option to increase bandwidth from 12Khz to 20Khz [fixed in v1.250]

edited January 2019 in Problems Now Fixed
would it be too much to ask for implementation to increase the current bandwidth from 12Khz to 20Khz ?
there are many high fidelity AM/SSB stations that are utilizing transmitted audio of 10Khz or better and 10Khz is an acceptable minimum.
this would obviously be used with 4 RX channels and not 8 RX channels as i suspect hardware limitation would be reached.


  • seeing no way to edit my post above, i received an answer to my inquiry here:
  • jksjks
    edited December 2018
    If you mouse-over the header line of your comment (the one with your user name) a little gear icon should pop-up on the right margin that has an "edit" menu entry. Editing is currently enabled for 24 hours after initial posting. Edit: maybe that doesn't work for the initial post of a new topic? I'm not sure because I think my admin view is slightly different from what you see.
  • yes - more than 24 hrs has passed since my initial post so the gear icon no longer appears, only a "star" bookmark icon appears.
  • I am also a fan of 20000HZ AM Bandwidth. Not only is it desirable for listening on some AM stations, but as a part time AM contract engineer, having 10khz audio output would allow Kiwi to be a viable AM air monitor option for AM stations. Even if it is necessary to perhaps eliminate a waterfall or even combine two receiver streams to provide one 20Khz stream (as long as this were a selectable menu item), that would provide the feature. The 6khz audio is already better than almost all AM radios and I appreciate that greatly. Any added bandwidth would be icing on the cake and we humans do love our icing :) Worth mentioning that AM in the USA often went out to 15khz as recently as 25-30 years ago. There was not upper limit...some stations made it to 20KHZ !
  • 20 KHz is available now if the Kiwi owner sets it up for that. I have my public one that way
  • edited January 2019
    Thanks ! I found it and added the feature to my public rx at . WJCP 1460 fully embraces the 10khz audio and plays music so it demo's the bandwidth well during the day.
  • jksjks
    edited January 2019
    Assuming your Kiwi is running a recent software version: Bring up the admin page, select the second tab labeled "Mode", click on the third menu item labeled "More bandwidth" and then click on the "KiwiSDR server restart" button when it appears.

    When your Kiwi come back up, in 45 seconds or so, it should be configured for 3 channels at 20.25 kHz of receiver bandwidth each. If your Kiwi is listed publicly on sdr.hu it will now display the "20 kHz" tag on the last line of the listing.
  • Thanks John...it sounds fantastic. I really appreciate you adding this option.
  • John, how about either having the AM setting default to 10khz or providing an option for the admin to select a default bandwidth ?
  • I assume you mean 20 kHz. The default b/w for the "AM" mode button is 10 kHz now (+/- 5 kHz either side of carrier) and 5 kHz for "AMN" (+/- 2.5 kHz). There has been a suggestion that rather than adding a third button (e.g. "AMW", for which there is no room) a single AM button toggle between 3 or 4 b/w choices (20, 15, 10, 5 kHz?).

    Adding an initial b/w field to the admin "config" tab to go along with the initial mode selection is certainly possible.
  • Yes, 20khz. What my goal would be is for it to be intuitive for the user so I can avoid having to explain that Shift + P is required each time I invite someone to use the feature. I like the idea of a 20/15/10/5 toggle as long as there is a way to identify it, such as Bandwidth Select. It may even be possible to consolidate the AM and AMN buttons into one if I am thinking clearly. That or the admin setup button (or both) would serve the purpose.
  • the single button toggle between bandwidth modes is a good idea.
    with each toggle, the button display changes:
    AM ~ 10Khz BW (default)
    AMN ~ 5Khz BW
    AMW ~ 20Khz BW
    but new users need to know this somehow.
    the now extra button (AMN) could perhaps be reassigned as DSB @ 10Khz BW or in the future, SAM.
  • I just updated the documentation to describe it (http://kiwisdr.com/quickstart/index.html#id-freq-entry), but a relatively new feature is the ability to just type "/20k" to set a 20 kHz b/w. This is done in the frequency box which normally has the current frequency already selected in blue so that as soon as you type the "/" it begins replacing the text (i.e. you don't have to first select the field).
  • jksjks
    edited January 2019
    SAM really needs to get implemented. Twente WebSDR has that.
  • As elitedata noted, the single button toggle idea is a good one and is growing on me but I would push for 15 as well as 20/10/5 with my reasoning being that in many cases, adjacent carriers will place a 9 or 10khz hetrodyne in the passband...not an issue on strong local signals but on weaker signals, 7.5khz audio maintains much of the Hi Fi sound while placing the hetro outside of the passband. A part of me would suggest 15 as the default however I do not feel strongly about that. Amen on the SAM....that extra button is calling it's name ! Thanks for being so responsive to suggestions....makes me feel quite good about investing $600 in a pair of them.
  • I understand this is an old thread, but has there been any consideration given to another FPGA configuration option that includes a single channel that maximises the available bandwidth e.g. 40kHz?
  • No. This is not a priority and you would likely run into other problems.

    Christoph has a way to merge multiple channels using kiwirecorder and GNURadio: https://hcab14.blogspot.com/2019/03/kiwisdr-iq-data-streams-with-2025-khz.html
  • Aha - that is a fairly clever approach, thanks.
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