Here’s an update from the lab on correlator troubleshooting. We are trying to get correlation understood and under control over the air.
We have two flowgraphs that we believe aren’t working due to the Correlation Estimation Issue here https://github.com/gnuradio/gnuradio/issues/1207
We don’t think it’s operator error, but we’re relatively new to GNU Radio, and would welcome any comment or critique that helps to solve this!
FM_ARAP_to_downlink.grc is the flowgraph we are using for transmit side.
What does it do?
It collects up four analog FM channels, digitizes, and transmits a time division multiplexed signal out. This is, in general, a simple model of our uplink for a Groundsat or payload.
We see the expected transmitted signal on a spectrum analyzer and on a HackRF portapack and on the receiving system across the lab.
The receiving flowgraph is called TDM_downlink_rx.grc
What does it do?
It takes the time division multiplex signal and is supposed to break the channels back out.
This demo has worked in the past, but not anymore, and definitely not over the air now.
The problem seems to be the correlator, and it seems to be the same trouble reported in the issue.
We want to write a DVB-S2/X correlator. I think we can also help fix this correlation estimation block. In all cases, we want to comply with the tag scheme produced, so that downstream blocks already in GNU Radio get what they’re expecting, if they are expecting these types of tags.
Plenty more at https://github.com/phase4ground
Tickets available now!
Open Research Institute will show at Hamvention held 18-20 May 2018.
Our booth will show projects associated with Palomar Amateur Radio Club, the AMSAT Member Society Open Research Institute‘s Phase 4 Program, GNU Radio , FaradayRF, and will host the first Trans-Ionospheric electronic badge sales.
Open Research Institute (ORI) is a non-profit research and development organization which provides all of its work to the general public under the principles of Open Source and Open Access to Research.
ORI includes Phase 4 Ground, an open source amateur radio project primarily intended for AMSAT. Our goal is to provide both designs and equipment for a radio that will operate with a 5GHz uplink and a 10GHz downlink. Our mission is to provide an open source implementation of DVB-S2 and DVB-S2X for both satellite and terrestrial amateur radio use. The reference design will be in GNU Radio, and a variety of radio recipes will be published. These solutions range from DIY to something you can purchase off-the-shelf. Phase 4 Ground radios are intended to be reusable and reconfigurable, supporting payloads at GEO (Phase 4B), HEO (Phase 3E), and beyond (Cube Quest Challenge). Additionally, these radios will work as terrestrial microwave stations. Groundsats on mountaintops or towers establish a fun and flexible digital microwave experience.
GNU Radio is a free & open-source software development toolkit that provides signal processing blocks to implement software radios. It can be used with readily-available low-cost external RF hardware to create software-defined radios, or without hardware in a simulation-like environment. It is widely used in research, industry, academia, government, and hobbyist environments to support both wireless communications research and real-world radio systems.
Faraday is more than just another Industrial, Scientific, and Medical band transceiver (ISM). Faraday takes advantage of the ISM hardware which works on the amateur radio 33cm band to let us focus on the real tasks we want to accomplish. The FaradayRF Master Plan details these tasks of which providing a well documented and educational digital wireless ham radio platform enabling an infrastructure to be built from is among the first goals. 500mW at 915MHz packs the power necessary to traverse over 40km required by last-mile communications infrastructure. The on-board Antennova M10478-A2 GPS adds location aware applications out of the box without the need for additional hardware. Overall, Faraday was designed to provide access to 33cm to radio amateurs and empower them to experiment and learn. A stronger ham radio is a more exciting ham radio.
Tickets are available now at http://hamvention.org/purchase-tickets/