[Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx does not?

David Hubbard david.c.hubbard+hackrf at gmail.com
Wed Nov 9 08:56:39 EST 2016


I just purchased a HackRF, so there's a good chance I overlooked something.
I followed http://greatscottgadgets.com/sdr/1/ and am able to receive FM
but not 70cm Ham Radio transmissions.

Here is how I tested it:

1. Received 96.5MHz fine on the HackRF. center_freq = 97.9e6,
channel_freq=96.5e6, channel_width=200e3, samp_rate=10e6

2. Tuned to 441.1MHz on a handheld ham radio close by, received ham
transmissions on it

3. Changed the flow graph center_freq to 440.0MHz and channel_freq to
441.1MHz, did not see any visible bumps in the FFT plot, and just a quiet
hiss on the audio.

4. Swapped antennas from the handheld ham radio and the HackRF. The ham
radio received transmissions at S9 with its antenna and S5 with the HackRF
antenna. But the HackRF did not receive anything with either antenna.

5. Swapped antennas back, double checked the ham radio was still receiving
transmissions.

6. Changed the flow graph center_freq back to 97.9e6, channel_freq back to
96.5e6, and double checked the HackRF could still receive 96.5MHz ok.

I can send the flow graph and a screen shot of the FFT but it's just the
flow graph from Lesson 1.

Cheers,
David
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