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More QO-100 orbit determination

In a previous post, I showed my orbit determination experiments of the GEO satellite Es’hail 2 using the beacons transmitted from Bochum (Germany) through the QO-100 amateur radio transponder on-board this satellite. By measuring the phase difference of the BPSK and 8APSK beacons, which are spaced apart by 245 kHz in the transponder, we can… Continue reading More QO-100 orbit determination

QO-100 orbit determination

In a previous post, I showed my experiment about measuring the phase difference of the 8APSK and BPSK beacons of the QO-100 NB transponder. The main goal of this experiment was to use this data to do orbit determination with GMAT. Over the last week I have continued these experiments and already have started to… Continue reading QO-100 orbit determination

Calculating the QO-100 beacons frequency separation

In my previous post I set out to measure the phase difference between the QO-100 8APSK and BPSK beacons. One of the things I mentioned is that the frequency separation between these two beacons was approximately 1.6 Hz larger than the nominal 245 kHz. A frequency error of a couple of Hz is typical when… Continue reading Calculating the QO-100 beacons frequency separation

Measuring the QO-100 beacons phase difference

Since a couple months ago, the QO-100 NB transponder has now two digital beacons being transmitted continuously: the “traditional” 400 baud BPSK beacon, and the new 2.4 kbaud 8APSK multimedia beacon. This transponder is an amateur radio bent-pipe linear transponder on board the Es’hail 2 GEO satellite. It has an uplink at 2400.25 MHz, a… Continue reading Measuring the QO-100 beacons phase difference

Decoding the QO-100 multimedia beacon with GNU Radio: part II

In my previous post I showed a GNU Radio demodulator for the QO-100 multimedia beacon, which AMSAT-DL has recently started to broadcast through the QO-100 NB transponder, using a downlink frequency of 10489.995 MHz. This demodulator flowgraph could receive and save to disk the files transmitted by the beacon using the file receiver from gr-satellites.… Continue reading Decoding the QO-100 multimedia beacon with GNU Radio: part II

Decoding the QO-100 multimedia beacon with GNU Radio

Last weekend, AMSAT-DL started some test transmissions of a high-speed multimedia beacon through the QO-100 NB transponder. The beacon uses the high-speed modem by Kurt Moraw DJ0ABR. It is called “high-speed” because the idea is to fit several kbps of data within the typical 2.7 kHz bandwidth of an SSB channel. The modem waveform is… Continue reading Decoding the QO-100 multimedia beacon with GNU Radio

LDPC code design for my QO-100 narrowband modem

A couple months ago I presented my work-in-progress design for a data modem intended to be used through the QO-100 NB transponder. The main design goal for this modem is to give the maximum data rate possible in a 2.7 kHz channel at 50 dB·Hz CN0. For the physical layer I settled on an RRC-filtered… Continue reading LDPC code design for my QO-100 narrowband modem

32APSK narrowband modem for QO-100

Some time ago I did a few experiments about pushing 2kbaud 8PSK and differential 8PSK through the QO-100 NB transponder. I didn’t develop these experiments further into a complete modem, but in part they served as inspiration to Kurt Moraw DJ0ABR, who has now made a QO-100 Highspeed Multimedia Modem application that uses up to… Continue reading 32APSK narrowband modem for QO-100

Ranging through the QO-100 WB transponder

One of the things I’ve always wanted to do since Es’hail 2 was launched is to perform two-way ranging by transmitting a signal through the Amateur transponder and measuring the round trip time. Stefan Biereigel DK3SB first did this about a year ago. His ranging implementation uses a waveform with a chip rate of only… Continue reading Ranging through the QO-100 WB transponder