Monthly Archives: October 2014

The Big Sunspot, with a sense of perspective…

Earlier this week, I snapped a couple of iPhone photos of the partial solar eclipse with my iPhone, through coworker Eric’s mighty spiffy little Questar, equipped with a filter. Despite the glare, I was shocked at how much detail was actually available, especially for sunspot group 2192, which has been busy kicking off solar flares all week (six major events at last count). I decided to crop the image, convert it to grayscale and work on enhancing the contrast. I also thought it would be nice to get some idea of how truly huge this spot was. Using eye protection, I could see the spot clearly without any magnification at all. But I thought it might be cool to see how big it was compared to the earth. I measured the diameter (roughly) of the solar disk on the image, and then divided it by 109 (the sun’s diameter is about 109x the diameter of the earth). Convert that to pixels, and you get the following picture:

howbig

At scale, the earth is only 14 pixels wide.

Does the universe make you feel small?

FTDI-gate…

My hardware hacking friends have been all a-twitter (and all a-pick-your-favorite-social-platform) about recent actions by FTDI. In case one of my three or so regulars haven’t heard about this dust-up, here’s a brief synopsis.

  • FTDI makes a series of chips which translate between USB and either RS232 serial or TTL level serial signals. These chips are used in (among many other devices) many types of Arduino boards and many USB dongles that are used to program them.
  • Because of their popularity, clones of these chips have been created. These chips are not simple copies, but functionally equivalent replicas, designed to operate the same as FTDI’s chips. There are benefits to this: since they operate the same as FTDI chips, they do not require separate drivers. They are also drop-in replacements for existing designs.
  • Because they are drop-in replacements, unscrupulous parts distributors have “rebadged” this clone chips as the genuine article. These chips are genuine counterfeits. But in many cases, the buyers of these chips have idea that counterfeits have been substituted for the genuine article.
  • Microsoft Windows has a mechanism that automatically updates operating system components (including device drivers) automatically. These updates, annoying as they are, are necessary to patch security vulnerabilities. FTDI releases driver updates as part of these regular updates.
  • FTDI decided to crack down on counterfeits. They released a new driver which attempts to detect non-FTDI chips. When it find ones, it disables the chip by overwriting the USB PID (the coded indentifier used by the USB system to find the proper driver for the device) to zero. This effectively keeps the USB system from using the device: it’s dead. Moving the device to any other machine (Mac OS X, Linux) doesn’t help either. The device is essentially bricked.
  • Note: while it is illegal to rebadge a chip and make it seem to be a genuine FTDI chip, clone chips are not illegal. The FTDI update does not attack counterfeits: it attacks clone chips. This puts all the pain not on the people guilty of fraud, but directly on end users, who have no way of even knowing if an FTDI chip or counterfeit is even in the product that for some reason, mysteriously stops working.
  • Because this update occurred as part of the silent windows update process, it now causes end-users to question whether they should accept updates. This is very, very bad for security.

FTDI: you screwed up. Big time. I know a number of people who manufacture goods using your chips, and they are scrambling to find alternatives because you have destroyed the trust relationship that they have with their customers.

Their reaction via Twitter has been equally without clue. To whit:

ZDNet’s article on FTDI debacle.

I was actually considering using an FTDI serial chip in my revision of my Minima project. Now, I’m looking for alternatives. Way to shoot yourself in the foot, FTDI.

Addendum:

From my twitter feed:

You reeky, motley-minded mammet!

Without further explanation:

[sourcecode lang=”python”]
#!/usr/bin/python

from random import choice
# ,, ,
# ‘ || || A Shakespearean insult generator
# \\ \\/\\ _-_, \\ \\ || =||=
# || || || ||_. || || || ||
# || || || ~ || || || || ||
# \\ \\ \\ ,-_- \\/\\ \\ \\,
#

c1 = [ "mewling", "paunchy", "pribbling", "puking", "puny", "qualling", "rank",
"reeky", "roguish", "ruttish", "saucy", "spleeny", "spongy", "surly"]
c2 = [ "idle-headed", "ill-breeding", "ill-nurtured", "knotty-pated",
"milk-livered", "motley-minded", "onion-eyed", "plume-plucked",
"pottle-deep", "pox-marked", "reeling-ripe", "rough-hewn",
"rude-growing", "rump-fed"]
c3 = [ "lewdster", "lout", "maggot-pie", "malt-worm", "mammet", "measle",
"minnow", "miscreant", "moldwarp", "mumble-news", "nut-hook",
"pidgeon-egg", "pignut", "puttock" ]

print "You %s, %s %s!" % (choice(c1), choice(c2), choice(c3))
[/sourcecode]

Inspired by an image that was posted to Facebook.

The Si570 and the Si5351

Thomas’ talk about the Minima at Pacificon has got me thinking about building one of my own. I actually have quite a few of the necessary parts in my junk box, but lacked a few things, so I made a quick list and sent a quick order off to Tayda. Tayda has really good prices on many of the discretes, connectors, sockets, etc… and even carries the ATMega 328 and LCD panels. Oh, and I got 25 20 Mhz crystals at $.10 each.

But they don’t carry the Si570 (not surprising). I found I could order those from Digikey, but they have an unusual footprint, and didn’t seem the most easy thing to breadboard. Most of the homebrewers seem to build the Minima on perfboard, but they seem to sketch over the details as to how they mount/solder this part down. I’ve been considering making my own version of the digital board and getting a pcb manufactured from OSHpark, and still might do that: I am reasonably capable at surface mount soldering. It might also allow me to make a couple of other changes to the digital circuitry:

  • I think relying on the disabling of pull ups in the ATMega to keep from frying the Si570 is just a bit sloppy. Two resistors and a 2N7000 will implement a simple level converter, and cost about $.50 for both lines.
  • I’ve actually thought it might be good to make the entire digital board run on 3.3v.
  • Considering a change in the LCD as well. Might be good to have a graphical LCD, or one that runs on lower power.
  • I like the idea of using rotary encoders instead of a pot.
  • A basic keypad might also prove useful.

Anyway, I’m getting a bit astray. To experiment, I thought it might be good to see if I could get an Si570 on a tiny breakout board so I could breadboard this up before building it for real. While surfing around and also reading today’s mail from the Minima mailing list, I learned about the Si5351. There is some speculation on the mailing list as to whether it is a reasonable chip to use in place of the Si570. In particular, people are concerned about its noise performance. But it does at least have some intriguing features:

  • It’s cheaper.
  • It is a more conventional package (10-MSOP, still surface mount, but more conventional)
  • It can generate 3 different clocks simultaneously (it could potentially replace both the BFO and LO)
  • NT7S has already written the code to interface to it.
  • Adafruit already has a nice little breakout board for it that only costs 8 bucks. It’s also already got pads to add some SMA connectors, which could make it a nice little bit of test equipment.

I’m not sure how to evaluate its performance, but it is at least possible to use it as the building block for an SSB transciever, as demonstrated by Jason NT7S using it in this reciever based upon the SA602:



And another early test in a QSO with AA7EE:

Jason has clearly been on top of this chip for a while, surfing his blog for the si5351 tag gives a ton of cool information. He even has his own board, quite similar to the Adafruit board, but it includes isolation transformers for each channel. Very nifty, and probably better suited for RF work than Adafruit’s board. Jason says he might e kitting a batch of the boards for sale: I’m gonna stay tuned.

Nifty stuff.

A day at Pacificon…

Pacificon is the local yearly hamfest, which took place at the Santa Clara Marriot this weekend. I couldn’t go for the entire weekend, but I decided that spending at least part of my Saturday amongst my fellow hams would be good fun, so I set my alarm to an annoyingly early time (for the weekend) so that I would be able to drive down ahead of the first Saturday session (which began at 8:15) and went to sleep.

The drive south was uneventful, I arrived at about 8:00. By then, the swap meet had been underway for about 2 hours or more (I never understood the desire of people to either sell or buy things so early in the morning) but I did a quick scan. I did see a few things that seemed pretty nice: I’ve been meaning to pick a Variac, and saw a couple of fairly nice ones for $80, but for whatever reason, I didn’t bite. I also saw an old TRS-80 Color Computer, which I thought was cool, but also decided against it (I’m sure to the great pleasure of my wife). I got myself registered, and headed off to my first session.

The first session I attended was the session on FreeDV given by Mel Whitten, K0PFX. FreeDV is a digital voice program that uses David Rowe’s Codec2 low-bitrate voice codec. Like many presentations which concentrate on software, it was fairly mundane, but I did come away with something I didn’t know: The FreeDV QSO finder. I had tried to play with FreeDV before, but had some difficulty locating people using it. The QSO finder might help. I also heard some progress on the SM1000 Smart Mic which is basically a computer that manages the digital codec stuff transparently, essentially turning any SSB transceiver into a digital voice transceiver. It’s still a work-in-progress, but sounds really cool. I also learned that FlexRadio has started shipping software that automatically integrates FreeDV, courtesy of a new architecture change that allows third-party code to be loaded into their proprietary SDR software. A nifty merger of open and closed software.

The next session I attended was given by Patrick Bunsold, WA6MHZ, entitled “Restoring Antique Radios”. You can check out his website here. He has an amazing, even a maniacal, collection of radios of all sorts. His presentation consisted of a huge number of slides of an incredible number of radios that he had acquired and restored. His presentation didn’t go into restoring the electronics, instead it was mostly centered on cosmetic restoration. While I found that a tiny bit less informative, ti was nevertheless a nice presentation. I ended up texting my wife that she should appreciate that my own enjoyment of the hobby didn’t involve acquiring dozens of each type of radio (he had 27 Heathkit Two-ers, for instance).

The third session was for me the most enjoyable. Thomas Sarlandie, KK6AHT, gave a talk entitled Building Minima, an HF Transceiver. The Minima is an all-band SSB transceiver, designed by Ashar Farhan, VU2ESE, who is also the designer of the popular BitX transciever. The Minima is a particularly interesting design. It is simple, inexpensive, modular, and frequency agile. It uses an ATMega328 (the same processor used in the Arduino) and an Si570 programmable oscillator chip from Silicon Labs. The Si570 can be instructed over the I2C bus to generate a wide variety of frequencies, which the Minima uses as the local oscillator signal. Very nice. Thomas’ presentation was really good. Luckily, you don’t need to take my word for it, you can look at his materials, as well as an audio recording on his web page. It’s inspiring: I’ve ordered some parts to start my own. More on that some other time.

During the lunch break, I bumped into Bruce Perens, K6BP. I first met Bruce over two decades ago when he was working at Pixar, and bump into him from time to time. He was giving a pair of presentations on on Alogram, his “HT of the Future” concept. I’ll try to dig out some online references to it, but the Bruce’s vision is basically to make an HT which is an open platform, and will allow you to create a more app-like environment where new modes can be quickly implemented. Nifty…

I also attended Joel Wilhite, KD6W’s talk on Building Your Own Microwave Rig. I’ve been interested in microwave operation for quite some time, but haven’t done much. I mostly filed it under “for future consumption”.

I bumped into a few other people, had some lunch, and then realized that I was getting tired. I stopped by the ARRL booth to renew my membership, and then headed home, thinking about crystal filters and the like all the way home.

A nice Saturday.