G8JNJ
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https://github.com/OH1KK/KiwiSDR-antenna-switch-extension https://github.com/OH1KK/KiwiSDR-antenna-switch-extension/blob/master/docs/ant-switch-backend-beagle-gpio.txt This extension uses Beagle GPIO pins P8 pin 11 - GPIO_45 - Antenna 1 P8 pin 1…
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"I also have 1:4 and 4:1 xfrmrs in/out of the filter assembly which results in a somewhat higher Q" Hi Jim, I tried this method, but I found that if I got the L/C ratio correct and used moderately good inductors, I didn't need to use any…
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"I received complaints that the local AM stations which previously had severely overloaded the Kiwi could no longer be heard." You could always put a variable resistor between the filter input and output connections so that you could vary…
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Hi Paul, You can also trade the overall notch depth against the notch bandwidth by varying the L/C ratio. In most cases you don't need to have more than 10 to 20dB notch depth in order to bring the worst offenders down to an acceptable level. Her…
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Hi Benson, That's interesting I'm not able to perform my own tests at the moment, but I did wonder if enabling the DSP noise reduction on the KiWi in conjunction with the CW decoder would help any further when signals start to get down to near the …
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Another thought is that although unlikely, it could possibly be the very high levels of BC station RF present at the antenna that may be saturating the small SMD inductors in the Nooelec filter causing IMD. Trying the attenuator trick before and a…
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Hi, I think it may not be a typical ADC overload but it's simply a case of a lot of regularly spaced BC signals that are close to the ADC threshold causing intermodulation products. SDR's don't behave in quite the same way as 'analogue' receivers …
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Hi John, I'm changing the tuning and moving the filter passband edges to match so that they are +/- 15Hz relative to the new center frequency. So I'm changing the BFO frequency. Regards, Martin - G8JNJ
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Hi John, As a quick test I set up four instances of the decoder with 30Hz BW centered on approx 430, 460, 490 & 520Hz all decoding 4XZ on 4331KHz. Although the messages are coded, it was still possible to see that the two lowest frequencies ga…
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It's difficult to tell 100% without using a local CW test signal and an attenuator, but subjectively I'd agree with Benson it does seem to decode slightly better when the CW tone is in the 400-450 Hz range and less so when it is higher in frequency.…
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Hi John, OK thanks, that fixed it. Regards, Martin - G8JNJ
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Hi John, Thanks for all your hard work. Unfortunately the v1.227 CW extension doesn't open on my iPad, the other extensions are OK, I suspect it's the same problem as previous times. Regards, Martin - G8JNJ
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Hi All, I'm not quite sure what level of performance folks were expecting for 'free' ? It seems good enough to me. I can decode most morse signals reasonably well if they register >S4 on the signal strength meter, I suspect that CwGet performs …
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Hi Ron, None of the CW decoding programs I have tried are particularly good and will certainly not beat a proficient human decoder. However I think the new extension holds up well in comparison to some of the other reasonably well regarded offerin…
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As others have already said, if you close and then try to reopen the CW decoder extension it seems to run but doesn't actually decode. A browser refresh is required before it will decode again. When it does run it's quite effective. I've been readi…
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Hi John, Great, thanks for considering the comments, I look forward to trying them out :-) Regards, Martin - G8JNJ
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Hi John, Good job, it works surprisingly well, not quite as good as CW skimmer, but at least as good as some other (paid for) CW decoders I have tried. I think this new extension will be of interest to the 'Numbers' Station spotters. Regards, Ma…
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Hi John, OK I've started a new thread titled "TDoA maps" to avoid cluttering up this discussion. Regards, Martin - G8JNJ
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Hi John, As an example MSF, Sainte Assise, DCF39, DCF47, DCF77, DHO38 behave in that way, if you click on the green TDoA marker to include it in the results map, they tune to the frequency. In cases where there is only one frequency in use at the …
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"I think another Massdrop should be coming up soon (it's been 6 weeks since the last one). That's a source for $220 Kiwis with free US shipping if you're willing to wait a bit for delivery." Definitely the way to go - I couldn't believe t…
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Hi John, Yes I had spotted that. The only issue I sometimes find is that if I wish to bring up a known TX site onto the map, and it happens to also be a VLF site. It sometimes tunes the KiWi to the VLF frequency if the site is included in the TDoA…
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I was just concerned in case it perhaps altered the filter group delay (or whatever the digital equivalent is) which may have altered the time delay at particular frequencies. Regards, Martin - G8JNJ
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Hi Jim, I think that model has got an internal SAW filter to define the 2m band, which would exclude the airband. What's really needed is a block down-convertor with approx 115-125MHz local oscillator (set the KiWi to tune 2-32MHz to avoid the LO …
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Hi Lonecrow, The only problem is where to obtain a suitable VHF to HF downconvertor to put ahead of the KiWi. I'm not aware of anyone making a suitable device, although it may be possible to modify a HF to VHF Upconvertor as used to provide shortw…
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And another CTA Portugal - TX site Nr. Lisbon 38.60, -9.03 (Image) https://www.google.co.uk/maps/@38.5989153,-9.021019,3a,15y,286.28h,90.56t/data=!3m6!1e1!3m4!1s30T7MUQl1R9FL3vw0NvYZw!2e0!7i13312!8i6656 Regards, Martin - G8JNJ
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"I should have done this long ago, but I finally figured out a simple way to implement CIC filter compensation by empirical measurement. The before and after pictures below show the result. No more 10 to 15 dB roll-off at the ends of a wide pas…
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"Except the top bar showing the wrong bands" There are a few other anomalies associated with the way the URL's and other references link to the actual KiWI tuned frequency rather than the displayed frequency, but most could probably be fi…
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Thanks John, That makes a huge difference to the speed and ease of use of the TDoA function. Much appreciated. Regards, Martin - G8JNJ
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Yes that works in 4 ch mode http://southwest.ddns.net:8077/?f=198.00amz8&wf=0
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Hmmm, it only seems to work with KiWi's that are in 8ch mode. Try my temporary airband KiWi which is in 8ch mode. http://g8jnj.proxy.kiwisdr.com:8073/?f=13602.40amz8&no_wf Regards, Martin - G8JNJ