APRS Receiver Champion / Challenger Experiment

What’s a better receiver for an APRS receiver for packets from the ISS? Let’s do a side by side test.

Left is the challenger Baofeng, Right is the RTL-SDR Champion

For several months now, I have been running signals from a discone antenna on my roof into a RTL/SDR receiver connected to a Raspberry Pi. On a good day, I pick up a few packets from the ARISS digipeater running on the ISS at 145.825 MHz.

I was wondering if I could hear more packets with a different receiver so I decided to create a side/-by-side A/B test. Here’s the configuration:

Discone Antenna fed into my “Tech Center” / Ham Shack
Split antenna with a coax “T” – one goes to champion setup, one to challenger. Using equal length coax with SMA connectors.

Champion Setup: $30 RTL/SDR dongle direct into a Raspberry Pi 4 B (8 GB) running Raspbian with the Direwolf software.

Challenger Setup: Baofeng UV5R ($20) connected via audio cable to a UGreen USB audio jack ($14) into a Raspberry Pi 4 B (8 GB) running Raspbian with the Direwolf software.

Both are tuned as best I can for audio quality using data on 144.390, and then switched to the ISS frequency.

The experiment was configured on Wednesday, December 21 in anticipation of a predicted 83 Degree Elevation pass on 22-Dec-22 at 17:26 UTC. I’ll update this blog as I get pass data in.

Update: 23-Dec-22 at 0955 UTC – A moderate height ISS pass (32 deg El) coming through this morning at 1007 UTC. Couldn’t gather data Wednesday because the ISS radios were off for the space walk.

Update: 23-Dec-22 at 1023 UTC – ISS radios were still off during the pass. Trying again later today (Friday).

Challenger radio on left, champion SDR on the right.

Update: 23-Dec-22 at 17:00 UTC – Good pass with many packets caught. There was an obvious winner in the SDR. You can see on the screen show it captured many packets while the Baofeng only reported 1 for the entire pass. Going to change HT’s and try again on a later pass.

iPhone 14 Pro and Apple Watch 8 Review

iPhone 14 and Apple Watch 8

Let’s start off with a true confession. I have GAS. Gear Acquisition Syndrome. I like to get new stuff and try it out. However, neither of these items are particularly new. So, why get the iPhone 14 Pro and the Apple Watch 8 now? Let’s take them in parts.

Back when the pandemic first started, I had an iPhone 10 (or is it X, I’m still not sure what I am supposed to say). Unfortunately something happened with it’s near field communications and I needed that. Not “I really want to have it” but “I have health related devices that use it, so I need it fixed.” Because COVID, I couldn’t get good help from Apple, the phone support sent me to the store, and the store sent me to phone support. You know the basic support circle-j***. I threw up my hands and got a Google Pixel 5 as a replacement.

Now, I like the Pixel 5. Fine phone with a really good camera. I think the Android platform lacks some of the fit and finish of Apple’s IOS, but nothing that was a real deal breaker for me. If it wasn’t for a couple of things I would have been content staying with Android. In fact, the transition from Apple to Android was much easier than the transition back. More on that in a moment.

What sold me on going back to Apple in general and the iPhone 14 Pro in particular were the emergency communications tools and the camera. As a ham radio operator I probably understand the limitations of wireless better than most people, but even then I have been let down by all the carriers while road tripping in places like South Georgia or the Blue Ridge Mountains. While I always seem to find a way in an emergency, I don’t like knowing I might go hours without coverage. The emergency messaging via satellite will help me fill in the gaps and give me peace of mind when I am on the road or in the mountains and that’s a huge value to me.

The other item I mentioned is photography, and I like to take pictures and videos so all types of changes in those areas get my attention. As I mentioned I am big on travel and one of the things I have been trying to do is reduce my load. When I go to the mountains for pictures I typically take a DSLR with tripods and computers to back up SD cards and it’s a lot of stuff. I felt that with the new camera – 48 Megapixels, lots of shooting modes and options, plus a much smaller footprint – I could break free of my DSLR. With a trip to England coming up, hitting 8 areas in 10 days, I wanted to keep my load low and this will help. The picture quality is very good versus the Pixel 5, not that the P5 is bad at all. See my first impressions blog post for a bakeoff. This article on PetaPixel gets into the upgrade benefits.

So, now you know why I made the switch. The how was painful, but it’s one time pain. Some brief takeaways:

– With the switch TO Android there was a nice tool to make the migration with a custom cable that connected the 2 devices. No cable here and I couldn’t even get the phones to talk to each other despite an app to promised to do that very thing.

– My wireless provider is AT&T Prepaid and they were not prepared to handle this type of conversion. The iPhone 14 Pro only uses and eSim while the Pixel 5 uses a physical one. I was without service for about 6 hours while I was sent from store to phone and almost back to store before a manager in Chat support saved me. I hope my experience became a support article so others don’t go through that pain.

Let’s talk a little about the watch. I had an Apple Watch 3 and it was fine. I didn’t feel like it was a critical device for me, and actually handed it down to a family member because I am more of a fan of mechanical watches. I did try a couple of Android watches, one from Samsung and one inexpensive knockoff. I wasn’t impressed and didn’t really integrate them into my lifestyle.

In the gap of 5 versions however, Apple has focused more on health apps and I have become more focused on my health. It was time to give the watch another try. A few week after getting the phone I went to West Farms Mall outside of Hartford and shopped the Apple store. My biggest question was, did I want to go with the Apple Watch Ultra or the Series 8. As much as I have that GAS I admitted earlier, I couldn’t bring myself to spend the extra $300 on the Ultra watch. First, I didn’t like the size. While I am OK with a big watch, that particular one just seemed very thick. Second, I didn’t need cellular connectivity on my watch. I don’t get separated from my phone that often that I need additional access, and I don’t want to pay the monthly vig for the privilege. Now in fairness, I don’t know if cellular activation is required, but it’s on more thing to break. So, I went with the base Series 8.

So far I am really pleased with all the integrations on the Series 8. Sleep tracking, exercise apps, health apps, controlling podcasts from the phone in my pocket, all good things so far. I also like the batter life. I charge it while in the shower and it runs most of the day without issues. Some nice watch faces too with different complications. That’s an area I want to explore more as I go.

So, outside of the computer (a custom built Windows PC with a bug that is fading) I am all in on Apple again. I’m not feeling like an Apple fanboy, just a user. One of the biggest lessons for me over the last year or so is that you may as well shop for the features you want and just be prepared to put in the time to fight with support, because no company these days is looking to have world class support.

The iPhone and watch are headed out on their first long road trip. I’ll update on performance if there is something significant to share. Thanks for reading and if you have any thoughts on this, please send me a tweet to @N4BFR on Twitter and help with the conversation.

Notification Process for 630 and 2200 Meter band Operation

While I haven’t played with these long wave bands yet, it would be nice to understand if I have any restrictions to that operation. Since the FCC requires me to notify the Utilities Technology Council 30 days before I start operation, I decided to do that.

The link wasn’t jumping out at me from the main utc.org page, but some Google-fu lead me here: https://utc.org/plc-database-amateur-notification-process/

Of course they want lat/long in Minutes and Seconds and all my GPS Pi’s deal in decimal coordinates, so I found this handy conversion tool on the FCC web site:
https://www.fcc.gov/media/radio/dms-decimal. It was only AFTER I found the FCC link that I noticed they linked to the same page. Usability opportunity to move that above the entry window or, heaven forbid, convert it themselves!

So, I dutifully entered the data right down to the 100th of a second because I am that kind of nerd and was informed I needed to round that to whole numbers. If they don’t mind a margin of error of 100 feet +/- in latitude, why not.

So my “notification” has been successfully submitted. Stay tuned for what happens next.

As always, provide feedback via my twitter @N4BFR.

The RFI Chase – Getting 20 Meters Back

For quite a while now I have been putting up with heavy RFI on 20 Meters in my shack and I have been really thinking it’s a neighborhood problem more than an in-home one. It looked like this on my waterfall:

Flex Smart SDR 20 Meter Band View

I was getting ready to call the power company and ask them to come fix the transformer outside my house. I based this on the fact that as I turned the antenna in a different direction, the closer I got to pointing at the transformer, the stronger the RFI became. Here is my chart.

Home made polar coordinate chart showing peak signal strength, along with a second measurement

So, step 1 was to identify the problem and a likely suspect. After reading a bunch of articles on RFI chasing, I wanted to 100% eliminate the chance that it could be something in the house, because if you look at the path between the Antenna and the Transformer, it goes over the house.

Antenna to Transformer

On to step 2 then, eliminate the house. So on Friday I set up one of my radios on battery, tuned to the peak of the signal and one by one turned off every breaker in the house and wouldn’t you know it went away!

So, one by one, I powered the breakers back up, starting with areas where I have a lot of electronics, including my shack, which is in that line. I needed to leave 30 seconds between each power up so all the devices would get to normal “radiating” state. The shack was clear, but when I got to the Living Room – there it was.

Step 3 was figure out what the offending device was. I had experience in the past with an ethernet switch causing interference. So I disconnected that and powered up the rest of the media center. All quiet. Here’s what happened to the waterfall when the switch was plugged in.

Waterfall showing RFI appearance when ethernet switch was powered on.

Gotcha! Because that switch was in heavy use, I wasn’t able to replace it immediately, but today was the day. I bought a smaller switch that was powered over POE instead of a brick and here’s what the waterfall looked like when that old switch was disconnected for the last time.

Waterfall of 20 Meters (top) when ethernet switch was disconnected for the final time.

So, a couple of lessons for me:
1) Troubleshooting using the directional antenna was a time saver because I knew where to focus my energy.
2) Don’t assume it’s outside the house when there are other potential issues in the path.
3) The scientific method of change one thing only and then go on REALLY shined in this test.

This didn’t solve it all. There is more noise to be chased, but the largest offender is no more, and that opens up a great deal more of 20 meters for me, which makes me happy.

Comments about this post? Leave them for me on Twitter @N4BFR.

iPhone 14 Pro vs Pixel 5 Camera Impression

I shot some pictures this morning on my daily walk but this time I was carrying two phones. One was my 2 year old Google Pixel 5, which I have always viewed as a fine camera and I’m able to take lovely pictures with it. The other is the brand new iPhone 14 Pro. While I didn’t need a phone upgrade, I did feel the need for a camera upgrade before I left on a couple of trips. I wanted something that shot better 4K video and my DSLR does not. Plus, weight is an issue.

So on to the photos. You can find lower res below, however you can find full res versions on Flickr at https://flic.kr/s/aHBqjA7vFs. I selected these 5 because they had the most variety of the dozen different shots I took, not particularly because they were the best or the worse. I put them side by side using GIMP with no additional photo processing, so they should be as oranges to oranges as I could make them. (I was going to say “apples to apples” but…

The Trains:
I find the iPhone photo a little over processed, for instance there was quite a bit of dew on the grass and since the processing seemed to focus more on the wood of the train, that element was lost. The Pixel photo picked up the dew, but overall the photos didn’t pop. I think my best picture would have processed it somewhere in the middle.

Garden Bunny:
I really prefer the Pixel photo here. I feel like it did a better job of capturing the actual light. The iPhone photo makes the bunny feel a little over-bright and same with the flower above the bunny. A little better depth of field on the Pixel photo as well, look at the logo on the barrel.

I’m mixed on this one. I feel like the Google Pixel 5 photo once again captured the breadth of the changes of the exposure better. It better conveys the mood of the actual time of the image. The brighter iPhone photo compromises the breadth of exposure for a photo that has richer tones and a sharper image to my eye. Again, like the Train, the truth would be somewhere between the two.

Stop Ahead:
The size of the picture that the two cameras shoot was one of the things that jumped out at me. The 4×3 picture is a different aspect than I am used to taking, with the Pixel set for taking 16×9 photos, so I will be interested to see if the iPhone will allow me to adjust that. Nice vibrant colors in the iPhone photo and that feels like the image that was closest to reality.

Tennis Court:
The iPhone wins this one with a sharper image and better processing of the colors and even the highlights in the trees. I feel like the aspect ration difference pays off here too.

I’d like to hear your comments. Message me on Twitter @N4BFR with your thoughts.

MegaMillions Experiment – Wrap Up – It was a Silly Experiment

Well, we have the data from all 5 drawings in this silly experiment and it is unimpressive. Here’s the raw results for each set of numbers in the 5 drawings.

Number Set8/168/198/238/278/30
Family NumbersNo matchesNo MatchesNo MatchesTwo 
No Matches
“Hot” Numbers (=>3x in last 20 draws)No matchesNo MatchesNo MatchesOne 
No Matches
“Cold” Numbers (=1x in last 50 draws)One matchNo MatchesNo MatchesTwo 
No Matches
Quick PickNo matchesOne matchNo MatchesNo
One Match

Let’s take the sum of these to see if we can see any differences in the way we chose numbers and the results.

Number SetTotal MatchesDifference from Average% of all numbers drawn (30 total)Dollars Won
Family Numbers2No Difference6.6%$0
“Hot” Numbers (=>3x in last 20 draws)1-13.3%$0
“Cold” Numbers (=1x in last 50 draws)3+110%$4
Quick Pick2No Difference6.6%$0
Average Total Matches2

There is a small argument to be made that cold numbers did get drawn more often, but I would put this into the area of “too close to call.” It’s not a material difference in my mind. To be a material difference I would have liked to see the dollars won be higher. We could have matched three numbers in the cold draws on different days and still not have won any, so the odds of us winning (1 in 89) were just “luck of the draw” at best.

If you are really interested in these probability type problems, I recommend checking out Kevin at the Vsauce 2 channel on YouTube. I particularly like his “The Perfect Illegal Lottery” video that talks about the history of the daily numbers.

My friend Ryan pointed out early on that this is doomed to fail based on the “Gamblers Fallacy” and he’s 100% correct. Let’s think of it on a simpler basis, flipping a coin. Assuming it’s a “fair” coin over time it should come up heads half the time and tails half the time. Just because it flipped “heads” 5 times doesn’t mean the odds on the 6th flip are greater than 50/50 that it will come up heads because the coin has no memory. So there are really no “hot” or “cold” numbers in the lottery.

Here’s some background on how the lottery drawing is executed. From working at a TV station that helped put on a state lottery drawing back in the day I know there are random sets of balls used, it’s not the same set in every drawing. There’s not only one drawing either, there are practice drawings held before the real thing. There are procedures done to weigh the balls and make sure they all weigh the same. Even the camera crew is vetted prior to the drawings, so you can’t sneak someone in.

So, there is no ‘best way” to pick your numbers for MegaMillions. Does all of this mean I’ll quit playing the lottery when it gets big? Probably not, because there is still a chance and all you need it $2 and a dream.

MegaMillions Experiment – Draw 4

Cold numbers give a return on investment!

Continuing on with the silly experiment I am doing by picking “hot” and “cold” numbers in the MegaMillions drawing. Had a few more numbers hit on Friday:

Number Set8/168/198/238/27
Family NumbersNo matchesNo MatchesNo MatchesTwo Matches
“Hot” Numbers (=>3x in last 20 draws)No matchesNo MatchesNo MatchesOne Match
“Cold” Numbers (=1x in last 50 draws)One matchNo MatchesNo MatchesTwo Matches
Quick PickNo matchesOne matchNo MatchesNo

Cold numbers are still ahead after four drawings but not a material difference in my mind. This drawing did make some money back! One of the “Cold” number matches is the Megaball, so we have won 10% of the $40 investment in the 5 draws.

Final draw is Tuesday night. Read about the previous drawings here: Drawing 1 | Drawing 2 & 3.

Lunar Eavesdropping, Curious Marc, and Tracking Artemis 1 Via RF

Originally published 27-August-22 at 5:00 PM ET
Updated 28-August-22 at 12:25 PM ET

Apollo 16 Command Module “Casper” at Space and Rocket Center in Huntsville, AL – Picture by N4BFR

Back in the days of Apollo, hams were listening in to Apollo 11 and other space flights. An article entitled “Lunar Eavesdropping” from the ARRL talks about how a couple of hams listened in on Apollo 11, and outside of getting a 10 second head start on the rest of the world, made it work but didn’t hear anything unique.

Over the last few months I’ve watched as Curious Marc on YouTube, known as AJ6JV in Ham Radio circles, has completely reconstructed signals from the Apollo gear in his basement. It’s been fascinating to understand the “RF Black Arts” as he says, of the really complex ways the capsules and LEM sent back their signals in a multiplexed method of FM and PM data. One thing I noted that this frequency range was around 2.287 GHz, in the “S-Band” frequency range.

NASA has had 50 years to be more sophisticated with it’s communications. It now breaks down comms into their “Near Space Network” which handles the communications around the globe, and the “Deep Space Network” which handles communications beyond earth orbit.

I’ve spend the last few hours going through documents on the NSN from as far back as 2000 and from what I can tell, they still primarily use S-Band frequencies. Here’s an example of frequencies listed in a doc related to Wallops Island, VA – part of the NSN.

11.3M Antenna (WGS 11.3M)
  TX 2.025 Ghz to 2.120 GHz 
  RX 2.220-2.400 GHz (S-Band)
     8.025-8.400 GHz (X-Band)
  Modes: PM, FM, BPSK, QPSK, 

4.7M Antenna (LEO-T)
  TX 2.025-2.210 GHz
  RX 2.200-2.300 GHz

So, there may be something there to trying to pick up some Artemis 1 or NSN signals while it’s in near Earth orbit on Monday. I do have some omni-directional 2 GHz receive coverage with an SDR. My mission would be to capture anything unique and record it for later analysis, though I expect it to be encrypted, since SpaceX encrypted their telemetry feeds after hams started to listen in.

About 2.5 hours after launch, Artemis 1 will start toward the moon and switch to the DSN according to NASA PR data. (Update: On the 8/27 media conference they mentioned this was right after the TLI event and could be 90 minutes in to the mission) DSN also has S-Band communications but needs to use X-Band or higher at least part of the time according to this JPL document:

X-Band, K and Ka-Bands are out of my range at the moment, but I will be checking in on the S-Band segment from time to time. If I was communicating, I probably wouldn’t be turning radios on and off, but instead looking at simulcasting the streams.

So, lots of fun to be had this week as I begin a look to peek at space comms! If you have something to add or share, hit me up on Twitter @N4BFR or on Facebook.

MegaMillions Experiment – Draws 2 and 3

Continuing on with the silly experiment I am doing by picking “hot” and “cold” numbers in the MegaMillions drawing. I was out of town for the Friday drawing so let’s catch up on drawings 2 and 3, and we’ll keep drawing 1 as a reference:

Number Set8/168/198/23
Family NumbersNo matchesNo MatchesNo Matches
“Hot” Numbers (=>3x in last 20 draws)No matchesNo MatchesNo Matches
“Cold” Numbers (=1x in last 50 draws)One matchNo MatchesNo Matches
Quick PickNo matchesOne matchNo Matches

After one drawing it looked like the cold numbers would be the ones to beat, but Quick Pick jumped on the board in drawing number 2 with a match. Tuesday was a bad drawing for the lot, with no matches to the array of 24 numbers.

I did note something interesting that I had not picked up on when creating this. The “Family” number and “Hot” number set share a selection. So do the “Cold” numbers and the Quick Pick.

One additional thought I had is that if I had truly wanted to stick with “hot” and “cold” numbers for each drawing I should have reset after each drawing, but this method will work for our simple experiment.

MegaMillions Experiment – Draw 1 of 5

I outlined the silly experiment I am doing by picking “hot” and “cold” numbers in the MegaMillions drawing. Here are the results from the August 16 draw:

Number SetDrawing 1
Family NumbersNo matching numbers
“Hot” Numbers (=>3x in last 20 draws)No matching numbers
“Cold” Numbers (=1x in last 50 draws)One matching number
Quick PickNo matching numbers

So, the cold numbers at least got on the board but there’s no real advantage to any of the combinations after the first draw.