Contrail® ALERT2™ TDMA Manager enables realistic ALERT2 network design in visual form.

  • ALERT Frequency

    An ALERT frequency is shared by many transmitters which transmit ALOHA messages and have potential for collisions and data loss.
    TDMA Views25
  • ALERT2 Frequency

    An ALERT2 frequency used for TDMA is defined by a frame length, block length, and slot lengths, that is divided into TDMA slots, which are then allocated to transmitters on the frequency.
    TDMA Views37

    ALOHA is a frequency use protocol in which transmitters transmit at any time when they have something to say and can potentially collide with other transmissions and lose data. The probability of success of ALOHA transmissions can be calculated, assuming...
    TDMA Views45
  • Block Length

    The block size is the minimum time interval possible for an ALERT2 transmission. In the ALERT2 specification, it is 250 milliseconds (ms), and is the smallest time that can be used for subdividing a frequency's frame into individual TDMA offsets and...
    TDMA Views38
  • Bytes

    Number of bytes to be transmitted during the slot.
    TDMA Views30
  • Calculated Load vs. Defined Capacity

    Ratio of incoming bytes over capacity of outgoing slot.
    TDMA Views28
  • Capacity

    Number of potential bytes that can be transmitted during the slot length.
    TDMA Views32
  • Cycles

    Transmission cycles for every receive cycle. Receive transmission frame length divided into the transmit frame length. This supports calculating capacity for each transmission. For each cycle, calculation of number of incoming slots and corresponding...
    TDMA Views24
  • Frame Capacity

    Number of ALERT2 bytes that can be transmitted over the time period of a single frame on a frequency. ALERT2 transmissions are limited to 5 seconds, so capacity is the number of 5 second periods available with a capacity of 977 bytes each, plus the amount...
    TDMA Views35
  • Frame Free Space

    Bytes capacity of free space over the frame capacity, as a percent free.
    TDMA Views42
  • Frame Length

    Frame Length is used to define the transmission repeat for transmitters on a frequency. For example, a transmitter on a 20 second frame would have an assigned TDMA slot with a predefined offset from the top of the frame and be able to transmit every 20...
    TDMA Views42
  • Frame Load

    Bytes assigned over frame capacity, as a percent load.
    TDMA Views26
  • Frame Offset

    Frames used to be able to be offset from 0:00:00 UTC, but now always have an offset of (zero).
    TDMA Views39
  • Free Space

    Available bytes for the slots transmission. Defined capacity of outgoing slot minus the calculated load. This number gives the remaining capacity of the transmitters slot in the transmitter or transceiver.
    TDMA Views26
  • Frequency

    A specific radio frequency (RF) is a resource used by ALERT and ALERT2 for both transmission and receive of signal. Frequency is usually defined in terms of MHz and is divided into 0.0250 MHz ranges.
    TDMA Views36
  • Incoming Slot Load

    Bytes carried by the sum of incoming slots.
    TDMA Views42
  • Incoming Slots

    Number of slots on input channel and corresponding total time.
    TDMA Views30
  • Message Type

    TDMA Views26
  • Network

    A network is a combination of frequencies, receivers, transmitters, transceivers used for ALERT and/or ALERT2. A network serves one or more agencies.
    TDMA Views29
  • Received

    List of sites that can be received by this receiver, on the same frequency.
    TDMA Views32
  • Receiver

    Base Station, receives on one or more radio frequencies.
    TDMA Views26
  • Routes

    List of potential routes from this transmitter to other potential receivers and transceivers ordered by closest to furthest and unblocked to blocked. This information will be used to support capacity planning and latency calculations. Blocked routes are...
    TDMA Views23
  • Slot Free Space

    Amount of time that is unassigned, divided by the frame length, represented in percent. (Not sure what Bytes are represented, since it was zero for a completely unassigned frequency).
    TDMA Views25
  • Slot Length

    It is the allocated division of time for a transmitter within a TDMA plan for a frequency. This is one or more whole units of block length. The TDMA plans we currently have use 500 milliseconds as the standard slot length, which with ALERT2 allows up to...
    TDMA Views50
  • Slot Load

    Amount of time used by assigned slots divided by frame length, represented in percent
    TDMA Views32
  • Slots Offset

    Time that slot begins as an offset from the beginning of the frame.
    TDMA Views22
  • Slots Used

    Number of assigned slots on a frequency, includes the milliseconds of assigned slots.
    TDMA Views20
  • TDMA

    Time Division Multiple Access (TDMA) is a frequency use protocol in which each transmitter is assigned specific times to transmit so that two transmitters on the same frequency do not transmit at the same time and eliminates data loss due to more than one...
    TDMA Views42
  • Transceiver

    Is comprised of both a receiver and a transmitter. A transceiver receives on one or more radio frequencies and transmits on a single radio frequency. They typically are repeaters that listen to data content on their receiver, and then retransmit that...
    TDMA Views26
  • Transmitter

    Transmits on a single radio frequency.
    TDMA Views36
  • Used Slot Capacity

    Sum of the number of Bytes that can be transmitted on all of the assigned slots.
    TDMA Views25
  • Used Slot Load

    Sum of the number of Bytes that are expected to be used by each assigned slot.
    TDMA Views38
Contrail® Help © 2004 - 2020