The parameter is normally stated in dBrnC, the actual measurement is expressed in dBrnC0 depending on the TLP where the measurement is made.
dBrnC - Weighted noise power in dBrn, measured by a noise measurement set with C-message weighting. dBrnC0 - Noise power in dBrnC referred to or measured at a zero transmission level point. --- Telephony's Dictionary by Graham Langley, April 1986, published by Telephony Publishing, Chicago "...power measurements are usually expressed in deciBels relative to one milliwatt (dBm) or in deciBels relative to reference noise, weighted or unweighted (dBrn or dBrnC). Further, such expressions aare often referred to zero (0) Transmission Level Point (TLP) and are expressed as dBm0, dBrn0, dBrnC0. Often the measurement of a single-frequency interference, such as a power-frequency harmonic, is made in dBm and translated into dBm0 or dBrnC0. Some wave analyzers designed for such measurements aare calibrated directly in dBrn. Some interfaces which cover a broad specrum are measured in the voiceband in dBrnC and translated into dBrnC0. The measurement may be made in dBm if the interference is being evaluated for wideband signal impairment. If the interference has impulse noise characteristics, the measurement must account in some way for interference amplitude and frequency of occurance. The measurement is often expressed in counts per minute, an evaluation of the average number of impulses measured in excess of a threshold value. The threshold depends on the type of signal for which the interference is being evaluated and, of course, on the TLP at which the measurement is made."--- Chapter 17-4 NOISE AND CROSSTALK MEASUREMENTS, page 437 of (the Red Book) Telecommunications Transmission Engineering Vol. 1 copyright 1977 by AT&T & Bell Labs, published by the Bell System Center for Technical Education. I have more information in my library at home if you need it. Hope this helps. Don Don Robert House, MTS Excelsus Technologies, Inc. (760) 476-1511 Office (760) 476-1519 FAX (760) 432-3397 Pager New e-mail address: dho...@excelsus-tech.com URL: http://www.excelsus-tech.com -----Original Message----- From: Ron Pickard [mailto:rpick...@hypercom.com] Sent: Thursday, June 15, 2000 2:20 PM To: t...@world.std.com; nebs@world.std.com Subject: GR-1089 query To all the audio members out there, I've been asked a question regarding GR-1089 ยง3.5.3c (voiceband noise). The question is "The max noise level is shown as -20dBrnC. Since this would depend on codec gain set, do they actually mean dBrnC0 ?" Any assistance with this question would be most appreciated. Also, I would be interested in the correlation between dBrnc and dBrnc0. Best regards, Ron Pickard rpick...@hypercom.com
