DV16401.03 Issue 04 May 2021 BD406/PBD406 107
3.10 Receive Operation – Message Detection
BD406 is a digital receiver of COSPAS/SARSAT compliant RF signal. It works in a range of
406.020...406.081 MHz.
The receiver continuously scans the rescue band to find beacon transmissions. When it finds a
beacon RF signal the full analysis starts to examine the signal amplitude, quality (phase and time
parameters), and frequency.
Advanced correction algorithms improve reception ability and supply a wider range in variable
environmental conditions. Even if the received signal is distorted due to a beacon malfunction, an
excessive distance, or harsh weather conditions, additional actions are started to validate and correct
such datagram.
Temperature Compensated VCO guarantees maintenance free, long term stability ≤ ± 5 ppm after
10 years at temperature range -40...+85 °C for BD406.
BD406 without control head
Usually, when rescue mission is started the
beacons database is empty. When device is
powered on this screen appears:
B --/--
1/6
PT: -----
CNTR: --- TAC: ----
BT: ----- SN: -----
Each restart (power-on/off) of the
remote-controlled BD406 results in automatic
reset of the beacon database. All received
distress messages are erased from memory.
The only way to monitor detected messages is
to observe transmission at target status output.
When the database is empty - an empty basic
frame is periodically broadcasted – it is a
“keep alive” signal for observers.
When rescue signal is received - BD406 analyses captured data stream (consisting 112 or 144 bits).
It automatically stores decoded data into the first free record of internal beacons database.
BD406 without control head
Voice notification is generated: ‘New Beacon’
and repeated every 6 seconds; a warning
message is shown:
WARNING 01/01
NEW BEACON
DETECTED
Press STO
to confirm
The target status protocol reflects that fact by
generating a frame with data corresponding to
received data.
For next received messages – next frames are
visible at target protocol.
The warning message and audio notifications
are active until user confirms it with a push to
STO key. If warning screen is confirmed beacon
detailed view is shown with decoded information
about the received message:
B 01/01
1/6
PT: STD-LOC
CNTR: 279 TAC: 0719
BT: EPIRB SN: 14000
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