• Kare Oksanen commented on 2010-11-12 08:15:37.15:
  In other industrial standards pre-calibration is recognized in 3GPP Technical specification 3GPP TS 51.010-1 for GSM/EDGE. In test case 12.2 Radiated spurious emissions it is mentioned in 12.2.1.4.2 (b): ''In case of an anechoic shielded chamber pre-calibration may be used instead of a substitution measurement.'' OATS measurement are still required to be done with substitution method obviously due to more unstable ambient factors, where pre-calibration may not be valid in all conditions.

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• Dennis Ward commented on 2010-10-26 16:47:43.61:
  On Oct 19th at the TCB training session the FCC stated that antenna substitution using a precalibrated field method was not acceptable and has never been accpeptable for compliance to the FCC rules. Is this statement meant to be taken to mean TCBs and test labs are to stop using this method immediately as of Oct 19th, 2010, or can a later date be used to stop using the method. For example, a month from the date the FCC stated the issue?

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• Dennis Ward commented on 2010-10-26 16:45:06.07:
  I can agree with Mike Heckrotte to a point. What seems to be missing in the explanation is that this measurement of path loss stated in TIA603 is done at the time of testing the EUT, not 6 months to a year or more before. So, while a path loss for radiated spurious emissions is in TIA, it is very explicitly stated to be done at the time of EUT testing not at any significant date prior. The issue is not if path loss is determined via set generator input level etc, the issue is, how does the lab control the calibration of the field and all instrumentation when previously done months to a year earlier? What controls are in place to ensure all the exact same test equipment is used, including cables, generators, separation distance and even EUT location; or that something has not happened to degrade the performance of this equipment? This latter can have significant effect on the readings. For example, look at the wide spread values obtained when 'calibrating' an immunity field using 16 points. The variation in field strength can be significant. It would be expected to be a similar situation in this instance; especially since it is not possible to guarantee that the transmit antenna of the EUT would always in all cases be placed at the exact same location of a precalibrated field point. In some instances this could lead to 3dB or more variance if not strictly controlled.

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• Mike Heckrotte commented on 2010-10-18 16:24:02.133:
  
  TIA 603-C already allows a similar procedure, under Clause 2.2.17.2. One merely needs to perform 2.2.17.2.2 steps c) and d) prior to performing 2.2.17.2.2 steps a), b), e), f) and applying the equation in 2.2.17.2.1 as applicable.
   
  This is similar in that it does not yield a pre-calibrated field per se; rather it is a predetermined path loss measurement.
   
  The LOSS of the chamber, which includes the half-wave dipole (or other antenna whose gain is known relative to an ideal half-wave dipole), radiated path loss, measurement antenna gain, receive-side cable loss, etc., is measured in steps c) and d). This LOSS measurement is independent of any particular EUT, which provides the justification for performing these two steps in advance.
   
  Regarding maximizing the reading during this LOSS measurement, a swept frequency method of measuring the LOSS of the chamber can be utilized as long as the frequency sweep rate is much faster than the antenna height scan rate.

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Note: It is important to understand that the staff guidance provided in the KDB is intended to assist the public in following Commission requirements and does not constitute rules. Accordingly, the guidance is not binding on the Commission and will not prevent the Commission from making a different decision in any matter that comes to its attention for resolution.