6.17 Threshold level:
6.17.1 Threshold 1 Adjustable over the range 2μV to 10μV (1368).
6.17.2 Threshold 2 Adjustable over the range 10 to 20μV (1369).
6.18 Aerial horizontal response Omnidirectional (1370).
6.19 Aerial polarisation Horizontal (1371).
6.20 Storage of results
6.20.1 Channel occupancy data shall be sent either directly to a printer or stored on computer disk or both (1372).
6.20.2 Modulation information shall be stored on a suitable audio recording device (1373).
NOTE: Suitable audio devices include such media as standard audio cassettes and solid state digital storage.
6.20.3 Recommendation. The results should be stored in a format which will facilitate further analysis (1374).
7 Calibration
7.1 Documented calibration procedures shall be applied to all equipment involved in the measurement of radio noise level (1375). All equipment and standards used in the calibration process shall have traceability to national or international standards (1376).
7.2 When any equipment used is claimed to be self calibrating, the internal processes involved shall be clearly defined (1377). This involves showing how the equipment’s internal standard is applied to each of the parameters which it can measure or generate. The internal standard shall have traceability to national or international standards (1378).
7.3 Calibration intervals shall be stated in the calibration records (1379). Evidence shall be available to support the quoted calibration intervals (1380).
8 Standard Settings
8.1 For normal operation, threshold settings shall be:
Threshold 1 4.5μV (1381)
Threshold 2 13μV (1382)
9 Data to be Recorded
9.1 For each scan across the frequency band, when any signal exceeds threshold 1, the following parameters shall be recorded: a) The date and time (1383). b) The frequency or channel number of each channel having a signal exceeding threshold 1 (1384). c) The strength of all signals exceeding threshold 1 (1385).
NOTE: For signals greater than 100μV, the absolute signal strength need not be recorded. It is sufficient to state '>100μV'.
9.2 Where the signal strength exceeds threshold 2 and modulation is present, the detected modulation shall be recorded (1386).
NOTE: Modulation is recorded to assist in identifying an offending transmission.
10 Location of Measuring Equipment
10.1 Horizontal position:
10.1.1 If a single measurement point is used for the complete airport, then the aerial shall be located near the mid point of the runway (1387). If an alternative location in the approach area is used, the measurements shall only apply to that particular approach (1388).
10.1.2 Measurements near the mid point shall only be made with equipment that is immune to blocking from the operational localiser (1389).
10.2 Vertical position:
The aerial shall be higher than any obstructions in the immediate vicinity (1390) but shall not be an obstruction to aircraft (1391).
11 Measurement Interval and Duration of Measurement
11.1 Interval:
The measurement shall be made on each Cat II and Cat III runway at intervals not exceeding one year (1393).
11.2 Duration:
The total measurement period shall be a minimum of 350 hours in any one year (1394). The measurement need not be made in one continuous period.
12 Report
12.1 The report shall show the total number of times that each channel has signals present with strengths :
a) Exceeding threshold 1 but not threshold 2 (1395).
b) Exceeding threshold 2 (1396).
12.2 The present acceptance limit is an interference rate equivalent to < 2 x 10-5 events per second. An event being a signal > 13μV. The total rate shall be calculated as an average over the total monitoring time (1397). Submitted results shall show the calculations used in producing the figures for the interference rate (1398). 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：CAP 670 Air Traffic Services Safety Requirements 2(42)
