Tut mir leid, aber da habe ich wohl etwas nicht berücksichtigt, denn die Aurora 9 (ja auch die 5 Jahre alte Anlage) entspricht bereits der neuen Norm 1.81, den sie macht LBT!
Man betrachte das Protokoll :
Der Register Befehl 0xF4 liest das Register 0x34 , also RSSI. Der vorausgehende Befehl (nicht im Screenshot gezeigt) versetzt den RF Chip in den Empfangsmodus, ready to listen for RSSI measurements!
Nun besagt die Regel 4.3.1.6.1.2 der neuen Norm 1.8.1 folgendes :
"4.3.1.6.1.2 Requirements & Limits
Adaptive Frequency Hopping equipment using LBT based DAA shall comply with the following minimum set of
requirements:
1) At the start of every dwell time, before transmission on a hopping frequency, the equipment shall perform a Clear
Channel Assessment (CCA) check using energy detect. The CCA observation time shall be not less than 0,2 % of
the Channel Occupancy Time (see step 3) with a minimum of 20 μs. If the equipment finds the hopping frequency
to be clear, it may transmit immediately (see step 3).
2) If it is determined that a signal is present with a level above the detection threshold defined in step 5. the hopping
frequency shall be marked as 'unavailable'. Then the equipment may jump to the next frequency in the hopping
scheme even before the end of the dwell time, but in that case the 'unavailable' channel can not be considered as
being 'occupied' and shall be disregarded with respect to the requirement to maintain a minimum of 15 hopping
frequencies. Alternatively, the equipment can remain on the frequency during the remainder of the dwell time.
However, if the equipment remains on the frequency with the intention to transmit, it shall perform an extended
CCA check in which the (unavailable) channel is observed for a random duration between the value defined for
the CCA observation time in step 1 and 5 % of the Channel Occupancy Time defined in step 3. If the extended
CCA check has determined the frequency to be no longer occupied, the hopping frequency becomes available
again.
The CCA observation time used by the equipment shall be declared by the supplier.
3) The total time during which an equipment has transmissions on a given hopping frequency without re-evaluating
the availability of that frequency is defined as the Channel Occupancy Time.
The Channel Occupancy Time for a given hopping frequency, which starts immediately after a successful CCA,
shall be less than 60 ms followed by an Idle Period of minimum 5 % of the Channel Occupancy Time with a
minimum of 100 μs. After this, the procedure as in step 1 shall be repeated before having new transmissions on
this hopping frequency during the same dwell time.
EXAMPLE: A system with a dwell time of 400 ms can have 6 transmission sequences of 60 ms each, separated
with an Idle Period of 3 ms. Each transmission sequence was preceded with a successful CCA
check of 120 μs.
ETSI
19 Final draft ETSI EN 300 328 V1.8.1 (2012-04)
NOTE: For LBT based frequency hopping systems with a dwell time < 60 ms, the maximum Channel Occupancy
Time is limited by the dwell time.
4) 'Unavailable' channels may be removed from or may remain in the hopping sequence, but in any case:
• there shall be no transmissions on 'unavailable' channels;
• a minimum of 15 hopping frequencies shall always be maintained.
5) The detection threshold shall be proportional to the transmit power of the transmitter: for a 20 dBm e.i.r.p.
transmitter the detection threshold level (TL) shall be equal or lower than -70 dBm/MHz at the input to the
receiver (assuming a 0 dBi receive antenna). For power levels below 20 dBm e.i.r.p., the detection threshold level
may be relaxed to TL = -70 dBm/MHz + 20 - Pout e.i.r.p. (Pout in dBm)."
4.3.1.6.1.2. eröffnet also 2 Möglichkeiten, wenn ein Kanal nach dem LBT belegt sein sollte, dann muss nicht zwangsweise auf einen andereren Kanal gesprungen werden, sondern der Sender kann (Option 2) auf dem Kanal "sitzen bleiben" und warten bis er frei ist.
und genau das macht die Aurora 9
Damit dürfen Udo und ich sie unbegrenzt weiter nutzen und die Optima Empfänger gibt es dann auch weiter......
Mit meiner Futaba T14MZ mit der Telemetriebox und den neuen S-Bus FAST FASTest Telemetrie Empfängern R 6308 SBT werde ich dann nach 2015 aber wohl "ausgehungert"....
Frank