NOAA 15 Experiencing a Failure?

This isn’t the first time we’ve seen issues with the NOAA-15 satellite. Last year the RTL-SDR blog posted about some issues the satellite was having.

These issues/errors appear to have been intermittent and even today these problems while apparent haven’t been constant. However, they do appear to be happening more and more frequently. There is a bit of uncertainly in the air about how much longer we’ll have this satellite and other which hold easily obtainable APT data.

We can only hope that this is just another intermittent problem but alas it seems like NOAA-15s clock is just about at its end.

MiTEE Cubesat Interview

Hi, Derek here with a few addenda to the video here.

I want to clarify that everything said here was my opinion and not necessarily representative of the University of Michigan or even MiTEE as an organization.

The CubeSat was not at all completely designed by students on an electrical level. I misspoke and didn’t realize that mistake until after editing. We received major help from the Space Physics Research Laboratory (SPRL) on campus here by adopting some of their electronics from a previous CubeSat mission they ran. Overall about 50% of the electrical design work though was completely lead by the students here.

Check out our twitter page at to stay up to date with the latest mission activities regarding our launch!
Finally, I want to give a huge shoutout to SPRL and Prof. Brian Gilchirst for all of their help in making this project possible for the countless number of students that have been involved. Without their knowledge and material resources, we would never have been able to get to a point where we are awaiting a final launch date to get into space.

Well, one more I guess. I’m a rising junior in electrical engineering and I’m actively looking for an internship for the summer of 2020. So if you enjoyed my semi-educational talk about students in the CubeSat world and didn’t catch my numerous mistakes regarding design and testing paradigms. If you might know of somewhere I should apply or want to contact me for further questions here’s my LinkedIn and my email is cheyndk@umich dot edu

Guest on Signals and Bits

I was recently interviewed on a new podcast [Signals and Bits] created by Ben Hilburn [@bhilburn]. Ben has been an influential individual within the radio and open source software community for many years. He is the President of the [GNURadio Project] that has no-doubt been at the core of the Software-Defined Radio community before anyone even knew what RTL (SDR) was. He also works on a multitude of other projects you can find on his [website].

Ben’s podcast will be in an interview style focusing not only around Software-Defined Radio but topics such as spectrum enforcement, consumer wireless, AI and much more. You’ll no doubt enjoy this episode and the many to follow. Please be sure to share feedback with Ben on twitter [@signalsandbits]

GPS To Inmarsat/Iridium Modification

If you’re in the market for a decent L-band antenna with a built in LNA, one you can power via a simple 5v bias tee. Look no further than a GPS antenna.

These antennas are generally housed with their own LNA which is powered via a bias-tee. Generally all you need to do in order to make them useful for L-Band is to remove the 1575 mhz filter that is used to ensure only GPS frequencies make it though to the receiver. Once you’ve done this you have a nice cheap L-band antenna.

In my case I’m using an NMO mounted antenna so I can have a nice L-Band antenna on the car/mobile. While I’m using NMO here you can generally use this to modify any active GPS antenna.

NMO Mounted GPS Antenna Unmodified

You’ll first want to flip this over and remove both the rubber pad (if it has one) and the rubber inserts that cover the screws.

Once this is complete you’ll want to separate the top from the bottom, for an NMO type GPS antenna I suggest a small flat head screw driver, careful not to mar the screw fitting.

With screws removed light pressure under the teeth with a screwdriver should pop it out.

After you’ve removed the top and bottom you’ll need to remove the screws holding the top of the antenna to the base which contains a pigtail to the NMO connection. You will in this case also need to de-solder the shield so you can access the raw board itself.

You should now be able to pull off your shield and expose the 1575 MHz filter.

Back of GPS Antenna Opened to Expose Filter and LNA

Grab some pliers and a heat gun (or soldering iron) and work the filter off the board.

Filter is Usually Labeled 1757 (The GPS Frequency)

In my case I broke the filter and was unable to fully remove it, I simply bridged the pads with some wire and while it doesn’t look pretty it works great!

Broken and Burned Filter with a Wire Bridge over It.

Reassemble your antenna and you’re in business!

Antenna Soldered back into Place
Modified NMO Antenna Installed on The Car

Now you just apply bias-tee voltage and tune anywhere you want in the L-Band. I’ve successfully pulled inmarsat and iridium with this.