G8JNJ

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 12 - GPIO_44 - Antenna 2
P8 pin 13 - GPIO_23 - Antenna 3
P8 pin 14 - GPIO_26 - Antenna 4
P8 pin 15 - GPIO_47 - Antenna 5
P8 pin 16 - GPIO_46 - Antenna 6
P8 pin 17 - GPIO_27 - Antenna 7
P8 pin 18 - GPIO_65 - Antenna 8 (not available in webui yet)
P8 pin 19 - GPIO_22 - Antenna 9 (not available in webui yet)
P8 pin 26 - GPIO_61 - Antenna 10 (not available in webui yet)

When you install the extension it will ask you which interface you wish to use.

Regards,

Martin - G8JNJ

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.

Here's a couple of filters I made using SMD parts. If you remove the 5.6R resistors and are using components with a good value of Q (L >40)
you can obtain >20dB notch depth.




This is the frequency response with the resistors fitted.



Regards,

Martin -G8JNJ

Hi John,

Great, thanks for considering the comments, I look forward to trying them out :-)

Regards,

Martin - G8JNJ

Hi Lonecrow

Try http://g8jnj.proxy.kiwisdr.com:8073/

It's a very quick and nasty lashup which is lying on the floor of my workshop so there is a lot more unwanted noise and hash than there should be.

VHF 144MHz band antenna, 100m of coax to workshop, 20dB low noise preamp, VHF BPF filter (6dB loss) , 10dB preamp, FM BC Band notch, 10dB preamp, Mini-Circuits Mixer, 115MHz LO injection from a signal generator, 40MHz LPF & into the KiWi.

I've edited a few DX labels with local airports, but I've not done anything fancy with removing or editing the HF Band markers etc.

Best performance is between about 120-130MHz as I had to quickly build a band pass filter to remove the FM Broadcast Band and it's not very good.

I'll leave it running for a few days until I need it for something else.

Have fun,

Martin - G8JNJ

Thanks John,

That makes a huge difference to the speed and ease of use of the TDoA function.

Much appreciated.

Regards,

Martin - G8JNJ

Hi John,

I was thinking about the possibility of using the KiWi with a down-convertor.

Some of the existing extensions are not that useful if the short wave bands are not being received or if the antenna isn't suitable for reception of stuff like Loran. Also the Development controls extension is always listed but hardly (if ever ) gets used.

Would it be possible to add an admin option to Enable / Disable individual Extensions and clear them from the drop down extension list ?

Regards,

Martin - G8JNJ

I had previously exchanged emails with Peter Martinez, G3PLX, on this subject, here are some more notes on the subject.

http://jcoppens.com/radio/prop/g3plx/index.en.php

I think it would be possible to use a KiWi to track the Ionosounders, the two sweeps (approx 5 seconds apart) from Cyprus are very strong in Europe and can be seen on most of the KiWi's in that continent.

There are several operating with known characteristics start time, start frequency, sweep rate etc. so writing a script to tune the KiWi ahead of the sweep and then recording the signal as it passes through the RX passband and time stamping it, then processing captured samples off-line to correct the frequency shift as the signal sweeps through the RX channel and 'stitch' the individually recorded samples back together may be possible. It may be that two or more RX channels would be required in order to ensure a frequency 'overlap' of recordings.

But I'm not a software guy either :-(

however I used to work with them, and they always told me that any problem 'could be fixed in the code' :-)

Regards,

Martin - G8JNJ

I have found that If you set the AGC threshold value to -80dB it sounds a lot nicer on the Airband :-)

And another site to add to the TDoA markers list



Regards,

Martin - G8JNJ

It's an option available to the KiWi Admin.

Users can't add or ammend entries but would usually welcome any information passed to them by using the email admin link in the yellow block linked stats page.

Regards,

Martin - G8JNJ