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Offset center spike?
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Dale Elshoff WB8CJW <dale.elshoff@...>
Simon,
I don't recall having this problem until recently but now it is most noticeable on weaker signals that are centered on the spectrum/waterfall where the interference is located. It produces a heterodyne that I have to move my the signal I am listening to away from the center so the squeal is no longer heard. If I use the zoom or center control the signal is set back to the interference. Is there a way to apply an offset to keep the spike away from the center? I am using a R820T2 and have tried my older R820T and an E4000 with the same result. The spike is about 8dBm off the noise floor most of the time until I change the gain setting or turn the AGC on or off which causes the spike to go to -80dBm or more with a ringing tone and within a few seconds settles back down. I thought maybe it had to do with AC power line noise or something local but then I tried using a server radio and found they also have the spike. On your Airspy HF+ I see a nasty looking thing but it is 5kHz. above center frequency and it remains at the same point when tuning. Thanks, 73 & congratulations on making really great software, Dale WB8CJW |
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Here;s some info on the DC Spike;
https://sdr-radio.groups.io/g/main/topic/center_spike/5928569?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,5928569 One can always put the RX'ed signal to either side of it until SDRC 'tames' it down. i.e. On my SDR-iq RXR's, it takes about 10-15 seconds of use before the DC spike disappears.Not sure how long (if at all) it is corrected using the RTL series sticks. 73 Kriss KA1GJU |
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jdow
In general you want to avoid straddling signals across the central spike. Offset it slightly so that does not happen. The central spike will leave a remnant present that is the self-conversion of the LO beating with itself. That's noise that reduces your signal's quality.
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{^_-} On 20190630 04:25:21, Kriss Kliegle wrote:
Here;s some info on the DC Spike; |
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Dale Elshoff WB8CJW <dale.elshoff@...>
Yes, I can manually offset with the slider each time but was looking
to make a program configuration entry so the offset is retained for
me even if I use the zoom or center function.
73 Dale WB8CJW On 6/30/2019 8:17 AM, jdow wrote:
In general you want to avoid straddling signals across the central spike. Offset it slightly so that does not happen. The central spike will leave a remnant present that is the self-conversion of the LO beating with itself. That's noise that reduces your signal's quality. |
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jdow
I've wished for a zoom that will zoom around the active receiver rather than the center teet since V2 days. But as my Ulster-Scot grandfather observed, "If wishes were horses beggars would ride." Maybe it is time to remind Simon of that wish.
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{^_-} On 20190630 16:35:08, Dale Elshoff WB8CJW wrote:
Yes, I can manually offset with the slider each time but was looking to make a program configuration entry so the offset is retained for me even if I use the zoom or center function. |
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I like that "If wishes were horses beggars would ride." Maybe a second look or thought about this? Vincent On Sun, Jun 30, 2019 at 5:17 PM jdow <jdow@...> wrote: I've wished for a zoom that will zoom around the active receiver rather than the |
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