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Topic: mcHF 0.7 STM32F7 2048kb: Phantom signals 24khz above real frequency (Read 1649 times)
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DL4SM
Neuling
 Offline
Posts: 2
Ich liebe dieses Forum!
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mcHF 0.7 STM32F7 2048kb: Phantom signals 24khz above real frequency
« on: 12. November 2018, 09:35:27 »
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Hello there,
as I have done quiet a lot of tests to my new mcHF during the weekend I am a little confused about some functions and features.
1. I am experiencing always (setting Xlate -12kHz) phantom signals which are located 24kHz above the real signal on the other side band and you can hear it there.
2. The waterfall also shows this phantom signal, but instead of being displayed above the real signal it is displayed 24kHz below the real signal and you can not hear it there.
Here you can see/hear the real signal on 14267kHz USB and can see the "just" displayed phantom signal on 14243kHz LSB:
https://filehorst.de/d/cifoJlCd
Here you can see/hear the phantom signal on 14291kHz LSB
https://filehorst.de/d/cIaFDcuq
I have tried various things without success:
a) Install older firmware (back to 2.9.15)
b) clear all settings F1/F3/F5
c) IQ Calibration of RX Phase / RX Balance
The only way how the phantom signals disappear is to either turn off the RX/TX Freq Xlate or to switch the RX IQ Auto correction to "ON"
If the IQ Auto correction is switched to "ON" the AGC is disabled and the RX is very low in sensitivity / turns deaf.
I really can´t imagine that I am the only one having these problems. I am quiet happy with the TRX, but those issues I would like to fix.
Any help / idea would be appreciated
Vy 73, Sascha
DL4SM
PS: I have posted this on the yahoo mcHF board as well as there are probably different readers then here
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peter_77
Urgestein
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Posts: 735
THE mcHF and UHSDR forum !
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Re:mcHF 0.7 STM32F7 2048kb: Phantom signals 24khz above real frequency
« Reply #2 on: 12. November 2018, 16:19:33 »
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Fully agree !
Its mandatory to switch on IQ autocorrection ! And if you correctly tune RX gain and also the AGC and AGC settings everything works just fine. The RX is even more sensitive as an IC 7300.
That can be proofed either on mcHF as well as I40 and SParrow !!
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| « Last Edit: 12. November 2018, 16:20:16 by peter_77 » |
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DL4SM
Neuling
Offline
Posts: 2
Ich liebe dieses Forum!
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Re:mcHF 0.7 STM32F7 2048kb: Phantom signals 24khz above real frequency
« Reply #3 on: 13. November 2018, 22:51:04 »
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Hi again,
if I want to use the manual setting of RX Phase and RX Balance it doesn't seem to have any effect on the signals.
When I use the IQ auto correction the signal levels drop by approx 30dB, but the noise level also drops by about that amount. So the signal stays as clear and loud as before
Not using the manual settings just confuses me, but if only the auto correction for the RX works, I probably have to live with that.
The Phase and Balance settings for the TX works though.
vy 73
Sascha
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