1. An evaluation of local interferences in the 0-3 GHz band
An evaluation of local interferences in the 0-3 GHz band. A case study in Meco (Spain)
Natalia Cañadilla Fernández, Pablo Luis López Espí and Rocío Sánchez Montero
University of Alcalá
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

2. Topics Introduction Broadband RFI Characterization
Measurement protocol
Broadband Measured Values
Narrowband Measured Values
Conclusions
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

3. Introduction VGOS Project BRAND Project
From S band 2,2 – 2.37 GHz (170 MHz) and X Band ( GHz) to ultra-wideband from 2 to 14 GHz.
VGOS receiver was installed at Yebes in RFI was a great problem to deal with due to fibber links saturation.
BRAND Project
One of the objectives is to design a broadband receiver from 1.5 GHz to 15.5 GHz
Many RFI problems are expected. Must be taken into account in the receiver design.
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

4. Broadband RFI Characterization
An idea about RFI levels may be broadband exposure limits
Electromagnetic radiowave exposure is a major concern in most countries due to possible adverse health effects.
Usually, local regulations follow the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) (ICNIRP, 1998).
The International Telecommunications Union (ITU) has published several recommendations about measurements, protocols and technical standards related to EMF emissions and protection. Recommendation ITU-T K.61, ITU-T K-83, ITU-T K.100 and ITU-T K.113.
The number of mobile telephony base transceiver stations (BTS) in Spain has doubled in the period
Other sources must be taken into account: WiFi, Wimax, TV…
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
GSM900
24,998
26,850
27,869
28,255
31,582
34,817
38,121
40,918
42,408
43,590
DCS1800
20,178
21,290
22,780
23,285
21,639
21,242
21,761
20,949
19,978
19,324
UMTS
16,921
22,874
27,382
31,304
34,324
42,474
46,281
45,273
47,260
51,786
LTE
5,649
14,654
23,801
Total
62,097
71,014
78,031
82,844
87,545
98,533
106,163
112,789
124,300
138,501
Number of mobile base stations in Spain. Source: National Commission for Markets and Competency.
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

5. Measurement Protocol
Broadband measurement is the optimal solution (from an exposure point of view) for a large number of measurements in a wide area involving various sources (from various locations) or a single source with various frequencies, because it is not as expensive as narrowband measurement and gives a value of the total electric field in that specific point. ICNIRP recommends 6 minute averaging.
FM ( MHz), DAB ( ), TETRA ( ), DVB-T/TV ( ), GSM900 (UL DL ), GSM1800 (UL DL ) DECT ( ) UMTS (UL DL ) LTE800 (DL UL ), LTE 1800 (DL UL ) LTE2600 (DL UL ) and WIFI 2G ( ).
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

6. Valor de la Intensidad de Campo Eléctrico (V/m)
Measured Values
Valor de la Intensidad de Campo Eléctrico (V/m)
Emáx (V/m)
Emín (V/m)
Mean
Std. Dev
Alcalá de Henares 2010 (Morning)
2,12
0,06
0,41
0,33
Alcalá de Henares 2010 (Evening)
1,97
0,03
0,40
0,35
Alcalá de Henares 2006
1,24
0,02
0,19
0,16
Campus UAH 2005 (Morning)
0,87
0,07
0,17
0,10
Campus UAH 2005 (Evening)
0,94
0,08
0,21
0,11
Campus UAH 2006
0,57
0,13
Campus UAH 2010
0,67
0,14
0,24
Torrejón de Ardoz
1,75
0,09
0,55
0,39
Basauri
2,44
0,77
0,47
Tudela
0,90
0,01

7. Measured Values (Alcala de Henares)
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

8. Measured Values
0.2
0.4
0.6
0.8
1.0
1.2
Electric Field (V/m) 1
Cumulative probability
□ 2006
+ 2010
○ 2015
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

9. Measured Values
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

10. Measured Values
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

11. Non Urban Environments (Meco)
Red: BTS, White: Broadband Measures, Blue: Narrowband Measures
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

12. Non Urban Environments (Meco)
(V/m) Total Non Urban
Max 1,9 1
Min 0,032 0,032
Mean 0,237 0,207
Std. Dev 0,242 0,170
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

13. Narrowband Measurements
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

14. Narrowband Measurements
Point 66 (Urban)
BTS Line of sight
Highest Broadband Value
Measured Power (dBm)
Over 50 Ohm
Blue: Horizontal Pol.
Red: Vertical Pol.
Max Hold over 2 min
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

15. Narrowband Measurements
Point 117 (Non Urban)
Top of the hill
Measured Power (dBm)
Over 50 Ohm
Blue: Horizontal Pol.
Red: Vertical Pol.
Max Hold over 2 min
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

16. Narrowband Measurements
Point 133 (Non Urban)
Lowest sea level
Lowest Broadband Level
Measured Power (dBm)
Over 50 Ohm
Blue: Horizontal Pol.
Red: Vertical Pol.
Max Hold over 2 min
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017

17. Conclusions
Electric Field Values show great time (short term and long term) and space variations.
Broadband measurement gives a value of the total electric field in that specific point.
Adv: Fast, less time consuming, easy to plot, easy to track.
Narrowband measurement gives full details about frequency variation.
Adv: Frequency and polarization information.
Local values show great variability, a customized study is necessary for each location.
Detection and measurement of RFI in radio astronomy, Yebes Observatory, 8-9 June, 2017