, for example the TK-5220/5320 P25 ones in my collection. There are some other Kenwood models I have with it too besides the ones above.

https://www.urci.com/downloads/kenwood/kenwood_tk_5220_5320_brochure.pdf

The TK-5320 with the band split of 450-520 has FCC Part 95 certification, FCC ID ALH378500. The radio can be programed and used for GMRS legally provided power, frequency, bandwidth and modes are followed as listed in the rules. One could use the MDC signaling as a means to keep unauthorized users out of a private GMRS repeater. 
 

Another use would be to identify which radio in your group is transmitting. This is advantageous when the radios are all operating under the same license. Let’s say you’re out camping, hiking etc. and one of your family members is injured and can’t speak. Simply keying up the radio will uniquely identify who it is.

 

[wayoverthere]

10 minutes ago, Lscott said:

However some of the other main stream commercial radio manufacturers have it as well, not universally on all models, so it’s not that huge of a limitation. I have it on some of my Kenwood’s, for example the TK-5220/5320 P25 ones in my collection. There are some other Kenwood models I have with it too besides the ones above.

I think pretty much all of my Vertex gear does MDC1200, including the analog, part 95 certified, vx4207's. (Double checked that, fairly sure the others do as well)

[gortex2]

16 hours ago, jwilkers said:

I call MDC "whacker tone" because whackers use it to sound "official". I really see no legitimate use for it at all.

Sent from my SM-A125U using Tapatalk
 

Sorry I use it on all my radios so I know which radio is being used. Each radio has its unique ID. With many users on a repeater its nice to keep track of who just called. JMHO 

[OffRoaderX]

17 hours ago, jwilkers said:

I call MDC "whacker tone" because whackers use it to sound "official". I really see no legitimate use for it at all.

Everyone in our GMRS group uses MDC so we know who is talking and/or what radio they are on.

[jwilkers]

16 hours ago, OffRoaderX said:

Everyone in our GMRS group uses MDC so we know who is talking and/or what radio they are on.

Does it actually display their call sign?  Just curious.....if there is something to this.  At any rate, reading replies to my comment has educated me a bit and I see that MDC is likely used in important ways.

[gortex2]

Depends on the radio. All my motorola gear allows alias. I can add an alias as a call sign but mostly its just a unit number or vehicle ID. We use a list thats standard and each ID represents something. ie: last digit 9 refers to a base radio... 

 

[OffRoaderX]

4 hours ago, jwilkers said:

Does it actually display their call sign?  

My radios display name and callsign per the way my radios are configured.

 

[tweiss3]

CS800D does MDC, as do all my Kenwoods. This thread might me using MDC now.

 

Are you guys using it pre, or pre+post?

[SteveC7010]

For those that are not familiar with MDC, the transmitting radio is programmed with a 4 character MDC identifier. Valid characters are 0001 through DFFF. Typical ID's are usually just 4 digit numbers, but hex can be used. That ID is what is transmitted in the "beep" squawk that is heard on the air. The sending of the code can be either "pre" or "post" on the actual voice message. I prefer "post" because it is sent as you unkey the mic so there's less chance of the voice and the MDC colliding with each other.

What is displayed on the receiving radio is also dependent on programming. Most agencies build a "call list" which is a matrix of MDC codes and what each code translates to. For example, I set my personal radio to transmit code 1001 for use in family convoys. If the receiving radio has no call list, but is set to decode MDC, it will display the same 1001. However, if the receiving radio has a call list defined, then the alias in the call list is displayed when that code is received. For my other radios, 1001 is programed to read "Steve Truck 1". It could just as easily be defined as "Steve WQPG808" for a community group setting or maybe "Steve Tail Gunner" for an offroad group. But the alias is programmed into the receiving radios. In a group setting, the complete call list would have to be programmed into all the radios in the group for the system to be effective.

[SteveC7010]

15 minutes ago, tweiss3 said:

CS800D does MDC, as do all my Kenwoods. This thread might me using MDC now.

Are you guys using it pre, or pre+post?

I much prefer post MDC only. Unkeying the mic triggers the post MDC transmission so there's much less chance of the sender's words being overridden by the MDC burst.

If one uses pre, the burst is sent immediately upon keying up. The mic won't pick up the voice until the burst is done which generally means that most users will find their first word or three is not heard by others so there's lots of "repeat your transmission". Most users don't remember to wait after keying until the burst is complete.

I suppose you could enable both, but the multiple MDC bursts for each transmission gets annoying pretty quickly.

[AdmiralCochrane]

People also generally don't know that most transmitters take a second to engage and "heat up" to full power even without sending a MDC tone.  

Key the mic and make sure you pushed the button all the way down. Then begin speaking, not as you are keying the mic

[Lscott]

1 hour ago, AdmiralCochrane said:

People also generally don't know that most transmitters take a second to engage and "heat up" to full power even without sending a MDC tone.  

Key the mic and make sure you pushed the button all the way down. Then begin speaking, not as you are keying the mic

It’s about the same thing using a VOX setup. It takes a bit to get use to giving the system about a second or so delay. Once you get in the habit it sort becomes second nature. I had used a VOX headset with an HT years ago running mobile. Didn’t take long to get it right.

[WROZ250]

17 hours ago, AdmiralCochrane said:

People also generally don't know that most transmitters take a second to engage and "heat up" to full power even without sending a MDC tone.  

Key the mic and make sure you pushed the button all the way down. Then begin speaking, not as you are keying the mic

Actually, if you throw the radio onto the bench, a quick check will show that the microphone line doesn't even go active until the MDC/PTT ID has been sent as the radio (or rather the PTT ID circuitry) accounts for the power delay before sending the PTT ID.  At least it does for Motorola radios. 

Worse case scenario is that the first syllable of your voice gets clipped if you're a bit quick to speak, which is the point of the PTT sidetone.  You wait for the sidetone to complete before speaking.

[PACNWComms]

1 hour ago, WROZ250 said:

At least it does for Motorola radios. 

I still have to explain to die hard dispatchers that this is the case. Analog sites complain about analog, while digital trunked sites complain about digital delay. Then others ask what the tones are, MDC ID, Basestation ID (BSI), which then leads to a discussion on Pre and Post sending of MDC ID versus Pre only. 

I like MDC ID on my own repeater, but respect those that do not want to hear it on theirs.....there are only a few other GMRS repeaters in my area.

[Radioguy7268]

For anyone planning to implement MDC signaling, you should investigate the use of DOS (Data Operated Squelch) and PTT Sidetone.

I'd recommend only using it in a group if everyone on the repeater is using MDC, and everyone agrees on the setup parameters. If properly done, the users on the system will not hear the MDC squawk, and every radio on the system can ID other users. MDC can also be used for selective calling, radio alerts, and Status updates. It's a pain to set up if you're using multiple radio models across different manufacturers.

DOS will silence the MDC turkey call noise (either pre, post, or both) for users that have it active - and a PTT sidetone can be useful to remind the user to pause for a moment until the MDC pre-burst is sent. Set the PTT sidetone to something less than obnoxious if you're using it.

Whackers like MODAT, MDC and PTT Sidetone - even when they're not actually using MDC for any signaling benefit. They just think extra noises sound cool & they heard all those noises on their Bearcat Scanner - so they think that the radio users must be hearing those noises too. Well designed radio systems don't annoy their actual users with squawks and obnoxious beeps.

 

[WRTZ740]

I'm wondering of the ramifications of using a technology that is clearly meant for business use, but as personal, without a business license on a wide spread basis

[OffRoaderX]

17 hours ago, WRTZ740 said:

I'm wondering of the ramifications of using a technology that is clearly meant for business use, but as personal, without a business license on a wide spread basis

According to the FCC Enforcement Database, since 2012, there are no ramifications.

Unintended consequences include more "pure" spectrum-use since virtually every LMR radio is better designed and has far less spurious output than pretty-much any consumer GMRS radio on the market.

Edited August 26, 2022 by OffRoaderX
I said "commercial", I meant "consumer"

[WRTZ740]

16 hours ago, OffRoaderX said:

According to the FCC Enforcement Database, since 2012, there are no ramifications.

Unintended consequences include more "pure" spectrum-use since virtually every LMR radio is better designed and has far less spurious output than pretty-much any commercial GMRS radio on the market.

Thank you, I appreciate the clarification.Google search pretty much begets more opinion from "Don't judge me by my radio, while I judge you for yours." Your response is to the point and accurate, very much appreciated, sincerely.

[Lscott]

On 5/18/2022 at 1:17 PM, Radioguy7268 said:

 Well designed radio systems don't annoy their actual users with squawks and obnoxious beeps.

Too bad that doesn't apply to FRS radios and their Roger beeps.

[KAF6045]

23 hours ago, Lscott said:

Too bad that doesn't apply to FRS radios and their Roger beeps.

"Roger" beeps are relatively innocuous -- it's those "call" tones that the kiddies seem enamored of (come on, you're supposed to press the call button once, and wait for someone in your group to respond... Not treat it like a police siren on a pursuit: ding-ding-ding, ding-ding-ding, ding-ding-ding for three or four minutes).

Granted, if one is running through a repeater, and the repeater is also providing a beep, having the user transmitting one is redundant and misleading. Simplex? Heh.

[SteveShannon]

You kids get off my lawn! 

Fortunately I live in an area where I can always find a clear channel, otherwise I’m sure I would feel similarly. 

[KAF6045]

7 minutes ago, Sshannon said:

You kids get off my lawn! 

Fortunately I live in an area where I can always find a clear channel, otherwise I’m sure I would feel similarly. 

I'm in such a dead zone for GMRS that I normally have the mobile in SCAN mode... So, yes, I end up on the kiddies shrieking between rings...

The KG935's tone scan did let me identify the one repeater with traffic in Grand Rapids -- in a 25 year-old GMRS repeater guide book. A grandfathered City of Grand Rapids "business" use -- at the time it was allowed to be used by the public for Emergency & Traveller Assistance unless one obtained written permission in advance. Book states it has a 30 mile radius, but I think it's down to 15 mile (30 mile would reach Lowell with plenty in excess). I suspect if one tried to use it for E/TA these days they'd be hit with "What, you don't have a cell-phone?"

Primary use for the system seems to be for the downtown paid parking lot operators... I've heard discussions of people wanting refunds because they'd bought tickets for x-vehicles, but their friend came in through a different gate; resetting machines so they'd start accepting plastic again, etc.

 

[Lscott]

4 hours ago, KAF6045 said:

I'm in such a dead zone for GMRS that I normally have the mobile in SCAN mode... So, yes, I end up on the kiddies shrieking between rings...

The KG935's tone scan did let me identify the one repeater with traffic in Grand Rapids -- in a 25 year-old GMRS repeater guide book. A grandfathered City of Grand Rapids "business" use -- at the time it was allowed to be used by the public for Emergency & Traveller Assistance unless one obtained written permission in advance. Book states it has a 30 mile radius, but I think it's down to 15 mile (30 mile would reach Lowell with plenty in excess). I suspect if one tried to use it for E/TA these days they'd be hit with "What, you don't have a cell-phone?"

Primary use for the system seems to be for the downtown paid parking lot operators... I've heard discussions of people wanting refunds because they'd bought tickets for x-vehicles, but their friend came in through a different gate; resetting machines so they'd start accepting plastic again, etc.

 

You check the FCC database to see if it really is grandfathered? If they let the license lapse, and didn't renew in time, the license is kaput and so is any use of it by the original business that held the expired license.

[KAF6045]

3 hours ago, Lscott said:

You check the FCC database to see if it really is grandfathered? If they let the license lapse, and didn't renew in time, the license is kaput and so is any use of it by the original business that held the expired license.

Last renewed in 2018 https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=195998

Quote

A non-individual licensee may operate only on the channel(s) that have been assigned to your station. This license authorizes use of the following channel(s) only: 462.575 MHZ, and 467.575 MHZ.  

They changed the contact person last fall.

[Lscott]

1 hour ago, KAF6045 said:

Last renewed in 2018 https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=195998

They changed the contact person last fall.

Well it looks like you're stuck with them. Being grandfather in with a current license I think that gives them primary privileges on the frequency. At least they are legally licensed.

You can request access and see what happens. The worse is they say no, which is the most likely result.

The GMRS repeater by me is owned by the city of Troy Michigan. It was their backup repeater for the fire department. I don't know their current license status for it. In any case all one has to do is request access. I don't think any reasonable request has been denied. There are well over 100 users who have been granted access so far.