The encryption in TETRA is based on Swiss Ascom‘s IDEA (International Data Encryption Algorithm), and it’s patented (US patent #5214703, expiring -probably- in 2012). The same algorithm used in PGP.



Key TETRA services:

  • Group Call
  • Pre-Emptive Priority Call
  • Call Retention
  • Priority Call
  • Busy Queuing
  • Direct Mode Operation (DMO)
  • Dynamic Group Number Assignment (DGNA)
  • Ambience Listening
  • Call Authorised by Dispatcher
  • Area Selection
  • Late Entry
  • Voice Encryption

Is it just me, or is the “Ambience Listening” service an awesome hacker target?

The concept of cognitive radio sounds strange to some people. They think “right, so if there’s no frequencies available I wont be able to talk?”. However, in my opinion it’s not such a large step forward from the ISM band (think DECT, WiFi, Bluetooth, and more recently also RFIDs).

Here’s a list of major crisis situations during the last decade and the public safety communications problems faced by first responders:

  1. NYC plane attacks (11.09.2001)
    • FDNY still used old VHF radios, new UHF radios were not yet deployed
    • Repeaters on helicopters only for NYPD UHF, not for FDNY VHF
    • VHF repeaters in Twin Towers not operational
  2. Madrid train attacks (11.03.2004)
  3. South Asian tsunami (26.12.2004)
  4. London subway attacks (07.07.2005)
  5. Glasgow airport attacks (30.06.2007)
  6. Abruzzo earthquake (06.04.2009)

(I will update as I find out more)

  • linear broadband rf frontends & power efficient power amps
  • mimo & beamforming antennas
  • faster & portable fpga & dsp programming
  • erlang programming language
  • cognitive radio
  • multicast & host identity protocol

One indicator of the direction things are going in sdr is the companies involved in the SDR Forum Board of Directors. So after the latest election we have:

  • Vanu (John Chapin)
  • Rohde & Schwarz (Ruediger Leschhorn)
  • US DoD & Motorola (Peter Cook)
  • Harris (Mark Turner)
  • US DHS (John Powell)
  • General Dynamics (Bruce Fette)
  • Xilinx (Manuel Uhm)
  • FCC & SSC (Peter Tenhula)
  • JTRS & IEEE (Bernard Eydt)
  • Tyco (Richard Taylor)
  • Elektrobit (Pekka Heikkinen)
  • SCA Technica (David Murotake)
  • CRC (Claude Belisle)
  • Thales (David Renaudeau)
  • Motorola (Bruce Oberlies)
  • Osaka Uni, Japan (Hiroshi Harada)
  • Hanyang Uni, South Korea (Seungwon Choi)

To sum up, we see a lot of the well-known big players (Harris, Tyco, Thales, Motorola, CRC, etc), we have 3 European players (R&S, Thales & EB), several US Government agencies & contractors and two Asian universities (an effort to open up the market also there?).

The influence of SCA is really strong (JTRS, CRC, Harris&Thales, R&S, SCA Technica). Xilinx could push for the MHAL standard. What is also interesting is the inclusion of some public safety players; will we see the SCA in police radios?

GPS is a satelite navigation system developed by the US DoD, composed of between 24 and 32 satellites (also called SV, for Space Vehicle) orbiting at approx. 20200 km. The SVs continuously transmit (at 50 bits-per-second) a CDMA-modulated signal, encoded using a different pseudo-random number for each SV. The Navigation Message (1500 bits, taking 30 seconds to transmit) is composed of 3 parts: the time the message was sent, the ephemeris (the satellite’s orbit), and the almanac (rough orbit and status of the other SVs). At any given time, from a point on Earth not obstructed by buildings or mountains, approx. 10 sattelites are visible. 4 SVs are necessary for successful trilateration, given the fact that the receiver’s clock is inaccurate and has to be corrected too. Several methods for increasing the positioning accuracy exist, such as DGPS (using ground-based stations that transmit signal corrections) and A-GPS (using GSM cell towers for a quick rough initial position).

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