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Degradation bug in GNU Radio "Decode CCSDS 27"
I am doing some BER simulations with GNU Radio (stay tuned for the next post), and during my experiments I have stumbled upon a bug in the "Decode CCSDS 27" block. This block is a Viterbi decoder for...
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BER simulation in GNU Radio
David Rowe always insists that you should simulate the bit error rate for any modem you build. I've been intending to do some simulations of the decoders in gr-satellites since a while ago, and I've...
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WSJT-X and linear satellites: part I
Several weeks ago, in an AMSAT EA informal meeting, Eduardo EA3GHS wondered about the possibility of using WSJT-X modes through linear transponder satellites in low Earth orbit. Of course, computer...
View ArticleD-SAT support added to gr-satellites
D-SAT is an Italian cubesat that will demonstrate a new deorbit hardware. Apparently this system uses dedicated propulsion to make the satellite re-enter from a 500km orbit in 30 minutes. It also...
View ArticleIPv6 for Amateur radio
Back in September 26 2016, I posted an email in Spanish to the Hamnet.es mailing list detailing my proposal for an IPv6 Amateur radio network, and trying to engage people into some preliminary tests....
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D-SAT image downlink
In a previous post, I spoke about the cubesat D-SAT. The thing that first caught my attention about this satellite is its image downlink and the quality of some of the images that Mike DK3WN has...
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Acquisition and wipeoff for JT9A
Lately, I have been playing around with the concept of doing acquisition and wipeoff of JT9A signals, using a locally generated replica when the transmitted message is known. These are concepts and...
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Frequency distribution of WSPR reports
Over the last few days I've been transmitting WSPR on 40m with 20dBm of power using my Hermes-Lite 2.0beta2. For this, I'm using the instrument output of the Hermes-Lite, which is driven by an OPA2677...
View ArticleÑuSat finally decoded
More than a year ago, I spoke about my efforts to decode ÑuSat-1 and -2. I got as far as reverse-engineering the syncword and packet length, and I conjectured that the last 4 bytes of the packet were a...
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Waterfalls from the eclipse
Last Monday I did a recording for the HamSci eclipse 2017 HF wideband recording experiment. I used my Hermes-Lite 2.0beta2 to record three 384kHz slices: the 40m band, the 30m band and the 20m band,...
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AGC for gr-satellites
In a previous post I discussed my BER simulations with the LilacSat-1 receiver in gr-satellites. I found out that the "Feed Forward AGC" block was not performing well and causing a considerable loss in...
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WSPR reports frequency distribution experiment: 20m
Last week I did an experiment where I transmitted WSPR on a fixed frequency for several days and studied the distribution of the frequency reports I got in the WSPR Database. This can be used to study...
View ArticlePolarization in Voyager signal from Green Bank Telescope
A few days ago I read the paper about the Breakthrough Listen experiment. This experiment consists in doing many wideband recordings of different stars using the Green Bank Telescope, and (in the...
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About critical damping
Having to deal with DSP texts written by engineers, I have sometimes to work a bit to get a good grasp the concepts, which many times are not explained clearly from their mathematical bases. Often, a...
View ArticleCharlas en IberRadio
English summary: Slides and recordings for the two talks I gave yesterday in IberRadio. One of the is about gr-satellites and the other one is about Linrad. All the material are in Spanish. Ayer estuve...
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Measuring a mains choke with Hermes-Lite VNA
I have made a mains choke for my HF station, following Ian GM3SEK's design, which involves twisting the three mains wires together and passing as many turns as possible through a Fair-Rite 0431177081...
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WSJT-X and linear satellites: part II
This is a follow-up to the part I post about using WSJT-X modes through a linear transponder on a LEO satellite. In part I, we considered the tolerance of several WSJT-X modes to the residual Doppler...
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First FT8 test through FO-29
Continuing with my research on using WSJT-X modes through linear transponder satellites in low Earth orbit (see part I and part II), a few days ago I transmitted and recorded an FT8 signal through the...
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Waterfall from the FT8 test through FO-29
In the previous post, I detailed my experiments transmitting FT8 through the FO-29 linear transponder. I recorded a complete pass of the FO-29 satellite while I transmitted an FT8 signal trough the...
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Building a feedline HF choke
My current HF antenna is a long wire (around 15 or 20m) connected to an MFJ-993BRT outdoor automatic antenna tuner. The tuner is fed with around 25m of M&P Airborne 10 coaxial cable which runs into...
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