DVB-T2 Can Distort GNSS Performance

Many researchers analyze the impact of radio interference on GNSS signal reception:

Impact Study of Unintentional Interference on GNSS Receivers
GNSS Interference: Effects and Solutions
EFFECTS OF RADIO FREQUENCY INTERFERENCE ON GNSS RECEIVER OUTPUT

Albeit, some of our clients doubt that GNSS receivers can be susceptible to out-of-band radio interference.

This article demonstrates the practical results of GNSS receiver performance degradation due to the second harmonic of the DVB-T2 transmitter.

Customer Challenge

Our customer complains of poor quality GNSS reception near the TV tower. Our task is to make long-term GNSS signal measurements at different points and find the GNSS antenna’s best position.

DVB-T2 Transmitter Parameters

Central Frequency768 MHz
Bandwidth8 MHz
Power, RMS5 kW
Modulation64QAM R5/6
Second harmonic level– 71 dB
Antenna height190 m
Antenna gain5 dB
Antenna radiation patternomnidirectional
DVB-T2 Transmitter View
DVB-T2 Transmitter View
DVB-T2 Transmitter View

GP-Probes Position

In this article, we provide measurement results at only two points. The first GP-Probe is 5 km from the tower. The second installation point is at the foot of the TV tower at a distance of 90 m:

DVB-T2 Transmitter Sattelates View

Measurement Results

5 km Measuring Point

90 m Measuring Point

Spoofing detection rate (false alarm rate) < 0.15%

GP-Probe 5km results - GNSS spoofing

Spoofing detection rate (false alarm rate due to interference) > 2.5%

GP-Probe 90m results - GNSS spoofing

CN0 Average – 38 dB

GP-Probe 5km results - CNO Average

CN0 Average – 28 dB

GP-Probe 90m results - CNO Average

PDOP Peak – 1.44
PDOP RMS – 1.0

GP-Probe 5km results - PDOP

PDOP Peak – 5.06
PDOP RMS – 1.5

GP-Probe 90m results - PDOP

Position error, Peak – 12 m
Position error, RMS – 2.5 m

GP-Probe 5km results - Position Error
GP-Probe 5km results - Position Deviation

Position error, Peak – 41 m
Position error, RMS – 12 m

GP-Probe 90m results - Position Error
GP-Probe 90m results - Position Deviation

Number of satellites in view:

  • GPS Max – 14
  • GPS Min – 6
  • GPS Average – 11
  • GLONASS Max – 11
  • GLONASS Min – 5
  • GLONASS Average – 9
  • Galileo Max – 8
  • Galileo Min – 5
  • Galileo Average – 8
GP-Probe 5km results - Number of satts

Number of satellites in view:

  • GPS Max – 14
  • GPS Min – 6
  • GPS Average – 11
  • GLONASS Max – 11
  • GLONASS Min – 5
  • GLONASS Average – 9
  • Galileo Max – 8
  • Galileo Min – 5
  • Galileo Average – 8
GP-Probe 90m results - Number of satts
GP-Probe 5km results - All Charts 1

Conclusions

Hundreds of meters from the DVB-T2 transmitter @ 768 MHz, a significant degradation of the quality of the GNSS signal reception transpired. GNSS positioning accuracy decreases by a factor of five.

The number of visible satellites has a weak correlation with the interference level.

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