5. Session D "Meteorological Radars" Presentation 5.2.A: "Wind profiler radars"

1. Workshop on Radiofrequencies for Meteorology 5. Session D "Meteorological Radars"Presentation 5.2.A: "Wind profiler radars" by Hans Richner, chairman SG RFCIACETH, Zurich, Switzerland

2. What is as wind profiling radar? • 1. active remote sensing system, i.e., it emits radiofrequencies • 2. specialized Doppler radar system with elaborate data processing

3. basic beam configuration of a wind profiler

5. horizontal motion can be decomposed into a radial and a perpendicular component

6. The CWINDE network in Europe

8. wind profilers come in many shapes an sizes!

9. height ranges for the different frequencies

10. 50 MHz here we have allocations for wind profilers! 400 MHz 1000 MHz rough representation of the different allocations in the frequency range 30 - 1300 MHz

11. 915 MHz (region 2 only!) 1290 MHz situation near 1000 MHz

12. RESOLUTION COM5‑5 (WRC‑97) IMPLEMENTATION OF WIND PROFILER RADARS ... 1 to urge administrations to implement wind profiler radars as radiolocation service systems in the following bands, having due regard to the potential for incompatibility with other services and assignments to stations in these services, thereby taking due account of the principle of geographical separation, in particular with regard to neighbouring countries, and keeping in mind the category of service of each of these services: 46 - 68 MHz in accordance with No. S5.162A 440 - 450 MHz 470 - 494 MHz in accordance with No. S5.291A 904 - 928 MHz in Region 2 only 1270 - 1 295 MHz 1 300 - 1 375 MHz; ...

13. 44 68 excerpt from Radio Regulations:

14. S5.162A Additional allocation: in Germany, Austria, Belgium, Bosnia and Herzegovina, China, Vatican, Denmark, Spain, Estonia, Finland, France, Ireland, Iceland Italy, Latvia, The Former Yugoslav Republic of Macedonia, Liechtenstein, Lithuania, Luxembourg, Moldova, Monaco, Norway, Netherlands, Poland, Portugal, Slovakia, the Czech Republic, the United Kingdom, Russia, Sweden, Switzerland and Turkey, the band 46 - 68 MHz is also allocated to the radiolocation service on a secondary basis. This use is limited to the operation of wind profiler radars in accordance with Resolution COM5-5 (WRC-97). 46 - 68 MHz is also allocated to the radio-location service on a secondary basis use is limited to the operation of wind profiler radars

15. RESOLUTION COM5‑5 (WRC‑97) IMPLEMENTATION OF WIND PROFILER RADARS ... 1 to urge administrations to implement wind profiler radars as radiolocation service systems in the following bands, having due regard to the potential for incompatibility with other services and assignments to stations in these services, thereby taking due account of the principle of geographical separation, in particular with regard to neighbouring countries, and keeping in mind the category of service of each of these services: 46 - 68 MHz in accordance with No. S5.162A 440 - 450 MHz 470 - 494 MHz in accordance with No. S5.291A 904 - 928 MHz in Region 2 only 1270 - 1 295 MHz 1 300 - 1 375 MHz; ...

16. 440-450 Radiolocation

17. 470 - 494 MHz is also allocated to the radiolocation service on a secondary basis • S5.291A Additional allocation: in Germany, Austria, Denmark, Estonia, Finland, Liechtenstein, Norway, Netherlands, the Czech Republic and Switzerland, the band 470 - 494 MHz is also allocated to the radiolocation service on a secondary basis. This use is limited to the operation of wind profiler radars in accordance with Resolution COM5-5 (WRC-97). use is limited to the operation of wind profiler radars

18. RESOLUTION COM5‑5 (WRC‑97) IMPLEMENTATION OF WIND PROFILER RADARS ... 1 to urge administrations to implement wind profiler radars as radiolocation service systems in the following bands, having due regard to the potential for incompatibility with other services and assignments to stations in these services, thereby taking due account of the principle of geographical separation, in particular with regard to neighbouring countries, and keeping in mind the category of service of each of these services: 46 - 68 MHz in accordance with No. S5.162A 440 - 450 MHz 470 - 494 MHz in accordance with No. S5.291A 904 - 928 MHz in Region 2 only 1270 - 1 295 MHz 1 300 - 1 375 MHz; ...

19. 902-928 Radiolocation

20. 707In Region 2, the band 902 - 928 MHz (center frequency 915 MHz) is designated for industrial, scientific and medical (ISM) applications. Radiocommunication services operating within this band must accept harmful interference which may be caused by these applications. ISM equipment operating in this band is subject to provisions of No. 1815.

21. RADIOLOCATION 1270 - 1295 CO-PRIMARY !!! Radiolocation 1300 - 1375 RADIOLOCATION CO-PRIMARY !!! RADIOLOCATION

22. Summary of basic allocations for wind profilers: • 50 MHz systems: • 46 - 68 MHz worldwide, case by case • 400 MHz systems: • 470 - 494 MHz in Region 1 (Europe) • 440 - 450 MHz in Region 2 (Americas) • 1000 MHz systems: • 1270 - 1295 MHz Region 1 • 915 MHz Region 2

23. EMC (electromagnetic compatibility) considerations Basically two different problems: (i) the profiler must be protected from receiving signals from other sources (ii) the profiler must not emit signals that interfere with other communication (e.g. TV) or location (e.g. radar) systems.

24. passive measures • siting • improving the antenna always alleviates both problems active measures • increasing transmitter power • increasing receiver sensitivity

25. EMC problems are specific for profiler families The most important potential interfering systems include: 50 MHz: band I television system (which, however, are gradually phased out), communication systemsnearby power lines 400 MHz: band IV television systems 1000 MHz: air route surveillance radars (ARSR)space-borne SAR (?)Galileo (?)

26. rule of thumb Wherever possible, a maximum frequency separation as well as a maximum distance separation should be sought. 400 MHz profilers can operate within television channel, if distance separation is about 40 km from TV servicing area. Maximal side lobe suppression is an effective measure for preventing problems.

27. summary for alleviating any of the EMC problems, proper distance and/or frequency separation, an optimized orientation of the inclined beams, plus a very "clean" radiation pattern are the most effective means. The latter can be improved by either "artificial" (fence) or "natural" (depression) shielding.

28. Antenna radiation pattern of the vertical and an oblique beam of a 482 MHz wind profiler

29. continuous wave modulated (here AM) pulsed the heartaches with pulsed systems…. frequency domaine(spectrum) time domaine

30. manufacturers and scientists have to get used to the fact that that they must not occupy excessive bandwidth! first wind profilers ratio 8 : 1 best wind profilers today ratio 1.5 : 1

31. cac cem Workshop RF for Meteorology, October 7/8, 2002, Geneva RASS: Radio-Acoustic Sounding System Bragg condition: ac = 2· em cac = 20.05·sqrt(Tv)

34. The End

35. Co-channel operation with ARSR has not been investigated; however, experiments were carried out where the spectrum of a 1260 MHz ARSR partially overlapped with that of a 1290 MHz profiler. A separation of 8 km proved to be sufficient to prevent the radar from interfering with the profiler. (Given the huge power of the ARSR, the problem of the profiler interfering with the radar is not an issue.)

36. The operators of Earth exploration satellites using synthetic aperture radar (SARs) repeatedly claimed to suffer from interference caused by wind profilers. However, there is no evidence -- neither experimental nor theoretic -- that a wind profiler ever interfered with a SAR system. It should be remembered that the power in the very narrow main beam of a profiler is about 20 dB less than the isotropically radiated power of an ARSR, and both are operated in the same frequency region.

38. f1 f1 f2 f2 u just a little theory: “classic” radar t = time delay between signal sent and echo received; distance = F(t) Doppler radar t = time delay between signal sent and echo received; distance = F(t) f = f1 - f2 = Doppler shift; radial velocity u = G(f)