-------- Original Message -------- From: coderman <coderman@gmail.com> To: wirelesswarrior@safe-mail.net Cc: falcon@ivan.harhan.org, cypherpunks@cpunks.org Subject: Re: Covert wireless (was: A crowdfunding campaign to build a free baseband) Date: Fri, 10 Apr 2015 16:11:15 -0700

On 4/10/15, wirelesswarrior@safe-mail.net <wirelesswarrior@safe-mail.net> wrote:

...

... I delivered a paper last October regarding the reasons such alternatives are needed, reviewed recent developments and offered some practical directions for future work (some of which I am pursuing):

http://www.paralelnipolis.cz/pp-congress-2014/WWPP.pdf

i didn't see mention of MIMO / beam forming systems for both better throughput and greater privacy.

I did not look closely at MIMO due to the lack of inexpensive SDR solutions and their lack of utility at lower bands.

and as common as HackRF is, there are better kits. why was this unit in particular chosen?

Mainly price and frequency coverage. Since my interest is mainly on apps that require transmitting I did not focus on receviers. Starting at twice the HackRF's cost the USRPs are a best buy at the low end. The HackRF's weakness main weakness is its 8-bit ADC and lack of pre-selector to limit strong out-of-band input signals and reduce out-of-band transmiter spurs. However, it has an internal header to which daughter boards can be added and its CPDL can be reprogrammed for these add-ons and other changes. On the receive side a cheap coax bandstop filter, with acceptable insertion loss, can easily be fabricated to knock down the FM broadcast and pager transmitter signals instead of a pre-selector. What other kits were you thinking of? WW

hard problems ahead!