ETSI TR 103 137 V1.1.1 (2014-01)

ETSI TR 103 137 V1.1.1 (2014-01)






Technical Report
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
System Reference document (SRdoc);
Surveillance Radar equipment for helicopter application
operating in the 76 GHz to 79 GHz frequency range

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2 ETSI TR 103 137 V1.1.1 (2014-01)



Reference
DTR/ERM-TGSRR-64
Keywords
aeronautical, radar, regulation, SRDoc
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3 ETSI TR 103 137 V1.1.1 (2014-01)
Contents
Intellectual Property Rights . 4
Foreword . 4
Executive summary . 4
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Abbreviations . 8
4 Comments on the System Reference Document . 8
5 Presentation of the system or technology . 8
6 Market information. 12
6.1 Accidents . 12
6.2 Market Potential . 13
7 Technical information . 14
7.1 Detailed technical description . 14
7.2 Technical parameters and implications on spectrum . 15
7.2.1 Status of technical parameters . 15
7.2.1.1 Current ITU and European Common Allocations . 15
7.2.1.2 Sharing and compatibility studies (if any) already available . 16
7.2.1.3 Sharing and compatibility issues still to be considered . 17
7.2.2 Transmitter parameters . 17
7.2.2.1 Transmitter Output Power / Radiated Power. 17
7.2.2.1a Antenna Characteristics . 18
7.2.2.2 Operating Frequency . 20
7.2.2.3 Bandwidth . 20
7.2.2.4 Unwanted emissions. 20
7.2.3 Receiver parameters . 20
7.2.4 Channel access parameters . 20
7.3 Information on relevant standard(s) . 21
8 Radio spectrum request and justification . 21
9 Regulations . 22
9.1 Current regulations . 22
9.2 Proposed regulation and justification . 23
9.3 Proposed ETSI actions . 23
History . 26

ETSI

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Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Electromagnetic compatibility and Radio
spectrum Matters (ERM).
Executive summary
The helicopter's unique hover and vertical take-off/landing capabilities make it ideally suited for transport in difficult
access areas, take-off and land in confined areas (Figure 1) and perform hoisting operations (Figure 2). In these
frequently encountered and demanding mission elements the pilot faces an increase in workload when scanning for
obstacles and monitoring helicopter state. Especially in degraded visual conditions and unknown or confined areas,
there is an imminent danger of collision with all kinds of obstacles, which continues to be among the top causes of civil
helicopter accidents.


© Eurocopter/Photo Patrick PENNA © Eurocopter/Wolfgang OBRUSNIK
Figure 1: Operations in confined areas Figure 2: Hoisting operations close to
obstacles

The present document describes the heliborne application of 76 GHz to 79 GHz radar technology, in a near environment
obstacle warning system. The application here used the benefit that automotive radar made the technology available but
the technical parameters and sensor architecture for helicopter are different. The intended function of this system is to
detect and inform the flight crew of obstacles in the direct vicinity of the helicopter environment. The surround
coverage of the radar system will aid the crew in the obstacle detection task while manoeuvring at low airspeeds
typically close to the ground. The system will help and improve the probability of detection of obstacles thereby
increasing situational awareness and flight safety. It will reduce pilot's workload and can save time in critical flight
phases, which is important especially for safety of life services.
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minimum altitude


obstacle


warning

area


Hospital

Helipad Accident

Figure 3: Typical operational profile for helicopter emergency medical service
Figure 3 shows a typical HEMS (helicopter emergency medical service) mission. The helicopter takes off from the
helipad/airfield using the obstacle warning system until it rises out of the obstacle scene. After arriving at the accident
site, the helicopter descends to the landing zone and picks up the person injured. During landing, hover and take-off, the
obstacle warning system inform the flight crew of obstacles in the direct vicinity of the helicopter environment. The
helicopter flies in cruise altitude to the hospital. During landing and take-off at the hospital, the flight crew again is
informed of obstacle by the obstacle warning system. The system will be switched off during cruise flight back to the
helicopters air base but will be active during the landing phase at the air base.
Minimum flying altitudes and off-field landing are regulated for each state.
Examples of regulation:
• Germany:
- Landing outside of airfield (off-field landing) is only allowed after permission from authority.
Exceptions are e.g. emergency landing and helicopter emergency medical service.
- Minimum altitude is 300 m (1 000 feet) above residential area, production plants, gatherings and accident
sites above the highest obstacle in an area of 600 m. For all other areas it is 150 m (500 feet) above
ground and water.
For cross-country flights, a minimum altitude of 600 m (2 000 feet) is applicable.
• France:
- Landing outside of airfield (off-field landing) is only allowed after permission from authority.
Exceptions are e.g. emergency landing and helicopter emergency medical service.
- Minimum altitude is 300 m (1 000 feet) above residential area, production plants, gatherings and accident
sites. For all other areas it is 150 m (500 feet) above ground and water.
The Size, Weight and Power (SWaP) characteristics of 76 GHz to 79 GHz sensors make them ideally suited for use on
smaller H/C types typically being used by civil operators. Due to the short wavelength and high bandwidth the precise
measurement (in range and doppler) enables an accurate and reliable detection of those obstacles posing a threat to safe
helicopter operations. The fact, that the automotive radar technology is proven and readily available makes it the only
affordable sensor technology for a short-term market entry for this novel kind of application.
The aim is to enable the usage of already existing technology available e.g. in the automotive area for helicopter
applications.
In the introduction of ERC Recommendation 70-03 [i.10], the following is stated:
"The CEPT has considered the use of SRD devices on board aircraft and it has concluded that, from the CEPT
regulatory perspective, such use is allowed under the same conditions provided in the relevant Annex of
Recommendation 70-03. For aviation safety aspects, the CEPT is not the right body to address this matter which
remains the responsibility of aircraft manufacturers or aircraft owners who should consult with the relevant national or
regional aviation bodies before the installation and use of such devices on board aircraft."
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6 ETSI TR 103 137 V1.1.1 (2014-01)
Introduction
The present document has been developed to support the co-operation between ETSI and the Electronic
Communications Committee (ECC) of the European Conference of Post and Telecommunications Administrations
(CEPT).
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1 Scope
The present document describes the radar based surveillance applications in the 76 GHz to 79 GHz frequency range for
a helicopter obstacle warning system. The 76 GHz RTTT Standard EN 301 091 [i.5] and the 77 GHz to 81 GHz RTTT
Standard EN 302 264 [i.8], could be used as a baseline to defines the technical characteristics and test methods for this
new radar equipment operating in the 76 GHz to 79 GHz range.
It includes in particular:
• Market information.
• Technical information (including expected sharing and compatibility issues).
• Regulatory issues.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] EASA: "Annual Safety Review 2010", 2011.
[i.2] ITU Radio Regulations (Edition of 2012).
[i.3] ERC Report 25: "The European table of frequency allocations and utilisations in the frequency
range 9 kHz to 3000 GHz".
[i.4] CEPT/ERC/Recommendation 74-01: "Unwanted Emissions in the Spurious Domain".
[i.5] ETSI EN 301 091 (Parts 1 and 2): "Electromagnetic compatibility and Radio spectrum Matters
(ERM); Short Range Devices; Road Transport and Traffic Telematics (RTTT); Radar equipment
operating in the 76 GHz to 77 GHz range".
[i.6] Commission Implementing Decision 2011/829/EU of 8 December 2011 amending Decision
2006/771/EC on harmonization of the radio spectrum for use by short-range devices.
[i.7] Commission Decision 2004/545/EC of 8 July 2004 on the harmonization of radio spectrum in the
79 GHz range for the use of automotive short-range radar equipment in the Community.
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[i.8] ETSI EN 302 264 (Parts 1 and 2): "Electromagnetic compatibility and Radio spectrum Matters
(ERM); Short Range Devices; Road Transport and Traffic Telematics (RTTT); Short Range Radar
equipment operating in the 77 GHz to 81 GHz band".
[i.9] ECC/DEC/(04)03 of 19 March 2004 on the frequency band 77 - 81 GHz to be designated for the
use of Automotive Short Range Radars.
[i.10] CEPT/ERC REC 70-03: "Relating to the Use of Short Range Devices (SRD)".
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
e.i.r.p. equivalent isotropically radiated power
EASA European Aviation Safety Agency
EESS Earth Exploration Satellite Service
EUT Equipment Under Test
FMCW Frequency Modulated Continuous Wave
FPGA Field Programmable Gated Array
H/C Helicopter
HEMS Helicopter Emergency Medical Services
ISM Industrial, Scientific and Medical
LPR Level Probing Radar
MIMO Multiple Input Multiple Output
MMIC Monolithic Microwave Integrated Circuit
PDCF Power Density Correction Factor
RBW Resolution Bandwidth
RCS Radar Cross Section
RF Radio Frequency
RTTT Road Transport and Traffic Telematics
SRD Short Range Devices
SRR Short Range Radar
TLPR Tank Level Probing Radar
UWB Ultra-Wideband
VLBI Very Long Baseline Interferometry
4 Comments on the System Reference Document
No comments raised by ETSI members.
5 Presentation of the system or technology
The proposed system concept consists of multiple radar sensors distributed around the helicopter fuselage to detect
obstacles entering a certain protective volume around the helicopter. The surround coverage of this Heliborne Obstacle
Warning system will aid the crew in the obstacle detection task while manoeuvring at low airspeeds typically close to
the ground. The system reduces the risk of collision with objects by an early detection of obstacles and will therefore
improve safety for aircrew, passengers and persons on the ground. The system is developed to perform adequately even
in degraded visual conditions in which the pilot's ability to visually detect obstacles might otherwise be severely
compromised.
Depending on the required coverage, the field-of-view of the individual sensors, the installation location and the
number of sensors to be integrated might vary.
The obstacle warning function can be decomposed in the following subfunctions:
• The Detection Subfunction for the perception of the environment as used by automotive radar technology
operating in the range 76 GHz to 79 GHz.
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• After subsequent processing the obstacle information can be presented to the flight crew.
In an example implementation the sensors are integrated below the main rotor head in a distributed manner such as to
cover a larger horizontal field-of-view (Figures 4 and 5). In this orientation the Heliborne Obstacle Warning System is
aimed at providing obstacle warning for obstacles that enter the main rotor plane. Typical use cases therefore involve
hovering flight as well as manoeuvring at low airspeeds.


© Eurocopter

© Eurocopter
Figure 4: E.g. sensor coverage
Figure 5: Landing in confined area
(360° configuration)

For a small helicopter type as depicted above, typically 4 sensors need to be integrated to cover the full 360° horizontal
field-of-view.
As described earlier, the operational benefit of this system is in the initial or final phases of flight in which the
helicopter manoeuvres in ground vicinity at low airspeeds. It is in those flight phases in which there is an increased risk
of collision with all kinds of obstacles. The system will be used in environment with obstacles in the vicinity of the
helicopter, only. It will be switched off if the helicopter leaves this environment. This will be defined in the flight
manual. The effective detection range of the sensor system is prescribed by the velocity at which the helicopter
approaches the environment as well as the minimum warning time needed for the pilot to assess the situation and
initiate evasive manoeuvres. When considering only hovering and low-airspeed manoeuvring phases of flight (e.g.
landing, hoisting operations, taxiing), the required detection range is limited to 250 m which is similar to detection
range of automotive radars for which the 77 GHz technology has been developed. The required transmit power as
described in the 76 GHz to 77 GHz regulation (refer to Recommendation 70-03 Annex 5, Frequency Band c [i.10]) is
sufficient.
However, in the 77 GHz to 81 GHz regulation (refer to Recommendation 70-03 [i.10], Annex 5, Frequency Band e) the
obstacle warning sensor will exceed the transmit power as it is not sufficient to detect all relevant obstacles within the
required 250 m detection range.
The performance of the system is defined by the probability of detection within the detection range of those obstacles
that typically pose a threat to helicopter operations in hover or at low airspeeds. Frequently encountered obstacles of
particular danger are for instance suspended wires (e.g. overhead power lines, guy wires), poles, fences, trees, buildings,
etc.
The Heliborne Obstacle Warning System is designed to inform the flight crew about the presence and location of
obstacles. In a first implementation the system is an aid to the pilot with the pilot being responsible to visually verify the
obstacle indications given by the system. The output of the system has to be interpreted as an indication and will
improve the probability of detection of obstacles by the pilot.
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The certification of the obstacle warning system will require a certification which is under the responsibility of
respective certification authorities (e.g. EASA) and is not discussed in the present document.
Table 1: Technical parameters of the obstacle warning system
Technical Parameter of the obstacle warning system

(example)
Frequency Range 76 GHz to 79 GHz
Range of Sensor 250 m
Peak Power (e.i.r.p.) 40 dBm/50 MHz
Mean power spectral density (e.i.r.p.) 32 dBm/MHz
Bandwidth for 76 GHz to 77 GHz 800 MHz
100 MHz with typical center frequencies of 76,05 GHz,
Bandwith for 76 GHz to 79 GHz
77,5 GHz and 78,95 GHz
50 ms, within this time the transmitter is active for 6 to
Operational cycle of transmitter
14 ms

Table 2: Technical parameters of the scenario
Technical Parameter of the scenario
Field of View coverage Full coverage

2
Typical minimum RCS of the objects detected
-10 dB/m
One helicopter, for specific scenarios like large scale
Typical number of helicopter operating in the scene operations of Emergency Medical Services or Police
Services, several helicopter can be in the scene

The following table gives an overview of the different mission types that will have a direct benefit of the proposed
system in various mission elements. It is obvious, that the proposed Heliborne Obstacle Warning System can offer
valuable support to the flight crew in a wide range of missions in a wide range of operating environments. Not only
does the flight crew benefit from the increase in flight safety, also passengers, victims to be rescued and people on the
ground have a direct benefit of safer helicopter operations.
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11 ETSI TR 103 137 V1.1.1 (2014-01)
Table 3: Mission types
MISSION MISSION ELEMENTS
HEMS - Helicopter Emergency Medical Services
• Off-field landings in confined areas or complex
obstacle environments. Typically primary rescue
mission, transport of medical personnel,
equipment and victims directly from the scene
(e.g. accident, disaster relief)
• Hoisting operations close to obstacles (e.g.
mountain rescue close to rock formations)
• Landing at terrain slopes
• Operations in degraded visual conditions

© Eurocopter/Photo Patrick PENNA
Figure 6
Offshore Operations
• Landing at ship deck or oil rigs
• Wind park maintenance. Hoisting operations of
maintenance personnel
• Search and Rescue operations (hover and
hoisting operations close to ship structure)

© Eurocopter/Photo Jérome DEULIN
Figure 7
Utility & Transport
• Forestry and logging (sling load operations)
• Firefighting (sling load operations with water
buckets)
• Power line inspection
• Gas pipe inspection

NOTE: The picture shows a low level operation.

© Eurocopter/Photo Christophe GUIBBAUD
Figure 8
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MISSION MISSION ELEMENTS
Private / Commercial Transport Use
• VIP flights
• Sightseeing
• Transfer flights

© Eurocopter/Photo Anthony PECCHI
Figure 9

6 Market information
6.1 Accidents
Figure 10 depicts a resent EASA (European Aviation Safety Agency) statistic on the accident numbers per cause for
civil commercial air transport in the period 2001 - 2010 [i.1].

ADRM Aerodrome
AMAN Abrupt manoeuvre
ARC Abnormal runway contact
CFIT Controlled Flight into Terrain
CTOL Collision with obstacle(s) during take-off and landing
F-POST Fire/smoke (post-impact)
FUEL Fuel related
GCOL Ground collision
ICE Icing
LOC-G Loss of Control - Ground
LOC-I Loss of Control in flight
LALT Low Altitude Operations
MAC Airprox/TCAS alert/loss of separation/near midair
collisions/midair collision
OTHR Other
SCF-NP System/Component failure or malfunction (non-powerplant)
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SCF-PP System/Component failure or malfunction (powerplant)
SEC Security related
UNK Unknown or undetermined
USOS Undershoot/overshoot
WSTRW Windshear or thunderstorm

Figure 10: Accident categories for fatal and non-fatal accidents for commercial helicopters

(2001 - 2010)
The category with the highest number of fatalities assigned is 'Controlled Flight into Terrain' (CFIT). When ignoring the
categories concerned with 'loss of control in flight' (LOC-I) and 'system component failure' (SCF-NP), two categories
rd th
related to obstacle collisions can be seen to take up the 3 and 5 place. The category 'low altitude operations' (LALT)
covers accidents with terrain or objects while intentionally flying close to the surface but excluding take-off and landing
phases of flight. The category CTOL comprises the collision with obstacles during take-off and landing. Although the
higher number of fatalities can be attributed to the higher speeds in cruise flight, collisions with obstacles during
landing and take-off are clearly the main cause for helicopter commercial air transport accidents in general.
Contributing to the above statistics are challenges typical for commercial operations such as Helicopter Emergency
Medical Services (HEMS). HEMS missions provide medical assistance in situations where either a traditional
ambulance cannot reach the scene easily or quickly enough, or the patient needs to be transported over a distance or
terrain that makes air transportation the most practical transport. Primary rescue missions in which patients or victims
need to be transported from the scene of an accident to the hospital often involve landings in unknown, unprepared
environments are part of the daily routine. Additional stress related to the urgency of the situation or deteriorating
weather conditions compromises safety even further. These Safety-of-Life services will greatly benefit from the system
described herein.
The aforementioned statistics once more reveal the need for a system which supports the pilot or crew in the obstacle
detection task. For this purpose, various systems have been developed using a wide range of active sensing
technologies. The majority of systems, however, come at a high cost often combined with a large physical size and
power consumption. These systems are therefore deployed on military platforms. The system described in the present
document realises a miniaturised, low-cost obstacle warning system specifically for civil operators.
Due to the missing awareness of the direct environment around the helicopter (especially to the rear side), the risk of
overlooking an obstacle and possible obstacle strike is increased. Especially in situations in which pilot workload is
already increased when for instance flying in degraded weather conditions, confined area or under high operational
pressure, etc.). Statistics reported an accident rate of 8,7 per 100 000 flight hours in 2007 where controlled flight into
terrain and collision with obstacles during take-off and landing claim a considerable share.
6.2 Market Potential
For 2008, it was estimated that approximately 6800 helicopters were registered in Euro
...