Abstract
The general Radio type 1921 real-time analyzer employs a combination of analog and digital techniques for determining the true rms levels within 13-oct bands. Samples of a filtered input signal are taken over spans of time varying from 18 sec to 32 sec at the operator's discretion. Each sample is converted to a digital value by an analog-to-digital converter. The resulting binary number is squared and added to any preexisting values in a memory bank. The memory contents at the end of each measurement represent a sum of the squares in digital form. This sum is decoded through a “hard-wired” routine to give a level in decibels. Dynamic range of 60 dB (plus a 10-dB crest-factor reserve at full scale) is provided. Frequency range depends on the analog filters selected; various combinations from 3.15 Hz to 80 kHz are available in standard instruments. Detector accuracy is ±1 dB for all combinations of amplitude and frequency; in most cases, it is ±0.5 dB. Answers are displayed by both analog and digital methods: a voltage proportional to level and a voltage proportional to band number are provided for deflecting an oscilloscope; digital results are shown on Nixie tubes, and made available as binary-coded-decimal voltages to operate computers or printers. Results are equally good with signals of all types: noise, sine waves, tone bursts, and AM and FM signals.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
