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Radiosonde Transmitter Standard

Radiosonde Transmitter Standard. A review for WMO information of the work of ETSI ERM Task Group TG028 2002-10-06 Ilkka Ikonen. Legal situation. Directive 1999/5/EC of the European Parliament and of the Council

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Radiosonde Transmitter Standard

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  1. Radiosonde Transmitter Standard A review for WMO information of the work of ETSI ERM Task Group TG028 2002-10-06 Ilkka Ikonen

  2. Legal situation • Directive 1999/5/EC of the European Parliament and of the Council of 9 March 1999 on radio equipment and telecommunications terminal equipment and the mutual recognition of their conformity • Apparatus put into service in the Member States (of EU) shall be submitted into the conformity assessment (of the essential requirements in the Article 3) • Manufacturer has the responsibility to show that apparatus comply with this directive and are properly marked

  3. Interpretations • One way to show the conformity is to apply harmonised standards. • Task of ETSI is to ensure that harmonised standards are appropriately updated and drafted in a way which allows unambiguous interpretation. • Apparatus meeting the appropriate standards shall bear CE marking. • Only CE marked apparatus are legal in EU.

  4. Why radiosonde transmitter standard ? • To comply with the R&TTE Directive 1999/5, and to show the conformity of the Article 3 • To take into account the radiosonde special requirements • wide temperature range, • disposable product. • To avoid the application of the EN300 220 SRD standard (presently applied in Germany) - Characterized by the use and telemetry distance radiosondes are not SRD but PMR (Personal Mobile Radio, Land Mobile Radio) equipment

  5. Specific radiosonde issues Two sondes at equal distance can co-exist • Hostile environment • temperature: +55oC to - 90oC • humidity: 0 - 100 % RH • pressure: down to 3 hPa • Large dynamical range - free space propagation loss: • 10 m >> 44 dB • 100 m >> 64 dB • 100 km >> 124 dB • 200 km >>130 dB • Observation cost issue - radiosonde is a disposable product Two sondes, one far away other close cannot co-exist

  6. Standardization process • Standards should be created co-operative basis within ETSI • All interested parties were welcome to participate • ETSI working group ERM-TG28 • work started early 2000 • PE - public enquiry from April to August 2002 • Working Group handling will be finished by late 2002 (after working group handling standard is de facto standard) • Standards are issued to the community in the EU official publication - should be applicable early 2003 • Accredited inspection body issues CE marking valid in EU

  7. What will the standard cover ? • Essential point is that different radiosondes are tested in the same way and same criteria are applied for acceptance. • Transmitter standard covers: • Test conditions, power sources and ambient conditions • General test conditions e.g. equipment used in testing • Measurement uncertainties • Methods of measurement and limits for transmitter parameters

  8. What will the standard not cover ? • Radiosonde transmitter standard covers only the test methods and spectrum usage issues. • Excluded from transmitter standardization are: • Quality of the product • Performance issues (other than spectrum related) • Modulation (but the standard covers digital modulation only) • Data transfer speed • Data contents and format • Receiving system properties and performance

  9. Test limits • Frequency error or drift: ± 20 kHz • Spectrum mask: Frequency relative Maximum relative to the nominal carrier power in 1 kHz BW ± 50 kHz to 100 kHz - 34 dBc/1kHz ± 100 kHz to 200 kHz - 40 dBc/1kHz ± 200 kHz to 300 kHz - 48 dBc/1kHz • Spurious transmissions when operating: Some freq. <1 GHz Other freq. < 1GHz Freq. > 1 GHz 200 nW (4 nW)* 1 μW (250 nW)* 1 μW (1 μW )* * SRD limits in brackets • ITU 1165-1 gives - 43 dBc which is about 10 μW

  10. Spectral mask example • A sample sonde transmitter has been tested. • The test result depends on the test method, e.g. Video Band Width setting. • Test methods should be unambiguous (!) - some times “plain” dB values are not enough

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