Dastels writes, “In my last post I described how I hacked a 2Mbyte SPI flash onto a Trinket M0 to give it the memory space for CircutiPython of one of the M0 Express boards. This time I supersized an M0 Express board, specifically a Feather M0 Express, although the same hack should work on a Circuit Playground Express.”
Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:
Free PCB Sunday. The classic. Every week, get free PCBs right here on the blog comments
Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
Facebook PCB Friday. Free PCBs while you wait for the weekend
This builds on a previous lab, where orthogonal frequency division multiplexing (OFDM) is used with on/off keying to send data over the channel. This scheme achieved a data rate of about 14,000 bits per second with zero errors, resulting in a figure of merit of about 14,000. The high performance design utilizes orthogonal frequency division multiplexing (OFDM) and quadrature amplitude modulation (QAM) to achieve a figure of merit much higher than the previous lab.
The overall OFDM system block diagram is shown below (taken from Professor Wagner’s course’s Scribe notes)
The gentlemen for whom I’m developing this hardware for has requested some additional functionality. The additional functionality requested is a Pulse Oximetry measurement. Pulse Oximetry is the measurement of a person’s pulse along with how much oxygen is present within their blood. It is a common measurement made by medical practitioners to ensure their patients are in good health. I suspect for the medical device, this information will be correlated with a person’s breathing to assess how well a person’s lungs are working and how much oxygen from the air is getting into their blood.
Teardown, repair and analysis of an Agilent E4443A 3Hz – 6.7GHz PSA series Spectrum Analyzer from The Signal Path:
In this episode Shahriar repairs an Agilent PSA Series Spectrum Analyzer. The instrument generates many errors during self-alignment and produces no measurements below 3.2GHz. The block diagram of the unit is thoroughly presented and various possible failure points are considered. Based on the observation of the noise floor, the most likely cause is the second LO module. The measurement of the LO power indicates that the second LO power is fall below nominal.