Internet Radio Linking Project Node 3747

Notice: The IRLP receiver may drop audio from local users if your signal into the repeater is not full quieting. This appears to the remote end of the IRLP connection as if your audio is dropping out.   Our method to signal the IRLP receiver when someone is transmitting locally on the repeater is sensitive to signal quality to the repeater.  We hope to resolve this in the near future. 

The Motorola Amateur Radio Club of North Texas, in cooperation with the National Weather Service (NWS) office in Fort Worth and Charter Pipeline Cable service, supports I.R.L.P. node 3747 on the 444.300 repeater. The following people deserve credit for the installation and operation of this I.R.L.P. system.

During weather emergencies this I.R.L.P. node may be used by the NWS office to exchange weather information traffic with Sky Warn storm spotters in North Texas counties. The N.T.R.A. Dallas I.R.L.P. reflector channel 9453 may also be used for NWS weather traffic during severe weather.

The 3747 I.R.L.P. node is currently open for use by all licensed amateur radio operators.  Use the standard I.R.L.P method to connect to remote nodes by sending the remote node 4 digit number with your DTMF pad. To disconnect, send "73" on your DTMF pad. Any remote node may also connect to node 3747, unless a control operator has disabled the node or otherwise limited I.R.L.P. connections.

If you have never talked over an I.R.L.P. connection, please review the links below.  One  important tip to remember, pause for a second after you key the MIC before you speak.  This allows the connection to complete across the network and helps avoid dropping syllables or words from the start of your transmission.

IRLP DTMF Controls

The following DTMF code list controls features of the K5MOT IRLP system.  IRLP DTMF controls will be prefixed with a DTMF hash (#), except for 73 and when calling node numbers and reflectors where no hash (#) is required.

Questions and Answers

Here are some questions and potential answers about IRLP operation under certain conditions.

Q.  Why doesn't the disconnect control (73) work when a radio operator on the remote Internet link is transmitting on the local system?

A.  The IRLP computer/radio/Internet link operates in simplex mode, so the local IRLP computer is not decoding received DTMF controls while the remote IRLP radio operator is transmitting.  Wait for the remote operator to stop transmitting, then send the DTMF control tones.  This is another reason we must pause more between transmissions while connected to a reflector, so as to allow other nodes to disconnect.  We may add the capability control the local node computer via full duplex operation later.  The radio/computer interface is capable of this operation.  But the Internet link will continue to operate  in simplex mode unless node owners and users provide a reason to change the IRLP system to full duplex operation.

Q. What timeouts could occur?

A. The following are timeout limits for IRLP operation.

• PTTLOCK timeout - 5 minutes.  This is the maximum time the IRLP node radio will continuously transmit locally from a remote IRLP connection. Upon exceeding this timer, the node connection is dropped and reset.   A timeout audio message is played on the node transmitter.
• CORLOCK timeout - 4 minutes.  This is the maximum time the IRLP node will continuously transmit received audio to a remote node. If a radio operator transmits to an IRLP node receiver with an active connection for more than 4 minutes, this timer will trigger. Upon exceeding this timer, the connection will be dropped and the IRLP node will be disabled.  A timeout audio message is played on the node transmitter.  A node control operator will have to re-enable the node after this timeout.
• Node to node local inactivity timeout - 4 minutes.  This timeout may be set by each node owner/operator.  Node 3747 is set to 20 minutes.  For node to node connections, when a node receiver does not receive any local transmissions (no COS activity) during this timeout period, the IRLP connection is dropped and both nodes reset.  A timeout audio message is played on each node indicating "inactivity timeout".   One scenario that may trigger this timeout is when a group of radio operators are talking in a round table fashion across a node to node connection. If the sequence of operators taking turns to transmit does not move back and forth between the two nodes within the timeout period, one node may drop the connection for inactivity.  This happens quite easily for the default 4 minute timeout period. So be careful to go back and forth between the two nodes, or use a reflector channel to minimize hitting this timeout on either node. 
• Node to reflector local inactivity timeout - 20 minutes.  This timeout may be set by each node or reflector owner/operator.  Node 3747 is set to 20 minutes.  We also have DTMF control codes to disable this timeout for selected reflector channels.  For node to reflector connections, when the node receiver does not receive any local transmissions that are sent over the IRLP connection during this timeout period, the IRLP connection is dropped.  A timeout audio message is played on the node indicating "inactivity timeout".  The reflector operator may also impose their own timeout, which would override the node setting if the reflector timeout is shorter.
• Timeout Loop.  During an active connection, the IRLP software monitors the network connection by regularly passing a status packet between the two nodes.  If this status packet is lost two times sequentially, the connection is considered lost and the node is reset.  An audio error message should be heard from the node radio when this occurs.

Q. What are the standard IRLP audio files?

A.  Refer to the audio files page.  Note that the audio files may be updated on the IRLP system at any time.