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 Frequency | 768 MHz |
| Bandwidth | 8 MHz |
| Power, RMS | 5 kW |
| Modulation | 64QAM R5/6 |
| Second harmonic level | – 71 dB |
| Antenna height | 190 m |
| Antenna gain | 5 dB |
| Antenna radiation pattern | omnidirectional |
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:
Measurement Results
5 km Measuring Point
90 m Measuring Point
Spoofing detection rate (false alarm rate) < 0.15%
Spoofing detection rate (false alarm rate due to interference) > 2.5%
CN0 Average – 38 dB
CN0 Average – 28 dB
PDOP Peak – 1.44
PDOP RMS – 1.0
PDOP Peak – 5.06
PDOP RMS – 1.5
Position error, Peak – 12 m
Position error, RMS – 2.5 m
Position error, Peak – 41 m
Position error, RMS – 12 m
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
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
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.
