IRLP

IRLP stands for the Internet Radio Linking Project.

IRLP

As with any new technology, it does take some time to adapt to operating procedures that differ from conventional FM repeater use. This work in progress can serve as a guideline for those wishing to use our local IRLP enabled repeater node.

All links are activated and de-activated by using DTMF tones received by the IRLP repeater/computer. You must be a TARRA member for access details. TARRA membership is used to offset the cost of setting up and running the TARRA repeater system and the IRLP node. Please contact TARRA for membership, which includes the local IRLP link codes.

The purpose of IRLP is to bring amateur radio operators an inexpensive linking system as a way to talk to many other sites using state-of-the-art-technology. This is one of the great advantages of IRLP. Each station (node) has the ability to connect to another node directly, or by the way of a reflector, to connect to several other nodes (virtually limitless). A reflector can be seen as a digital repeater of sorts. Reflectors have been designed so that we can link three or more nodes together.

Operating Hours

The TARRA node is generally available during normal repeater hours from 8:00 AM to 10:00 PM. You may occasionally find the node disabled or inaccessible. This may be due to a time-out, node down for system maintenance or an Internet connection problem.

Timers

There are a couple of timers involved in this system, they are:

Time-out Timer

This timer is set to 4 minutes. The IRLP Time-out Timer is similar to a Repeater Time-out Timer. It is the maximum amount of key-down time for a single transmission. If you exceed the time allowed by the Time-out Timer, the link is terminated and the node is disabled until a Control Operator can restart the node.

Local Activity Timer

The value of this timer is dependent upon the type of link connection. When in a direct (one-to-one) link, the timer is set to 5 minutes. When in a reflector (one-to-many) link, the timer is set to 20 minutes. Therefore, when connecting to another node or reflector you may monitor an active conversation already in progress or wait for a station to come up on the air; however, this timer starts counting the time since the last key up on the local node and will drop the link at the end of the time-out period. Activity from the remote station does not reset this timer. If the distant node has a shorter inactivity timer they may close the connection first. This means that you cannot link and just monitor without taking part in the conversation. Do not kerchunk the node to keep the link up, this would be a violation of our node rules! It is also discouraged by the IRLP.

There are certain situations where it is necessary to be linked for an extended period of time (e.g. the Space Shuttle transmissions). The Control Operator has the capability of overriding the activity time-out timer so that the link will remain active until it is manually reset. Only the Control Operator is allowed to override this timer.

Procedures

Common Modes

There are two types of connections, direct (one-to-one) and reflector (one-to-many).

Direct - Is just like it sounds, where node "A" connects directly to node "B". With this type of link the two nodes are interconnected and no other IRLP connections are possible. While nodes "A" and "B" are connected, anyone attempting to connect with either node will be told by a recording that - "The node you are calling is currently connected to callsign."

Reflector - While Direct link is preferred for a person-to-person chat, the most common type of connection in use today is via a reflector. A reflector node is a special node sitting on a high bandwidth Internet connection that takes whatever audio streams it receives and resends them out to all of the other nodes that are connected to the reflector, thereby allowing all of the nodes involved in the connection to communicate with each other. At any given time there may be 6 to 10 nodes around the world interconnected via a reflector or conference.

Avoid local traffic while connected to the reflector. By its nature, the reflector has a large footprint and a wide audience, therefore if local users would like to have a discussion, they should disconnect from the reflector. If we hear a local conversation (all participants coming from the same node) that continues, I, or one of the other reflector control ops will likely ask them to disconnect. If attempts to break into the conversation are unsuccessful, the node may be blocked from the reflector (more on blocking later).

Along the same line, if two stations become engaged in an extended dialog involving only themselves, then I would recommend they both move off the reflector and make a direct node to node connection, freeing up the reflector for others. If more than two nodes are involved, then moving to one of the lesser used reflectors might be an alternative, especially if one of the stations can check the web site for an available reflector. In the future, moving to one of the available sub-channels will become an option.

Node Use

The first thing we must all remember is to leave a gap between transmissions. Having said that, this is a good time to list the three main rules when connected to a node or reflector:

  1. Pause
  2. Pause
  3. Pause

 

All this waiting is necessary because many of the nodes participating in Internet linking are parts of large multi-linked repeater systems where there can be significant key-up delays as all of the repeaters in the system come up. Therefore, it could take 1 to 2 seconds before last repeater in the link comes on-line, thus chopping the first several syllables off of your transmission. Please adjust your operating habits accordingly.

Also, leaving a pause between transmissions ...

allows users on other nodes a chance to check in.

allows other nodes time to send DTMF commands to drop their node.

The most important thing to remember is to pause after pressing the PTT as well as pausing between transmissions.

Local Conversations

It is not necessary to bore the world with your shopping list requests or complaints about the plumber; therefore, Please drop the IRLP connection when having a local conversation.

Making Connections

All commands accepted by the TARRA node, will cause some sort of audible signal to be returned to the user. This may be in the form of spoken words.

Just as you would listen before transmitting on any repeater, you must listen for at least 10-15 seconds for link activity before making any transmissions as there may already be an active connection or local conversation in progress.

Always identify before using any control codes.

Example:

  1. "This is <callsign>", then send DTMF
  2. wait for link up message then
  3. listen, listen, listen then announce yourself.
    It's a good idea to announce your location as in "<callsign> Jackson Hole, Wyoming"

When traveling to other areas it should noted that many nodes require different commands than those found on the TARRA node. Many people decry this as closing a system which should be open, when in fact, it is just a necessary evil to make the node coexist within the command structure of the repeater to which it is connected. This could be compared using CTCSS, not all repeaters that use CTCSS are closed, nor do they all use the same tones. Therefore, it is highly recommended that you contact the owner of the node you wish to use prior to your travels to obtain codes and/or procedures for their systems.

Calling

To call it is preferable to say "This is W7TAR calling, is anyone available for a contact?" as opposed to "W7TAR Listening" ...silence for 2 minutes, followed by a disconnect. However "Q codes" are unnecessary and should be left for CW/SSB frequencies where tuning around is the observed practice. Odds are we heard it the first time.

It IS acceptable to talk about the weather, or anything else that is geographically significant. But like anything else, within reason. A station in Indiana that says to a Wyoming op, "Hey I heard that you have a mountain out there" will probably cause eyes to roll worldwide.

In general though, long winded, channel consuming conversations should be avoided. Remember there are usually a dozen or two connected systems, with perhaps hundreds of users that might like a chance to use the system.

A few other Reflector operational guidelines:

Listen first. When connecting to the main channel on a Reflector, odds are that you are dropping into an existing conversation. Wait for at least 15 seconds to make sure you are not interrupting an existing conversation before calling.

Pause between transmissions. Many nodes are connected using simplex links, therefore the only time it is possible for them to disconnect is between transmissions. Be sure to pause AT LEAST 5 seconds between transmissions.

Key your transmitter and wait before speaking. There are propagation delays across the Internet, as well as delays caused by sub audible tone decoders and other devices that cause a delay before the audio path goes through. If you speak immediately upon PTT, the beginning of your transmission will not be heard.

Being BLOCKED from Reflectors.

IRLP reflectors have a management function allowing reflector control operators to block specific nodes from accessing the reflector. When a node is blocked, the reflector ALWAYS automatically generates an e-mail message to the e-mail address of the Node owner. The e-mail should contain the specific reason for the block. This blocking is NEVER personal. It does NOT mean that we don't like you, but is only done to ensure continued operation of the reflector. 

Nodes are usually blocked for a technical malfunction, such as a locked COS, open squelch noise, extended hang time, or your repeater ID (with no user traffic) or courtesy beeps audible to IRLP, or any other problem that that impairs operation of the Reflector. Your node may also be blocked for rapid fire local traffic making it impossible for nodes to break in between transmissions.

Cross-linking other VoIP networks on IRLP reflectors is not allowed as very few non IRLP VoIP systems mute Station IDs, hang timers and courtesy tones.  IRLP does not permit retransmission of any source that is not part of a users PTT transmission.  With 20 or more repeaters connected together, sheer chaos would result if this hard rule was not enforced. 

The reflector control ops may try to contact a local control op on the air to advise the problem, however this may not always be possible. It is important that the node owner respond to the e-mail message advising the problem has been corrected.

If you have any other specific questions I can address, please send them along. 

MAKING A DIRECT CONNECTION
First of all listen on your local repeater for at least 15 -30 seconds before transmitting and then ask if the repeater is currently in use.  Assuming all is clear, identify yourself and give the node name or number you wish to call .  Example:  "VE3xyz for the Sydney node" - - then enter the ON code for the node and release your PTT. Your local repeater should come up with a carrier as it waits for the connection to be authenticated. This can take a few seconds of dead-air so don't be concerned. When the connection is confirmed, the voice ID of the destination node will be transmitted back to you as well as your nodes voice ID to the other repeater.

NOTE: If your node is already connected to another node or reflector, a greeting will play saying; - "your node is currently connected to...ID of the connection")  In this case confirm if anyone desires the connection to remain up before dropping by using the OFF code.. 

Once connected and after hearing the confirming voice ID, wait at least 15 seconds before transmitting as.......

    The repeater may be in use, and your entry may have occurred between transmissions.

    The voice ID of your node is longer than the voice ID of their node, and the connection is not made until the ID is fully played.

    Their computer may be slower, and hence take longer to process the connection than yours.

Press and hold the microphone PTT for a second and then announce your presence and your intention such as you are calling someone specifically or just looking for a conversation with another ham in that city.

If no response is heard, announce your call and your intent to drop the link and then touch-tone in the OFF code. Not a good idea to transmit touch-tone commands without first giving your call-sign. Not only is this courteous it is a regulatory issue in some countries who may be connected to the reflector.

Some nodes are configured so you cannot connect to them if that repeater is active. In this case you will receive the message "The node you are calling is being used locally" If you receive this message wait 5 or 10 minutes and then try again.

If  you stay connected to a node and there is no activity on your repeater for 4 minutes, the connection will time out and automatically disconnect with a voice ID disconnect message on both nodes.

CONNECTING TO THE REFLECTOR
As above, listen to your local machine for local use and then announce your intention for the Reflector before keying the ON command. When you hear the confirmation ID always WAIT at least 15 seconds before transmitting as you are most likely now connected with many repeaters and a conversation could be in progress. If after 15 seconds you hear nothing, identify yourself and indicate you are listening to the Reflector  from "City and, Prov./State, Country" . With the world wide IRLP activity your local repeater now has world wide coverage thus the suggestion to better detail your location.

Don't be in a hurry to hear someone come back to you. You may have to do a bit of pleading from time-to-time to dislodge someone from whatever they are currently involved with. 

By default, connections to the reflectors now time out with no activity however many node owners set this period for a long period so it is not unusual for repeaters with minimal traffic to stay connected to the Reflector for extended periods of time. When or if  the node times out from a Reflector connection a standard time-out greeting will precede the timeout saying, "Activity time out ... Reflector xxxx, link off"

If you are new to IRLP you should always consult with your local node sponsor to confirm the local guidelines on reflector connections in your area.

If you hear or wish to engage in a prolonged rag-chew on your local repeater (long discussion of a local nature)  out of courtesy to other node listeners drop the reflector.

 

IRLP Error Messages

From time-to-time you may receive error messages when attempting to connect with a node or reflector. The most common ones are:

"The node you are calling is not responding, please try again later"
This is caused by a loss of Internet connectivity to one end of the call attempt.

"bee-boop Error- The call attempt has timed out, the connection has been lost"
This error occurs when a node is OFF-LINE. Some nodes such as in the UK use dial-up connections and then, only for short periods. Also there may be temporary net or node problems.

"The connection has been lost"
If the Internet connection drops, this error message will be heard.

"The node you are calling is currently connected to callsign."
If the node you a calling is already connected to another node or reflector, you will hear this message.

"The node you are calling is being used locally."
If the node you are calling has local activity on the repeater or frequency, you will hear this message. Try calling again in a minute or so.

"<busy signal>"
The node you are calling is not connected to another node or reflector; however, the repeater or frequency is in use locally or the IRLP node hardware is being used for some other function.

DO'S and DON'TS

In summary there are a few do's and don'ts:

DO pause between transmissions to let others in or to enter DTMF command.

DO identify before sending DTMF command tones.

DO hold your microphone PTT for about 1-2 seconds before talking to allow all systems time to rise.

DO pause and listen for 10 seconds or more when connecting before talking.

DO NOT ragchew on your local repeater while connected to a reflector.

DO NOT start or plan a Net on a reflector without pre-authorization from the reflector owner

 

For more information about IRLP check the IRLP web site.

 

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