A 400-to-900 MHz Receiver with Dual-domain Harmonic Rejection Exploiting Adaptive Interference Cancellation

Wideband direct-conversion harmonic-rejection (HR) receivers for software-defined radio aim to remove or relax the pre-mixer RF filters, which are inflexible, bulky and costly [1,2]. HR schemes derived from [3] are often used, but amplitude and phase mismatches limit HR to between 30 and 40dB [1,2]. A quick calculation shows that much more rejection is wanted: in order to bring harmonic responses down to the noise floor (e.g. −100dBm in 10MHz for 4dB NF), and cope with interferers between −40 and 0dBm, an HR of 60 to 100dB is needed. Also in terrestrial TV receivers and in applications like DVB-H with co-existence requirements with GSM/WLAN transmitters in a small telephone, high HR is needed

New measurements of cosmic infrared background fluctuations from early epochs

Cosmic infrared background fluctuations may contain measurable contribution from objects inaccessible to current telescopic studies, such as the first stars and other luminous objects in the first Gyr of the Universe's evolution. In an attempt to uncover this contribution we have analyzed the GOODS data obtained with the Spitzer IRAC instrument, which are deeper and cover larger scales than the Spitzer data we have previously analyzed. Here we report these new measurements of the cosmic infrared background (CIB) fluctuations remaining after removing cosmic sources to fainter levels than before. The remaining anisotropies on scales > 0.5 arcmin have a significant clustering component with a low shot-noise contribution. We show that these fluctuations cannot be accounted for by instrumental effects, nor by the Solar system and Galactic foreground emissions and must arise from extragalactic sources.Comment: Ap.J.Letters, in pres

Digitally-Enhanced Software-Defined Radio Receiver Robust to Out-of-Band Interference

A software-defined radio (SDR) receiver with improved robustness to out-of-band interference (OBI) is presented. Two main challenges are identified for an OBI-robust SDR receiver: out-of-band nonlinearity and harmonic mixing. Voltage gain at RF is avoided, and instead realized at baseband in combination with low-pass filtering to mitigate blockers and improve out-of-band IIP3. Two alternative “iterative” harmonic-rejection (HR) techniques are presented to achieve high HR robust to mismatch: a) an analog two-stage polyphase HR concept, which enhances the HR to more than 60 dB; b) a digital adaptive interference cancelling (AIC) technique, which can suppress one dominating harmonic by at least 80 dB. An accurate multiphase clock generator is presented for a mismatch-robust HR. A proof-of-concept receiver is implemented in 65 nm CMOS. Measurements show 34 dB gain, 4 dB NF, and 3.5 dBm in-band IIP3 while the out-of-band IIP3 is + 16 dBm without fine tuning. The measured RF bandwidth is up to 6 GHz and the 8-phase LO works up to 0.9 GHz (master clock up to 7.2 GHz). At 0.8 GHz LO, the analog two-stage polyphase HR achieves a second to sixth order HR > dB over 40 chips, while the digital AIC technique achieves HR > 80 dB for the dominating harmonic. The total power consumption is 50 mA from a 1.2 V supply

Cosmic Infrared Background Fluctuations and Zodiacal Light

We have performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution, or from IRAC observations of high latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field, at low ecliptic latitude where the zodiacal light intensity varies by factors of $\sim2$ over the range of solar elongations at which the field can be observed. We find that the white noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales ($\gtrsim100"$) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large scale power in the infrared background is not being caused by the zodiacal light.Comment: 17 pp. Accepted for publication in the Ap

Using Twitter and Curation Rotation as a Branding Strategy

As social media becomes deeply embedded in traditional marketing and marketing and branding campaigns, it has evolved from a supporting role to the main attraction in more innovative campaigns. One example is that Sweden’s Tourism Department, Visit Sweden, is using Twitter to show transparency, democracy and ingenuity, to allow Swedish citizens be the twitter voice of the country for one week, until the next Curator of Sweden is passed the account. This study examines how social media platform such as Twitter is used to excite new branding and marketing methods. It focuses on the method being “curation rotation” introduced by @Sweden

Teacher Professional Learning and High School Students\u27 Mississippi Subject Area Test Performance

The purpose of this study was to determine if there was any significant relationship between specific elements of professional learning and students’ performance on the state mandated Mississippi Subject Area Testing Program (SATP2). The study includes the design qualities of professional learning, the level of teacher involvement in the professional learning process, teacher beliefs regarding professional learning, and perceived administrative support of professional learning programs. The researcher utilized an original survey instrument entitled Professional Learning Design and Perception to gather quantitative data for the study. High school teachers of Algebra I, Biology I, English II, and U. S. History in sixteen districts across coastal Mississippi during the 2013-2014 were asked to voluntarily participate in the study since their students were required to take end of course assessments in these subject areas. Participating districts’ percentages of passing scores in each subject area were utilized as archival data for the study. Data indicated that while respondents’ participated in a wide variety of professional learning opportunities, peer collaboration, workshops, and PLCs were the most attended. Additionally, data revealed that a majority of respondents were not given much choice when it came to the type of professional learning they attended; however, learning did align with state curriculum standards. Respondents also indicated that they did not have much input into their own professional learning, nor did student data play a significant role in the professional learning process. One significant relationship revealed during the research was a slight positive correlation between teacher input in the professional learning process and students’ scores on the SATP2 assessment. Additionally, data indicated that collectively all of the professional learning elements targeted for research were significant in the prediction of SATP2 scores, while individually, the only coefficient indicating significance was respondents’ beliefs