5-tone sequence

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A 5-tone sequence (also called selective call) is used to selectively address an individual radio subscriber (individual call) or an entire group ( group call ), especially in analog BOS radio . This scheme is also used in other radio systems.

Example coding: 88022; Tones: 2000 - 2600 - 2400 - 1160 - 2600 (in Hertz)

requirements

In order to be able to trigger the alarm, a radio device needs the following assemblies, depending on its desired function as a transmitter or receiver:

The alarm is triggered by the device itself or by a corresponding additional device.

Function and application

If a stored call, i.e. the 5-tone sequence stored in the device, is received, there are many possible reactions:

  • Collective call: only the loudspeaker opens
  • Group call: like collective call, an additional ringing tone sounds once
  • Individual call: like group call, the call tone is repeated several times, the call lamp lights up

In BOS radio, the BOS technical guideline prescribes precise reactions of the receiver; in addition to an acoustic signal, an optical signal is required. Optionally, haptic signaling can be carried out using a vibration alarm.

In more complex radio networks, the caller's number can also be transmitted in another 5-tone sequence. It is then shown in the display of the called party. However, this is not supported by all devices.

Modern devices can also use the 5-tone sequence to transmit texts stored in the device as status, similar to the BOS FMS , but the texts can be freely selected.

Further applications for 5-tone sequence:

  • simple remote control, e.g. B. Pump on / off, controlled by the elevated water tank
  • Relay opening , and therefore use only by authorized persons
  • Request to speak from the control center. Otherwise the loudspeaker and talk button will be locked
  • STUN / UNSTUN to deactivate stolen radios
  • Emergency call, e.g. B. Taxi radio sends its ID and 30 seconds of speech from the passenger compartment
  • Silent query: the control center can request the device to send

Coding

The coding of 5-tone sequences is based on national standards. Modern devices (which should be successful worldwide) can switch between ten different standards and another freely definable user standard. In Germany it is the ZVEI standard. In other countries CCIR, EEA, EIA or Natel is used. The different frequencies of the individual tones according to ZVEI1 are:

Digit 1 2 3 4th 5 6th 7th 8th 9 0 R.
Pitch / Hz 1060 1160 1270 1400 1530 1670 1830 2000 2200 2400 2600

A typical sequence consists of five digits, i.e. five different tones, all of which have a fixed duration of 70  ms . In order to increase the security of the alarm, the 2000 Hz tone is not sent twice when a digit is repeated (for example at 88 ). Instead, the original tone (2000 Hz) is replaced by the alternative tone ( R , 2600 Hz) for the second tone in order to ensure that successive tones can be distinguished. With ZVEI2, which is not used in Germany, the alternative tone is replaced by a 970 Hz tone.

BOS application

The 5-tone call is usually used in the analog BOS radio to alert emergency services. Another common expression for the 5-tone sequence is the term loop . 5-tone sequences can be assigned person-related, location-related, vehicle-specific or based on a desired release strength. When a wireless transmitter receives the sequence assigned to it, the alarm is triggered. Also sirens can be 5-tone sequences triggered, but there is still a after 5-tone signal transmitted dual (superposition of two tones, each with a different frequency, but the same volume level) needed. According to the applicable regulations, the tone sequence must be sent twice. In order to guarantee a higher alarm security, two tone sequences can also be sent twice. In the BOS radio, certain times for the tone duration and tolerances for the tone frequency and duration must also be adhered to, which are recorded in the TR-BOS .

and display information about the image
Timing of a 5-tone sequence

In an analog radio network, the alarm and the announcement are usually made on the same channel in the 4 m band . In the case of digital alarms, the radio alarm receiver is addressed and the data bits are transmitted in the 2 m band . The digital counterpart to the 5-tone sequence is the Radio Identification Code ( RIC for short ).

The disadvantage of analog alarms becomes apparent when looking at the alarm duration critically. A single alert lasts at least 2.5 seconds, followed by a subsequent announcement according to the guidelines at least five seconds pause and the duration of the actual voice announcement. Should it be necessary to alarm several loops, the total duration of the alarm increases significantly.

Another disadvantage is the security against eavesdropping. The BOS analog BOS radio network, in which this type of alerting is used, is rarely encrypted and therefore it is not a problem to eavesdrop on the radio network. In addition, willful false alarms can be generated with a radio device.

The double tones for siren control in Germany consist of the following frequency pairs:

Alarm type Duration volume Frequency pair
Fire alarm 3 × 15 s Continuous tone 675 Hz + 1240 Hz
Test alarm 1 × 15 s Continuous tone 675 Hz + 1860 Hz
Warning of the population (howling sound) 60s Howling 675 Hz + 825 Hz
ABC alarm 150 s 3 × 15 s howling, 30 s pause, 3 × 15 s howling 1240 Hz + 1860 Hz
All clear 60 s Continuous tone 825 Hz + 1860 Hz
Disaster alert 150 s 3 × 15 s continuous tone, 30 s pause, 60 s continuous tone 825 Hz + 1240 Hz

The double tones for siren control in Austria consist of the following frequency pairs:

Alarm type Duration volume Frequency pair
Fire alarm 3 × 15 s Continuous tone 675 Hz + 1240 Hz
Test alarm 1 × 15 s Continuous tone 675 Hz + 1860 Hz
Civil defense alert 1 min Howling 675 Hz + 825 Hz
Civil defense warning 3 min Continuous tone 675 Hz + 2280 Hz
Civil defense all clear 1 min Continuous tone 675 Hz + 1010 Hz

The double tones for the siren control in Germany and Austria are different, so if the transmission is overreach , it can not be triggered in neighboring municipalities / cantons.

Software to decode 5-tone sequences

program Operating system / runtime environment License
BosMon Windows free
FMS32 / FMS32pro Windows commercially
FMS Crusader Java Runtime Environment commercially
monitor Linux
monitor Windows / Linux Open Source under GPL (v3)
PersonalFME Windows / Linux Open source under GPL (v3 or newer)
Radio operator Windows / Linux Creative Commons Attribution-NoDerivs 3.0
5tone-web ( source code ) Web (HTML + JS) Open source under GNU Affero General Public License v3.0

See also

Web links