Hello
May I suggested a few things not related to the "Programming" issues but related to the Radio Astronomy subject? Just like retail, about "Location, Location, Location," Radio Astronomy's is about the "Antenna, Antenna, Antenna." One thing the TV Dongle offers for Radio Astronomers is the ease of placing the receiver (Dongle) on the Antenna. The USB must be extended from the Computer to the Antenna, instead of bringing the Signal from the Antenna to the Dongle. The advantage is lower noise and higher gain (without noise). There are many references on the Internet for extending USB, some for purchase, some DIY.
Extending the USB is not limited to Radio Astronomy...
-----Original Message----- From: osmocom-sdr-bounces@lists.osmocom.org [mailto:osmocom-sdr-bounces@lists.osmocom.org] On Behalf Of Michel Pelletier Sent: Sunday, October 21, 2012 12:25 PM To: osmocom-sdr@lists.osmocom.org Subject: Beginner question about rtlsdr
Hello everyone, I hope this is an appropriate forum for a beginner question about using an E4000 dongle.
I'm an amateur astronomer, and lately I've been wanting to get into amateur radio astronomy. The rtlsdr seems like a really cheap way to get involved. It can tune many interesting frequencies, in particular channel 37 around 608-614 Mhz.
I am a Python programmer by trade so I am using roger-'s amazing pyrtlsdr library which is great, I can read samples from the device and they get returned as numpy arrays. The scipy.signal package allows me to correctly decimate the signal and I am working on a simple graphing program to graph signal levels in realtime, by hour, by day, and by week. I hope to basically reproduce the Jansky experiment that started the entire science of radio astronomy:
http://en.wikipedia.org/wiki/Karl_Guthe_Jansky
I have a question though about how to use the dongle that I can't quite figure out. roger-'s demo_waterfall program, for example, sets the default sample_rate to 1.4e6, but then on each scan only calls read_samples(2**16). The demo displays the entire megahertz of bandwidth, so I'm a bit confused as to how the 64K samples map onto the 1M samples of the device. It doesn't seem to make sense taht the device only returns the first 64K samples. Can anyone clue in a total beginner on the sample rate and reading samples from the device correlate?
Thank you!
-Michel
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