Project TouCans Digital noise issue fixed-ish

The intermittent noise issues in Wireless TouCans are fixed! Sort of. After a variety of fixes that involved resoldering the audio jack and taping the audio cables in various locations, I finally arrived at a solution yesterday. The solution came in two parts and is still a little bit rough.

First, I replaced the rig's headphone jack with a headphone plug. It doesn't make a lot of sense for the rig to have a headphone jack, except for debug purposes—on rare occasions I plug in headphones while the rig is being worked on. It does make sense for it to have an audio micro-stereo plug since that's the format the Bluetooth audio transmitters expect.

You can see the original version of the audio out plug and patch cable in the picture of an early TouCans version below.

Notice the headphone jack to the left of the Bluetooth transmitter under the rain shield. That's the bit that's been removed. Now, the audio wires from the rig that were attached to the jack are soldered to a plug that plugs directly into the transmitter. That has helped by removing a few flaky connections.

The second change also had great affects for very little work. I moved the audio output wires so that they were not draped over the rigs power wires. This significantly reduced the noise heard in the headphones!

The Brand of Bluetooth Transmitter Matters... For Now

Due to a battery outage last night on the ML300 model of the 1Mii transmitter pictured above, I also tried our Aluratek transmitter and learned a few things. First, it's noise performance is better. Second, when it's battery is fully charged, it produces RFI that causes the Rockmite keyer to reboot on the first character it sends... Not good. Finally, it's range is not as wide as the 1Mii

For now, we're sticking with the 1Mii. It doesn't reboot the Rockmite's keyer and has a larger range. I wish it had better noise performance.

Next Steps

The next step will be to route the audio wires out of the can through a notch opposite to the current notch for the power wires. That will take the audio as far from the RFI causing power lines as possible.

UPDATE

I was able to try routing the audio connector out the other side of TouCans this morning. I also moved the ground wire for the audio so that it was plugged directly into the USB-C power supply. That helped with the noise issue. Taping the Bluetooth transmitter to TouCans so that it couldn't move quite as much resolved the rest of the noise issue! I now just hear white noise static for noise, you know, like you'd hear with a normal radio. Here's a look at the Bluetooth transmitter's current position with respect to the rig.

You can see it next to the cut off bag handle of the rain cover. You can see the arrangement even better in this video. There's a post coming soon about the new rain cover as well :)

There is still an RFI issue. With the keyer set at 20 wpm, the Rockmite will reboot after "cq de" The simple fix was to turn the keyer speed down to 18 wpm where the problem disappeared. I'll need to debug this further in the future.

The rig is proved out. I just had a QSO with W7SUB near Portland, Oregon!

The Valentine's Day Magnetic Monopole

There's an assymetry to the form of the two Maxwell's equations shown in picture 1. While the divergence of the electric field is proportional to the electric charge density at a given point, the divergence of the magnetic field is equal to zero. This is typically explained in the following way. While we know that electrons, the fundamental electric charge carriers exist, evidence seems to indicate that magnetic monopoles, the particles that would carry magnetic 'charge', either don't exist, or, the energies required to create them are so high that they are exceedingly rare. That doesn't stop us from looking for them though! Keeping with the theme of Fairbank[1] and his academic progeny over the semester break, today's post is about the discovery of a magnetic monopole candidate event by one of the Fairbank's graduate students, Blas Cabrera[2]. Cabrera was utilizing a loop type of magnetic monopole detector. Its operation is in...

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

Now available as a Kindle ebook for 99 cents ! Get a spiffy ebook, and fund more physics The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems , there seem to be fewer explanations of the procedure for deriving the conversion, so here goes! What do we actually want? To convert the Cartesian nabla to the nabla for another coordinate system, say… cylindrical coordinates. What we’ll need: 1. The Cartesian Nabla: 2. A set of equations relating the Cartesian coordinates to cylindrical coordinates: 3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system: How to do it: Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables. The chain ...

More Cowbell! Record Production using Google Forms and Charts

First, the what : This article shows how to embed a new Google Form into any web page. To demonstrate ths, a chart and form that allow blog readers to control the recording levels of each instrument in Blue Oyster Cult's "(Don't Fear) The Reaper" is used. HTML code from the Google version of the form included on this page is shown and the parts that need to be modified are highlighted. Next, the why : Google recently released an e-mail form feature that allows users of Google Documents to create an e-mail a form that automatically places each user's input into an associated spreadsheet. As it turns out, with a little bit of work, the forms that are created by Google Docs can be embedded into any web page. Now, The Goods: Click on the instrument you want turned up, click the submit button and then refresh the page. Through the magic of Google Forms as soon as you click on submit and refresh this web page, the data chart will update immediately. Turn up the:...

Copasetic Flow

Search This Blog