DEVA Broadcast DB7007 User manual

MAINTENANCE AND OPERATION
INSTRUCTION MANUAL
Publish Date: 21-Oct-2015
DB7007
Advanced FM Radio Re-Broadcast Receiver
with IP Audio & MP3 Backup Players

Contents
Introduction........................................................................................................................................ 6
Typographic conventions .................................................................................................................. 7
General Information.......................................................................................................................... 8
Product Features ................................................................................................................................ 9
Technical Specications ................................................................................................................ 10
Panel Indicators, Switches and Connectors................................................................................... 12
OLED Display............................................................................................................................... 12
Soft Buttons ................................................................................................................................... 12
Navigational Buttons..................................................................................................................... 12
Front panel.................................................................................................................................... 12
Phones ...................................................................................................................................... 12
Indicators.................................................................................................................................. 13
LED bargraphs ......................................................................................................................... 14
Rear Panel..................................................................................................................................... 15
Rear Panel Alarm Terminal .......................................................................................................... 16
Before you start ................................................................................................................................ 17
Safety Precautions......................................................................................................................... 17
Operating Environment Recommendations................................................................................... 17
RF Environment – precautions, installation specications and antenna types............................. 18
De-emphasis and Pre-emphasis selection..................................................................................... 18
Connecting – AC Power and Voltage Selection ............................................................................ 19
Operation.......................................................................................................................................... 20
Re-broadcasting limitations .......................................................................................................... 20
Signal Strength ......................................................................................................................... 20
Multipath Distortion................................................................................................................. 20
Co-channel Interface................................................................................................................ 21
First time power on ....................................................................................................................... 22
Front Panel LCD Display, Navigational & Soft Buttons .............................................................. 23
Header Area ............................................................................................................................. 23
Soft Buttons............................................................................................................................... 24
How to change device parameters ........................................................................................... 25
Set-up menu title ................................................................................................................. 25
Navigation area .................................................................................................................. 25
Numerical parameter........................................................................................................... 25
Enumerated parameter ........................................................................................................ 25
IP address ............................................................................................................................ 26
IP port.................................................................................................................................. 26
Date...................................................................................................................................... 26
Time...................................................................................................................................... 26
Timer .................................................................................................................................... 26
String.................................................................................................................................... 27
Main screen working area............................................................................................................. 29

Operating Modes and Pages ........................................................................................................... 30
Bandscan Page.............................................................................................................................. 31
Span control state ................................................................................................................ 33
Marker control state ............................................................................................................ 35
Parameter control state ....................................................................................................... 36
Bandscan page parameters.................................................................................................. 37
Levels Page ................................................................................................................................... 38
Graphs Page.................................................................................................................................. 41
Settings Page................................................................................................................................. 45
Main Station ............................................................................................................................. 45
Backup Station.......................................................................................................................... 46
Tuner......................................................................................................................................... 46
Backup ...................................................................................................................................... 47
MPX.......................................................................................................................................... 48
MPX out Conguration .......................................................................................................... 48
Stereo Generator ..................................................................................................................... 49
Injection levels ......................................................................................................................... 49
MPX limiter ............................................................................................................................. 49
RDS........................................................................................................................................... 50
Communication......................................................................................................................... 51
Security..................................................................................................................................... 53
Keyboard lock ...................................................................................................................... 53
Keyboard unlock .................................................................................................................. 54
Alarms....................................................................................................................................... 55
GP Outputs ............................................................................................................................... 56
Audio/MPX Outputs.................................................................................................................. 56
Device....................................................................................................................................... 57
Status Page.................................................................................................................................... 58
[RDS Decoder] PAGE................................................................................................................... 60
RDS/RBDS Page Main view..................................................................................................... 60
RDS/RBDS RAW Data view .................................................................................................... 61
RDS/RBDS AF list view............................................................................................................ 61
RDS/RBDS Statistics view ........................................................................................................ 61
RDS/RBDS Sequence view ...................................................................................................... 62
WEB Interface.................................................................................................................................. 63
Manual IP address Identication .................................................................................................. 63
Network Discovery ........................................................................................................................ 63
Access............................................................................................................................................ 64
Main Screen................................................................................................................................... 65
RDS/RBDS Screen......................................................................................................................... 70
BandScan Screen........................................................................................................................... 71
Status Screen ................................................................................................................................. 72
Log Screen..................................................................................................................................... 73
General Settings Screen ................................................................................................................ 74
Tuner Settings Screen .................................................................................................................... 75
RF Loss Protection Mode ......................................................................................................... 76
PI Protection Mode .................................................................................................................. 77

Backup Settings Screen ................................................................................................................. 78
MP3 les upload via FTP......................................................................................................... 78
MPX Settings Screen ..................................................................................................................... 79
RDS/RBDS Settings Screen ........................................................................................................... 80
Alarms Settings Screen.................................................................................................................. 81
Communication Settings Screen.................................................................................................... 82
Network .................................................................................................................................... 82
HTTP Server............................................................................................................................. 83
FTP Server................................................................................................................................ 83
SNMP Agent ............................................................................................................................. 83
Syslog........................................................................................................................................ 83
GSM Modem............................................................................................................................. 83
Audio Stream Server................................................................................................................. 83
E-mail ....................................................................................................................................... 84
USB Port................................................................................................................................... 84
Outputs Settings Screen................................................................................................................. 85
Other Settings Screen .................................................................................................................... 86
Firmware Update .................................................................................................................... 86
Storage...................................................................................................................................... 86
System Log................................................................................................................................ 86
Factory Defaults....................................................................................................................... 86
Reboot....................................................................................................................................... 86
APPENDIX 1.................................................................................................................................... 87
Alarm Triggers .............................................................................................................................. 87
Alarm Notication......................................................................................................................... 89
WARRANTY TERMS AND CONDITIONS................................................................................. 90
Product Registration Card.............................................................................................................. 91
APPENDIX A ................................................................................................................................... 92
RDS: Europe vs America .............................................................................................................. 92
The RDS System ........................................................................................................................... 92
APPENDIX C.1................................................................................................................................ 93
PTY Code Description Used in RBDS Mode – North America..................................................... 93
APPENDIX C.2................................................................................................................................ 94
PTY Code Description Used in RDS Mode – Europe, Asia .......................................................... 94

THIS PAGE
IS INTENTIONALLY
LEFT BLANK

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- 6 -
Introduction
DEVA Broadcast Ltd. is an international communications and high-technology manufacturing
organization, its corporate headquarters and facility located in Burgas, Bulgaria. The company
serves the broadcast and corporate markets worldwide – from consumers and small businesses to
the largest global organizations. It is dedicated to the research, design, development and provision
of advanced products, systems and services. DEVA launched its own brand back in 1997 and has
nowadays evolved to become known as a market leader and internationally reputed manufacturer
of user-friendly, cost-effective and innovative broadcast products.
Creativity and innovation are deeply woven into DEVA corporate culture. Through successful
engineering, marketing and management our team of dedicated professionals creates future-
oriented solutions to improve customers’ performance. You may rely that all issues communicated
to our crew would be addressed accordingly. We pride ourselves on our pre and post-sales support
and purchase services, which along with the outstanding quality of our radio gear have won us due
respect and the market authority position.
DEVA best-of-breed solutions have become the best sellers for our partners. The strategic
partnerships which have been formed with industry leaders during all these years that we have been
operating on the broadcasting market, have proved us a reliable business partner and a valuable
asset, as our dealers worldwide would conrm. In constant pursuit of precision and long-term
satisfaction, DEVA enhances the reputation of our partners and clients alike. Furthermore, we have
already a proven merit as a credible partner provider.
Our portfolio offers complete line of high quality and competitive products for FM and Digital
Radio, Radio Networks, Telecommunication Operators and regulation authorities. For almost
two decades of intensive software and hardware development, we have achieved a unique price-
performance and endurance of our product lines. Our company’s multitude of equipment and
services is in line with the latest technologies and key trends. The most recognizable characteristics
attributed to DEVA products are their clear-cut, streamlined design, easiness of use and cost-
effectiveness: simplicity of forms but multiplicity of functions.
For us there is no stage when we deem that we have reached the most satisfactory level in our
work. Our engineers are in constant pursuit of new ideas and technologies to be captured in DEVA
solutions. Simultaneously, a strict control is being exercised at each step of any new development.
Experience and hard work are our fundament but the continuous improving process is what we
never leave aside. DEVA participates on a regular basis in all landmark broadcasting events, not
only to promote its products, but to exchange valuable know-how and experience. We are also
engaged in international large-scale projects involving radio and audio solutions which makes us
even more competitive on the global market.
All DEVA products are developed and produced in accordance with the latest ISO 9001 quality
control standards.

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- 7 -
Typographic conventions
This manual uses the following typographic conventions:
Style Used for
NOTE Important notes and recommendations
Example Used when example text is cited
0 dB Menu element value
“Menu” on page XX. References
[OK] Front panel navigation and soft buttons.
WEB Interface interactive buttons.
Settings Menu element and soft button name. Menu path are represented as
follows: Settings> Security> Front Panel> Access control

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- 8 -
General Information
DB7007 is a second generation digitally-tuned FM Re-Broadcast Receiver. Considering the
needs of the most demanding broadcasters and continuously supplementing new features to our
devices, DEVA has enhanced DB7007 to be smarter and fully functional unit, equipped with two
high-selective DSP-based FM tuners.
Thanks to the built-in monitoring system, upon audio loss at the inputs, DB7007 will not only
notify the maintenance staff, but will also automatically switch to the second back-up RF Station.
In case a fail of the second station is detected, DB7007 will shift to the incorporated IP Stream,
MP3/AAC back-up audio source player. It is essential that the back-up sources priority is user-
dened. The audio les and playlists can be uploaded in the device’s internal memory directly
from your PC, via any FTP client. When the signal at the default input is restored, the DB7007 will
automatically switch back to it. Depending on your preferences, several types of alarm notications
are utilized - E-mail, SNMP and SMS (via the optional GSM modem).
The DB7007 has an easy to read, high-resolution OLED graphical display, front panel alarm
indicators and ultra-bright bargraphs with up to 40 LED segment indicators that allow reading at a
glance of the MPX, Left and Right audio and the RF level, as well. The RF (IF) signal is digitized
as soon as it enters the device and all signal processing is then made through DSP algorithms,
thus guaranteeing measurement reproducibility over time. The IF bandwidth lters guarantees
unprecedented signal selectivity, while the difcult adjacent-channel problem will be completely
solved. DEVA advanced DB7007 will measure all important parameters of the FM transmission.
Additionally, the RDS information contained in the processed MPX signal is easily visualized
and represented as RDS/RBDS Data and detailed RDS/RBDS Statistics. The utilized Band
Analyzer function presents an overview of all available FM signals, plus the RF signal strength.
Scans can be performed within any section of the FM band in 4 different frequency steps. The
consequently generated spectrum diagram visualizes the relation RF Level vs. Frequency.
Adhering to the underlying principle of all DEVA products to be as much user-friendly as
possible, the DB7007 can be also easily controlled through the built-in Web server - you can use a
standard web browser to monitor the status or to make any adjustments (iOS and Android devices
are also supported); the supplied free of charge DEVA Device Manager Software or alternatively,
through the very intuitive user interface.
Designed to ensure premium broadcasting experience, DB7007 will meet and even exceed
your expectations for a rst rank re-broadcast receiver.

65 Aleksandar Stamboliyski Str., 8000 Bourgas, Bulgaria
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- 9 -
Product Features
• Two independent DSP based Digital FM Tuners
• Dual antenna ports with built-in RF attenuator
• Up to 100 dBµV direct RF Antenna Input
• Selectable wide range IF lter bandwidths
• FM Band 87.1 - 107.9 MHz Basic Spectrum Analyzer
• Built-in DSP based Stereo Re-encoder
• Advanced SNMP Ver.2C support
• Professional AES/EBU, SPDIF and Optical Digital audio outputs
• Wide angle, easy to read OLED display
• Very Intuitive Navigational Menu
• Selectable De-emphasis - 50µs and 75µs
• Real Time Audio Program Streaming
• Remote Listening via optional GSM modem
• Apple and Android devices support
• SNTP for automatic sync of the built-in clock
• RDS and RBDS decoder with BER meter
• TCP/IP Remote monitoring and control via SNMP and WEB Interface
• Alarm dispatch via E-mail, SMS, SNMP and GPO
• Multiformat Backup IP Audio player
• Built-in Backup MP3 Player
• Lots of Storage for over 24 hours of non-repeating audio playback
• Adjustable MIN/MAX alarms for RF, Pilot, L & R Audio Levels
• Adjustable MIN/MAX alarms for MPX & RDS
• Digital Volume Control of all Audio Sources
• Complete status reporting with SMS via optional GSM modem
• Protected access to the device settings
• Balanced Analog Audio Outputs on XLR Connectors
• USB communication interface for local connectivity
• Headphone output with front panel level control
• Easy and intuitive Windows Application
• Firmware updates will ensure improved operation
• Accurate front-panel metering for local use
• Restore Factory Parameters option
• Wide operating voltage range: 100-240V AC
• 19” Professional Case for high RF immunity
• Easy Installation and Setup

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- 10 -
TECHNICAL SPECIFICATIONS
RF INPUT
Tuning Range 87.1 to 107.9 MHz, Frequency Agile
Tuning Step 10, 20, 50, 100 kHz
Tuner Sensitivity 30 dBµV
Antenna Ports Dual, 2 x BNC Connectors, 50Ω
Antenna Ports Isolation > 40 dB
Internal Attenuator 0, 10, 20 and 30 dB
Dynamic range 100 dB
FM DEMOD
IF Filter Bandwidth 15 Increments (25kHz - 157kHz, Auto)
Frequency Response ±0.1 dB, 10 Hz to 86 kHz
Dynamic range 90 dB
STEREO DECODER
Frequency Response (L&R) ±0.1 dB, 10 Hz to 15 kHz
SNR (Stereo) 60 dB, 50 µs de-emphasis
THD 0.1%, 10 Hz to 15 kHz, 50 µs de-emphasis
Separation 50 dB, 50 Hz to 10 kHz, 50 µs de-emphasis
Crosstalk 52 dB
BACKUP IP AUDIO PLAYER
Number of Streams one main and two alternative streams with auto-switch on failure
Stream Clients shoutcast, icecast
Stream Formats PCM (32, 44.1, 48kHz), MPEG1 Layer 3 (MP3), HE-AAC (v.1
and v.2)
Bit Rates All standard bit rates, including VBR
Number of Channels Mono, Stereo
Buffer Size Adjust 5Kb to 64Kb
Digital Gain Adjust -10db to +10dB
BACKUP MP3 PLAYER
Storage Capacity 2Gb on SD Card
Supported encoders HE-AAC (v.1 and v.2), MPEG-1 Layer 3
MP3 bit rates 32-320 kbps and VBR
Sample rates All sampling frequencies specied by MPEG1 L1/L2/L3 (32,
44.1 and 48kHz); MPEG2 L1/L2/L3 (16kHz, 22.05kHz and
24kHz) and MPEG2.5 L3 (8kHz, 11.025kHz, and 12kHz)
Supported le types *.MP3, *.AAC, *.M4A, *.M3U
Playback modes Alphabetical ascending and descending, Shufe, Playlist and
Shufed playlist
Remote le management Build-in FTP server
Digital Gain Adjust -10db to +10dB

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- 11 -
RDS DECODER
Standards European RDS CENELEC; United States RBDS NRSC
Error Correction & Counting Yes
AF Decoding Yes
CT (Time/Date) Yes
PI, PTY, DI, MS Yes
TA/TP Yes
RT (Radio Text), RT+ Yes
PS (Program Service name) Yes
ODA Yes
Group Analyzer Yes
BER Analyzer Yes
Group Sequence Display Yes
RDS RAW Data Display Yes
METERING ACCURACY
RF Level ±1 dB, 0 to 100 dBµV
Total, Pos, Neg ±2 kHz, 10 to 100 kHz, 1 kHz resolution
Pilot, RDS ±0.5 kHz, 1 to 12 kHz, 0.2 kHz resolution
Audio ±1 dB, +10.0 to -55.0 dB, 0.1 dB resolution
OUTPUTS
Composite +12 dBu @ 75kHz, 75Ω, unbalanced BNC Connector
Audio (L, R) +6 dBu, 600Ω balanced XLR Connector
AES3 (L, R) 5.0 Vp-p, 110Ω , balanced XLR Connector
SPDIF (L, R) 3.0 Vp-p, 110Ω, unbalanced BNC Connector
Optical (L, R) Transmitter, TOSLINK
Alarms Programmable terminals on rear panel, optoisolated
Headphone 6,3mm (1/4”) Phone Jack
COMMUNICATION INTERFACES
USB B-type Connector
Ethernet 10/100 Base-T RJ45 Connector
GSM Modem 15 pin Male D-Sub Connector
MEASUREMENT STORAGE
Storage 2GB Build-in Memory Card
Data format Text, CSV
POWER
Voltage 100-240V / 50-60 Hz / 25W
Connector IEC320
SIZE AND WEIGHT
Dimensions (W;H;D) 485 x 44 x 180 mm
Shipping Weight 540 x 115 x 300 mm / 2.7kg

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- 12 -
Panel Indicators, Switches and Connectors
NOTE: Unless where otherwise clearly stated, all front panel and display indicators,
measurements and graphs represent the information received from the Main Station tuner (ANT1).
OLED DISPLAY
DB7007 has easy to read, high-resolution OLED graphical display that visualizes all
measurements of the received signal and DB7007 settings.
SOFT BUTTONS
Used for navigation through the menus, quick access to the parameters, modes, functions and to
alter their values. The Soft Buttons indicators are placed on the bottom side of the OLED display.
Depending on the currently selected menu context the indicators change their function. The Soft
Buttons will be referred as (left-to-right) [SB1], [SB2], [SB3] and [SB4].
NAVIGATIONAL BUTTONS
[UP], [DOWN], [LEFT], [RIGHT] and [OK] buttons, as the Soft Buttons, are used to navigate
through the menus selecting various functions and parameters of DB7007.
FRONT PANEL
NOTE: Unless where otherwise clearly stated, all front panel and display indicators,
measurements and graphs represent the information received from the Main Station tuner (ANT1).
Phones
Phones jack to monitor the signal. Headphones volume can be adjusted in two methods:
1. Using the [UP] and [DOWN] buttons in the home screen;
2. Through the front panel navigational menu: Settings> Audio / MPX Outputs> Phones
Volume.

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- 13 -
Indicators
• Mpath – Indicates the presence of strong multipath distortion of the RF signal. The indication
threshold and time can be set trough: Settings> Device> Loss> Multipath Threshold /
Multipath Timeout
• ANT 1 – Indicates that the Main Station is the current audio source.
• ANT 2 – Indicates that the Backup Stationis the current audio source.
• MP3 – Indicates that the MP3 backup player is the current audio source.
• IP Audio – Indicates that either the IP Audio Client or the RTP receiver is the current audio
source.
• RF LOSS – will be indicated whenever the level of the RF signal of the Main Station drops
below the selected threshold. The RF LOSS detection threshold and time can be set trough:
Settings> Main Station> RF Loss Threshold / RF Loss Timeout

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• AUDIO LOSS will be indicated whenever the level of the Left and Right audio channels
drops below the selected threshold. The AUDIO LOSS detection threshold and time can be
set trough: Settings> Device> Loss> Audio Threshold / Audio Timeout
• RDS LOSS will be indicated whenever the level of the RDS drops below the selected
threshold. The RDS LOSS detection time can be set trough: Settings> Device> Loss> RDS
Loss Timeout
LED bargraphs
• MPX – composed of 26 segments, the bargraph indicating the deviation in kHz (European
RDS mode) and in % (US RDBS mode).
• RF – composed of 10 segments,the bargraph shows the measurements from 10 dBµV to
100 dBµV.
• Left Audio Channel – composed of 40 segments, the bargraph shows the measurements
from -50 dB to +10 dB;
• Right Audio Channel – composed of 40 segments, the bargraph shows the measurements
from -50 dB to +10 dB;

- 15 -
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REAR PANEL
1
2
3 45
6
7
8910
11 12 13
14
3. Mains connector, 110-240VAC, IEC-320 C14 type;
4. Fuse holder – 1A;
5. Audio Left Output - XLR;
6. Audio Right Output - XLR;
7. Audio AES/EBU Output - XLR;
8. Audio SPDIF Output - RCA;
9. Audio Optical Output - TOSLINK;
10. MPX Output - BNC;
11. RF Input 1 (Antenna 1) - BNC;
12. RF Input 2 (Antenna 2) - BNC;
13. Ethernet T-BASE10/100 RJ45;
14. USB – type B;
15. GSM Modem – Male D-Sub 15 pins High Density;
16. GPO – Opto-isolated, Female D-Sub 15 pins.

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- 16 -
REAR PANEL ALARM TERMINAL
12345678
9101112131415
1 - GPO1 Collector 9 - GPO1 Emitter
2 - GPO2 Collector 10 - GPO2 Emitter
3 - GPO3 Collector 11 - GPO3 Emitter
4 - GPO4 Collector 12 - GPO4 Emitter
5 - GPO5 Collector 13 - GPO5 Emitter
6 - GPO6 Collector 14 - GPO6 Emitter
7 - GPO7 Collector 15 - GPO7 Emitter
8 - GND
LOAD
1
9
GPO1
LOAD
1
9
GPO1

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- 17 -
Before you start
SAFETY PRECAUTIONS
• The servicing of electronic equipment should be performed only by qualied personnel;
• Before removing the covers DB7007 must be switched off and the mains cable unplugged;
• When the equipment is open, the power supply capacitors should be discharged using a
suitable resistor;
• Never touch the wires or the electrical circuits;
• Use insulated tools only;
• Never touch the metal semiconductor. They might carry high voltages;
• For removing and installing electronic components, follow the recommendations for
handling MOS components.
ATTENTION: DB7007 has an internal Lithium battery. Do not try to re-charge this battery!
Please contact us for detailed instructions in case the battery should be changed.
OPERATING ENVIRONMENT RECOMMENDATIONS
For normal operation of DB7007, we recommend following the instructions listed below.
• Install the unit in places with good air conditioning. DB7007 is designed to operate within the
ambient temperature range of 10 to 50°C. The equipment rack should be ventilated in order
for the device to keep its internal temperature below the maximum ambient temperatures;
• We do not recommend installation in rooms with high humidity, dusty places or other
aggressive conditions;
• Locate the device away from abnormally high RF elds;
• Use only checked power supply cables. We strongly recommend the usage of shielded
cables;
• Connect DB7007 only to reliable power supply sources. In case of unstable power supply,
please use Uninterruptible Power Supply (UPS);
• Use the device only with its top cover on to avoid electromagnetic anomalies. Otherwise,
this may cause problems with the normal functionality of the unit;
• For the normal remote operation of the unit, connect DB7007 to a good quality Internet
connection;
• For the normal operation of DB7007, check if the network settings past through all the
required data trafc.

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- 18 -
RF ENVIRONMENT – PRECAUTIONS,
INSTALLATION SPECIFICATIONS AND ANTENNA TYPES
The observation of the RF Environment, in which DB7007 is functioning, is necessary for
ensuring normal and reliable function of the device. In order for the device to work properly, the
best conditions according the standards listed below should be provided.
The usage of an external antenna is required because DB7007 is used for off air re-broadcasting
away from the transmitter site. Proper outdoor FM antenna, antenna location and direction should
be selected. The three most popular antenna types are: omni directional, unidirectional dipole and
directional multi-element array antenna.
Because of the low antenna gain, the bad signal to noise ratio (compared to any directional
antenna) and its high multipath interfaces reception, we do not recommend the usage of omni
directional antenna with DB7007.
The other type antennas: unidirectional dipole and directional multi-element array antenna are
much proper for your needs. We recommend the usage of factory made antenna or antenna system,
manufactured specially for the FM Radio Band 88 – 108 MHz.
The recommended working RF signal strength is in the range of 55-90 dBμV. If the input RF
level is above this range, we recommend using external RF attenuators with attenuation value
between 20 – 90dB.
After selecting the antenna type that will meet your needs, the next step is its installation. The
following important principles should be considered:
- Install the antenna far enough from walls, roofs, buildings or any transmitting equipment;
- The minimum spacing between the antenna and the closest object should be more than 3
meters.
One unit DB7007 re-broadcast receiver is used for re-broadcasting of one transmitter site,
transmitting more than one program. In such cases, the best antenna that can be used is a directional
antenna directed exactly to this site.
DE-EMPHASIS AND PRE-EMPHASIS SELECTION
As well known, there are three different de-emphasis selections. One of the problems with the
high quality VHF FM transmissions is that the increased audio bandwidth means that background
noise can often be perceived. It is particularly noticeable towards the treble end of the audio
spectrum, where it can be heard as a background hiss. To overcome this, it is possible to increase
the level of the treble frequencies at the transmitter. The frequencies are correspondingly attenuated
at the receiver in order to restore the balance. This also has the effect of reducing the treble
background hiss which is generated in the receiver. The process of increasing the treble signals
is called pre-emphasis, and reducing the treble signals in the receiver is called de-emphasis. The
rate of pre-emphasis and de-emphasis is expressed as a time constant. It is the time constant of the
capacitor-resistor network used to give the required level of change.
In UK, Europe and Australia the time constant is 50μs whereas in North America it is 75μs. The
de-emphasis and pre-emphasis should be selected depending on the region you are located or can
be disabled.

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- 19 -
CONNECTING – AC POWER AND VOLTAGE SELECTION
Before connecting the AC Power, make sure that the fuse rating is in accordance with the mains
supply at your location. DB7007. Power Supply Factory Settings are:
- 100-240 VAC;
- 1Amp Fuse.
CAUTION:
DB7007. will be damaged permanently if improper AC power supply voltage is applied. The
warranty DOES NOT cover damages caused by applying improper supply voltage or usage of
improper fuse.

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- 20 -
Operation
RE-BROADCASTING LIMITATIONS
Signal Strength
The signal strength is a major factor when a signal is re-broadcasted, measured and evaluated.
FM compared to AM is less susceptible to the inherent noise of the radio reception.
When speaking about FM broadcasting, it is the monaural reception which can tolerate and
prot from a much narrower IF bandwidth. The stereo reception adds all noise present in the 23 –
53 kHz sub-band. The amplitude component (AM) of the sub band is converted down to audible
noise and added to the program signal. That is why the noise performance of FM-stereo can be as
much as 20 dB worse than that of monaural broadcast.
Better reception and measurement can be obtained by using highly directional outdoors antenna.
This will improve the signal strength and contribute in eliminating the multipath distortion.
Multipath Distortion
In FM reception, regardless of overall signal strength, a very important consideration is that
obstacles, which an FM signal may encounter in the line-of-sight path tend to reect and disperse
the signal in many directions. In many locations, especially in urban areas where many tall
buildings interfere with the direct transmitted signal or in suburban areas surrounded by hills or
mountains, an FM receiver may pick up a station’s primary signal but, also, several secondary
reections coming from various directions. These reections arrive at the receiver out-of-phase,
slightly delayed in time with the primary signal and tend to blur or distort the principal signal. The
degree of distortion depends on the number and relative strength of the reections.
The result, known as multipath distortion in FM reception can range from a low-level fuzziness
to a severely distorted sound quality, particularly at the high frequencies or treble. Multipath
distortion is especially troublesome in FM stereo reception.
DB7007 has a multipath distortion detector and Front panel multipath LED indicator with
adjustable threshold. A bar graph indicator representing the multipath level of the received signal
can be reached under LEVELS menu.