Q: Assuming one sets up a D-Star transceiver with the appropriate call signs for the amateur operator at the other end, the D-Star repeater in between, etc., can other D-Star equipped stations “hear” the repeater traffic? Or is the D-Star repeater contact essentially limited to the two amateur operators who are in contact with one another? If the latter is the case, what happens if another D-Star station attempts to initiate a contact through the D-Star repeater while the first contact is in progress? Does the system generate a “repeater busy” message or similar?
A: Yes… anyone can “hear” any traffic. They don’t even need to set up any call signs. Also “yes” on the “repeater busy”, but it’s controllable via a setting in most of the Icom D-Star rigs… see “busy lockout” in your menus.
Since we don’t have one on-air yet, I’m unsure as to what happens if you have busy lockout turned OFF in your rig and try to drop over the top of existing repeater traffic.
I would recommend the use of “busy lockout” but there are some glitches. For one, the “auto” squelch mode in digital appears to be (from simplex testing) too “open” for most of us, and it was blocking some people’s ability to transmit. Additionally, if you turn on busy lockout, it gets turned on across the board… both analog and digital on the IC-91AD, anyway… and that’s HIGHLY annoying on repeaters that have short courtesy-tone intervals but have long transmitter tails when using the rig for analog.
To go back to the question you’re really interested in — “Can I hear others?”
D-Star is designed to have features similar to some of the digital Public Safety systems in that you can be set up to hear specific traffic instead of all traffic, by looking at call signs or a two-digit “digital squelch” number that any station can transmit/receive.
In D-Star, you as the rig user can CHOOSE to only hear calls to yourself, or to a “digital code” group… but you can’t make the transmissions truly “private” in any way. Others can still hear your transmissions if they’re in range of you (simplex or reverse pair) or the repeater.
Most of the rigs (not the early ones) also have a feature where you can “auto-copy” the last call sign heard and your rig will talk back to that call sign specifically on your next key-up. I’m not sure I like this, but it works… the default “placeholder” to send for a call sign if you’re talking amongst a group is “CQCQCQ” instead of a specific station’s call sign, but we’ve mixed and matched people using “CQCQCQ” and people using “auto-call sign” in a round-table with no ill effects… we all still hear the transmission of the person sending different call signs on simplex.
Auto-call sign will be “interesting” on routed calls via the gateway system. It will work well for local users on the SAME repeater, but there are some special routing things you’ll want to use with the new Gateway 2.0 software that can force the gateway to provide up to a 10 repeater — but never more than one repeater in a single stack locally — “conference” — according to the documentation.
(And we’ve seen reports that the documentation doesn’t always match reality — so we’ll know for sure once the system is up and running.)
But anyway… see how complex it can get? We’ll try to come up with some “easy to remember” general rules for various types of communication as we go forward.
But back to the topic at hand…
For “call sign squelch” operations, any Amateur between you and the other Amateur who can copy both of you in the RF domain, can hear your conversations, copy your low-speed data, whatever… just like most things in Ham Radio.
There’s also a “BK” mode called “Break-In Mode” where a third party listening in can get one of the other operator’s attention by activating that on his rig and then keying up.
And finally, there’s an “EMR” mode.
(This mode probably stands for “Emergency” mode, but is NEVER referenced by that name anywhere in any manual — the lawyers apparently got to it and didn’t want the liability if it didn’t work right in a real emergency.)
“EMR” mode FORCES other user’s rigs to hear your transmissions EVEN IF they’re in one of the more restrictive squelch modes, as long as you’re transmitting on their receive frequency.
In fact, on some rigs it even turns up the volume to 1/2 if the rig was turned all the way down.
The EMR mode makes sense, if you think about a normally running repeater system where everyone who just happens to have a rig on at a particular time could be monitoring in “call sign” or “digital code squelch” — and you’re out there somewhere in need of help. Similar to EMR buttons on Public Safety radios. Push the button for two seconds, switch your rig to “HELP!” mode and key up… someone will hear you.
Kinda nice, actually. I can also imagine situations where people will ABUSE it! If too many people “play” with it at first, or over-use it later to alert their buddies — it will make it less useful.
More likely, someone will turn it on and talk for an hour and forget about it, forcing all the people in call sign squelch to hear half of the conversation which will drive us all nuts! (GRIN)
The main differences between Public Safety digital rigs and D-Star appear to be in little implementation things like the above.
In Public Safety, someone programs the rig for the user, hands it to them, and they might not be able to hear anything other than their “talk group” and a “interoperability” group, or may have to go through their dispatcher to “patch” groups together when working with other agencies.
Even though the traffic is right there unencrypted and their rig COULD copy it for other agencies or jurisdictions, it often isn’t programmed to.
Additionally they can add rig-to-rig encryption that we can’t for legal and ethical reasons when they REALLY need security. We can’t.
In the Ham Radio D-Star system, the design is the opposite — you have control of what you hear and no encryption, ever.
Nate WY0X
Tags: D-STAR Info
