CC1000

SWRS048A Page 22 of 55

13. Receiver sensitivity versus data rate and frequency separation

The receiver sensitivity depends on the

data rate, the data format, FSK frequency

separation and the RF frequency. Typical

figures for the receiver sensitivity (BER =

-3

) are shown in Table 6 for 64 kHz

frequency separations and Table 7 for 20

kHz separations. Optimised sensitivity

configurations are used. For best

performance the frequency separation

should be as high as possible especially at

high data rates. Table 8 shows the

sensitivity for low current settings. See

page 28 for how to program different

current consumption.

433 MHz 868 MHz Data rate

[kBaud]

Separation

[kHz]

NRZ

mode

Manchester

mode

UART

mode

NRZ

mode

Manchester

mode

UART

mode

0.6 64 -113 -114 -113 -110 -111 -110

1.2 64 -111 -112 -111 -108 -109 -108

2.4 64 -109 -110 -109 -106 -107 -106

4.8 64 -107 -108 -107 -104 -105 -104

9.6 64 -105 -106 -105 -102 -103 -102

19.2 64 -103 -104 -103 -100 -101 -100

38.4 64 -102 -103 -102 -98 -99 -98

76.8 64 -100 -101 -100 -97 -98 -97

Average current

consumption

9.3 mA

11.8 mA

Table 6. Receiver sensitivity as a function of data rate at 433 and 868 MHz, BER = 10

-3

frequency separation 64 kHz, normal current settings

433 MHz 868 MHz Data rate

[kBaud]

Separation

[kHz]

NRZ

mode

Manchester

mode

UART

mode

NRZ

mode

Manchester

mode

UART

mode

0.6 20 -109 -111 -109 -106 -108 -106

1.2 20 -108 -110 -108 -104 -106 -104

2.4 20 -106 -108 -106 -103 -105 -103

4.8 20 -104 -106 -104 -101 -103 -101

9.6 20 -103 -104 -103 -100 -101 -100

19.2 20 -102 -103 -102 -99 -100 -99

38.4 20 -98 -100 -98 -98 -99 -98

76.8 20 -94 -98 -94 -94 -96 -94

Average current

consumption

9.3 mA

11.8 mA

Table 7. Receiver sensitivity as a function of data rate at 433 and 868 MHz, BER = 10

-3

frequency separation 20 kHz, normal current settings

433 MHz 868 MHz Data rate

[kBaud]

Separation

[kHz]

NRZ

mode

Manchester

mode

UART

mode

NRZ

mode

Manchester

mode

UART

mode

0.6 64 -111 -113 -111 -107 -109 -107

1.2 64 -110 -111 -110 -106 -107 -106

2.4 64 -108 -109 -108 -104 -105 -104

4.8 64 -106 -107 -106 -102 -103 -102

9.6 64 -104 -105 -104 -100 -101 -100

19.2 64 -102 -103 -102 -98 -99 -98

38.4 64 -101 -102 -101 -96 -97 -96

76.8 64 -99 -100 -99 -95 -96 -95

Average current

consumption

7.4 mA

9.6 mA

Table 8. Receiver sensitivity as a function of data rate at 433 and 868 MHz, BER = 10

-3

frequency separation 64 kHz , low current settings

CC1000

SWRS048A Page 23 of 55

14. Frequency programming

RX mode:

(low-side) f

(high-side)

(Receive frequency)

TX mode:

(Center frequency)

sep

(Lower FSK

frequency)

(Upper FSK

frequency)

vco

Figure 15. Relation between f

vco

, f

, and LO frequency

The frequency synthesiser (PLL) is

controlled by the frequency word in the

configuration registers. There are two

frequency words, A and B, which can be

programmed to two different frequencies.

One of the frequency words can be used

for RX (local oscillator frequency) and the

other for TX (transmitting frequency, f

This makes it possible to switch very fast

between RX mode and TX mode. They

can also be used for RX (or TX) on two

different channels. The MAIN.F_REG

control bit performs selection of frequency

word A or B.

The frequency word, FREQ, is 24 bits (3

bytes) located in

FREQ_2A:FREQ_1A:FREQ_0A and

FREQ_2B:FREQ_1B:FREQ_0B for the A

and B word, respectively.

The frequency word FREQ can be

calculated from:

16384

8192+⋅+

⋅=

TXDATAFSEPFREQ

refVCO

where TXDATA is 0 or 1 in transmit mode

depending on the data bit to be

transmitted on DIO. In receive mode

TXDATA is always 0.

The reference frequency f

ref

is the crystal

oscillator clock divided by PLL.REFDIV, a

number between 2 and 14 that should be

chosen such that:

1.0 MHz ≤ f

ref

≤ 2.46 MHz

Thus, the reference frequency f

ref

is:

EFDI

xosc

ref

VCO

is the Local Oscillator (LO) frequency

in receive mode, and the f

frequency in

transmit mode (lower FSK frequency). The

LO frequency must be f

– f

or f

+ f

giving low-side or high side LO injection

respectively. Note that the data on DIO will

be inverted if high-side LO is used.

The upper FSK transmit frequency is

given by:

= f

+ f

sep

where the frequency separation f

sep

is set

by the 11 bit separation word

(FSEP1:FSEP0):

16384

FSEP

refsep

⋅=

Clearing PLL.ALARM_DISABLE will

enable generation of the frequency alarm

bits PLL.ALARM_H and PLL.ALARM_L.

These bits indicate that the frequency

CC1000

SWRS048A Page 24 of 55

synthesis PLL is near the limit of generate

the frequency requested, and the PLL

should be recalibrated.

It is recommended that the

LOCK_CONTINOUS bit in the LOCK

frequencies and when changing between

RX and TX mode. If lock is not achieved, a

calibration should be performed.

15. Recommended RX settings for ISM frequencies

Shown in Table 9 are the recommended RX frequency synthesiser settings for a few

operating frequencies in the popular ISM bands. These settings ensure optimum

configuration of the synthesiser in receive mode for best sensitivity. For some settings of the

synthesiser (combinations of RF frequencies and reference frequency), the receiver

sensitivity is degraded. The FSK frequency separation is set to 64 kHz. The SmartRF®

Studio can be used to generate optimised configuration data as well. Also an application note

(AN011) and a spreadsheet are available from Chipcon generating configuration data for any

frequency giving optimum sensitivity.

ISM

Frequency

[MHz]

Actual

frequency

[MHz]

Crystal

frequency

[MHz]

Low-side /

high- side

LO*

Reference

divider

REFDIV

(decimal)

Frequency word

RX mode

FREQ

(decimal)

Frequency word

RX mode

FREQ

(hex)

315 315.037200 3.6864 High-side 3 4194304 400000

7.3728 6 4194304 400000

11.0592 9 4194304 400000

14.7456 12 4194304 400000

433.3 433.302000 3.6864 Low-side 3 5775168 580000

7.3728 6 5775168 580000

11.0592 9 5775168 580000

14.7456 12 5775168 580000

433.9 433.916400 3.6864 Low-side 3 5775360 582000

7.3728 6 5775360 582000

11.0592 9 5775360 582000

14.7456 12 5775360 582000

434.5 434.530800 3.6864 Low-side 3 5783552 584000

7.3728 6 5783552 584000

11.0592 9 5783552 584000

14.7456 12 5783552 584000

868.3 868.297200 3.6864 Low-side 2 7708672 75A000

7.3728 4 7708672 75A000

11.0592 6 7708672 75A000

14.7456 8 7708672 75A000

868.95 868.918800 3.6864 High-side 2 7716864 75C000

7.3728 4 7716864 75C000

11.0592 6 7716864 75C000

14.7456 7716864 75C000

869.525 869.526000 3.6864 Low-side 3 11583488 B0C000

7.3728 6 11583488 B0C000

11.0592 9 11583488 B0C000

14.7456 12 11583488 B0C000

869.85 869.840400 3.6864 High-side 2 7725056 75E000

7.3728 4 7725056 75E000

11.0592 6 7725056 75E000

14.7456 8 7725056 75E000

915 914.998800 3.6864 High-side 2 8126464 7C0000

7.3728 4 8126464 7C0000

11.0592 6 8126464 7C0000

14.7456 8 8126464 7C0000

*Note: When using high-side LO injection the data at DIO will be inverted.

Table 9. Recommended settings for ISM frequencies

Part #	CC1000-RTB1
Description	RF Transceiver FSK 3V 28-PinTSSOP Tube - Rail/Tube
Category	IC
Availability	In Stock
Qty	143

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CC1000-RTB1

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