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Re: [Discuss-gnuradio] RSSI calculation
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From: |
Marcus D. Leech |
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Subject: |
Re: [Discuss-gnuradio] RSSI calculation |
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Date: |
Wed, 30 Mar 2011 10:58:19 -0400 |
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User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 |
On 30/03/2011 8:33 AM, Fengyuan Gong wrote:
Shouldn't the second one also read ADC value on the
RFX900/1200/1800/2200/2400 and then calculate out the analog signal
strength?
You should also be aware that the analog RSSI input is the signal power
over the analog-detector bandwidth in the demodulator chip, which
is typically *much* wider than the bandwidth that you ultimately
process, so if you're processing the I and Q signals for other reasons, you
might as well also compute RSSI from those signals, which is cheap.
Also, analog square-law detectors (as used in the demod chip) typically
only produce reliable results over a narrow range of input powers,
whereas the reliability of the *computed* value is much better (it's
limited in the main by the linearity of the signal-path ADCs).