Fiddler on the Tree - A Bush-Cricket Species with Unusual Stridulatory Organs and Song
Insects of the order Orthoptera are well-known for their acoustic communication. The structures used for this purpose show a high diversity which obviously relates to differences in song parameters and to the physics of sound production. Here we describe song and morphology of the sound producing organs of a tropical bush-cricket, Ectomoptera nepicauda, from East Africa. It has a very unusual calling song consisting of frequency-modulated, pure-tone sounds in the high ultrasonic range of 80 to120 kHz and produced by extremely fast wing movements. Concerning morphology, it represents the most extreme state in the degree of left-right fore-wing differentiation found among Orthoptera: the acoustic parts of the left fore-wing consist exclusively of the stridulatory file, comparable in function to the bow of a violin, while the right wing carries only the plectrum ( =  string) and mirror ( =  soundbox).
Ultrasonic reverse stridulation in the spider-like katydid Arachnoscelis (Orthoptera: Listrosceledinae)
This paper illustrates the biomechanics of sound production in the neotropical predaceous katydid Arachnoscelis arachnoides (Insecta: Orthoptera: Tettigoniidae). Described and previously known from only one male specimen, this genus of predaceous katydids resembles spiders in their general body appearance. To call distant females, male katydids produce songs by stridulation where one forewing possessing a sclerotized file rubs against a row of teeth (scraper) on the other wing. In most katydid species, the songs are produced during the wing-closing phase of the stridulation. Morphological comparative studies of the stridulatory apparatus of the type specimen of Arachnoscelis arachnoides and males of other closely related species suggest that this insect sings with a frequency of ca. 80 kHz to attract conspecific females. We found an abundant population of A. arachnoides in Central Northeast of Colombia and undertook a complete analysis of the biomechanics of stridulation in this species. Using ultrasound-sensitive equipment and high-speed video, we determined that male A. arachnoides sing at ca. 74 kHz and use elastic energy and wing deformation to reach such ultrasonic frequencies. In contrast to most katydids, males of this species produce their calls during the opening phase of the wing; this form of stridulation is discussed.
Third order nonlinear distortion of SAW duplexers in UMTS system
Nonlinearity distortion characterization and accurate modeling techniques for leaky surface acoustic wave (LSAW) devices have been desired in the recently years due to the applications of the Radio Frequency (RF) SAW duplexers in the third-generation (3G) telecommunication system, such as Universal Mobile Telecommunications System (UMTS). In the work, we first discuss the approaches to measure and characterize the 3rd order harmonic generation of the resonators on lithium tantalate YXl42° wafer and YXl48° wafer, with resonance frequency of 800MHz to 900 MHz; Second, we present an effective nonlinear Butterworth-van-Dyke (BVD) model to simulate the multi-tone 3rd order intermodulation effects of a band 5 duplexer; simulation result vs. measurement of 3rd order harmonic generation, 3rd order intermodulation (IMD3) and triple beat are presented.