System Considerations And Guidelines; Srd Regulations; Frequency Hopping And Multi-Channel Systems - Texas Instruments CC1101 Manual

RX_SYMBOL_TICK and RX_HARD_DATA, see
Table 41. RX_HARD_DATA
decision symbol.
contain data for 4-ary modulation formats
while RX_HARD_DATA[1] contain data for 2-
ary modulation

28 System Considerations and Guidelines

28.1 SRD Regulations

International regulations and national laws
regulate the use of radio receivers and
transmitters. Short Range Devices (SRDs) for
license free operation below 1 GHz are usually
operated in the 315 MHz, 433 MHz, 868 MHz
or 915 MHz frequency bands. The
specifically designed for such use with its 300
- 348 MHz, 387 - 464 MHz, and 779 - 928
MHz operating ranges. The most important
regulations when using the
MHz, 433 MHz, 868 MHz, or 915 MHz
frequency bands are EN 300 220
and FCC CFR47 Part 15 (USA).

28.2 Frequency Hopping and Multi-Channel Systems

The 315 MHz, 433 MHz, 868 MHz, or 915
MHz bands are shared by many systems both
in industrial, office, and home environments. It
is therefore recommended to use frequency
hopping spread spectrum (FHSS) or a multi-
channel protocol because the frequency
diversity makes the system more robust with
respect to interference from other systems
operating in the same frequency band. FHSS
also combats multipath fading.
CC1101
is highly suited for FHSS or multi-
channel systems due to its agile frequency
synthesizer and effective
interface. Using the packet handling support
and data buffering is also beneficial in such
systems as these features will significantly
offload the host controller.
Charge pump current, VCO current, and VCO
capacitance array calibration data is required
for each frequency
frequency hopping for
ways of obtaining the calibration data from the
chip:
1) Frequency hopping with calibration for each
hop. The PLL calibration time is 712/724 µs
(26 MHz crystal and TEST0 = 0x09/0B, see
Table 35). The blanking interval between each
frequency hop is then 787/799 µs.
[1:0] is the hard
RX_HARD_DATA
[1:0]
formats. The
CC1101
is
CC1101
in the 315
(Europe)
communication
when implementing
CC1101
. There are 3
SWRS061H
RX_SYMBOL_TICK signal is the symbol clock
and is high for one half symbol period
whenever a new symbol is presented on the
hard and soft data outputs. This option may be
used for both synchronous and asynchronous
interfaces.
For compliance with modulation bandwidth
requirements under EN 300 220 in the 863 to
870 MHz frequency range it is recommended
to use a 26 MHz crystal for frequencies below
869 MHz and a 27 MHz crystal for frequencies
above 869 MHz.
Please note that compliance with regulations
is dependent on the
performance. It is the customer‟s responsibility
to ensure that the system complies with
regulations.
2) Fast frequency hopping without calibration
for each hop can be done by performing the
necessary calibrating at startup and saving the
resulting FSCAL3, FSCAL2, and FSCAL1
register values in MCU memory. The VCO
capacitance calibration FSCAL1 register value
must be found for each RF frequency to be
used. The VCO current calibration value and
the charge pump current calibration value
available in FSCAL2 and FSCAL3 respectively
are not dependent on the RF frequency, so the
same value can therefore be used for all RF
frequencies for these two registers. Between
each frequency hop, the calibration process
can then be replaced by writing the FSCAL3,
FSCAL2 and FSCAL1 register values that
corresponds to the next RF frequency. The
PLL turn on time is approximately 75 µs (Table
34). The blanking interval between each
frequency hop is then approximately 75 µs.
3) Run calibration on a single frequency at
startup. Next write 0 to FSCAL3[5:4] to
disable the charge pump calibration. After
writing to FSCAL3[5:4], strobe SRX (or STX)
with MCSM0.FS_AUTOCAL=1 for each new
frequency hop. That is, VCO current and VCO
capacitance calibration is done, but not charge
pump current calibration. When charge pump
current calibration is disabled the calibration
CC1101
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