• Login
    View Item 
    •   Home
    • Conference Proceedings
    • International Telemetering Conference
    • International Telemetering Conference Proceedings, Volume 22 (1986)
    • View Item
    •   Home
    • Conference Proceedings
    • International Telemetering Conference
    • International Telemetering Conference Proceedings, Volume 22 (1986)
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    MEANINGFUL FM TRANSMITTER MODULATION LINEARITY MEASUREMENTS

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    ITC_1986_86-0882.pdf
    Size:
    61.18Kb
    Format:
    PDF
    Download
    Author
    Jeske, Harold O.
    Affiliation
    Sandia National Laboratories
    Issue Date
    1986-10
    
    Metadata
    Show full item record
    Rights
    Copyright © International Foundation for Telemetering
    Collection Information
    Proceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection.
    Publisher
    International Foundation for Telemetering
    Journal
    International Telemetering Conference Proceedings
    Abstract
    In Frequency Division Multiplex (FDM) systems, nonlinearities in the modulation and demodulation processes of the transmission system produce intermodulation (IM) products which are effectively added to the desired modulation. The effect of these added products is the degradation of data accuracy in the form of noise on the subcarrier data. Currently there are no standard test procedures or specifications that permit the prediction of the level of these IM products during system design. The characterization of transmitter modulation linearity by the measurement of IM, or cross-products, produced by simultaneous modulation by two tones, is considered ideal. This is because the test conditions can closely simulate the highest modulation level subcarriers used and the necessary demodulation equipment can he readily calibrated using common frequency modulated sources. The modulation tones used are both in the upper portion of the transmission system’s baseband and at a modulation level near the level of intended use. Measurement of only the difference frequency IM component, (f !f ), is considered 2 1 adequate for the determination of 2nd order nonlinearities. The 3rd order IM components are measured only at (2f !f ) and (2f !f ) and are normally found to be of equal 1 2 2 1 amplitudes with FM transmitters. All higher order products, as well as direct harmonics, are ignored. From the three IM level measurements, and the two desired tones, the 2nd and 3rd order modulation intercept points (IP and IP ) are determined in essentially the 2 3 same manner as the intercept point, or IP, that is common in specifying the linearity of broadband RF amplifiers. When the amplitude of the various signal and IM components are plotted on log-log scales, the desired signals have a slope of one while the 2nd and 3rd order products have slopes of two and three respectively. On log-log plots the intercept point is the modulation level at which extensions of the low level values of the IM components meet the extension of the desired modulation level. Once the IP values are determined, they may be readily used for system IM calculations. Measured IM levels in a sixteen channel FDM system compared very favorably with predicted levels using the IP values obtained from two-tone tests. The nonlinearities of the demodulator employed in the test system may be evaluated by the use of the “beat” frequency of two independently modulated FM signal sources as the required input to the demodulator. The IM products in the demodulator output in this case are due only to the demodulator’s transfer characteristics. IM product levels of the test system greater than 60 dB below the simultaneous modulation level of ±300 kHz each by 400 and 450 kHz tones are obtained at Sandia Laboratories. The use of two-tone IM tests for the evaluation and specification of FM transmitter modulation linearity is strongly recommended.
    Sponsors
    International Foundation for Telemetering
    ISSN
    0884-5123
    0074-9079
    Additional Links
    http://www.telemetry.org/
    Collections
    International Telemetering Conference Proceedings, Volume 22 (1986)

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.