172pilot

Member Since: February 23, 2010

Country: United States

Profile

Bio

Geek, pilot, dad.

Role

Network engineer

  • I dont think this is entirely true.. Saying that “The worst-case for acoustic couplers talking to carbon microphones is somewhere around 300 baud” can only be true when you take into account several other factors, such as acceptable error rate (what is “worst case” based on? one error bit out of how many???) and also, saying it’s how fast the carbon mic can react ignores the fact that it’s using FSK and the actual tone being sent is between 1070hz and 2225hz depending on whos the initator/answerer, and if it’s a 0 or 1 being sent. (https://en.wikipedia.org/wiki/Bell_103_modem).. In the 80s, we were sometimes able to get these couplers to run at 150% rate (450 baud) depending on the quality of the phone line (some of my friends were out of the same telco CO, so better quality between us) so this isn’t telling the whole story. The frequencies chosen for the FSK had to take into account that the 4 tones needed (for each side to have separate frequency for 0 and 1), and make sure each tone fell within the range the phone system was created to convey ( I believe 300-3300 hz) and that the frequencies weren’t going to be related in frequency in such a way that they could cancel each other out or otherwise be confused for one another by the PLL circuitry on the other end that had to decode it. Once optimal frequencies were determined, I’d bet that the speed of a bit (and therefore BPS) had more to do with how long it took the PLL to lock on and detect the bit, while still having over ½ bit time to actually convey the correct bit to the attached computer. At 2225hz, with 300 BPS, that’s just over 7 audible sine waves per bit. That seems reasonable, considering it probably needs 2 cycles to lock.. I have no hard evidence that this had anything to do with design, but from years of playing with 300 baud modems and the physics of sound, I’m betting this is what was boiled down to “how fast a carbon mic can react”

  • I snipped the wires and used it on a Raspberry pi with a screw terminal proto top.. Not pretty but it works..

  • So.. This seems like a great little GPS.. I am making a position logger for a cruise I’m going on this weekend, and I’ve got it set just to record everything into giant NMEA text files, and I’ll figure out what to do with it when I get back, but I have one big problem.. There doesn’t seem to be a provided GPS sentence that would give me the current DATE.. I can get the TIME from the $GPGGA but there’s no DATE! It doesn’t send the $GPZDA sentence apparently, so I’m bummed.. I wanted this thing to set the time and name the output files based on the GPS provided date/time, but now I’m going to have to plug it in and make sure it gets the date set at least, so my files are correct.. Does anyone see anything I’m missing? –EDIT – False alarm… It DOES send the $GPRMC sentence, which also has the date, so it looks like I’m good!!

    That being said, sitting here in my house on my workbench, I just turn it on and I get 4 sats and a good fix in just a few seconds. I’m sure it’ll be great when it can see the sky!

  • OK.. This is a cool product, but in the demo video, he talks about effects pedals like the one that made Frampton’s “talk box” sound.. If I’m not mistaken, I believe there was no box for that.. He connected a tube from a funnel by the speaker to pick up the guitar sound, and then put that tube in his mouth by the mic, and used the shape of his mouth to make the guitar sound like it was talking… No box needed!

  • SIGN ME UP.. If I could get an Arduino to talk straight z-wave to my Vera, I’d be all over that!!

  • Oh wait.. there’s that sparkfun bilge pump I bought… Why did I buy a bilge pump? I dont know.. I have a pool and a hot tub.. somewhere in my brain there’s an arduino controlled pool water level controller project, or some way to pump hot tub water into the pool to heat it, but for now, it sits in the box.. :-)

  • Wow.. it’s as if you ONLY read my response.. Those were all my answers! :-) And yes.. the number of STARTED projects FAR exceeds the finished project, as I sit at this keyboard looking at an 8266 Thing Dev board plugged in and running but not doing anything, and Arduino UNO with Ethernet shield, plugged in and running nothing, a Pro Mini plugged into my computer running nothing, an Arduino mega sitting sadly unplugged, 2 RPis in boxes still, and a sparkfun robot chassis half built with a motor controller hanging off the side…. oh wait.. there’s another UNO.. And, that’s just the tech visible on the SURFACE of my messy desk, each related to separate projects that bumped another off of the front burner.. :-)

  • So.. that’s interesting, because I was actually coming here to post a question about it’s ability to DETECT a cat.. The video says it works best with a flat surface (of course) but if I just need to detect the existance of a fluffy cat getting ready to jump up on a birdcage, would it work… OR, would the 40khz be annoying enough to keep the cat away, and/or should I NOT do it because it will annoy/hurt the canary?!

  • For me, it’s the reliability and consistent quality, the support site, and often times the speed to get it to me.. I buy my fair share of “cheap stuff” off of the internet when I see something interesting, but dont have a particlar project in mind, but if I know I need something specific, I try to go to sparkfun.

  • But what does the WHITE button do?!

No public wish lists :(