SE24 Meeting M65
BNetzA, Mainz, 25-26 December 2012
M65_24R1_SE24
Date issued: 21st June 2012
Source:
Josef Schuermann
Status:
For discussion
Subject:
13.56 MHz RFID, TR 102 059 Transmitter Mask
Summary:
 M65_07 / TR 103 059 identified the need for higher data rates and longer reading ranges for RFID’s
operating at 13.56 MHz; presenting the industry largest RFID production volumes.
 The proposed TX mask defines higher near-carrier modulation sidebands, secondly the modulation width
is up to +/-7 MHz
 WGSE, WGFM noted that the proposed modification was to be checked by SE24 with regard to
compatibility.
 The present document:
1. Includes a first compatibility assessment to the ERC/REC 70-03 Annex9; ( i.e. f1: 13,56 MHz; l2: 5-30 MHz)
2. Initial interference tests, description and results for an 13.56 MHz RFID Reader interfering into a
TECSUN PL 600 Receiver tuned to SW band 13.57 MHz to 13.87 MHz SW Stations.
3. A proposal to determine possible BC radio interference, protection distance and to report results to
the next WGSE #62 in Sept. Wroclaw
Proposal:
The paper concludes:
(a) The attached initial Field Test yielded only critical reception degradation of BC stations below ~ 20 30 m. A commonly used type of short wave World Radio Receiver was used.
(b) Beyond a receiver distance of 50 m to a RFID reader, no noticeable degradation was recorded.
The –5 dB/µA/m limit of range l2 of Annex 9 is considered applicable because RFID readers
produce wideband emissions for the powering & downlink signals and the modulation components
are narrow.
(c) Considering (a), it can be concluded that the results of the initial test are also suggest that the
interference potential to other services in the bands up to +/- 7 MHz is also very low.
Background:
WGSE #61 Minutes noted:
- ETSI activities on RFIDs (SE(12)Info004 & SE(12)036 (actual)).
WG SE considered document SE(12)36 from ETSI ERM dealing with TR 103 059 on Short-Range
Devices (SRD) for operation in the 13.56 MHz band; for Radio Frequency Identification (RFID)
equipment. Concerns were expressed with regard to this document since it proposed a relaxation of the
existing mask. SE24 was tasked to investigate further the compatibility of the proposed mask with
regard to the existing regulations and compatibility reports. SE24 was invited to report the results of its
investigation to the next WG SE meeting.
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Attachments:
1) Comments/ Assessment of the new TX mask;
2) Interference Test Set up and initial field test results
3) Program proposal
1) Comments to the new TX mask of TR 103 059 & ERC/Rec70-03 Annex 9 limits
The Annex 9 specifies in :
“
l2 5-30 MHz, -20 dBμA/m at 10 m;
In case of external antennas only loop coil antennas, the maximum field strength is
specified in a bandwidth of 10 kHz.
The maximum allowed total field strength is -5 dBμA/m at 10 m for systems operating at
bandwidths larger than 10 kHz whilst keeping the density limit (-20 dBμA/m in a bandwidth
of 10 kHz)
“
ISM band
+60 dBµA/m
+27 dBµA/m
-3,5 dBµA/m
-5 dBµA/m
f0
13,56 MHz
-7 MHz
-450 kHz
-100 kHz +100 kHz
-200 kHz
+200 kHz
-16 dBµA/m
+450 kHz
+ 7MHz
There are 2 different RFID systems are operating under this TX mask
a) Large range, “Narrowband” type RFID systems, operating at 60 dBµA/m with lower modulation BW for e.g.
access & production control, manufacturing applications etc…
b) Very short range, wideband and low power systems at ~42 dBµA/m or much lower with BW up to +/- 7 MHz
for transaction / security systems as electronic passport, payment & Bank cards according to ISO 14443
(Smart Cards) and widely used in NFC systems or applications.
Type a) Applications are potentially interfering with the nearby 22 meter band SW radio (13.570 – 13.870 MHz)
The mask extension is as defined in the TR 103 059 for the modulation sidebands closer to the carrier.
The modulation level is increased to 27 dBµA/m but drops rapidly down to –3.5 dBµA/m & +/- 200 kHz.
Type b) Applications are potentially interfering with several services but due to the low operating fieldstrength the
potential interference is low and covered by I2 of Annex 9.
All RFID systems especially this smart card type security (transactions) application must operate at large
BW >>10 kHz while the modulation components are narrow so that the density limit of – 20 dBμA/m in 10
kHz is considered to be met.
The compatibility to other services can be discussed and verified by additional field tests and comparing the results
with existing studies in order to verify protection distances under worse case conditions.
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2) Interference test set-up, test proposal and initial field test results
a) General comments and description
The most critical service is the short wave radio Broadcast in the 22 m Band.
Receiver interference free field tests were made in a rural environment at different off-set frequencies with RFID as
interferer and a TECSU PL 600 as victim receiver. The test determined interference free distances for several BC
transmitter frequencies.
The frequency range for the 22 m Band is 13.570 to 13.870 MHz and is therefore very close to the interference carrier
in the ISM band, (see the graph in c) test set-up)
The world radio receiver PL 600 is very sensitive and has a high performance. These type receivers are sold by a
number of suppliers e.g. Sony, TECSUN, and many others.
b) Criteria / validation of interference
For detecting the worst case interference threshold the desired signal (BC transmitters) need to be just above the
actual noise level.
The criteria for interference detection can be simply the just noticeable perceived audible interference.
It is difficult to judge interference on a real received Broadcast Stations because of the varying audio content and
varying signal which also suffers fading and propagation effects including distortion of modulation.
To overcome these effects a desired signal was created from a signal generator with a steady modulation tone of 1
kHz which allowed a better interference identification
Consequently: more easy discrimination of interference / non-interference with a “clean” 1 kHz modulation signal as
compared to an interfered BC station reception.
- Results are more reproducible
- Propagation independent victim signal reception.
- Modulation independent perception of the desired signal
c) Test set-up and Description and Interference
Signal
3
d) Sequence of set-up and actual measurements:
1.
2.
3.
4.
5.
6.
7.
Install Signal Generator plus TX antenna and Receiver at convenient distances e.g. 10 m.
Receiver and Signal Generator is tuned to the nearest first frequency test e.g. 15.573 MHz,
Adjust frequency amplitude of Signal Generator for Receiver for approx. 3 dB above receiver noise level
Set audio signal modulation at 1 kHz ca 80%
Maintain constant distance for Receiver and Signal generator Antenna during the whole test
Install and activate RFID system + loop antenna (avoid metal environment) and set first test point at D=10 m.
Orientate TX loop antenna of RFID system for maximum interference effect.
First measurement:
8. Increase distance between RFID system and Receiver until interference is to be either:
a) well noticeable
(strong)
b) just audible interference
(Low) reception is feasible
c) no interference noticeable
9. Note the distance for a), b) and c) between the RFID loop antenna and the SW Receiver.
10. Repeat measurements by switching interferer off and on several times.
Second and following measurement items:
11. Set TX and Signal Generator at other frequencies
12. Control or repeat step #3 and #4 if needed
13. Repeat steps #8, #9 and #10
e) Interference Signal
Spectrum of RFID reader 13.56 MHz (operating at +42 dBµA/m power level)
4
Ref
41.8
40
Offset
dBm
Att
39
35
dB
* RBW
10
kHz
VBW
30
kHz
* SWT
60
s
dB
A
30
SGL
20
LVL
2 PK *
VIEW
10
0
-10
HF-MOD1
3DB
-20
-30
-40
-50
Center
13.56
Date: 1.JAN.2003
f)
MHz
200
kHz/
Span
2
MHz
01:04:05
Test Location
5
SW Broadcast Receiver
Interferer Set-up with loop antenna
(commonly in use by SW BC listeners)
g) Test Results
6
Frequency
Distance
10 m
15 m
20 m
25 m
30 m
35 m
40 m
50 m
60 m
13.573
(MHz)
13.600
(MHz)
13.709
(MHz)
S+
S+
S+
S
SL
LO
O
S
S
L
LO
O
O
O
O
S
SL
O
O
O
O
O
O
Legend:
S+ to SL to SO
Strong interference; S+ no reception feasible, S- reception just feasible
Low interference; BC reception is feasible
No noticeable interference
3) Proposal
- Description of an interference test in Kolberg and spectrum definition
- Conduct the test and prepare the report for the next SE24 meeting

June
 July / August
- Submit result to SE24, discussion, review previous reports and
determine recommendation to next WGSE

e/o August
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