3
laptop through a USB port. The report includes the num-
ber of good packets received, the number of packets sup-
posed to be received based on the packet ID, the number
of errored bits, the number of lost or errored packets, and
other parameters of interest. By inspecting the report, we
can evaluate the bit error rate, packet loss or error rate, and
packet drop time (time between successful packet recep-
tions) of the remote-control communication system under
various conditions in underground mines.
Interference was generated using a signal generator with
configurable modulation schemes, frequencies, and power
levels. The interference waveforms replicated the actual
wireless communication near the machinery involved in
the communication dropout issue in the mine, employing
Gaussian frequency-shift keying (GFSK) modulation with
a 200 kbps data rate and a 100 kHz channel bandwidth.
An external trigger was connected to the signal generator to
control the duty cycle and the duration of the interference
signal. The following two tables, Table 1 and Table 2, show
the communication parameters that we used in our testing.
The tests were conducted in a closed-ended min-
ing tunnel in the Pittsburgh Safety Research Coal Mine
approximately 4 meters wide and 2 meters high, shown in
Figure 1. A spectrum analyzer and a measurement antenna
were utilized to assess the signal power from both the trans-
mitter and interference sources. The measurement antenna
was positioned 3 meters from the tunnel’s closed end and
2 meters from the side walls, with a height of 1.2 meters.
The receiver board was mounted on a tripod in alignment
with the measurement antenna, while the transmitter
was placed at the far end of the tunnel to ensure that the
received signal power at the antenna was adequate, but not
excessive. The interference antenna, used to transmit signals
from the signal generator, was placed 3 meters away from
the measurement antenna, also 1.2 meters in height and
2 meters from the tunnel walls.
The testing procedure began by measuring the trans-
mitter’s signal power using the spectrum analyzer, with the
signal generator turned off. Next, the interference signal
power was measured by turning off the transmitter and
activating the signal generator at a specified power level.
Finally, both the transmitter and receiver boards were acti-
vated, along with the signal generator at the predetermined
power setting. Each test lasted between 20 to 30 minutes,
collecting data until at least 5,000 packets or 320 Kbits
were received for analysis.
TEST RESULTS
Test 1: Assessment of wireless communication quality
when there is active communication in an adjacent
channel
In this test, we evaluated the impact of interference from
an adjacent wireless channel on a communication chan-
nel within a mining tunnel environment. The interference
Table 1. Wireless evaluation board settings
Carrier Frequency 915 MHz
Modulation Gaussian Frequency-Shift
Keying (GFSK)
Frequency Modulation
Deviation
20 kHz
Data Rate 38.4 kbps
Receiver Channel Filter
Bandwidth
100 kHz
Table 2. Wireless interference signal settings
Carrier Frequency 914.4 MHz
Modulation Gaussian Frequency-Shift
Keying (GFSK)
Frequency Modulation
Deviation
128 kHz
Data Rate 200 kbps
Transmit Channel Gaussian
Filter Bandwidth
100 kHz
Figure 1. Measurement setup
laptop through a USB port. The report includes the num-
ber of good packets received, the number of packets sup-
posed to be received based on the packet ID, the number
of errored bits, the number of lost or errored packets, and
other parameters of interest. By inspecting the report, we
can evaluate the bit error rate, packet loss or error rate, and
packet drop time (time between successful packet recep-
tions) of the remote-control communication system under
various conditions in underground mines.
Interference was generated using a signal generator with
configurable modulation schemes, frequencies, and power
levels. The interference waveforms replicated the actual
wireless communication near the machinery involved in
the communication dropout issue in the mine, employing
Gaussian frequency-shift keying (GFSK) modulation with
a 200 kbps data rate and a 100 kHz channel bandwidth.
An external trigger was connected to the signal generator to
control the duty cycle and the duration of the interference
signal. The following two tables, Table 1 and Table 2, show
the communication parameters that we used in our testing.
The tests were conducted in a closed-ended min-
ing tunnel in the Pittsburgh Safety Research Coal Mine
approximately 4 meters wide and 2 meters high, shown in
Figure 1. A spectrum analyzer and a measurement antenna
were utilized to assess the signal power from both the trans-
mitter and interference sources. The measurement antenna
was positioned 3 meters from the tunnel’s closed end and
2 meters from the side walls, with a height of 1.2 meters.
The receiver board was mounted on a tripod in alignment
with the measurement antenna, while the transmitter
was placed at the far end of the tunnel to ensure that the
received signal power at the antenna was adequate, but not
excessive. The interference antenna, used to transmit signals
from the signal generator, was placed 3 meters away from
the measurement antenna, also 1.2 meters in height and
2 meters from the tunnel walls.
The testing procedure began by measuring the trans-
mitter’s signal power using the spectrum analyzer, with the
signal generator turned off. Next, the interference signal
power was measured by turning off the transmitter and
activating the signal generator at a specified power level.
Finally, both the transmitter and receiver boards were acti-
vated, along with the signal generator at the predetermined
power setting. Each test lasted between 20 to 30 minutes,
collecting data until at least 5,000 packets or 320 Kbits
were received for analysis.
TEST RESULTS
Test 1: Assessment of wireless communication quality
when there is active communication in an adjacent
channel
In this test, we evaluated the impact of interference from
an adjacent wireless channel on a communication chan-
nel within a mining tunnel environment. The interference
Table 1. Wireless evaluation board settings
Carrier Frequency 915 MHz
Modulation Gaussian Frequency-Shift
Keying (GFSK)
Frequency Modulation
Deviation
20 kHz
Data Rate 38.4 kbps
Receiver Channel Filter
Bandwidth
100 kHz
Table 2. Wireless interference signal settings
Carrier Frequency 914.4 MHz
Modulation Gaussian Frequency-Shift
Keying (GFSK)
Frequency Modulation
Deviation
128 kHz
Data Rate 200 kbps
Transmit Channel Gaussian
Filter Bandwidth
100 kHz
Figure 1. Measurement setup