RF Collect Tutorial
Complexity: | Easy |
---|---|
Payloads: | SDR |
Windows: | PAYLOAD_SDR |
This tutorial will demonstrate receiving signals from the S-BAND radio on the SDR
using the rfcollect
utility, and download the produced IQ
and log files. The frequency can be changed to capture specific signals.
Prerequisites
All tutorials require the steps outlined in the Getting Started Guide.
Overview
The tutorial comes with 2 scripts:
rf_collect_demo
- runs in-orbit on the SDR to demonstraterfcollect
runningdeploy
- run by the user on the ground to uploadrf_collect_demo
and schedule it to execute in aPAYLOAD_SDR
window
In-Orbit Script
A script has been created to run on the SDR
Linux payload called rf_collect_demo
. The default options of rfcollect
make a 10 second 1MHz wide sample of the 2.0225 GHz S-BAND spectrum with a sample rate of 1MHz. This produces a 4MB IQ file (16bit in-phase + 16bit quadrature (4 bytes per sample) @ 1MHz).
Mark it executable and test it. An error message is expected because rfcollect
is likely not available.
chmod 755 rf_collect_demo
./rf_collect_demo
Output:
Tue Dec 14 05:20:03 UTC 2021
Linux 66891b47365c 5.10.16.3-microsoft-standard-WSL2 #1 SMP Fri Apr 2 22:23:49 UTC 2021 x86_64 Linux
rf_collect_demo: line 4: rfcollect: not found
rfcollect error: 127
Deploy
The rf_collect_demo
script is uploaded and scheduled to run by using the deploy
script:
$ ./deploy "[YOUR_AUTH_TOKEN]" [YOUR_SAT_ID]
Response:
...
{"data": {"id": "d25c7a43-b70d-4f57-81d5-ff5177b26158"}}
...
At this point the file has been queued for upload at the next possible contact, and a window scheduled to run it in 24 hours.
Review
After the windows completes and enough time is given for download, the files can be found in S3 with the timestamp appended to guarantee uniqueness. The awscli
can be used with the --recursive
option to see the files:
aws s3 ls --recursive s3://user-s3-bucket/a/directory/${SAT_ID}/downlink/
Response:
2021-09-06 04:32:29 0 2021/
2021-09-06 04:32:29 0 2021/09/
2021-09-06 04:32:29 0 2021/09/06/
2021-09-06 04:32:29 2568 2021/09/06/20210906T043229Z_rf_collect.log
2021-09-06 04:32:29 4000000 2021/09/06/20210906T043229Z_rf_collect.iq
The IQ file can be further analyzed using digital signal analysis (DSP). For example the file can be loaded in Universal Radio Hacker to view the spectrum: