Monitoring and evaluation of radio frequency coverage in terrestrial digital video broadcasting systems

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RESEARCH ARTICLE | FE BR UA RY 21 2024
Monitoring and evaluation of radio frequency coverage in
terrestrial digital video broadcasting systems 
Krasen K. Angelov ; Panagiotis G. Kogias; Stanimir Μ. Sadinov; Michail N. Malamatoudis
AIP Conf. Proc. 3063, 050002 (2024)
https://doi.org/10.1063/5.0196206
27 February 2024 09:50:09

Monitoring and Evaluation of Radio Frequency Coverage in
Terrestrial Digital Video Broadcasting Systems
Krasen K. Angelov1, a), Panagiotis G. Kogias 2, b),
Stanimir Μ. Sadinov1, c), Michail N. Malamatoudis2, d)
1 Technical University of Gabrovo, Department of Communications Equipment and Technologies, 4 H. Dimitar str.,
5300 Gabrovo, Bulgaria
2 International Hellenic University, Department of Electrical Engineering, Ag. Loukas, 65404 Kavala, Greece
a) Corresponding author: kkangelov@tugab.bg
b)kogias@teiemt.gr
c)murry@tugab.bg
d)malamatoudismichail@yahoo.gr
Abstract. The digital terrestrial television network should provide reliable and high-quality transmission of television
signals. However, there are serious problems with ensuring the coverage for areas with complex topography. This paper
presents a monitoring, performance analysis and evaluation of the quality of radiofrequency coverage in digital terrestrial
television (DVB-T) system operating on the territory of the town of Gabrovo, Bulgaria. The analysis and evaluation are
established with respect of the main signal parameters, which are measured. The results are discussed and shown in
graphical and tabular form.
INTRODUCTION
Terrestrial digital video broadcasting (DVB) in the Republic of Bulgaria, parallel to analog broadcasting, began
on March 1, 2013, and in September 2013 analogue broadcasting was completely discontinued. After September
2013 terrestrial television broadcasting is digital only and can be viewed with TVs with a built-in digital tuner with
an MPEG-4 decoder or an external MPEG-4 decoder. The programs broadcast after 30.09.2013 are: BNT1, BNT2,
BNT1 HD, BNT HD (public multiplex, coverage of over 96.2% of the population of Bulgaria), bTV, Nova TV,
News 7, TV 7 (second commercial multiplex, coverage of over 96.2% of the population of Bulgaria), Bulgaria on
Air (first commercial multiplex, coverage of over 85% of the population of Bulgaria) [1,2]. In the development of
the DVB-T standard, one of the requirements is that the system should use the existing terrestrial television
broadcast network, and digital terrestrial distribution should allow the reception of the programs with both a fixed
roof antenna and a portable antenna in buildings and outside buildings. Nevertheless, long after the introduction of
digitization in the Republic of Bulgaria, serious problems occurred in many places with the provision of quality
coverage and, accordingly, reliable reception of signals for digital terrestrial television [3,4].
This paper presents a study and performance analysis and evaluation of the quality of radio frequency coverage
for digital terrestrial television on the territory of the town of Gabrovo, Bulgaria. Gabrovo is a town with an
extremely complex topography, with districts located along the banks of the tributaries of the Yantra River. This
creates great difficulties in achieving reliable line-of-sight communication.
International Conference on Electronics, Engineering Physics, and Earth Science
AIP Conf. Proc. 3063, 050002-1–050002-8; https://doi.org/10.1063/5.0196206
Published by AIP Publishing. 978-0-7354-4856-8/$30.00
050002-1
27 February 2024 09:50:09

METHODS FOR MEASURING SIGNAL PARAMETERS IN DIGITAL TELEVISION
NETWORKS
The quality of the signals carried over the broadcast television network can only be evaluated by specialized
measurements. Measurement methods in digital television systems are regulated in the document ETR 290 [5]. In
this document, the measurements in the television digital broadcast networks are divided into four groups, one of
them being the measurement of the parameters of the digital broadcast network during construction and during its
operation. This refers to the measurement of all parameters and at all points of the digital system. The main
parameters discussed and measured in this paper are:
 control of the signal spectrum – with a analyzer;
 control of side emissions – with a spectrum analyzer;
 measuring the signal-to-noise ratio (SNR);
 measurement of the bit error rate (BER);
 measurement of the modulation error ratio (MER);
 control of modulation IQ-diagrams.
In digital television, a phase- or amplitude- and phase-modulated digital stream is transmitted, the spectral
energy of which is previously equalized in the frequency band of the connection channel. Before modulation, the
digital stream is passed through a filter. As a result of this, the signal power is evenly distributed over the link
channel bandwidth, and therefore only the total average power over the entire frequency channel can be measured.
Modern precision spectrum analyzers have the ability to measure the average signal power in specified frequency
ranges [4,5].
Bit Error Rate (BER) is one of the most important parameters of a digital system that characterizes its quality. In
a digital television system, there is a clearly defined limit of digital error values at which the system operates. Error
protection achieved by convolutional and Reed-Solomon (RS) coding in the terrestrial broadcasting ensures quasi-
error-free reception [3,6,7]. The limit at which RS-coding is able to correct the signal is BER=10-4, and after
correction the bit error rate becomes BER = 10-11. In convolutional coding, a digital error of 10-2 is corrected to 10-4.
The value of the digital error coefficient is uniquely related to the value of the signal-to-noise ratio. By
convolutional coding, bit error rate of 10-2 is reduced to 10-4. The value of the BER is directly related to the value of
the signal-to-noise ratio (SNR). The sources that cause BER deterioration are on the one hand the modulator and the
transmitter and on the other hand the transmission system. In the transmission path, BER degradation is caused by:
 output stages in digital terrestrial television transmitters;
 intermodulation distortions caused by signals in an adjacent channel or by interfering signals from the same
channel;
 interferences;
 link channel noise and reflected signals.
The main control points where it is important to measure BER are:
 immediately after the demodulator – this is the value of the bit error rate at the output of the transmission
channel before the correction circuits; this this error is called “pre-Viterbi BER” (or preVBER), i.e. the bit
error rate value before convolutional decoding and correction;
 after the first level of error correction (after the internal error protection) – this parameter is accepted to be
called “post-Viterbi BER” (or postVBER).
The Modulation Error Ratio (MER) is a parameter that covers all parameters of the vector (IQ) diagram. In
practice, this is the parameter that is controlled in the QAM vector diagram. To calculate the MER, the influence of
the error vector for each I/Q point is determined and calculated:
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27 February 2024 09:50:09

In the Table 1 the MER values at 64-QAM modulation format and the corresponding signal quality are given.
For DVB-T, the MER value is considered good when MER >35 dB [5].
Vector diagram control is fundamental to digital broadcast networks. Since the vector diagram of digitally
modulated signals is very sensitive to the effects of external factors on the signal, it gives a very good indication of
the quality of the signal, the influence of noise or the state of the transmission equipment [8,9]. For an optimal signal
in QAM modulation, the vector diagram is a matrix of slightly fuzzy point states. In the presence of noise in the
signal, the point states of the vector diagram expand, and at very high levels of noise, "clouds" are formed for the
individual states.
TABLE 1. MER value and corresponding signal quality at 64-QAM modulation format.
MER value, dB Quality
MER > 40 Very good
36,5 > MER > 32 Good
32 > MER > 28 Normal
28 > MER > 26 Acceptable
26 > MER Poor
The recommended signal levels for DVB-T are presented in the Table 2.
TABLE 2. Recommended signal levels for DVB-T.
Standard Modulation FEC Signal level
min, dBµV max, dBµV
DVB-T
COFDM
QPSK
1/2 26 74
2/3 28 74
3/4 30 74
5/6 33 74
7/8 35 74
16-QAM
1/2 32 74
2/3 36 74
3/4 39 74
5/6 42 74
7/8 45 74
64-QAM
1/2 42 74
2/3 45 74
3/4 48 74
5/6 51 74
7/8 54 74
MONITORING AND EVALUATION OF DVB-T RADIO FREQUENCY COVERAGE
AND SIGNAL PARAMETERS FOR THE TERRITORY OF TOWN OF GABROVO
On the territory of the town of Gabrovo, through the radio relay and television station (RRTS) “Gradishte” [9],
signals from multiplexes 1, 2 and 3 are received. Table 3 summarizes the parameters of the three main multiplexes.
TABLE 3. Digital television multiplexes received on the territory of Gabrovo
Multiplex Parameters
MUX-1 − TV channel №26
− 514MHz − COFDM-QAM64,
− channel bandwidth 8MHz,
− 8k mode,
− Guard interval 1/4,
− FEC 2/3
MUX-2 − TV channel №49
− 698 MHz
MUX-3 − ТV channel №58
− 770 MHz
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The survey and evaluation of the radio frequency coverage of the digital terrestrial television for the territory of
the town of Gabrovo was carried out in control points in 4 different directions, related to the individual main
districts of the city. These directions are presented in Fig. 1 and are as follows:
Direction 1: RRTS “Gradishte” - Rusevtsi district;
Direction 2: RRTS Gradishte - Gachevtsi district;
Direction 3: RRTS Gradishte - Smirnenski district;
Direction 4: RRTS Gradishte - Etara district.
FIGURE 1. Main directions of surveying the quality of DVB-T coverage for the town of Gabrovo.
The scheme of the experimental set-up, through which the survey and the measurements of the parameters of the
DVB-T signals were realized, is shown in Fig. 2. The investigation of the signals transmitted by RRTS “Gradishte”
(position 1) is carried out using a digital analyzer of DVB-T signals Planar IT-088 (position 2), a global positioning
system (GPS - position 4) and connected to them portable computer station (position 3), providing data collection
and processing of information and connection to the GIS system of the Municipality of Gabrovo.
FIGURE 2. The scheme of the experimental set-up for surveying and measuring the parameters of DVB-T signals.
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The initial control point (CP 0) for each of the directions has been accepted to be in close proximity to RRTS
“Gradishte”. The spectrum of the signals for the three broadcast multiplexes measured in CP 0 is presented in Fig. 3.
From the figure it can be seen that on three adjacent frequencies significantly attenuated signals are also received
from three other multiplexes. These are signals from a neighboring radio relay and television station, which are
received due to the high altitude of RRTS “Gradishte”.
FIGURE 3. Spectrum of the signals for the three broadcast multiplexes, measured at RRTS “Gradishte”.
Measurements related to vector diagram control, signal spectrum control, and side emission control are shown in
Fig. 4, carried out in CP 0 (in the immediate vicinity of RRTS “Gradishte”) for multiplex MUX-2 at frequency 698
MHz.
(a) (b)
FIGURE 4. Control of (a) vector diagram and (b) signal spectrum and side emissions for CP 0 and channel frequency 698 MHz.
From the measurements, it can be seen that the MER of the signal is within normal limits, and the level of the
signal and side emissions corresponds to those set by the DVB-T standard.
Since the town of Gabrovo is characterized by a complex topography, the main challenge is to ensure high-
quality broadcasting of television signals even to the most remote and complex points of the settlement.
Unfortunately, without suitable antenna equipment with an amplifier, the signals in some of the outer districts are
received with parameters that are significantly below the required minimum. As an example, Fig. 5 showing the
level and spectrum of the 698 MHz signal measured in the Smirnenski district (CP 3.7 of Direction 3).
Using the digital DVB-T signal analyzer IT-088, multiple measurements are made of the following more
important parameters: signal level, preVBER, postVBER and MER. The results are summarized in Table 4, Table 5,
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Table 6, and Table 7 for the relevant directions. Based on these tables, an analysis was made, the results of which
are shown in Fig. 6.
FIGURE 5. Signal spectrum control for CP 3.7 and channel frequency 698 MHz.
TABLE 4. Measuring the quality of DVB-T coverage in Direction 1.
Direction 1: RRTS “Gradishte” - Rusevtsi district
CP
№
Signal level, dBμV preV-BER postV-BER MER, dB
514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz
0 70 66.4 85 0 0 0 0 0 0 35 35 34.9
1.1 59.5 66.7 52.1 7.6.10
-3
0 9.2.10
-5
6.9.10
-6
0 0 25.7 32.5 33.7
1.2 40 48.3 49.4 2.6.10
-2
3.7.10
-4
2.0.10
-3
0 0 0 23.3 23.8 29.3
1.3 39.9 46.2 47.6 5.0.10
-3
7.6.10
-3
4.2.10
-3
0 0 0 26.8 22.5 21.9
1.4 49 53.5 54.4 4.9.10
-3
9.9.10
-3
5.1.10
-3
- - - 26.7 25.6 27.1
TABLE 5. Measuring the quality of DVB-T coverage in Direction 1.
Direction 2: RRTS “Gradishte” - Gachevtsi district
CP
№
Signal level, dBμV preV-BER postV-BER MER, dB
514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz
0 70 66.4 85 0 0 0 0 0 0 35 35 34.9
2.1 57.4 62.3 67.9 7.3.10
-3
1.4.10
-5
0 0 0 0 25,7 31.3 33.5
2.2 48.2 53.5 48.6 1.7.10
-5
1.2.10
-4
5.1.10
-3
0 0 0 30.5 31.3 29.5
2.3 47.7 55 53.4 1.4.10
-3
8.4.10
-4
3.10
-8
0 0 0 26.9 27.4 33.7
2.4 43.2 57.4 47.7 9.1.10
-5
1.6.10
-7
4.6.10
-6
0 0 0 26.4 33.7 30.9
2.5 20 36.3 26.6 6.3.10
-2
1.5.10
-2
2.0.10
-2
2.6.10
-2
1.3.10
-7
3.0.10
-5
9.5 21.8 19.4
2.6 17 23 25 - - - - - - - - -
TABLE 6. Measuring the quality of DVB-T coverage in Direction 3.
Direction 3: RRTS “Gradishte” - Smirnenski district
CP
№
Signal level, dBμV preV-BER postV-BER MER, dB
514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz
0 70 66.4 85 0 0 0 0 0 0 35 35 34.9
3.1 56.7 55.7 55.4 1.5.10
-6
1.1.10
-3
4.3.10
-3
0 0 0 31.5 24.7 24.3
3.2 43.1 50.2 45.7 3.5.10
-3
5.8.10
-3
3.9.10
-3
0 0 0 28.4 24.1 24.6
3.3 49.8 51.7 48.7 7.3.10
-3
2.9.10
-3
4.7.10
-3
0 0 0 23.5 29 25.2
3.4 60.8 58.2 55.8 9.4.10
-4
4.7.10
-3
4.5.10
-4
0 0 0 28.9 25.3 27.2
3.5 46.1 51.5 46 9.6.10
-6
3.0.10
-6
5.7.10
-4
0 0 0 29.2 32.2 29.4
3.6 47.7 57.1 57.7 1.6.10
-3
5.3.10
-5
2.7.10
-4
0 0 0 24.2 30.7 27.5
3.7 25.8 23.8 23.3 - - - - - - - - -
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TABLE 7. Measuring the quality of DVB-T coverage in Direction 4.
Direction 4: RRTS “Gradishte” - Etara district
CP
№
Signal level, dBμV preV-BER postV-BER MER, dB
514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz 514MHz 698MHz 770MHz
0 70 66.4 85 0 0 0 0 0 0 35 35 34.9
4.1 55.3 55.9 52.8 6.0.10-5 2.1.10-3 4.3.10-5 0 0 0 27.9 28.8 29.4
4.2 38.9 45.1 25.1 3.3.10-2 1.1.10-2 - 1.2.10-4 1.9.10-6 - 19.6 22.1 -
4.3 65.7 55.4 59.8 4.9.10-6 2.8.10-6 1.0.10-7 0 0 0 32.3 34.1 34.6
4.4 39.6 43.6 42.5 1.3.10-2 6.4.10-3 1.1.10-2 2.1.10-5 2.7.10-8 1.7.10-5 23.5 24.5 25
4.5 22.8 22.1 17.7 - - - - - - - - -
(a) (b)
(c) (d)
FIGURE 6. Signal level changes depending on the terrain along: (a) Direction 1: RRTS “Gradishte” - Rusevtsi district;
(b) Direction 2: RRTS “Gradishte” - Gachevtsi district; (c) Direction 3: RRTS “Gradishte” - Smirnenski district;
(d) Direction 4: RRTS “Gradishte” - Etara district.
The figures above show the change in signal level for the three multiplexes depending on the terrain. As can be
seen from the graphs presented, the signal level in the central city area is very good. But taking into account the
complex topography of the city, a large part of the remote districts of the city, located behind hills, suffer from the
lack of quality radio coverage and reception of DVB-T signals, respectively.
CONCLUSION
The presented results of the monitoring and analysis of the quality of the radio frequency coverage for digital
terrestrial television on the territory of the town of Gabrovo show the importance of good planning while observing
all the necessary parameters. As can be seen, the relief significantly affects the coverage, as a result of which in
certain extreme parts of the city it is impossible to reliably receive signals from the digital terrestrial television. In
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this case, it is necessary to build additional radio broadcasting towers, which will significantly increase the cost of
the infrastructure.
ACKNOWLEDGMENTS
The presented work is supported under project 2205Е/2022 “Planning, design and optimization of wireless
communication platforms, services and solutions for 5G and IoT applications” by the University Center for Research
and Technology at the Technical University of Gabrovo.
REFERENCES
1. E. Ibroscheva and M. Racheva-Stover, Development of Digital TV in Bulgaria: Opportunities and Problems,
International Journal of Communication, 3, 87-107 (2009).
2. A. Bizopoulos, P. Lazaridis, E. Paparouni, D. Drogoudis, S. Kasampalis, I. Dalis, L. Gavrilovska, “Coverage
Prediction and Validation for DVB-T services, ETAI Ohrid 2011, pp. 1-6.
3. T. B. Iliev, G. Y. Mihaylov, E. P. Ivanova, I. S. Stoyanov and D. I. Radev, "Experimental study of the basic
parameters and the field strength of a television transmitter in the single frequency network (SFN)," 2017 27th
International Conference Radioelektronika (RADIOELEKTRONIKA), Brno, Czech Republic, 2017, pp. 1-4,
doi: 10.1109/RADIOELEK.2017.7936640.
4. C. Weck, “DVB: Coverage aspects of digital terrestrial television broadcasting”, EBU Technical Review
Winter, 1996, pp. 21-30.
5. ETR 290 - Digital Video Broadcasting (DVB); Masurement guidelines for DVB systems
6. G. Y. Mihaylov, T. B. Iliev, E. P. Ivanova, I. S. Stoyanov and L. Iliev, “Performance analysis of low density
parity check codes implemented in second generations of digital video broadcasting standards”, 2016 39th
International Convention on Information and Communication Technology, Electronics and Microelectronics
(MIPRO), Opatija, Croatia, 2016, pp. 499-502, doi: 10.1109/MIPRO.2016.7522195.
7. V. Kadrev and R. Pasarelski, “Specifics of modeling and simulation of the risk on the communication and
ensure systems”, 2020 Yearbook Telecommunications, vol. 7, Sofia, Bulgaria, 2020, pp. 17-28.
8. R. B. Palipana and Kah-Seng Chung, “Frequency Domain IQ Correction in a Direct conversion Receiver for
DVB-T”, 2005 Asia-Pacific Conference on Communications, Perth, WA, Australia, 2005, pp. 590-594.
9. W. Guo, H. Zhao, C. Song, S. Shao and Y. Tang, Direct-Link Interference Cancellation Design for Backscatter
Communications Over Ambient DVB Signals, IEEE Transactions on Broadcasting, 68 (2), 317-330 (2022).
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