Texas Instruments | DN006 -- CC11xx Settings for FCC15.247 Solutions (Rev. B) | Application notes | Texas Instruments DN006 -- CC11xx Settings for FCC15.247 Solutions (Rev. B) Application notes

Texas Instruments DN006 -- CC11xx Settings for FCC15.247 Solutions (Rev. B) Application notes
Design Note DN006
CC11xx Settings for FCC 15.247 Solutions
By Kristian Skogvang and Sverre Hellan
Keywords
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1
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FCC 15.247 and 15.249
Wideband Requirements
CC11xx System Parameters
AN001 SRD Regulations
Digital Modulation
CC1100
CC1101
CC1110
CC1111
CC1150
CC430
Introduction
FCC CRF Section 15.249 restricts the
fundamental radiated power to 50 mV/m at
3 meters distance (approximately -1 dBm
EIRP) in the US 902-928 MHz ISM band.
FCC CRF Section 15.247 specifies
requirements that allow for up to 1 W
transmit output power. High output power
can be used if the system employs
Frequency Hopping Spread Spectrum
(FHSS) or uses a digital modulation
technique that gives a 6 dB bandwidth of
minimum 500 kHz [1][1].
This design note shows how CC11xx can
be configured for output powers above -1
dBm and meet FCC Section 15.247
requirements without the need for
frequency hopping.
The CC1101EM 868-915 MHz reference
design [2] is used as an example in this
design note, but the results are also
applicable for CC1100, CC1110, CC1111,
CC430, or CC1150.
SWRA123B
Page 1 of 7
Design Note DN006
Table of Contents
KEYWORDS.............................................................................................................................. 1
1
INTRODUCTION............................................................................................................. 1
2
ABBREVIATIONS........................................................................................................... 2
3
FCC 15.247 MEASUREMENTS ..................................................................................... 3
3.1
FCC 15.247A2 BANDWIDTH MEASUREMENT ............................................................... 3
3.2
FCC 15.247B POWER MEASUREMENT ....................................................................... 4
3.3
FCC 15.247D POWER SPECTRAL DENSITY MEASUREMENT ......................................... 4
4
MEASUREMENT SETUP ............................................................................................... 5
5
CC1101 TEST RESULTS FOR FCC 15.247.................................................................. 5
6
CONCLUSION ................................................................................................................ 6
7
REFERENCES................................................................................................................ 7
8
GENERAL INFORMATION ............................................................................................ 7
8.1
DOCUMENT HISTORY.................................................................................................. 7
2
Abbreviations
CRF
EM
FCC
FHSS
IF
ISM
PSD
RBW
VBW
Code of Federal Regulations
Evaluation Module
Federal Communications Commission
Frequency hopping Spread Spectrum
Intermediate Frequency
Industrial, Scientific, Medical
Power Spectral Density
Resolution Bandwidth
Video Bandwidth
SWRA123B
Page 2 of 7
Design Note DN006
3
FCC 15.247 Measurements
Table 1 gives the FCC 15.247 digital modulation requirements
Section
15.247a2
15.247b3
Requirement
The 6 dB bandwidth shall be at least 500 kHz
The maximum conducted power shall not exceed 1 W (+30
dBm)
The power spectral density (PSD) shall not be greater than 8
dBm in any 3 kHz band during any time interval during
continuous transmission
15.247e
Table 1. FCC 15.247 Digital Modulation Requirements
In this design note the PSD sets an upper limit on the maximum output power.
3.1
FCC 15.247a2 Bandwidth Measurement
Most spectrum analyzers have a measurement option that automatically measures a fixed dB
bandwidth. If this is not available the 6 dB bandwidth must be measured manually by setting
up markers. The spectrum analyzer should be configured as shown in Figure 1.
Spectrum Analyzer Plot
Spectrum Analyzer Setting
* RBW 100 kHz
* VBW 1 MHz
Ref
15 dBm
Att
40 dB
* SWT 5 ms
3
10
1 PK
MAXH
2
1
0
RBW=100 kHz
VBW=1 MHz
Max hold on
Delta 2 [T1 ]
-0.16 dB
572.115384615 kHz
Marker 1 [T1 ]
4.90
914.692307692
Delta 3 [T1 ]
5.98
110.576923076
dBm
MHz
A
dB
kHz
Measure the 6 dB Bandwidth
-10
In the plot CC1101 is
configured for 100 kbps data
rate and PATABLE = 0xC0.
-20
-30
-40
3DB
-50
-60
-70
-80
Center
915 MHz
Date: 28.JUL.2010
300 kHz/
Span
3 MHz
13:04:24
Figure 1. Test Setup for FCC 15.247a2
SWRA123B
Page 3 of 7
Design Note DN006
3.2
FCC 15.247b Power Measurement
The maximum allowed output power is 1 W, but when a wideband digital modulation
technique is used the Power Spectral Density (PSD) described in Section 3.3 will limit the
output power to less than 1 W.
Output power is measured by setting the RBW higher than the measured 6 dB bandwidth.
The spectrum analyzer should be configured as described in Figure 2.
Spectrum Analyzer Plot
Spectrum Analyzer Setting
* RBW 1 MHz
Marker 1 [T1 ]
7.34 dBm
914.682692308 MHz
* VBW 1 MHz
Ref
15 dBm
Att
* SWT 5 ms
40 dB
Set RBW= 1 MHz
Set VBW= 1 MHz
1
10
A
0
1 PK
MAXH
-10
Measure the output power
-20
In the plot CC1101 is configured for 38.4
kbps data rate and PATABLE = 0xCA.
-30
-40
3DB
-50
-60
-70
-80
Center
915 MHz
Date: 28.JUL.2010
150 kHz/
Span
1.5 MHz
15:04:42
Figure 2. Test Setup for FCC 15.247b
3.3
FCC 15.247d Power Spectral Density Measurement
The peak power spectral density at any 3 kHz bandwidth shall not exceed +8 dBm. This
should be measured over at least 3 times the modulation bandwidth. The spectrum analyser
should be configured as given in Figure 3.
Spectrum Analyzer Plot
Spectrum Analyzer Setting
* RBW 3 kHz
Ref
15 dBm
Att
40 dB
* VBW 100 kHz
* SWT 500 s
Marker 1 [T1 ]
6.98 dBm
915.153846154 MHz
*
1
10
A
SGL
1 PK
MAXH
0
-10
-20
Set RBW = 3 kHz
Set VBW = 100 kHz
Set Span = 1.5 MHz
Set Sweep = 500 seconds
Set Max hold on
Set single sweep
-30
-40
3DB
-50
Measure the power spectral density on
the highest peak in the span.
-60
In the plot CC1101 is configured for 38.4
kbps data rate and PATABLE = 0xCA.
-70
-80
Center
915 MHz
Date: 28.JUL.2010
150 kHz/
Span
1.5 MHz
15:03:30
Figure 3. Test Setup for FCC 15.247d
Note that the sweep time is slow in order to ensure that the max peak is captured. A faster
test approach with more or less same results could be to reduce the sweep time to 300 us
and use max hold instead. The official test however, requires a sweep time of 500 seconds.
SWRA123B
Page 4 of 7
Design Note DN006
4
Measurement Setup
•
•
•
•
•
5 devices were tested
All measurements were performed at 3V, 25oC
Measurements were performed on the CC1101EM 868-915 MHz reference design [2]
An automated test setup was used and LabView was used to control the measuring
equipment
The results presented in Section 5 are the average numbers of the 5 devices tested
5
CC1101 Test Results for FCC 15.247
The SmartRF® Studio Software tool from Texas Instruments includes a list of preferred
settings for a wide range of data rates. However to comply with the FCC 15.247 minimum 500
kHz 6 dB bandwidth requirement, the frequency deviation needs to be wider compared to the
preferred settings. When increasing the frequency deviation the RX filter bandwidth needs to
be increased. The IF frequency (register FSCTRL1) and registers FREND1, TEST2, TEST1,
AGCCTRL2, AGCCTRL1 as well as AGCCTRL0 must be set depending on the RX filter
bandwidth for optimum performance. For data rates at and below 250 kbps, the 250 kbps
preferred settings were used as a starting point and the data rate and frequency deviation
changed for the different test cases.
Data Rate
Modulation
Deviation
PATABLE
6 dB BW
(15.247 a2)
Power
(15.247 b)
PSD
(15.247 d)
500 kbps
250 kbps
100 kbps
76.8 kbps
38.4 kbps
10 kbps
4.8 kbps
2.4 kbps
MSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
Phase 0
165 kHz
177 kHz
177 kHz
177 kHz
177 kHz
177 kHz
177 kHz
C0
C0
C0
C2
C9
CA
CA
CB
650 kHz
647 kHz
577 kHz
547 kHz
523 kHz
516 kHz
505 kHz
513 kHz
11.4 dBm
11.4 dBm
11.4 dBm
10.5 dBm
8.1 dBm
7.8 dBm
7.8 dBm
7.5 dBm
0.00 dBm
3.10 dBm
6.68 dBm
7.27 dBm
7.70 dBm
7.74 dBm
7.74 dBm
7.47 dBm
Table 2. CC1101 TX Test Results for FCC 15.247
Data Rate
500 kbps
250 kbps
100 kbps
76.8 kbps
38.4 kbps
10 kbps
4.8 kbps
2.4 kbps
Modulation
MSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
Deviation
Phase 0
165 kHz
177 kHz
177 kHz
177 kHz
177 kHz
177 kHz
177 kHz
RX Filter
812 kHz
650 kHz
540 kHz
540 kHz
540 kHz
540 kHz
540 kHz
540 kHz
Sensitivity
-89 dBm
-95 dBm
-96 dBm
-98 dBm
-100 dBm
-104 dBm
-107 dBm
-108 dBm
Table 3. CC1101 RX Test Results for FCC 15.247
Data Rate
500 kbps
250 kbps
100 kbps
76.8 kbps
38.4 kbps
10 kbps
4.8 kbps
2.4 kbps
Modulation
MSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
2-FSK
Deviation
Phase 0
127 kHz
47 kHz
32 kHz
20 kHz
19 kHz
25.4 kHz
5.2 kHz
RX Filter
812 kHz
540 kHz
325 kHz
232 kHz
100 kHz
100 kHz
100 kHz
58 kHz
Sensitivity
-89 dBm
-96 dBm
-100 dBm
-101 dBm
-104 dBm
-105 dBm
-110 dBm
-109 dbm
Table 4. CC1101 RX Test Results Preferred Settings
SWRA123B
Page 5 of 7
Design Note DN006
6
Conclusion
This design note has shown that CC11xx is suited for systems targeting compliance with
digital modulation systems defined under FCC Section 15.247. Comparing Table 5 and Table
6 we see that there is a significant improvement in link budget, and hence range, when
operating under FCC Section 15.247 compared to FCC Section 15.249. As an example, at
500 kbps the difference in link budget is 12 dB, which corresponds to a theoretical
improvement in range of a factor 4. Note also from Table 2 that for data rates above 100 kbps
it is possible to increase the output power further by using an external power amplifier and
still meet PSD requirements. As an example, for 500 kbps it is possible to transmit at +18
dBm, using an external power amplifier, and still comply with FCC Section 15.247.
Data Rate
500 kbps
250 kbps
100 kbps
76.8 kbps
38.4 kbps
10 kbps
4.8 kbps
2.4 kbps
Sensitivity
-89 dBm
-95 dBm
-96 dBm
-98 dBm
-100 dBm
-104 dBm
-107 dBm
-108 dBm
Output power
11.4 dBm
11.4 dBm
11.4 dBm
10.5 dBm
8.1 dBm
7.8 dBm
7.8 dBm
7.5 dBm
Link Budget
100 dB
106 dB
107 dB
108.5 dB
108 dB
112 dB
115 dB
115.5 dB
Table 5. CC1101 FCC 15.247 Settings Link Budget
Data Rate
500 kbps
250 kbps
100 kbps
76.8 kbps
38.4 kbps
10 kbps
4.8 kbps
2.4 kbps
Sensitivity
-89 dBm
-96 dBm
-100 dBm
-101 dBm
-104 dBm
-105 dBm
-110 dBm
-109 dbm
Output power
-1 dBm
-1 dBm
-1 dBm
-1 dBm
-1 dBm
-1 dBm
-1 dBm
-1 dBm
Link Budget
88 dB
95 dB
99 dB
100 dB
103 dB
104 dB
109 dB
108 db
Table 6. CC1101 Preferred Settings Link Budget
SWRA123B
Page 6 of 7
Design Note DN006
7
[1]
[2]
8
8.1
References
SRD regulations for license free transceiver operation (swra090.pdf)
CC1101EM 868-915MHz Reference Design (swrr045.zip)
General Information
Document History
Revision
SWRA123B
Date
2010.08.17
SWRA123A
2007.12.17
SWRA123
2007.01.04
Description/Changes
Significant update to the design note.
- Measurements performed on CC1101
- Changes to frequency deviation to meet 6 dB BW requirement
- Updated PSD and output power measurement results
- Sensitivity figures significantly improved. Non-optimum register
settings used in previous revision
- Added CC430 to keywords
Added CC1100, CC1101, CC1110, CC1111, CC1150 to keywords
Removed logo from header
Initial release.
SWRA123B
Page 7 of 7
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