G8JNJ

@ Kovalr

Yes, some time ago I asked Kari if he could include the ability to map GPIO ports to specific antennas so that it would be easier to accommodate binary switching of banks of relays as you have done. Unfortunately he hasn't so far) been able to do this.

You have two (or maybe more) options. You could modify Kiri's code to switch more than one GPIO pin at a time when an antenna is selected, or alternatively use some diodes to provide simple logic to 'steer' switching signals from each GPIO output to drive one or more relays at a time or as otherwise required.

I use the second method, as I'm not really a software guy and diodes are cheap.

Regards,

Martin - 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

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