Motorola's SmartNet Systems

Trunked System Features

• Busy Tone:
  This is generated when PTT is depressed at a time when all channels that can support the type of requested call are busy.

• Busy Queue/Call back:
  When all voice channels capable of supporting the requested call are in use, system requests are put in a waiting queue and are served on a FIFO (First In First Out) basis. When a channel that can support the requested call becomes free, the central controller sends a channel grant to the first request in the queue.

• Out of Range/Out of Service:
  If control channel data cannot be detected by the radio, this is an indication that either the radio is out of range or the trunking central controller is out of service. The indication is a reject tone whenever the radio operator depresses the PTT button. The LCD display may display "out of range".

• Talk Permit (optional):
  This feature provides a radio operator with a brief series of talk permit tones upon channel grant or following a PTT on a voice channel. This is an indication that the operator may successfully transmit on the voice channel without clipping.

• Automatic Retry:
  Radio units are designed to continue sending channel requests until the request is acknowledged by the central controller, or 4 seconds (up to 16 retries) have elapsed. The operator does not need to continually depress PTT. Automatic retries are randomized to eliminate the possibility of contention on the control channel. This could be due to ISW collision, propagation delay, or radio signal too weak to be detected.

• Recent User Priority:
  A recent user is a Talk Group who previously had a voice channel and stopped transmitting. Such a Talk Group will have priority over other system users with the same level of access (for up to 10 seconds after the end of transmission if the system is busy).

• Call Priorities:
  Even on a trunked system, busy periods may occur that could tie up all repeaters in the system. In order to provide immediate access to the most critical service during busy periods, eight levels of user priority are available for all mobiles and portables and talkgroups. Level I is reserved for Emergency calls. Assignable levels 2 through 8 are determined by the System Manager. In the event the system is busy, priorities will be processed in this order: level 1 (Emergency), levels 2 through 8, as channels become available.

• System Time-Outs: These parameters may be edited through the System Manager's Terminal:
  
  
  • Carrier Time-Out Period:
    This determines the time period for which an assigned voice channel remains un-muted and active, receiving only carrier and no handshake Connect Tone. The time can be activated after a Disconnect Tone is detected by the trunking central controller.

  • Fade Time-Out Period:
    This determines the time period for which an assigned voice channel remains active, even though no tones and carrier are received. After the time-out expires, the channel is unassigned. The timer is activated after the trunking central controller fails to detect the Disconnect Tone after loss of the low speed Connect Tone and carrier.

  • Message Trunk Time-Out Period:
    This determines the time period for which a voice channel remains active after receiving a Disconnect Tone from a radio and there is no further connect tone and carrier. After the time-out the channel is unassigned.

  • Carrier Malfunction Time-Out Period:
    This determines how long an interfering signal must be present on an unassigned channel before it is removed from system use. An entry of 254 seconds disables the time out.

System Reliability Features

• Multiple Channels:
  Channels are assigned as needed so users are not dependent on any given channel for communications. The failure of any one channel would not be readily apparent.

• Control Channel Switching:
  If the control channel fails, the trunking central controller is programmed to assign another repeater as a control channel. Up to four frequencies in a Motorola trunked system are eligible for assignment as a control channel.

• Receiver Jamming:
  A trunked radio system repeater may be jammed by the receipt of an unauthorized signal. The trunking central controller is programmed to make the repeater unavailable for assignment, when it detects a carrier on a channel that has not been assigned to members of the system. The repeater is reassigned only when the unwanted carrier is removed.

• Transmitter Failure:
  The trunking central controller is programmed to detect any loss or reduction in the output of any of the transmitters. When the transmitter output power falls below a certain level (factory setting is half power), the channel is automatically made unavailable for assignment. Transmit/Receive synthesizer lock is also monitored.

• Misdirected Radio Protection:
  This feature ensures user privacy from other users in the system. All radios in the system receive a voice channel grant and channel assignment. It is up to the unit to decide if it should be involved in the call. In the event a unit decodes b grant incorrectly and moves to the assigned voice channel, its receiver would not unmute unless it decoded another data packet, which contained information particular to the assigned group.

• Continuous Updating:
  Once an Announcement Group or Talk Group channel grant is issued, the control channel will continue to transmit update assignments for as long as the Announcement/Talk Group is using the channel. A radio just coming into service will be sent over to the appropriate voice channel to join the rest of the Announcement/Talk Group. The assignment updates are sent out serially on the control channel by the central controller.

• System Diagnostics:
  The system controller has the ability to detect problems. Checks performed are: central controller integrity, repeater receiver interface checks, and repeater transmitter interface checks. The results of the checks can activate visual or audible alarms. Major and Minor Alarm relay contacts on the central controller can activate external alarm systems (optional).

• System Alarm Reporting:
  Relay closures may be used to operate any desired alarm indicating device. LED indicators are located on the front panel to indicate alarm conditions to the individual board level.

• Failsoft:
  If the system controller is rendered inoperative, system radios can revert to preassigned failsoft channels. This results in standard community repeater operation on that channel. Announcement and Talk Group privacy will be lost. To ensure that radios will not operate in failsoft when out of range, a sub-audible data handshake is activated on each channel when repeaters go into failsoft. Units only become operative and stay operative as long as they receive the sub-audible failsoft code word. The radio user is informed of failsoft by the automatic sounding of an audible alert tone every ten seconds. TDATA (fast failsoft) or Tickle (slow failsoft) from the central controller keeps a time-out circuit in each repeater from sending 150 Hz failsoft code word and 900 Hz failsoft alert tone. Out of range generally results in a steady out of service tone when keyed up.

System Calling Features
Group Calls

• TalkGroup Calls:
  The talkgroup is the primary level of communication in a trunked radio system, so the majority of conversations take place within a talkgroup. Therefore, radios assigned to a given talkgroup are provided with the TalkGroup Call feature and usually communicate only with other number of the same talkgroup. This provides the effect of a private channel down to the talkgroup level.

• Multigroup (Announcement Group) Call:
  A Multigroup is a group of talkgroups. It allows a radio user to transmit a message to two or more talkgroups simultaneously. A Multigroup group call can be set to wait while talkgroups that are pelt of the Multigroup finish any calls in progress, which allows all the radios in the Multigroup to hear the call. Alternatively an Multigroup call can be set to interrupt existing talkgroup communications for talkgroups that are part of the Multigroup, not waiting for other transmitting radio users to stop keying their radios. Those users join the call in progress when they stop pressing their Pusb-To-Talk buttons. Multigroup calls can use message trunking, allowing those who receive the call to talk back to the Multigroup or transmission trunking for calls without talkback. Even in interrupt mode a voice channel must be available for assignment before the call can be processed.

• System Wide Calls:
  With properly programmed equipment, a user can transmit a call to all radios in a system simultaneously. System calls can be placed only from authorized users. A. user who initiates a system call must wait for other users currently in conversations to finish transmitting and be available to join the call. Anyone else gets a busy signal if they try to make a call during this period. Users engaged in telephone interconnect or private calls are not aware of the system call until they complete their own calls; then they join the system call in progress.

System Calling Features
Selective Calls

• Call Alerts:
  An authorized caller (dispatcher or supervisor) can leave a paging message, called a Call Alert, in an unattended radio. Upon receiving a Call Alert, a radio automatically sends an acknowledge signal back to the originating user. The alert indicators are audible or visual, depending on the capabilities of the receiving radio. The alerts continue until the user presses the PTT button. The radio may display the calling party's ID (the ID can also be stored). All of this is accomplished over the control channel, so Call Alerts do not affect voice channel efficiency.
  
  Radios can be equipped with the following types of Call Alert capabilities:
  • Decode Only - The radio can only receive a Call Alert page.
  • Single Encode - The radio can send a Call Alert page to only one radio, which is predetermined.
  • Multiple Encode - The radio can send a Call Alert page to up to eight predetermined radios.
  • Unlimited Encode - The radio can send a Call Alert page to any radio in the system (capable radios).
  
  
• Private Conversations:
  With Motorola's Private Conversation II feature, two radio users can talk privately without other users on the system hearing their conversation. Once a private Conversation is established, the two radios do not hear any other normal radio traffic that occurs while the Private Conversation is in progress. Private Conversation II can cross group boundaries. With Private Conversation II, if the user of a receiving radio has a display radio, the ID of the calling party may be viewed. Initiating and Receiving users must be authorized to use this feature. Private Conversation is typically set up so that supervisors and dispatchers have the multiple encode capability and all other users have single encode or decode only.
  
  Private Conversation II capabilities are:
  • Decode Only - Receive but not initiate a Private Conversation.
  • Single Encode - Initiate a Private Conversion to one predetermined radio.
  • Multiple Encode - Initiate a Private Conversation to up to eight predetermined radios.
  • Unlimited Encode - Initiate a Private Conversation to any radio in the fleet that is authorized.
  
  
• Enhanced Private Calls:
  Like Private Conversation II, Enhanced Private Call (EPC) is a feature that lets a radio user communicate privately with another user. Unlike PC-II, EPC offers the advantage of notifying the initiating radio whether or not the target radio has received the EPC request To initiate an EPC, a radio user selects Private Call mode, enters the target radio's ID on the keypad, and presses the PTT switch. The target radio beeps twice to indicate that an EPC request has been received. The initiating radio receives a phone like ringing to indicate that the target radio is on the control channel and has acknowledged the EPC ring. The target radio can respond to the request by pressing the PTT switch and the call proceeds as a normal. The distinct advantage of an EPC is the positive feedback it gives a caller, indicating that the target radio received the call request. EPCs are not available in the 806/821 Mhz bands.
  
  PC-II Radios can be equipped with the following types of EPC capabilities:
  • Response Only Private Call - The radio may only receive an EPC.
  • List Only Private Call - The radio may initiate EPCs only to radios on a predetermined list.
  • Unlimited Private Call - Initiate EPCs to any radio in the system that is capable.

System Calling Features
Telephone Interconnect

The Telephone interconnect feature allows a radio user to make or receive telephone calls on a radio. Telephone interconnect calls eliminate the need for radio users to travel to find a phone. In addition, a person who is authorized can make a dispatch call to an entire talkgroup from any telephone.

Three types of telephone interconnect calls can be made:

• Radio to landline phone:
  To call a landline phone from a radio, a radio user accesses the programmed interconnect feature by pressing the phone button, waits for a dial tone, and enters the phone number to be called. If all interconnect channels are busy, the user receives a busy signal and is placed in a queue to receive an interconnect channel on a first-in-first-out basis.

• Land line phone to radio:
  To call a radio from a land line phone, a telephone user dials one of the access numbers for the radio system. When the system answers the ring, a prompt tone signals the caller to enter the four- or six-digit access number of the radio user being called. A telephone-like ring alerts the radio user to press the phone button and respond to the call.

• Land line phone to talkgroup:
  To call the radios in a talkgroup from a landline phone, a telephone user dials one of the access numbers for the radio system. As with a call to a single radio, when the system answers the ring, a prompt tone signals the caller to enter the access number for the talkgroup. The central controller then dispatches the call like any other talkgroup call by assigning an interconnect capable voice channel to the target talkgroup.

System Calling Features
Radio User Monitoring

Motorola trunked radio systems offer two types of radio user monitoring:

• Trunked TalkGroup Scan:
  With Trucked TalkGroup Scan, a radio user can monitor a list of predetermined talkgroups without a preference being assigned to any talkgroup. This allows the user to automatically scan trunked systems, talkgroups, conventional channels, or a combination of those things. The number of combinations that can be scanned depends on the capability of the specific type of radio. This means the radio continuously checks all channels on the scan list for messages.

  The scan list is pre-programmable and may be on the same system or a combination of systems and talkgroups. For example, a scan list may contain talkgroups 1 and 2 on system A and talkgroup 3 on system B. If a user wants to join the conversation of the talkgroup be or she hears, the radio may be manually switched over to that talkgroup or the radio may be programmed for a short "talk back" time. If the user transmits dining this "talk back" time, the talkgroup just heard will be joined.

  The advantage of Trunked TalkGroup Scan is tat it allows users to operate automatically in more than one talkgroup from a single radio. For example, supervisors can monitor communications of several work crews, one at a time, and enter any transmissions simply by picking up the microphone. This makes it easier for the operator to monitor channels in a multiple system environment.

• Priority Monitor:
  Priority Monitor allows a radio user to automatically switch to a priority talkgroup channel even if the radio was assigned to another voice channel. With Priority Monitor, a user can monitor a channel list of up to eight talkgroups with the possibility of two talkgroups being given priority status.

  When a priority talkgroup is heard while in the monitoring mode, the user can talkback to that group if she or he responds within a preset time. A conversation with a priority talkgroup will not be interrupted by other monitoring activity it a radio is involved in a secure (coded) voice call, it will not be interrupted by any monitoring activity, even from a priority talkgroup.

  Priority Monitor ensures that radio users receive information from important talkgroups immediately, even if they are listening to conversations of lower priority communications. This can help a radio user provide immediate attention to a specific call or problem.

System Calling Features
Conventional (Non Trunking) Capabilities

Motorola offers three features that allow radio users in a trunked system to use conventional radio communications:

• Dual Mode Operation:
  Dual Mode Operation allows a radio user to operate in both trunked and conventional systems from a single radio. A special switching arrangement lets the user select either a trunked system and talkgroup or a conventional channel with a specific squelch scheme. Conventional repeaters are often designed into a trunked system to extend coverage to fringe areas. In such systems, Dual Mode Operation allows a user to communicate throughout the entire system with a single radio.

• Talkaround:
  Repeater Talkaround allows a radio user who is out of range of the system to communicate with other radio users who are close by. For example, road crew members in a remote area that is out of the system's range can communicate with each other in a simplex mode based on the radio's RF range.

• Conventional TalkGroup Patch:
  Using appropriate equipment (for example a Carrier Operated Relay, COR, in CENTRACOM II for optimal audio throughput), a dispatcher can connect a conventional channel to a trunked talkgroup.

System Calling Features
Emergency Alarm/Call

Radio users can use Emergency Alarm/Call to inform dispatchers of life threatening situations. By pushing the emergency button on a radio, a user can initiate an emergency alarm. The Emergency Alarm appears immediately on the dispatcher's display with the sending radio's ID, helping the dispatcher identify the radio user in trouble even before a voice channel is assigned. The transmission of the alarm takes precedence over any other signaling activity in process.

Depending on how the system is configured, the Emergency Alarm message automatically repeats a predetermined number of times or repeats until a dispatcher acknowledges it. Emergency Alarm/Call capability eliminates the need to wait for a clear voice channel to declare an emergency situation. Even if a voice channel is not immediately open for the emergency caller to speak with the dispatcher, at least the dispatcher is aware of the alarm and the caller's ID.

When an Emergency Alarm/Call is initiated by pressing the PTT switch and no voice channel is free, there are three possible methods for giving the emergency caller quick access to a voice channel:

• Top of Queue
  The initiating unit is given a priority I and is first in the queue. All active calls are switched to transmission trunking. As soon as any user on any one of the channels dekeys, the emergency caller is granted that channel. This eliminates the possibility of RF channel contention and ensures that the first available, clear channel will be assigned to the emergency caller.

• Ruthless Preemption
  A repeater currently in use is assigned. to the emergency caller. The central controller selects one of the repeaters with a lowest priority user on the system and sends out a disconnect on his channel and change the call in progress to transmission trunking (no hang time). The Emergency caller is then directed to this channel. At this point, the emergency caller must contend for the channel with the original user until the non-emergency user dekeys. Once this happens, the channel belongs to the emergency user. The Top of Queue method is usually preferred, since access to a channel is usually very quick, and a caller gets a channel without the possibility of RF contention with other callers.

System Management Features

Motorola's trunked systems can provide the following radio management capabilities that allow dispatchers and system managers to monitor and direct operations using desktop computers or terminals:

• Selective Radio Inhibit:
  Allows a dispatcher to send a signal over the an that can deny a specified radio access to the trunked system. Once inhibited, the radio is inoperable until the dispatcher restores it to operation. Status feedback is displayed at the dispatcher's terminal. Selective Radio Inhibit is typically used when a radio is lost or stolen.

• Dynamic Regrouping:
  Dynamic Regrouping lets a dispatcher bring together individuals from different talkgroups to communicate in special situations. This feature lets a supervisor or dispatcher change the talkgroup assignments of individual radios. Regrouping assignments can be initiated rapidly but not instantaneously. For example, radios to be regrouped must be turned on, in range, and listening only to the control channel. Therefore, regrouping is not intended for emergency responses such as high speed chases.

• Storm Plans:
  Storm plans enable a dispatcher to create special radio groups in advance of situations such as severe weather, plane crashes, civil disturbances, etc. When activated, a pie constructed storm plan automatically regroups specified radios into other talkgroups.

• Logging:
  Provides the ability to view and print call processing activities and/or voice recording.

• Status/Message:
  Allows a radio user to send a preprogrammed status update, or message, to a dispatcher. Signaling is accomplished over the control channel.

• Push-To-Talk (PTT) ID:
  PTT ID allows a dispatcher to display the identity of the radio user currently speaking. Each radio is programmed with a unique ID that is sent automatically when a radio is keyed. PTT ID provides a means for logging system traffic by individual ID, for documenting responses in critical situations or emergencies, and for building channel usage statistics by individual ID. It also eliminates the need to use additional air time to verbally identify callers. PTT ID discourages inappropriate use of a radio since management has positive identification of who is on the air at any given time.

• Unit Affiliation:
  Unit Affiliation allows the central controller to identify the talkgroup association of a radio user. The first time a radio powers up (without even pressing the PTT and using Auto Affiliation) its ID and talkgroup affiliation are sent to the central controller to be stored in an affiliation table.

  The talkgroup affiliation is retained until the radio user:
  a) changes talk groups, or
  b) is dynamically regrouped.
  

  If a radio changes talkgroups, it automatically re-affiliates. If the radio has been turned off after initial affiliation, it will only re-affiliate if the talkgroup has been changed. The radio detects this change by storing its last talkgroup affiliation prior to power down. When a radio has been dynamically regrouped, the regroup acknowledgment automatically acts as an affiliation.